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Diet shifts of Caribbean grunts (Haemulidae) and snappers (Lutjanidae) and the relation with nursery-to-coral reef migrations
Abstract
The spatial size distribution of grunts and snappers have previously indicated the separation of juveniles in nursery habitats from the adults on the coral reef. This implies life cycle migrations from nursery habitats (such as seagrass beds and mangroves) to the coral reef. If diet shifts are related to such migrations, then the diets of these fish must change before or around the fish size at which such migrations take place. A wide size range of juveniles of two grunt species (Haemulon sciurus and Haemulon flavolineatum) and of two snapper species (Lutjanus apodus and Ocyurus chrysurus) were caught in seagrass beds and mangroves, and their gut contents identified and quantified. Regression analysis between fish size and dietary importance of small crustaceans showed a negative relationship in all four species. Positive relations were found for H. sciurus, L. apodus and O. chrysurus between fish length and the dietary importance of decapods, and for L. apodusand O. chrysurus between fish length and prey fish importance. Critical changes in the fish diets with fish size were examined by application of a Canonical Correspondence Analysis (CCA). The CCA yielded three clusters of size-classes of fishes with similar diets, and application of a Mantel test showed that each of these clusters had significantly different diets, and that each cluster diet was significantly specialised. The size at which a fish species ‘switched’ from one cluster to another was compared with size-at-maturity data and with the typical size at which these species migrate from the nursery habitats to the coral reef. H. sciurus and H. flavolineatum may be prompted to migrate from the nursery habitats to coral reef habitats because of dietary changes, or because of the development of the gonads. For L. apodus and O. chrysurus, a dietary changeover forms a more likely explanation for nursery-to-reef migrations than does sexual maturation because these species reach maturity at sizes much larger than the maximum size of individuals found in nursery habitats. Although other factors may theoretically initiate or promote the migration patterns, the results of this study indicate that ontogenetic dietary changes may crucially influence the nursery-to-coral reef migrations of these reef fish species.
... This variation of δ 13 C with size probably reflects an ontogenetic change in diet from pelagic carbon source dominated at larval stage to benthic carbon source dominated for adults. Such changes were observed for other reef species like Mullidae (Kolasinski et al. 2009), the red snapper Lutjanus campechanus , carnivorous reef fishes (Kulbicki et al. 2005) and for reef fishes in general (Cocheret De La Morinière et al. 2003). In particular, showed a change in diet with growth for L. campechanus, from low trophic level prey items in the water column (i.e. ...
... In addition, this is coherent with the general hypothesis that size and trophic position are positively correlated in marine ecosystems, that is larger consumers are able to eat larger prey that have a higher trophic position . Other studies also observed enrichment in δ 13 C and δ 15 N values with increasing size and age in different snapper species (Cocheret De La Morinière et al. 2003;. ...
... Habitat use and diet are known to vary with age and growth (e.g. Cocheret De La Morinière et al. 2003;). ...
Food security, that is guarantying food supply and quality while sustainably managing
resources, is closely linked to knowing the biology and ecology of consumed species.
In a context of global changes that are threatening seafood safety, it is thus necessary
to establish baselines on marine ecosystem functioning, as well as nutrient availability
and contamination occurrence in seafood. This is all the more important in Small Island
Developing States (SIDS), where populations rely on marine resources for their
subsistence, and where capture fisheries resources are the main sources of proteins
and micronutrients (i.e. essential trace elements) in local populations’ diet. In spite of
the importance of tropical systems in ensuring food security, they remain largely
understudied compared to polar and temperate systems.
This thesis thus aims to better understand the functioning of tropical marine systems,
and to establish a baseline on micronutrient availability and metal(loid) contamination
in a wide diversity of capture fisheries resources from the Seychelles (Western Indian
Ocean), a tropical SIDS. By investigating trace element concentration patterns at the
inter- and intraspecific levels, it was possible to identify intrinsic and extrinsic factors
influencing trace element bioaccumulation in tropical capture fisheries resources. We
thus highlighted the importance of considering different scales (individual, species, and ecosystem) to better understand essential trace element availability and nonessential trace element occurrence in seafood.
... This variation of δ 13 C with size probably reflects an ontogenetic change in diet from pelagic carbon source dominated at larval stage to benthic carbon source dominated for adults. Such changes were observed for other reef species like Mullidae (Kolasinski et al. 2009), the red snapper Lutjanus campechanus , carnivorous reef fishes (Kulbicki et al. 2005) and for reef fishes in general (Cocheret De La Morinière et al. 2003). In particular, showed a change in diet with growth for L. campechanus, from low trophic level prey items in the water column (i.e. ...
... In addition, this is coherent with the general hypothesis that size and trophic position are positively correlated in marine ecosystems, that is larger consumers are able to eat larger prey that have a higher trophic position . Other studies also observed enrichment in δ 13 C and δ 15 N values with increasing size and age in different snapper species (Cocheret De La Morinière et al. 2003;. ...
... Habitat use and diet are known to vary with age and growth (e.g. Cocheret De La Morinière et al. 2003;). ...
Food security, that is guarantying food supply and quality while sustainably managing resources, is closely linked to knowing the biology and ecology of consumed species. In a context of global changes that are threatening seafood safety, it is thus necessary to establish baselines on marine ecosystem functioning, as well as nutrient availability and contamination occurrence in seafood. This is all the more important in Small Island Developing States (SIDS), where populations rely on marine resources for their subsistence, and where capture fisheries resources are the main sources of proteins and micronutrients (i.e. essential trace elements) in local populations’ diet. In spite of the importance of tropical systems in ensuring food security, they remain largely understudied compared to polar and temperate systems. This thesis thus aims to better understand the functioning of tropical marine systems, and to establish a baseline on micronutrient availability and metal(loid) contamination in a wide diversity of capture fisheries resources from the Seychelles (Western Indian Ocean), a tropical SIDS. By investigating trace element concentration patterns at the inter- and intraspecific levels, it was possible to identify intrinsic and extrinsic factors influencing trace element bioaccumulation in tropical capture fisheries resources. We thus highlighted the importance of considering different scales (individual, species, and ecosystem) to better understand essential trace element availability and non-essential trace element occurrence in seafood.
... Yeager et al. (2012) showed that higher food availability associated with increase seagrass cover positively correlates with abundance of white grunts (Haemulon plumierii). Where sponges are present, fish communities include species typically associated with reefs, such as grunts, damselfish (Pomacentridae spp.), and Nassau grouper (Epinephelus striatus; Cocheret de la Morinière et al. 2003;Nagelkerken et al. 2008). These live sponge plot-associated taxa all rely, at least in part, on invertebrate prey. ...
... These live sponge plot-associated taxa all rely, at least in part, on invertebrate prey. Juvenile grunts use seagrass as nursery habitat (Arrivillaga and Baltz 1999;Cocheret de la Morinière et al. 2003;Yeager et al. 2012), and they and beaugregory damselfish (Stegastes leucostictus, observed in sponge plots) rely on invertebrates as a food source (Cervigon 1966). Nassau groupers associate with structure and younger individuals use seagrass beds to feed on crustaceans (Eggleston et al. 1998). ...
Ecosystem engineers (e.g., seagrasses) have profound effects on biodiversity and community structure. Sponges possess traits (e.g., providing structure) that suggest they may act as ecosystem engineers, but we know little about their relationships with the animal communities that inhabit seagrass beds. This study explored the effects of the marine sponge, Ircinia felix, on fish and invertebrate taxa richness, abundance, turnover, and community composition in a seagrass bed through a 1-year field experiment performed in The Bahamas. We recorded the fish and invertebrate communities present in 5 × 5 m plots with the addition of either a live sponge, a polypropylene sponge replica (structure), or no additional structure (control). Both taxonomic groups responded to the addition of a live sponge. Taxa richness and abundance increased at least fourfold over a year in the presence of I. felix, but decreased twofold or more in the other plot types. Live sponge presence increased the number of new taxa gained by at least 24%, and reduced the number of taxa lost compared to other plot types. Finally, we found that the fish community composition shifted in a more consistent direction in the presence of a live sponge than in the other plots. Our study shows that sponges can act as ecosystem engineers in subtropical seagrass systems and additional research is needed to determine the full extent and implications of their ecological effects.
... In nature, the role of diet as a major factor initiating the shift toward adult habitat (Cocheret et al. 2003) is unclear, particularly since the feeding habits of many lutjanid fish can change between life history stages and between size classes. For example, Szedlmayer and Lee (2003) found that juvenile Lutjanus campechanus from 1.8 to 28 cm (SL) in the northeast Gulf of Mexico changed diets with increasing size. ...
... Data were expressed as percentage by number (%N), percentage by frequency of occurrence (%O), and percentage by volume (%V), as proposed by Hyslop (1980). A volumetric measure was chosen to provide an estimation of biomass to reduce potential errors (Cocheret et al. 2003). Contribution of each prey item to fish diets was estimated according to the Index of Relative Importance (IRI) (Pinkas et al. 1971, Cortés 1997. ...
The habitat and dietary requirements necessary to ensure optimal survivorship and growth of settled juveniles L. argentimaculatus are poorly-known. This study examined ontogenetic diet shift in juvenile mangrove red snapper in coastal areas of central Vietnam. Juvenile fish of various size classes were captured in two widely-separated coastal locations, and their stomach contents analysed. Subsequently, the importance of providing natural prey for cultured juvenile fish was investigated. Strong differences were found between the diets of fish at different ontogenic stages, and smaller differences appeared to reflect feeding habits during different tidal cycles. In nature, the smallest juveniles fed almost exclusively on mysid shrimps and lesser amount of copepods and luciferid shrimps, while larger juveniles fed predominantly on sergestid shrimps in addition to grapsid crabs and terapontid fishes. Feeding intensity appeared to be maximal on the incoming tide for all size classes. Inclusion of the dominant prey found in wild fishes' stomachs (Acetes and Mysidae) in juvenile culture of L. argentimaculatus improved growth and survival of juvenile fish during culture. Mysid and sergestid shrimps comprise an important part of juvenile diet for all size classes, and the addition of such live food in juvenile culture is likely to create productivity gain for the industry.
... Although there were no significant differences in day versus night comparisons, perhaps due to limited sampling and time of year, communities collected in the few night catches in our sandflat site closely resembled those found in the mangrove site (Fig. 2). Previous research conducted in native mangroves indicates distinct diel trends in the utilization of the mangrove habitat by fishes (Thayer et al. 1987, Rooker and Dennis 1991, Nagelkerken et al. 2000b, Cocheret de la Moriniere et al. 2003, where species present in mangroves during the day may be reduced in number or absent at night (Rooker and Dennis 1991). Additional day-night sampling across seasons, as well as the incorporation of acoustic telemetry and chemical tags (e.g., stable isotopes), would improve estimates of diel patterns of Hawaiian mangrove habitat utilization and megafaunal movement (e.g., Huijbers et al. 2015). ...
... While it was not feasible to consistently resolve juveniles (i.e., reproductively immature individuals) in the many different species examined, smaller-sized individuals for several species were more prevalent in mangrove than sandflat study sites, and we can infer that some of these individuals were juveniles. The functional role of mangroves as important juvenile habitat in other parts of the world has been well established, where they support higher abundances of smaller size classes than adjacent sandflats (e.g., Laegdsgaard and Johnson 2001, Cocheret de la Moriniere et al. 2003, Sheridan and Hays 2003, Dorenbosch et al. 2004, MacKenzie and Cormier 2012. Some of these studies also demonstrated that mangroves can provide habitat for pre-reproductive juveniles, supporting the nursery hypothesis (Thayer et al. 1987, Nagelkerken andvan der Velde 2002). ...
... Numerous species, including many commercially important fish, migrate offshore later when the mangrove or seagrass roots can no longer provide sufficient shelter for their size (Nagelkerken et al., 2000;zu Ermgassen et al., 2020). Change in diet may also be responsible for ontogenetic habitat shifts from mangroves and seagrasses to coral reefs (Cocheret de la Morinière et al., 2003). ...
... On the other hand, fish such as seabream and gray snapper avoid the "risky" mangrove-seagrass zone to avoid predators, although the highest food abundance is within this zone (Hammerschlag et al., 2010). Thus, the foraging behavior of prey fish is species specific, and likely depends on factors such as predator avoidance, structural complexity, and shade (Cocheret de la Morinière et al., 2003). The tradeoff between food and shelter is evident in the "halo" effect, where patch reefs adjacent to seagrass beds are bordered by a diameter of cropped seagrass cover (Hay, 1984). ...
Mangroves, seagrasses, and coral reefs interact in tropical regions throughout the world. These ecosystems exhibit strong synergies, as the health of each ecosystem supports the functioning of adjacent habitats. We present a global spatial analysis of mangrove, seagrass, and reef communities, identifying regions where these habitats co-occur. While only an estimated 18% of interaction zones are covered by protected areas, boundaries between mangroves, seagrasses, and reefs represent areas of high conservation efficiency, where benefits of conservation amplify synergistically as land-sea ecosystems are jointly managed. We discuss four types of conservation efficiencies in these coastal ecosystems: 1) increased resistance to disturbance through inter-ecosystem feedbacks, 2) high biodiversity within small geographic areas, 3) habitat portfolio effects giving rise to climate refugia, and 4) synergistic ecosystem services, where building one ecosystem service inherently increases others. Given these synergistic benefits, global campaigns to expand marine and terrestrial protection should focus on the tightly connective interface between mangroves, seagrasses, and reefs, in order to more efficiently build resilience within and between these habitats.
... A 24-h active tracking period likely did not encapsulate day-to-day variations [32], therefore, the stark differences between daytime and nighttime activity spaces may become less detectable with the lower spatial resolution and added daily variance present in this study. Alternatively, while L. analis and L. apodus are closely related, these species may exhibit behavioral variation due to differential predation risk and use of different habitat types to meet dietary needs [64]. Diet studies have suggested that unlike other species of snapper, L. analis forage opportunistically throughout the day [25,26], with some feeding proportionately more in morning and evening than midday [22], which would explain the habitat similarity between daytime and nighttime activity spaces. ...
... Seagrass beds, which are an important food source for snapper and other reef fish, can change quickly in size and coverage with shifting environmental conditions or disturbances [66], and while the effects of natural disasters such as hurricanes cannot be prevented, disturbances from human activity could be limited by prohibiting specific practices, such as anchoring in known seagrass beds and along reef edges. As habitat variability in an area is an important component of its suitability for many species, spatial management efforts should focus on zones with proximity to multiple habitat types [67], including mangroves and seagrasses as well as nearshore and offshore coral reefs, which support coral reef fish across diel movements and ontogenetic stages [23,61,64]. ...
Background
The movement ecology of mutton snapper Lutjanus analis is poorly understood despite their ecological and economic importance in the Caribbean. Passive acoustic telemetry was used to determine home ranges of six adult L. analis , including diel patterns, in Brewers Bay, St. Thomas, US Virgin Islands. Understanding long-term space use, including site fidelity and habitat usage, is necessary to implement effective and appropriate management actions for a species with extensive space and resource needs.
Results
Individual L. analis were tracked over an average period of 316 days (range 125–509 days) and showed high site fidelity to relatively small home ranges (mean ± SD: 0.103 ± 0.028 km ² , range 0.019–0.190 km ² ) and core use areas with low overlap among individuals. Most home ranges had a habitat composition dominated by seagrass and to a lesser degree, coral reef and/or pavement. Nighttime activity spaces were distinct from but contained within daytime areas.
Conclusions
Mutton snapper showed strong site fidelity to home ranges in Brewers Bay. Two individuals that were absent from the array for more than a few hours were detected at separate arrays at spawning aggregation sites. This study expands upon knowledge of mutton snapper home range characteristics, highlights the importance of maintaining adjacent high-quality habitat types in any spatial management plan, and encourages the adoption of other types of management strategies, particularly for transient-aggregating species.
... The 24 h tracking period likely did not encapsulate day-to-day variations [33], therefore, the stark differences between daytime and nighttime activity spaces may become less detectable with the lower spatial resolution and added daily variance present in this study. Alternatively, while L. analis and L. apodus are closely related, these species may exhibit behavioral variation due to differential predation risk and use of different habitat types to meet dietary needs [65]. Diet studies have suggested that unlike other species of snapper, L. analis forage opportunistically throughout the day [26,27], which would explain the habitat similarity between daytime and nighttime activity spaces. ...
... Seagrass beds, which are an important food source for snapper and other reef sh, can change quickly in size and coverage with shifting environmental conditions or disturbances [66], and while the effects of natural disasters such as hurricanes cannot be prevented, disturbances from human activity could be limited by prohibiting speci c practices, such as anchoring in known seagrass beds and along reef edges. As habitat variability in an area is an important component of its suitability for many species, spatial management efforts should focus on zones with proximity to multiple habitat types [67], including mangroves and seagrasses as well as nearshore and offshore coral reefs, which support coral reef sh across diel movements and ontogenetic stages [24,63,65]. ...
Background: The movement ecology of mutton snapper Lutjanus analis is poorly understood despite their ecological and economic importance in the Caribbean. Passive acoustic telemetry was used to determine home ranges of six adult L. analis, including diel patterns, in Brewers Bay, St. Thomas, US Virgin Islands. Understanding long-term space use, including site fidelity and habitat usage, is necessary to implement effective and appropriate management actions for a species with extensive space and resource needs.
Results: Individual L. analis were tracked over an average period of 316 days (range 125 - 509 days) and showed high site fidelity to relatively small home ranges (mean ± SD: 0.103 ± 0.028 km², range 0.019 - 0.190 km²) and core use areas with low overlap among individuals. Most home ranges had a habitat composition dominated by seagrass and to a lesser degree, coral reef and/or pavement. Nighttime activity spaces were distinct from but contained within daytime areas.
Conclusions: Mutton snapper showed strong site fidelity to home ranges in Brewers Bay. Two individuals that were absent from the array for more than a few hours were detected at separate arrays at spawning aggregation sites. This study expands upon knowledge of mutton snapper home range characteristics, highlights the importance of maintaining adjacent high-quality habitat types in any spatial management plan, and encourages the adoption of other types of management strategies, particularly for transient-aggregating species.
... Stable isotope analysis allows quick insight into trophic niche sizes and overlap and into overlap in dietary items of sympatric species. One sampling campaign of the food web of co-occurring native and alien species is already sufficient to identify their trophic position, ontogenetic differences in diet, feeding migrations, main food sources, and niche overlap (Cocheret de la Morinière et al. 2003;Paalvast and Van der Velde 2013;Como et al. 2018;Chapter 4). This is advantageous compared to quantifying adverse effects by correlative studies that take years to determine the population trends. ...
Introductions of organisms outside their natural range are increasingly taking place due to the increasing globalisation of human activities. The establishment of invasive alien species can have far-reaching adverse ecological and socio-economic consequences with high societal costs (Chapter 1). Not every introduced (alien) species is invasive. This thesis comprises five studies that analyse the risks of recently introduced alien species in Dutch freshwater ecosystems. Based on these studies, appropriate management measures for high-risk species can be applied.
Ecological impact studies of alien species require sound information on the reference situation of ecosystems. Monitoring in the period 2005-2015 showed a population increase of the native Rhine sculpin (Cottus rhenanus) in the River Geul catchment, coinciding with a water quality improvement (Chapter 2). The recent emergence of the invasive round goby (Neogobius melanostomus) poses a threat to the sustainable conservation of Rhine sculpin populations. Dispersal barriers (weirs) can prevent or delay the upstream spread of round gobies.
The abundance of the invasive topmouth gudgeon (Pseudorasbora parva), an asymptomatic carrier of the parasite Sphaerothecum destruens, correlates negatively with that of sunbleak (Leucaspius delineatus), ninespine stickleback (Pungitius pungitius) and three fish biodiversity indices (Chapter 3). The ongoing invasion of the topmouth gudgeon and its parasite poses a threat to native fish communities.
Using stable isotopes (nitrogen, carbon), the dietary overlap between two alien (Asian weather loach Misgurnus bipartitus, western tubenose goby Proterorhinus semilunaris) and three native (stone loach Barbatula barbatula, spined loach Cobitis taenia, gudgeon Gobio gobio) benthic fish species was investigated (Chapter 4). The invaders show a high plasticity of their resource use, indicating niche differentiation and coexistence with the native species.
Risk assessments of nine alien crayfish species show that all North American species pose a high risk of adverse impacts to biodiversity, water security and ecological status of water bodies due to their burrowing and feeding behaviour (Chapter 5). Eradication of crayfish populations is unfeasible. Feasible strategies for population control or the mitigation of adverse impacts combine measures that increase ecosystem robustness and resilience with crayfish trapping by professional fishermen, water authorities and trained volunteers.
The invasive crayfish species with the highest risk score concerns the red swamp crayfish (Procambarus clarkii). The number of burrows of this species was significantly less in natural banks compared to non-natural and semi-natural banks (Chapter 6). The construction of more natural banks may significantly reduce adverse impacts caused by burrowing activities. An inclination experiment mimicking terrestrial dispersal barriers showed that overland movement reduces at inclinations from 20°, and on sand and grass substrates. Sophisticated design of embankments along watercourses can help reduce colonisation of nearby water bodies with high nature values.
... con ambientes arrecifales (Coheret de la Moriniére et al., 2003). Sin embargo, según Sylvester y Dammann (1973), se ha encontrado una relación de estos lutjanidos con los fondos blandos y semiblandos en su etapa adulta. ...
... This study aimed to answer the following questions: (i) because some snapper species rely on estuarine environments as nursery grounds (e.g., Aschenbrenner et al., 2016;Menezes et al., 2021;Cocheret de la Morinière et al., 2003;Sales et al., 2018;Sheaves, 1995), is the Abrolhos Bank a settlement area for species of the genus Lutjanus?; (ii) if so, what is the larval duration of these species?; and (iii) are there interspecific differences in growth, age, and settlement date? Therefore, this work aimed to document the larvae's daily age, growth rate, and PLD of L. analis, L. jocu, and L. synagris in Abrolhos Bank, southern Bahia, Brazil. ...
The age and daily growth of fish are registered through the deposition of increments in their otoliths, which are concretions formed by the precipitation of substances present in the endolymphatic fluid, mainly calcium carbonate (CaCO3). Faced with the need to fill some of the gaps in the knowledge on the occurrence and duration of the initial stages of snapper species' life cycles in the Abrolhos Bank, this study aimed to describe the growth rates, age, and period of pelagic larval duration (PLD) of three snapper species during the larval pre‐settlement phase, in the Abrolhos Bank region. The post‐larvae were captured using light traps. Otoliths were removed from 117 samples of snapper species; however, only 69 were viable for age estimation, of which 15 were Lutjanus analis, 25 were Lutjanus jocu, and 29 were Lutjanus synagris. Together, the samples presented individuals with total lengths ranging from 16.14 to 24.76 mm and ages from 21 to 39 days. Settlement marks were found for all three species, and the average PLD was ~25 days. The somatic growth of the snapper species was positively correlated with otolith growth. L. jocu presented the greatest daily growth compared to the other species. The three species use the Abrolhos Bank as a larval settlement site, demonstrating plasticity by using different habitats throughout their lives.
... Takahashi et al. (2020) identified significant diet partitioning patterns between these lutjanid species during their cryptic juvenile stage. Given that habitat association and diet partitioning are typically exhibited between sympatric species (Cocheret de la Morinière et al., 2003;Szedlmayer & Lee, 2004;Takahashi et al., 2020), this infers that despite the cryptic appearance or phenotype of the juveniles, they occupy different microhabitats that are yet to be defined. To facilitate these assessments at a species level, there is a need to develop a robust, cost-effective identification tool to discriminate between the cryptic juveniles of L. erythropterus and L. malabaricus. ...
The sympatric red snappers, Lutjanus erythropterus and Lutjanus malabaricus, are highly valued by commercial and recreational fishers along the tropical northern coasts of Australia and throughout their distribution. Studies on the life history and ecology of these congeners are confounded by difficulties in distinguishing the cryptic juveniles of each species (i.e., < 200 mm total length). This study aimed to validate a robust and cost‐effective method to discriminate these juveniles using body and/or otolith morphometric data in a multivariate analysis. Juvenile samples were collected from the northwest (n = 71) and northeast (n = 19) coasts of Australia, and species identification was confirmed using DNA barcoding. The most parsimonious multivariate models achieved accurate species prediction rates of 98.8%, which consisted of just three body variables (dorsal fin length, the distance from the snout to the anterior edge of the eye, and either jaw length or distance from the snout to the preoperculum). The high level of discrimination for these cryptic juveniles highlights the robustness of this morphometric approach. The slightly lower rate of discrimination using otolith morphology (84.9%) was associated with greater regional variation in L. malabaricus between the northwest and northeast coasts. Slight variations in otolith shape are typically used to determine stock structure, which highlights the potential need to collect samples over a broader area of a species geographic range when using an otolith morphometric discrimination model. The method outlined in this study could be applied to distinguish other cryptic congeneric fish species, including from archived otolith collections. Moreover, this method has the potential to be utilized in assessing species compositions using body measurements from in situ stereo‐video.
... Many invertebrate and marine fish species possess complex life cycles that require the use of multiple habitats through ontogeny (Beck et al. 2001). For example, the use of inshore seagrass and submerged boulders as nursery habitats by juvenile fish (Gotceitas et al. 1997, Jackson et al. 2001, Auster et al. 2003, Lugendo 2007) and the use of deeper or offshore areas as adults (Cocheret de la Morinière et al. 2003) is well documented. ...
Sea cage aquaculture can alter the spatial distribution of wild fish populations; however, little is known about the dietary habits and subsequent effects on wild fish. In this thesis, I used stable isotopes δ 13 C and δ 15 N values and proportions of vegetable oil-based fatty acids (VOFAs) to investigate the dietary habits of wild cage-associated Atlantic cod Gadus morhua and Atlantic redfish Sebastes fasciatus. Furthermore, I compared the length, weight and condition of cage-associated G. morhua ages 2-4 years old to reference sites within the local division and outside divisions removed from aquaculture, and used VOFAs as biomarkers for waste feed consumption to identify any role(s) in explaining differences in length, weight and condition among age classes. Juvenile G. morhua captured around sea cages had depleted δ 13 C and δ 15 N values and elevated proportions of VOFAs consistent with waste feed consumption and sea cage residency, whereas differences in δ 13 C, δ 15 N, and VOFAs in cage-associated adult G. morhua and S. fasciatus were predominately absent. Interestingly, waste feed consumption by age 2 cage-associated G. morhua resulted in lower condition than age 2 G. morhua from the local reference division; however, age 4 cage-associated G. morhua were longer and heavier than the local reference division, despite no evidence to support direct or indirect waste-feed consumption. Overall, the results of this thesis suggest that δ 13 C, δ 15 N and VOFAs are suitable biomarkers for tracing sea cage residency and dietary habits of cage-associated wild fish, but waste feed consumption patterns and subsequent effects on wild fish were paradoxical and dependent on species and life stage.
... As discussed above, depending on the study, the diet of adults may vary between autochthonous and allochthonous resources, often including both, but usually composed of terrestrial insects, with which our results agree. In many fish species, the prey size usually increases with fish size (Morinière et al., 2003;Sánchez-Hernández & Cobo, 2012), and different size classes typically consume different prey types as a result of, for example, differences in foraging abilities or habitat use (Mittelbach & Persson, 1998;Nunn et al., 2012). Fish undergo ontogenetic dietary shifts during their development (Blanco-Garrido et al., 2003;Fochetti et al., 2008). ...
Aim In the present work we describe and analyze the diet of a small characin species, Piabarchus stramineus, from the Ibicuí River, Uruguay River Basin, southern Brazil. Methods Samples were collected monthly from April 2001 to March 2002 with seine net. All fish were measured, weighed, and had its stomach extruded for gut content analysis. Months were grouped in seasons and fish were classified within three standard length classes (SLC). We tested for possible alimentary differences between the different seasons of the year and standard length classes. Results The analysis of the content in 301 stomachs identified 27 food items and low to intermediary niche breadth. The main food item/category was allochthonous insects, regardless of the seasons, and P. stramineus can be classified as an insectivorous species. We observed no food overlap between smaller and larger fish (SLC1 and SLC3). On the other hand, we observed food overlap between small and intermediary fish (SLC1 and SLC2) and between intermediary and large fish (SLC2 and SLC3), evidencing a transition in food consumption along size classes. A temporal variation in diet composition was also observed among size classes. Thus, different sized fish differed in their diets, with smaller fish feeding mainly on cladocerans (SLC1 and SLC2) and larger fish (SLC3) feeding mainly on allochthonous Diptera and Hymenoptera. Conclusions The species diet varies in time (seasons) and such variation is different in each size class. Allochthonous food items were important in the diet of the species in the different developmental phases, especially for larger fish, with autochthonous items also important, especially for smaller fish. The allochthonous food items are strongly related to the ciliary forest; thus, we emphasize the importance of the conservation of such environments.
... Decapods are important keystone organisms that influence the structure of benthic habitat (Boudreau and Worm, 2012). They are also important food species and constitute the diet of many higher organisms such as pelagic and demersal fish, rays, sharks, reptiles, aquatic mammals and birds (Cocheret de la Morinière et al., 2003;Fanelli et al., 2009;Jaworski and Ragnarsson, 2006;Labansen et al., 2007;Mehlum and Gabrielsen, 1993;Quadros and Monteiro-Filho, 2001;Šantić et al., 2012;Wallace and Leslie, 2008). The transfer of microplastics to higher trophic levels via Decapods is highly possible and can be a threat to these higher organisms. ...
The presence of microplastics in the aquatic environment poses a serious threat not only to aquatic organisms but also to human beings that consume them. The uptake and effects of microplastics have been studied in almost all groups of aquatic organisms. This review details the different aspects of microplastics exposure in an ecologically and economically important group of crustaceans, the Decapods. A majority of Decapod crustaceans such as prawns, shrimp, crabs, lobsters and crayfish are consumed as seafood and play important roles in food chains and food webs. Numerous studies are available on the accumulation of microplastics in tissues such as the gills, hepatopancreas and gastrointestinal tract in these organisms. Experimental studies have also highlighted the toxic effects of microplastics such as oxidative stress, immunotoxicity and reproductive and developmental toxicity in them. This review also summarizes the ecological impacts and implications in human beings as well as lacunae with regard to microplastic uptake in Decapods.
... During ontogeny, juvenile grunts undergo a series of migrations between habitats (and associated resting schools) [2,5,6,11,12]. These migrations are associated with changes in diet and behavior [2,10,13,14] and appear to be strongly correlated with fish length [10,15]. There are six eco-behavioral stages of development reported for Haemulon flavolineatum and H. plumierii [2,16]. ...
Many coral reef fishes undergo ontogenetic migrations from inshore nurseries to offshore reefs. Quantifying cross-habitat connectivity is important for understanding reef fish spatio-temporal dynamics, essential habitat and spatial planning. Past studies show connectivity is mediated by distance and habitat arrangement. Few studies have documented the pathways linking juveniles and adults, nor suggested underlying orientation/navigation processes important for a more generalized understanding of ontogenetic habitat use. Ontogenetic movements of juvenile grunts, primarily Haemulon flavolineatum, in Puerto Rico were studied using mark-recapture. Small juveniles were tagged at a back-reef site designed to determine their potential movement through a series of size-specific daytime resting schools and posing a choice of direction in migration. Larger juveniles were tagged at mid-shelf reefs to capture off-reef migration to adult locations, including a proposed marine reserve. Small juveniles moved toward more exposed areas, accomplished by progressively shifting locations through existing resting schools. Movement was size-related and alongshore, but direction was primarily parallel to the coast, leading fish away from adjacent areas more directly offshore. Direction may have resulted from the potential mechanism of fish transfer between resting schools rather than by orientation cues. Larger juveniles were tracked from back-reef to fore-reef sites, but no fish were recaptured off-reef. Slower growth than predicted may have contributed to the perceived lack of movement. Localized behavior and habitat distribution appear important in determining the initial pathways of ontogenetic migration, and these may fix later directional movements to unexpected areas.
... Sergeant major fish forage in the water column and near the rocks and therefore do not generally stray far from their associated structure (Davis & Birdsong, 1973;Alves et al., 2016). As fish migrate from one habitat to the next with ontogeny, their food habits also change (Cocheret de la Moriniere, Pollux, Nagelkerken, & van der Velde, 2003). Migration typically occurs when adults, juveniles, or larvae seek out nursery or reproduction areas. ...
Many fish species use intercoastal jetties throughout their life cycle to migrate to and from the ocean into bays and estuaries. During migration, fish may encounter rock, algae, sand, sea-grass, and coral. Anecdotal information indicates that some migrating fish of intercoastal jetties preferentially select colonies of gorgonian coral (Leptogorgia spp.) vs. any other habitat when encountering a predator. Since very little information exists regarding Leptogorgia, we focused our study in determining the importance of such coral as fish habitat. Stationary field sampling was conducted seasonally to determine the abundance of these coral, the type of migrating fish, and the habitat they associated with. Mesocosm studies were then conducted to determine whether Leptogorgia habitats are important to fish in the presence or absence of a predator. Five different habitats were compared (rock, algae, sand, Leptogorgia, and seagrass) and 6 species of fish (sergeant major, pinfish, mangrove snapper, spotfin mojarra, pigfish, and red drum). In the field study component, more than 600 colonies of Leptogorgia were observed and 17 different fish species. The most commonly observed fish were sergeant major, pinfish, mangrove snapper, and spotfin mojarra, however, sergeant majors were the most abundant species using coral as habitat. The use of mesocosms showed that all fish species significantly selected for structured habitat over non-structured habitat (e.g. sand), but that the fish commonly called ‘sergeant major’ significantly (ANOVA; p ≤ 0.001) selected for Leptogorgia.
... Although it is clear that their ontogenetic migrations play an important role in maintaining seascape-wide ecological connectivity, there remains a paucity of information on habitat suitability across the seascape for L. griseus and H. sciurus. Additionally, there may be considerable inter-species variation in habitat suitability, and consequently, functional connectivity, stemming from unique preferences for nearshore strata [51,52], tolerances to salinity fluctuation [53], and motivations for movement [54,55]. Addressing these knowledge gaps is of critical importance as L. griseus and H. sciurus play key ecological and economic roles in the region as abundant members of the fish assemblage, highly mobile predators and vectors of nutrient transfer, and valued sport and commercial fishery targets [56,57]. ...
Coastal habitats have experienced significant degradation and fragmentation in recent decades under the strain of interacting ecosystem stressors. To maintain biodiversity and ecosystem functioning, coastal managers and restoration practitioners face the urgent tasks of identifying priority areas for protection and developing innovative, scalable approaches to habitat restoration. Facilitating these efforts are models of seascape connectivity, which represent ecological linkages across heterogeneous marine environments by predicting species-specific dispersal between suitable habitat patches. However, defining the suitable habitat patches and migratory pathways required to construct ecologically realistic connectivity models remains challenging. Focusing on two reef-associated fish species of the Florida Keys, United States of America (USA), we compared two methods for constructing species- and life stage-specific spatial models of habitat suitability—penalized logistic regression and maximum entropy (MaxEnt). The goal of the model comparison was to identify the modeling algorithm that produced the most realistic and detailed products for use in subsequent connectivity assessments. Regardless of species, MaxEnt’s ability to distinguish between suitable and unsuitable locations exceeded that of the penalized regressions. Furthermore, MaxEnt’s habitat suitability predictions more closely aligned with the known ecology of the study species, revealing the environmental conditions and spatial patterns that best support each species across the seascape, with implications for predicting connectivity pathways and the distribution of key ecological processes. Our research demonstrates MaxEnt’s promise as a scalable, species-specific, and spatially explicit tool for informing models of seascape connectivity and guiding coastal conservation efforts.
... This has resulted in a piecemeal understanding of their habitat utilization patterns over longer timescales and multiple habitats. For example, by focusing on single habitats and seasons in reef systems, whether juveniles use the same habitats as adults or if, like many reef fish, they undergo an ontogenetic shift in ecosystem location or role, is unknown (Cocheret de la Morinière et al. 2003;Aburto-Oropeza et al. 2009;Luo et al. 2009;Huijbers et al. 2015). ...
Surprisingly, little is known about basic life history of the largest moray eel species in the Caribbean region, the green moray eel (Gymnothorax funebris). Sixteen eels were captured from the mangrove fringe in multiple bays on St. Croix, USVI, implanted with coded acoustic transmitters, and their movements were tracked for up to 11 months using an array of 37 stationary acoustic receivers. They exhibited high site fidelity in the bays during their residence, using the same general parts of individual bays and did not switch bays except for one individual. There was no relationship between eel size (mean TL = 83 cm, range = 54–126 cm) and home range size (mean area of 95% KUD = 5.8 ha ± 0.7 SE). Most individuals were more frequently detected at night than during the day suggesting greater nocturnal activity. Several of the larger eels (mean TL = 93 cm ± 5.9 SE) showed clear and permanent emigration tracks out of the mangrove estuary to coral reef habitats offshore. For some individuals, these habitat shifts were preceded by exploratory movements away from the eel’s typical home range the night before emigration. All final emigration events took place nocturnally, happened during a single night, and occurred during months from December to May. Mean emigration speed was 3.4 km/h. This study is the first documentation of an ontogenetic habitat shift in moray eels, as well as the first determination of home range size for this species and their site fidelity in mangrove habitats.
... Many invertebrate and marine fish species possess complex life cycles that require the use of multiple habitats through ontogeny (Beck et al. 2001). For example, the use of inshore seagrass and submerged boulders as nursery habitats by juvenile fish (Gotceitas et al. 1997, Jackson et al. 2001, Auster et al. 2003, Lugendo 2007 and the use of deeper or offshore areas as adults (Cocheret de la Morinière et al. 2003) is well documented. Ontogenetic habitat shifts occur to limit overlap of resource use (Werner & Gilliam 1984) or as a response to ontogeny limiting the efficacy of their surroundings for protection from predation (Nagelkerken et al. 2000), and often to satisfy ontogenetic shifts in diet (Link & Garrison 2002) that can be detected with stable isotope signatures (Rundel et al. 1989) deposited in fish muscle tissue (Pinnegar & Polunin 1999, MacNeil et al. 2005. ...
Sea cage aquaculture can alter the spatial distribution of wild fish populations, however little is known about the dietary habits of wild fish frequenting sea cages. We used wild juvenile cod (Gadus morhua) reared in the laboratory and fed either an aquafeed pellet or marine-based diet to determine trophic discrimination factors (TDFs) of stable carbon (𝛿13C) and nitrogen (𝛿15N) isotope values in white muscle tissue and baseline liver proportions of vegetable-oil based (VOB) fatty acids. We then used 𝛿13C and 𝛿15N and proportions of VOB fatty acids to investigate the dietary habits of wild cage-associated juvenile and adult Atlantic cod and adult Atlantic redfish (Sebastes fasciatus). Cod and redfish were collected in the immediate area of sea cages and reference areas of no aquaculture production. Juvenile cod captured around sea cages had both elevated 𝛿13C and 𝛿15N values and proportions of VOB fatty acids, and isotopic fractionation comparable to laboratory cod fed an aquafeed diet. However, differences in 𝛿13C and 𝛿15N and proportions of VOB fatty acids between cage-associated and reference site adult cod and redfish were predominately absent. Results suggest that sea cages may provide an energetic subsidy to juvenile cod but perhaps not at the level to sustain adult cod or redfish. Therefore, the lack of differences suggests that both adult groups may be using cage sites opportunistically and only for short duration, as isotopic values and fatty acid proportions were not consistent with waste feed consumption despite individuals being collected in close proximity to sea cages.
... With maturation, most species are relatively generalized feeders on motile or sessile invertebrates, often from either softbottom or hardbottom environments (Randall 1967;Sierra et al. 2001). Cocheret de la Morinière et al. (2003) found that two species of invertebrate-feeding grunts shifted from vegetated to reef habitats due to dietary shifts or maturation. ...
Based on new and prior information, 266 species of fishes from 72 families are now recorded from nearshore reef habitats of east Florida. The most species rich families include wrasses and parrotfishes (26), jacks (17), grunts (14), gobies (12), scaly blennies (11), sea basses (10), damselfishes (9), snappers (7) and combtooth blennies (7). We estimate over 30 fish species spawn on or adjacent to nearshore hardbottom reefs. Several different families, including the site-attached blennies and damselfishes, build nests on hardbottom microhabitats. Many species are primarily represented by early life stages. The most prevalent trophic category among species is generalized invertivory followed by planktivory and piscivory. Composition of ichthyofaunal assemblages can differ between the southern and northern areas of mainland east Florida. Potential explanations for differences in prominent species (sailors choice, black margate, hairy blenny) along the north-south gradient of east Florida’s mainland may include species-specific habitat preferences, temporal variation in recruitment, differences in reef structure, differences in sampling designs, species reaching biogeographic distributional limits, and other factors. Relative frequency of fishes in visual censuses reveals approximately 40 species that typify the assemblage; top ranked species are hairy blenny, silver porgy, black margate, slippery dick, sergeant major, porkfish, cocoa damselfish, seaweed blenny, doctorfish, and sailors choice.
... In Tanzania, even if the main eaten preys were brachyurans for all size classes of L. fulviflamma, there was a gradual ontogenetic shift in diet for the secondary prey groups, mostly fish. Indeed, juvenile and sub-adult diets were mainly constituted of small shrimps and prawns which were replaced by demersal teleosts, the most abundant prey of the adult blackspot snapper (Cocheret de laMorinière et al. 2003b, Kamukuru & Mgaya 2004. ...
La connectivité écologique se mesure via l'estimation des mouvements réalisés par les organismes au cours de leurs vie. Parmi les outils existants, seule la microchimie des otolithes est capable de reconstruire les mouvements des poissons au cours de leur vie entière, notamment lors des migrations ontogénétiques. Son utilisation au sein des milieux oligotrophes et chimiquement peu contrastés tels que les récifs coralliens reste cependant marginale. C'est dans ce contexte que s'inscrit ce travail sur la microchimie des otolithes des poissons des récifs coralliens et mangroves de Nouvelle-Calédonie. Il se divise en deux parties. La première, méthodologique, est axée sur l'estimation du potentiel de l'outil microchimie des otolithes en Nouvelle-Calédonie, avec un chapitre sur la détermination des signatures multi-élémentaires caractéristiques des différents habitats de la Grande Terre et un chapitre sur l'étude de la relation entre la microchimie de l'environnement et celle des otolithes. La seconde partie se concentre sur l'application de la méthodologie précédemment développée a des thématiques écologiques, avec un chapitre sur le rôle des mangroves sur le cycle de vie et la distribution géographique d'une espèce de Lutjanidae, Lutjanus fulviflamma, et un chapitre centré sur les mouvements réalisés au cours de la vie de cette espèce. Les résultats démontrent que la microchimie des otolithes présente un potentiel élevé en Nouvelle-Calédonie avec un fort pouvoir de discrimination entre la mangrove et les récifs coralliens. La relation entre la microchimie de l'environnement et celle des otolithes est complexe et dépend fortement des espèces considérées. Cependant, les contrastes chimiques marqués de l'environnement se retrouvent au sein des otolithes. Les résultats démontrent une connexion forte entre les différents habitats pour L.fulviflamma, particulièrement entre la mangrove et les récifs coralliens avec une importance cruciale de la mangrove comme zone de nurserie. Trois différents patrons de mouvements entre habitats ont été identifiés. Cette diversité illustre une forte variabilité de la connectivité écologique entre les individus, avec pour certains d'entre eux, une fréquentation de l'habitat juvénile durant la phase adulte.
... On the other hand, L. jocu ate Brachyura and Penaeidae at all size classes, which has been noted in other studies in tropical estuaries (Monteiro et al., 2009;Pimentel & Joyeux, 2010). The juvenile reef fish presented ontogenetic dietary changes once they were in the nursery habitats (Cocheret de la Moriniére et al., 2003;Wells et al., 2008). The switch of a diet based on microcrustaceans to a Brachyura-or Penaeidae-based diet probably occurred because these items are more energetically profitable for larger individuals, maximizing energy input (Yeager et al., 2014). ...
Resource partitioning is important for species coexistence. Species with similar ecomorphological characters have a high potential for competition, especially when close phylogenetically. The diet and resource partitioning of four snappers ( Lutjanus alexandrei , L. analis , L. jocu and L. synagris ) was studied in the Tubarão River, north-eastern Brazil, between March and November 2012. Specimens were caught using a beach seine, and a total of 731 stomachs were analysed. The highest abundance of snappers was found near to vegetated habitats in the middle estuary. Crustaceans were dominant in the diet of all four species, being found in over 90% of the stomachs, followed by fish and molluscs. The species did not appear to compete for common resources, probably because there was not always spatial overlap, and differences in the proportions of consumption of items were observed. Ontogenetic comparisons of dietary compositions suggested differences among species, with changes in the diet related to changes in the mouth area as the body size increased. The changes were more evident in L. analis and L. synagris where microcrustaceans (Calanoida, Cyclopoida and Amphipoda) were dominant in the diet of the smaller size classes, and benthic crustaceans (Brachyura) and fish in the diet of larger individuals. The intra- and inter-specific differences in the dietary compositions, differences in the mouth area and feeding strategy contribute to allow the co-existence of these snappers in the study area.
Habitat mapping is crucial for understanding habitat connectivity and for spatial planning, environmental management, conservation, and targeted research, including long-term change monitoring. However, such information has been lacking for many Dutch Caribbean islands, especially regarding marine habitats. This study used 2144 georeferenced images from different surveys to develop habitat models predicting the distribution of habitat types within the Saba Bank National Park. The habitat models link environmental factors to species or habitat occurrence, enabling predictions in unsurveyed areas with known covariates. Machine learning techniques (Random Forests, Gradient Boosting, and weighted K Nearest Neighbor) were applied to interpret and predict ten habitat types over the Bank. Three models were created for each technique: 1) utilizing only geographic coordinates; 2) incorporating covariables such as depth, distance to the edge of the Bank, Topographic Position Index (TPI), and Terrain Ruggedness index (TRI); 3) a combination of the previous two models. All models performed well, accurately predicting habitat types between 67 and 74% of the georeferenced images. However, the most natural representation occurred with models combining geographic and covariate variables. Predicted habitats include coral reef, patch reef, gorgonian reef, sargassum fields, cyanobacteria-dominated fields, Lobophora fields, Neogoniolithon- Lyngbya habitat, other macroalgae fields, sand with a mix of species, and bare sand. Habitat distribution appears to be related to the main currents in the area and depth, with coral reefs occurring mainly along the southern and eastern edge of the Bank, with gorgonians and other soft corals dominating there the shallow areas. Macroalgae, including fields of Sargassum, dominate the back-reef area. Extensive sand plains dominate the center of the Bank, and along the north-western and northern edge of the Bank, between 40 and 60m depth Lobophora fields can occur. In the south-eastern back reef area a number of mounds built up by the coralline alga Neogoniolithon occur. The Luymes Bank, the northeastern part of the Saba Bank, was the only area that was not correctly predicted, indicating that additional field-based observations are needed to refine results in this aree.
Monogeneans are a diverse group of flatworms, being ectoparasites of marine and freshwater fish, with great morphological and ecological variety. Analyzes of monogenetics in fish with great habitat diversity such as snappers are scarce in the literature, which already emphasizes the need for an update in this regard. The presente study found, morphologically characterized and mapped the geographic distribution and in known hosts the species Microcotyloides incisa and Microcotyloides impudicus, describing the first occurrence of these monogeneans for South America and in new hosts. The survey of hosts in the literature shows that M. incisa seems to have a greater Affinity with congener species of Lutjanidae and fish from other families, which may indicate a preference or specificity for fish of this family because they are congeners of their host type. The introduction of these parasites into South American waters may have occurred due to the migratory behavior of snappers, which are well distributed along the Mexican coast, where the parasites are usually reported. Here, we also bring the first occurrence of M. incisa for Lutjanus analis and Lutjanus jocu and M. impudicus for Ocyurus chrysurus and Lutjanus synagris, helping in the mapping and distribution of these monogenetic species in the Americas.
Snappers are opportunistic carnivores with a leading role in energy flows between trophic interactions within tropical ecosystems. In the southern Gulf of Mexico, the few reported trophic-structure models are based on snapper stomach content data from other geographic regions (e.g., Atlantic coast of United States, Northern Gulf of Mexico, Caribbean Sea and Brazil). To optimize the reliability of these models, we present new information on the diet composition of two commercially important species: lane snapper Lutjanus synagris and yellowtail snapper Ocyurus chrysurus. From January 2008 to 2009, The stomach contents of 1,074 L. synagris and 1,516 O. Chrysurus were collected from three fishing sites off the northern coast of Yucatan, Mexico. Contents were analyzed using frequency, number and weight of the identified prey species. A three-level, nested PERMANOVA analysis was used to assess differences between the potential prey and their biomass using the factors of snapper species, fishing site and climate season. Multidimensional Scale (MDS) and SIMPER analyses were run to establish dissimilarity within the discriminating factors. The main food items found in the L. synagris diet were Brachyura, Penaeioidea and unidentified shrimps. Penaeioidea were the most abundant items in the O. chrysurus diet. Prey biomass analysis revealed a dissimilarity in diet composition between the two snapper species, as well as between fishing sites and climate seasons. The principal discriminatory prey categories were Brachyura, Penaeioidea, Osteichthyes, with Caridea and unidentified shrimps accounting for slightly smaller proportions. The results confirm the trophic position of these two sympatric snappers, showing that each plays a different trophic role in the ecosystem of the northern coast of the Yucatan Peninsula.
Near‐future climate change projections predict an increase in sea surface temperature that is expected to have significant and rapid effects on marine ectotherms, potentially affecting a number of critical life processes. Some habitats also undergo more thermal variability than others, and the inhabitants therefore must be more tolerant to acute periods of extreme temperatures. Mitigation of these outcomes may occur through acclimation, plasticity or adaptation, although the rate and extent of a species' ability to adjust to warmer temperatures is largely unknown, specifically as it pertains to effects on various performance metrics in fishes that inhabit multiple habitats throughout ontogenetic stages. Here, the thermal tolerance and aerobic performance of schoolmaster snapper (Lutjanus apodus Walbaum, 1792) collected from two different habitats were experimentally assessed under different warming scenarios (temperature treatments = 30, 33, 35, 36°C) to assess vulnerability to an imminently changing thermal habitat. Larger subadult and adult fish collected from a 12 m deep coral reef exhibited a lower critical thermal maximum (CTmax) compared to smaller juvenile fish collected from a 1 m deep mangrove creek. However, the CTmax of the creek‐sampled fish was only 2°C above the maximum water temperature measured in the habitat from which they were collected, compared to a CTmax that was 8°C higher in the reef‐sampled fish, resulting in a wider thermal safety margin at the reef site. A generalized linear model showed a marginally significant effect of temperature treatment on resting metabolic rate (RMR), but there were no effects of any of the tested factors on maximum metabolic rate or absolute aerobic scope. Post hoc tests revealed that RMR was significantly higher for creek‐collected fish at the 36°C treatment and significantly higher for reef‐collected fish at 35°C. Swimming performance [measured by critical swimming speed] was significantly lower at the highest temperature treatment for creek‐collected fish and trended down with each successive increase in temperature treatment for reef‐collected fish. These results show that metabolic rate and swimming performance responses to thermal challenges are somewhat consistent across collection habitats, and this species may be susceptible to unique types of thermal risk depending on its habitat. We show the importance of intraspecific studies that couple habitat profiles and performance metrics to better understand possible outcomes under thermal stress.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
Coral reefs are the 'rain forests' of the ocean, containing the highest diversity of marine organisms and facing the greatest threats from humans. As shallow-water coastal habitats, they support a wide range of economically and culturally important activities, from fishing to tourism. Their accessibility makes reefs vulnerable to local threats that include over-fishing, pollution and physical damage. Reefs also face global problems, such as climate change, which may be responsible for recent widespread coral mortality and increased frequency of hurricane damage. This book, first published in 2006, summarises the state of knowledge about the status of reefs, the problems they face, and potential solutions. The topics considered range from concerns about extinction of coral reef species to economic and social issues affecting the well-being of people who depend on reefs. The result is a multi-disciplinary perspective on problems and solutions to the coral reef crisis.
In the Southeastern Tropical Atlantic, Haemulidae family play an important role
both environmentally, acting as a link between lower and higher trophic levels,
and socioeconomically, being widely caught by artisanal fleets. This study aimed
to describe the trophic ecology of three grunt species (Haemulon aurolineatum,
H. plumierii and H. squamipinna) considering spatial, temporal and ontogenetic
aspects, integrating stomach content and stable isotopes analysis. Sampling
occurred in 26 stations along the Northeast of Brazil (04°– 09°S), in August 2015
and April 2017, using bottom trawling net. There was greater feeding intensity at
night, at latitudes below 08°S and in the inner continental shelf. Higher values of
δ¹⁵N were reported for H. aurolineatum and H. plumierii collected near coastline.
The isotopic niche breadth indicated that H. aurolineatum has a narrower diet
than H. plumierii. For the three species, the trophic level ranged between three
and four. Considering stomach content and isotopic niche, diet was similar
comparing species. Th is trophic ecology pattern reveals a likewise use of the
habitat, which may be essential for identifying priority areas for conservation
on an ecosystem basis, especially in rich reef zones that are subject to several
increasing pressures, such as those in Northeast Brazil.
The main goal of the present study was to carry out an integrated analysis of the feeding habits of a set of species which use the same general food source (benthic invertebrates and small fishes) in a coastal lagoon of the Mexican Pacific. The specific objectives were to explore the patterns of diet overlap among the 12 species included; to relate the differences in diet composition with differences in species morphology and to measure the predator-prey size relationship across the whole set of species. Original primary data on diet composition were obtained from former research whose results were already published in five separated papers dealing with different species or groups of species. Data included information on stomach content (percentage weight) from a total of 2138 individuals pertaining to 12 species (nine of them further split in size groups) and 3953 pairs of prey's size vs predator's size measurements. Eight prey categories made 74% of all food consumed, namely non-identified fishes, penaeids, gobiids, polychaeta, alpheids, upogebiids and engraulids. Using a combination of diet overlap testing based on a null model approach, multivariate methods and regression analyses (linear and quantile), it is concluded that the existence of a relatively homogenous functional group of 12 fish species consuming invertebrates and small fishes is not a realistic assumption. Indeed, several species-size group subsets are clearly identifiable based on the percentage of different prey categories in their diets. The most plausible explanation for the observed patterns of diet composition are the differences in morphological characteristics of the species involved. Other factors allowing the sharing of food resources are the ontogenic change in the size of main prey consumed, notable differences in the abundance of fish species with higher diet overlap values and, perhaps, a high abundance of food resources.
The ecology of the marine environments of the Murciélago Islands and the Santa Elena Peninsula have been studied little despite their high biodiversity. This area is influenced by a coastal upwelling. In 2014, 2016 and 2018, the region was visited to assess the composition and diversity of its reef environments. Bottom coverage, macroinvertebrate diversity and abundance, and reef fish biomass were quantified. The substrate was dominated by turf and crustose calcareous algae. Live coral coverage has decreased compared to previous reports for the area. Sea urchins were the macroinvertebrates with the highest densities, while species of commercial interest presented low densities, this may suggest some degree of fishing pressure. 84 reef fish species were identified, making the islands area with the greatest diversity of reef fish in the North Pacific of Costa Rica. Coral biotopes in this region are key to the conservation of connectivity between reef areas due to their high diversity.
The ecology of the marine environments of the Murciélago Islands and the Santa Elena Peninsula have been studied little despite their high biodiversity. This area is influenced by a coastal upwelling. In 2014, 2016 and 2018, the region was visited to assess the composition and diversity of its reef environments. Bottom coverage, macroinvertebrate diversity and abundance, and reef fish biomass were quantified. The substrate was dominated by turf and crustose calcareous algae. Live coral coverage has decreased compared to previous reports for the area. Sea urchins were the macroinvertebrates with the highest densities, while species of commercial interest presented low densities, this may suggest some degree of fishing pressure. 84 reef fish species were identified, making the islands area with the greatest diversity of reef fish in the North Pacific of Costa Rica. Coral biotopes in this region are key to the conservation of connectivity between reef areas due to their high diversity. Resumen Las Islas Murciélago y la península de Santa Elena han sido ambientes marinos poco estudiados a pesar de la alta biodiversidad de sus ecosistemas. Esta zona está influenciada por un afloramiento costero. En el 2014, 2016 y 2018 se visitó la región para evaluar la composición y diversidad de sus ambientes arrecifales. Se cuantificó la cobertura del fon-do, la diversidad y abundancia de macroinvertebrados y la biomasa de peces arrecifales. El sustrato estuvo dominado por tapetes algales (turf) y algas calcáreas costrosas. La cobertura de coral vivo se ha reducido con lo previamente reportado para la zona. Los erizos de mar tuvieron las densidades más altas entre los macroinvertebrados, mientras que especies de interés comercial presentaron bajas densidades, lo que sugiere cierta presión pesquera. Se observaron 84 especies de peces arrecifales, lo que hace de esta área una de las mayores diversidades del Pacífico norte de Costa Rica, esto puede atribuirse a la presencia de áreas marinas protegidas. Los biotopos coralinos de esta región son claves para la conservación de la conectividad entre zonas arrecifales, debido a su alta diversidad. Palabras clave: ecosistemas costeros, islas continentales, arrecifes de coral, arrecifes rocosos, algas.
• A pregnancy imposes a heavy reproductive burden on females. Some live-bearing species have evolved reproductive adaptations to reduce this burden, which may influence their ability to use specific microhabitats.
• We investigate whether two such reproductive adaptations, placentation (embryo provisioning via a placenta) and superfetation (the ability to carry multiple broods at various developmental stages), influence microhabitat selection by five sympatric Costa Rican live-bearing fish species (family Poeciliidae). Theory predicts that placentation and superfetation should both reduce the reproductive burden of females during pregnancy, improve their body streamlining, and swimming performance, and consequently allow them to use more performance-demanding microhabitats.
• Here we apply underwater visual fish surveys to test a key prediction of this hypothesis, which is that the presence of these two reproductive adaptations is correlated with the use of microhabitats in the river that are characterised by a higher-flow velocity.
• Consistent with our predictions, we observed significant interspecific differences in daytime microhabitat use: species that had both placentation and superfetation were found in deeper and faster-flowing parts of the river, species that lacked both adaptations were confined to shallow slow-flowing areas, and species with one adaptation (i.e. only superfetation) inhabited intermediate areas. This interspecific daytime microhabitat use was strongest in reproductive adults, intermediate in immatures, and absent in juveniles (the latter of which were all found in shallow low-velocity zones), suggesting that ontogeny influences species-specific microhabitat use. Finally, at night, all fishes, regardless of the species or age-class, congregated in shallow slow-flowing waters to rest (sleep) on the river bottom.
• Taken together, our results suggest that placentation and superfetation may be hitherto unrecognised reproductive features that help to explain differences in ontogenetic and diurnal microhabitat preferences between sympatric live-bearing fish species living in environments characterised by large flow variation.
Caranx caninus, C. sexfasciatus, Chloroscombrus orqueta, Selene brevoortii, S. peruviana, and Selar crumenophthalmus are species with economic importance for local artisanal fisheries and are regular components of the fish assemblage at Barra de Navidad coastal lagoon in the Pacific coast of Mexico. The working hypothesis was that carangid species in the lagoon share a common food base but the proportion of main food categories in the diet will be different for some groups of species due to differences in key morphological characteristics of the carangids. A total of 1251 individuals were used for diet analyses. Stomach content analyses showed that five species feed on benthic invertebrates and small fish while one species was mostly a plankton feeder. A partial sharing of main food resources was found for most of the studied species, but significant differences in the proportion of food categories in the diet were identified for several groups of species. Another aspect of diet variation was associated with predator size whereby larger individuals tended to consume the largest prey. A plausible explanation for the variation observed in feeding habits is based on morphological differences among groups of species which favor piscivory or planktivory in some cases. This paper is the first published report on the feeding habits of all six species in anyMexican estuarine habitat and of four species in Eastern Pacific estuarine waters.
Seagrasses – a group of foundation species in coastal ecosystems – provide key habitat for diverse and abundant faunal assemblages and support numerous ecosystem functions and services. However, whether the habitat role of seagrasses is influenced by seagrass diversity, by dominant species or both, remains unclear. To that end, we sought to investigate the specific seagrass characteristics (e.g., species diversity, seagrass traits) that influence tropical fish assemblages, and place this in the context of small-scale fishery use. We surveyed seagrass variables at 55 plots, nested within 12 sites around Zanzibar (Tanzania) in the Western Indian Ocean, and used Baited Remote Underwater Video (BRUV) systems to assess fish assemblages across plots. Using linear mixed models, we reveal that seagrass structural complexity and depth were the best predictors of fish abundance, with higher abundance occurring in deeper meadows or meadows with high canopy, leaf length and number of leaves per shoot. Moreover, an interaction between seagrass cover and land-use was the best predictor of fish species richness, where sites closer to human impacts were less affected by cover than sites with lower human impact. Overall, models with seagrass species richness or functional diversity as predictors poorly explained fish assemblages. Fish taxa that were important for small-scale fishery sectors (e.g., emperors, snappers, rabbitfish, and parrotfish) were primarily driven by seagrass structural complexity. Our results provide a unique analysis of the relationship between seagrass habitat and its associated fish assemblages in that we show that seagrass species diversity had little effect on seagrass fish assemblages, which instead appear driven by specific seagrass traits and seagrass cover. If conserving high value species that support adjacent fisheries is the priority for protecting seagrass meadows, then seagrass areas should be chosen with high cover and structural complexity that are in deeper waters. Any conservation measures also need to balance the needs of fishers that use the resources supported by seagrasses.
The diverse algae, invertebrate, fish, and sea turtle species found on east Florida nearshore hardbottom reefs are also largely found on Caribbean coral reefs. The distributions and abundances of NHR organisms vary broadly with latitude. More than 1174 species inhabiting east Florida nearshore reefs are subjected to high levels of physical disturbance (e.g., wave activity, sand scour, and burial). These dynamic conditions can affect reproduction, larval dispersal, larval settlement, shelter use, and food webs, ultimately fostering non-equilibrium assemblage dynamics. Managers need more information on the impacts of fill projects that exceed natural effects in magnitude and duration of reef burial. Changes in ocean heating, acidification, and sea level due to climate change are considered for primary groups of organisms. Research opportunities involving mitigation include the design, monitoring, and evaluation of artificial reef efforts to compensate for reef burial. To achieve effective mitigation, it is important to develop reef structural configurations that do not become buried over time and that foster intertidal and subtidal assemblage recovery, particularly for foundation species. Perceptions of habitat values are based on conditions that are being imprinted now, but do not represent conditions 50 years before the onset of large-scale reef burial projects, evidence of shifting baselines syndrome. East Florida nearshore reef systems are socio-economically important and represent opportunities to use social science research and traditional ecological knowledge to aid research to advance long-term nearshore conservation policies.
Nearshore reefs of mainland east Florida function as habitat for a diverse assemblage of marine organisms. This chapter provides an overview of multiple attributes (e.g., latitude and water depth, habitat use, feeding, disturbance processes, and connectivity) that shape shelter and trophic level functions for these communities. Reef structure and hard substratum provide shelter and attachment sites for invertebrates fishes, algae, and cyanobacteria. Some of these species, particularly the polychaete, Phragmatopoma lapidosa, and macroalgae, modify reefs and provide shelter that supports substantial invertebrate and fish assemblages. The abundance and diversity of organisms based on trophic status differs among latitude and depth gradients along nearshore reefs. For example, the numbers of herbivorous fishes decline with increasing latitude while the density of juvenile green turtles appear to be higher in east-central Florida. The type and availability of macroalgae, as well as competition among herbivores, may play a key role in these observed patterns. Natural disturbances in the form of wind and wave events, and periodic sand burial and scour, often affect recruitment and survival of sessile organisms and their faunal associates. Numerous macroalgal, invertebrate, and fish species are adapted to intermediate levels of disturbance, using these reefs for reproduction, as well as feeding sites and refuge from predators. The high abundance of newly settled and early juvenile fishes suggests these habitats serve important functions for settlers that grow out and emigrate to other environments. Such diverse inflows and outflows of propagules and nutrients suggest semi-continuous connectivity among nearshore reefs and other habitats of the larger east Florida coastal seascape.
The purpose of this research was to investigate differences in diet composition between Achirus mazatlanus and Syacium ovale, two flatfishes inhabiting in a tropical coastal lagoon and to investigate the relationship of their feeding habits to size, body morphometry and mouths characteristics. Fish were collected during sampling trips conducted regularly from 2011 to 2016 using several types of fishing gear. Total number of analyzed stomachs with some food content was 328 for Achirus mazatlanus from 1.4 to 21.3 cm total length (TL) and 203 for Syacium ovale with 1.3 to 24.0 cm TL. Results indicate that both species share a general diet based on benthic invertebrates and fishes but S. ovale has a more piscivorous habit, which can be explained by a more slender body shape and larger teeth, characteristics which increase prey fish catching performance. Important changes in composition of food categories related to size were not found for any species, but larger fish of both species eat larger ranges of prey sizes, and this ontogenetic change is consistent with recent developments on optimal foraging theory.
Lutjanus erythropterus and L. malabaricus are sympatric, sister taxa that are important to fisheries throughout the Indo-Pacific. Their juveniles are morphologically indistinguishable (i.e. cryptic). A DNA metabarcoding dietary study was undertaken to assess the diet composition and partitioning between the juvenile and adult life history stages of these two lutjanids. Major prey taxa were comprised of teleosts and crustaceans for all groups except adult L. erythropterus, which instead consumed soft bodied invertebrates (e.g. tunicates, comb jellies and medusae) as well as teleosts, with crustaceans being notably absent. Diet composition was significantly different among life history stages and species, which may be associated with niche habitat partitioning or differences in mouth morphology within adult life stages. This study provides the first evidence of diet partitioning between cryptic juveniles of overlapping lutjanid species, thus providing new insights into the ecological interactions, habitat associations, and the specialised adaptations required for the coexistence of closely related species. This study has improved our understanding of the differential contributions of the juvenile and adult diets of these sympatric species within food webs. The diet partitioning reported in this study was only revealed by the taxonomic resolution provided by the DNA metabarcoding approach and highlights the potential utility of this method to refine the dietary components of reef fishes more generally.
The damselfishes are one of the dominant coral reef fish lineages. Their ecological diversification has involved repeated transitions between pelagic feeding using fast bites and benthic feeding using forceful bites. A highly-integrative approach that combined gene expression assays, shape analyses, and high-speed video analyses was used to examine the development of trophic morphology in embryonic, larval, juvenile, and adult damselfishes. The anatomical characters that distinguish pelagic-feeding and benthic-feeding species do not appear until after larval development. Neither patterns of embryonic jaw morphogenesis, larval skull shapes nor larval bite mechanics significantly distinguished damselfishes from different adult trophic guilds. Analyses of skull shape and feeding performance identified two important transitions in the trophic development of a single species (the orange clownfish; Amphiprion percula): (a) a pronounced transformation in feeding mechanics during metamorphosis; and (b) more protracted cranial remodeling over the course of juvenile development. The results of this study indicate that changes in postlarval morphogenesis have played an important role in damselfish evolution. This is likely to be true for other fish lineages, particularly if they consist of marine species, the majority of which have planktonic larvae with different functional requirements for feeding in comparison to their adult forms.
Fish community structure of a non-estuarine inland bay on the Caribbean island of Curacao was determined in the mangroves, seagrass beds, algal beds, channel, fossil reef boulders, notches in fossil reef rock, and on the adjacent coral reef, using visual censuses in belt transects. Fish communities varied among biotopes, but some overlap was present. Fish density and species richness were highest at the boulders and on the coral reef, and extremely low on the algal beds, whereas the total number of individuals calculated for the entire bay was highest on the seagrass beds. Differences in fish densities between biotopes were related to differences in structural complexity and amount of shelter. Fishes in the bay largely consisted of 17 (mainly commercially important) reef fish species, which used the bay biotopes only as a nursery during the juvenile part of their life cycle. Small juveniles of these species were most often found in the mangroves, whereas at intermediate sizes some were found in the channel. Large individuals and adults were found on the reef, and densities of several of these species were higher on the reef near the bay than on reefs located farther down-current. Fishes which spent their entire life cycles in either the bay or on the coral reef were also found, and the latter group showed a strong decrease in abundance with increasing distance into the bay. The density distribution of individual fish species was not homogeneous within the bay. In the mangroves and seagrass beds, spatial distribution of fishes was correlated with distance to the mouth of the bay, water transparency, amount of shelter, and the structural complexity of the biotope. juveniles of 3 reef species showed an increase in size on the seagrass beds with distance from the mouth into the bay, whereas 1 bay species showed a decrease in size with this distance.
Day-night changes in fish communities were quantified in 6 associated shallow-water biotopes within a single bay: mangroves, seagrass beds, algal beds, channel, fossil reef boulders, and notches in fossil reef rock. All biotopes, except the algal beds, showed a strong reduction in fish density and species richness at night, caused by absence of diurnally active fishes and migrations of Haemulidae and Lutjanidae to the seagrass beds. The fish fauna of the different biotopes showed a relatively high dissimilarity between day and night. This dissimilarity is largely caused by absence of Acanthuridae, Chaetodontidae, Labridae, Pomacentridae, Scaridae and Sparidae at night. These fishes seek shelter at night in, amongst others, the channel, notches and boulders. The balloonfish Diodon holocanthus utilised almost all biotopes as shelter as well as feeding sites. The wide distribution of its preferred food (molluscs) probably explains its distribution in most biotopes at night. The nocturnally active Haemulidae and Lutjanidae, on the other hand, migrated from their daytime shelter sites to the seagrass beds at night to feed. Some of these fishes also migrated to the algal beds to feed. The preference of Haemulidae and Lutjanidae for the seagrass bed as a feeding biotope, instead of other bay biotopes, appears to be related to the relatively high availability of their preferred food (Tanaidacea and Decapoda) as determined by digestive tract analysis. Other bay biotopes showed much lower densities of such food items compared to the seagrass beds.
Cited By (since 1996): 55, Export Date: 12 April 2011, Source: Scopus
Documents the widespread existence of ontogenetic shifts in diet and habitat and explores the consequences of such shifts for species interactions and community structure. Most examples are from the lower vertebrates and invertebrates in freshwater communities. The second part offers a conceptual framework for predicting ontogenic shifts and suggests preliminary approaches for exploring their ecological and evolutionary consequences. It is shown how such life histories may be incorporated into a population dynamics framework.-from Authors
A combined stomach content and stable isotope analysis was used to determine if seagrass provides a base of nutritional support to the gray snapper, Lutjanus griseus. The results provided a quantitative evaluation of the relative contribution of carbon and nitrogen from various primary organic sources to gray snapper taken from each a mangrove and a seagrass dominated location in south Florida. Stomach content analysis revealed that gray snapper from the two areas had similar diets which were primarily composed of penaeid shrimp (>60%). Isotopic results provided a distinction between food webs on the basis of carbon values. The δ13C of components from the seagrass location were greater than -17‰ in contrast to values of less than -19‰ for those from the mangrove area. Quantitative estimates indicated that gray snapper from the seagrass area derived more than 90% of their carbon and nitrogen from sediment or water column particulate organic matter. Gray snapper from the mangrove area were supplied by carbon and nitrogen from these sources in addition to detritus. The main contributors appeared to be particulate organic matter from the water column and the brackish water grass, Ruppia maritima. Together, these sources accounted for 35 to 100% of the ultimate source of prey item dietary carbon and nitrogen. These results suggest that within both food webs carbon and nitrogen are transferred from a detrital base by similar mechanisms and emphasize the use of multiple isotopes as a tool for quantitatively evaluating food webs.
Juvenile fishes (TL 30-210 mm) in the families Lutjanidae (snappers), Scorpaenidae (scorpion fishes), Haemulidae (grunts) and Mullidae (goatfishes) collected from Panamanian seagrass meadows fed predominantly on decapod crustaceans and fishes and less frequently on a variety of other taxa. In most cases, prey items were identified to either the specific or generic level, allowing conclusions to be drawn about the microhabitats from which prey were taken. Overlap in diet was usually greatest among closely related species. These results correspond well with those of Randall's (1967) study of the feeding habits of the same fish species in the Virgin Islands, with most differences seeming to reflect the larger size of individuals examined by Randall.
Mangroves and seagrass beds have received considerable attention as nurseries for reef fish, but comparisons have often been made with different methodologies. Thus, relative importance of different habitats to specific size-classes of reef fish species remains unclear. In this study, 35 transects in 11 sites of mangroves, seagrass beds and coral reef were surveyed daily, in and in front of a marine bay on the island of Curaçao (Netherlands Antilles). The density and size-frequency of nine reef fish species (including herbivores, zoobenthivores and piscivores) was determined during a five-month period using a single methodology, viz. underwater visual census. All species were ‘ nursery species ’ in terms of their high densities of juveniles in mangroves or seagrass beds. Relative density distribution of the size-classes of the selected species over mangroves and seagrass beds suggested high levels of preference for either mangroves or seagrass beds of some species, while other species used both habitats as a nursery. Spatial size distribution of the nine species suggested three possible models for Post-settlement Life Cycle Migrations (PLCM). Haemulon sciurus, Lutjanus griseus, L. apodus, and Acanthurus chirurgus appear to settle and grow up in bay habitats such as mangroves and seagrass beds, and in a later stage migrate to the coral reef (Long Distance PLCM). Juveniles of Acanthurus bahianus and Scarus taeniopterus were found only in bay habitats at close proximity to the coral reef or on the reef itself, and their migration pattern concerns a limited spatial scale (Short Distance PLCM). Some congeneric species carry out either Long Distance PLCM or Short Distance PLCM, thereby temporarily alleviating competition in reef habitats. Haemulon flavolineatum, Ocyurus chrysurus and Scarus iserti displayed a Stepwise PLCM pattern in which smallest juveniles dwell in the mouth of the bay, larger individuals then move to habitats deeper into the bay, where they grow up to a (sub-) adult size at which they migrate to nearby coral reef habitats. This type of stepwise migration in opposite directions, combined with different preference for either mangroves or seagrass beds among (size-classes of) species, shows that reef fish using in-bay habitats during post-settlement life stages may do so by choice and not merely because of stochastic dispersal of their larvae, and underline the necessity of these habitats to Caribbean coral reef systems.
Behaviors that precede the daily migrations of mixed-species schools of juvenile grunts (Pomadasyidae), from patch reefs to grass beds at dusk and vice versa at dawn, are defined and utilized to ascertain the precision of the migrations. Although premigratory behaviors differ at dusk and dawn, the migrations are precise twilight events which occur at the same light intensities during dawn and dusk. Histological sections of the retina reveal that both cones and rods are fully exposed to ambient light during the migrations. Under the difficult photic conditions that prevail during migration, the retina is structured photomechanically to maximize the absorption of ambient light. Body colorations of the grunts, which consist mostly of intense colored stripes during the day, are replaced at night by cryptic melanic patterns. The precision of migration, the photomechanical movements in the retina, and the changes in body coloration are considered adaptive because they reduce predation on grunts when they migrate and are most vulnerable to attack. In support of this conclusion, the migrations take place just before the evening and just after the morning quiet period - thus they avoid that period during twilight when predation is highest in tropical fish communities.
Although ontogenetic changes in resource use within species are common in animals, these changes have not been widely considered
in studies of guild structure within communities. The occurrence of one or more shifts in resource use in an individual of
a given species during its life should mean that it would also belong to different guilds at different life stages. We specifically
addressed this issue by describing the feeding habits of ten species of carnivorous fishes occurring in tidepools in rocky
intertidal areas along the coast of central Chile. Most of these species undergo clear ontogenetic dietary shifts and a feeding
guild structure of this group of fishes was established that takes these dietary shifts into account. Each species was divided
into a number of size classes. Dietary overlap values between both intraspecific and interspecific size-class pairs in the
entire group of ten species were used to construct a phenogram of dietary similarity through an UPGMA cluster analysis. Numbers
of guilds and their memberships were established objectively by applying a bootstrapping procedure. Four “ontogenetic” feeding
guilds (OFGs), each consisting of size-classes of species, were recognized. The majority of species belonged to more that
one guild. Interestingly, when the bootstrapping procedure was applied to a phenogram based on the diets of “taxonomic” or
complete species, only one significant guild was found. The implications of these ontogenetic dietary shifts for interspecific
interactions are substantial because the identity of the species with which each fish species shares resources change through
their lives. The usefulness of taxonomic species for investigating potential competitive interactions in this assemblage is
greatly undermined.
Quantitative gravimetric analyses of stomach contents were carried out on juveniles of 21 species of fishes that cohabit seagrass beds near Crystal River, Florida. Our analyses were based on dry weights of food items and are expressed as percent of total stomach contents. The species analyzed were Harengula pensacolae, Opisthonema oglinum, Anchoa hepsetus, Anchoa mitchilli, Synodus foetens, Strongylura marina, Hyporhamphus unifasciatus, Oligoplites saurus, Trachinotus falcatus, Eucinostomus gula, Haemulon plumieri, Orthopristis chrysoptera, Bairdiella chrysura, Cynosciorc nebulosus, Diplodus holbrooki, Lagodon rhomboides, Microgobius gulosus, Chasmodes saburrae, Menidia beryllina, Trinectes maculatus, and Sphoeroides nephelus. Analyses of stomach contents taken from small, sequentially arranged size classes enabled us to delineate discrete ontogenetic changes in food habits in many of the species. In the 15 species in which planktivorous feeding stages were detected, only zooplankters were consumed in measurable amounts. Juveniles of H. pensacolae, O. oglinum, A. hepsetus, A mitchilli, and M. beryllina were almost exclusively planktivorous throughout most of the available size ranges and exhibited a distinct selection for molluscan veliger larvae. Copepods, mysids, and larval crustaceans were the principal plankters consumed by juveniles of other species. Only three species, D. holbrooki, L. rhomboides, and H. unifasciatus, exhibited herbivorous feeding stages. In both D. holbrooki and L. rhomboides, the herbivorous habit began quite early in juvenile development and followed a preliminary plank-tivorous stage. Larger specimens of L. rhomboides became carnivorous, whereas adults of D. holbrooki (and H. unifasciatus) were herbivorous. Juveniles of eight species exhibited carnivorous feeding stages, consuming primarily benthic invertebrates. Of these species, O. saurus, H. plumieri, O. chrysoptera, and B. chrysura consumed primarily shrimp and mysids; E. gula and T. maculatus utilized primarily polychaetes; C. saburrae consumed primarily amphipods; and T. falcatus consumed mainly crabs after utilizing mysids, small shrimp, and fishes in earlier feeding stages. In O. saurus, an intermediate stage was apparent in which material obtained from a “cleaning” habit made an important contribution to the diet. Juveniles of two species, L. rhomboides and C. nebulosus, exhibited carnivorous stages in which both benthic invertebrates and small fishes were important in the diet. Specimens of S. marina and S. foetens were primarily piscivorous. Detritus was an important dietary component in six species. In S. nephelus, M. gulosus, and C. saburrae, detritus was a major food item throughout most of the available size ranges. In M. beryllina, detritus was the major food item in the smallest size class examined. Appreciable amounts of detritus were also consumed by juveniles of O. oglinum and adults of H. unifasciatus.
The vertical and horizontal patterns of the distribution of corals and coral reefs (to a depth of 90 m) are discussed in relation to the environmental factors: geomorphology of the bottom, available substrate, light, turbidity, sedimentation, water movement and temperature. There is a general pattern which is comparable to other well-developed Caribbean reefs. However, as in other areas variations are found, e.g. the depth and growth form of Acropora palmata will depend on the degree of exposure to water movement. There are strong correlations between the environmental variables and the occurrence of coral species and their growth form, the species composition of coral communities and the character of the coral reef. In some cases the relationship is not that obvious. The absence of Agaricia species at certain points along the coast of Aruba and the dominance of Sargassum on the deep bottom at some places along the windward coast of Curaçao is not yet explained.
The relative importance of the different factors in an environmental setting is shown by a comparison of reef communities and reef habitats with a coral community of a muddy, shallow inland bay. The community of the bay consists, apart from the hardier coral species, of corals which are characteristic of the deep reef: Scolymia lacera , S. cubensis and Helioseris cucullata . These corals are adapted to sedimentation and low light intensities and are apparently able to withstand a temperature and salinity range much broader than that of their deep reef habitat.
The paucity of corals and coral reef development around the islands of the Windward Group (deeper habitat included) can generally be explained by the morphology of the sea floor, the lack of suitable substrate and the effect of hurricanes. The exposed coasts of Saba and St. Eustatius, being virtually unexplored, may have richer coral growth.
A new list of species of the Scleractinia of the Leeward and Windward groups, consisting of 57 species, is included.
We visually censused fishes along transects on the back-reef and adjacent lagoons of bank-barrier reefs at 6 sites on St. Croix, US Virgin Islands, to determine the extent to which coral reef fishes use lagoon habitats as nurseries. Fishes were recorded by size class (small, <3 cm; medium, 3 to 5 cm; large, >5 cm) on the back-reef, and on 5 lagoon habitat types: patch-reef, rubble, seagrass, algal plain, and sand. We examined densities of 4 focal 'species' (Acanthurus spp. [A. bahianus and A. chirurgus], Haemulon spp. [all species of the Haemulon genus]. Sparisorna aurofrenatum, and Scarus iserti), and densities of all species combined to determine spatial and temporal patterns of habitat use. Although there was a general tendency for coral reef fishes to use lagoon habitats as nurseries, we discerned 2 patterns of habitat use: 1 group, exemplified by Acanthurus spp. and Haemulon spp., use lagoon patch-reef and rubble as nurseries in preference to back-reef and other lagoon habitats; in contrast, Sparisoma aurofrenatum and Scarus iserti preferentially use back-reef and, to a lesser extent patch-reef, as nursery, juvenile, and adult habitat. Temporal variation was greatest in the small size class and least in the large size class. Most settlement occurred during summer, which is when settlement in lagoon habitats was greatest, with a little settlement in winter in the back-reef habitat. For species that use lagoons as nurseries, lagoon habitats must provide advantages that offset the additional energy expense and predation experienced by both incoming larvae, as they cross over the reef and search for patch-reef and rubble, and juveniles, as they return to the reef during the juvenile-to-adult transition. Given the use of lagoon habitats as nurseries, there is a need for inclusion of lagoons in coral reef reserves.
Many common features of aquatic habitats provide complexity in an otherwise unstructured water column. Abiotic elements include consolidated and unconsolidated sediments as well as many types of rock, whereas biotic elements include woody debris, coral and oyster reef formations and emergent and submersed vegetation. Special attention has been focused on submersed vegetation and its role in the functioning of aquatic systems, because of its very frequent occurrence in both freshwater (ponds and streams) and coastal marine ecosystems (estuaries and lagoons) and, more importantly, because animal abundances in vegetated habitats are frequently several orders of magnitude greater than in nearby unvegetated areas (cf. Rosine, 1955; Gerking, 1957; Harrod, 1964 for freshwater sites; Tabb et al., 1962, Thayer et al., 1975; Livingston, 1975 for marine sites). In fact, over 70 years ago Victor Shelford (1918) recognized the importance of plant surface as a factor governing the species composition of the freshwater fauna (cited in Rosine, 1955). At about the same time, Peterson (1918) described the richness of the fauna associated with European seagrass meadows.
Several problems arise if niche overlaps are equated with species similarities or interspecific competition coefficients. Niche overlaps based on food types in the diet rely on proportional utilization rates of the different food types. But because proportional utilizations reflect consumer-environment interactions, measures of similarity based on such proportions may reflect similarities between environments rather than similarities between species pairs. Competition coefficients, as derived by MacArthur, weight renewable resources on the basis of their productivity--not their relative abundance. Use of proportional utilization rates intrinsically incorporates relative resource abundance and ignores differences in resource productivity. Thus, equating overlaps based on proportional utilizations with competition coefficients will overestimate the contribution of abundant resources, which will be actually less limiting if they are very productive. These problems are illustrated with the MacArthur-Levin's measure of niche overlap, but the same problems will arise with other measures of overlap. On the other hand, measures of species' similarities which are independent of resource abundance may reflect evolutionary divergence of consumers' resource utilization patterns due to past competitive pressures.
Factors affecting recruitment and early survivorship of juvenile coral reef fishes were studied on St Croix, US Virgin Islands. The faunal assemblage studied included diurnally active fishes found in the rubble/sand habitat. The most abundant members were: beaugregory Stegastes leucostictus, foureye butterflyfish Chaetodon capistratus, mahogany snapper Lutjanus mahogoni, surgeonfishes Acanthurus bahianus and A. chirurgus, and French grunt Haemulon flavolineatum. Recruitment of juveniles of almost all species in the rubble/sand fish assemblage occurred more heavily on reefs that were built 20-40 m away from the main reef (into the lagoon) than on those built at the edge of the backreef, probably due to differences in available shelter and differences in encounter rates with predators. Seagrass and algae, which provide shelter to very small juvenile fishes, are absent in a 'halo' zone close to the reef due to the feeding activities of reef-associated grazers (fishes and urchins). Part of the explanation for the observed spatial pattern of fish recruitment is the spatial pattern of the shelter provided by seagrass and algae. Risk of predation for small juvenile fishes was considerably higher close to the reef than it was 20 m away. -from Author
Methods for analysing fish stomach contents are listed and critically assessed with a view to their suitability for determining dietary importance—this term is defined. Difficulties in the application of these methods are discussed and, where appropriate, alternative approaches proposed. Modifications which have practical value are also considered. The necessity of linking measurements of dietary importance to stomach capacity is emphasized and the effects of differential digestion upon interpretation of stomach contents outlined. The best measure of dietary importance is proposed as one where both the amount and bulk of a food category are recorded.
Seagrass communities are a major feature of shallow marine areas throughout the world. The marine spermatophyte Thalassia testudinum is the dominant seagrass in southeast Florida and the Florida Gulf coast. The trophic interaction between the fishes and the macrobenthic and cryptic fauna found in the area was examined.Based on digestive tract analysis, the principal interaction between the primary consumers of the study area and the higher trophic level predators was via the polychaetes and peracaridean crustaceans. The mollusks which contributed significantly to the benthic biomass were not a preferred food for the animals frequenting the study site. The maximum mollusk biomass in any benthic and cryptic sample was 2.31 g dry/m. It was felt that the predator population was limited by the small stock of polychaetes and peracaridean crustaceans which had a maximum biomass in any one sample equivalent to 1.74 g dry/m. The majority of the fishes captured were foragers over a wide area. The main residents were the syngnathids and the gold-spotted killifish, Floridichthys carpio.
Differences in prey taxa utilisation between closely related species are difficult to estimate statistically. The Mantel test can be used to perform this function.
The inherent difficulty of sampling the red mangrove prop root habitat has impeded our understanding of the utilization of this habitat by fishes. A block net and rotenone method was developed and used to sample 2 sites in each of 4 regions in Everglades National Park, Florida (USA). At each site a 3 mm mesh net was used to enclose 3 sides of a mangrove stand while an onshore berm formed the fourth side. Samples collected from the mangrove prop root environment were compared with samples collected using a 2-boat otter trawl in the immediately (8 to 10 m) adjacent, fringing seagrass habitat. The density and biomass of fish collected by the 2 gear were greater in the prop root habitat than in the adjacent fringing seagrass areas. There also were consistent differences in species composition between the 2 habitat types across all 4 geographic regions. Analysis of the stomach contents of gray snapper Lutjanus griseus suggested that smaller snapper tend to feed in the prop root habitat while larger snapper may forage out into adjacent areas to feed. The red mangrove prop root habitat is utilized by a wide variety of fish, and greater attention should be given to evaluating its contribution to fish production in south Florida and elsewhere.
Quantitative gravimetric analyses of stomach contents were carried out on juveniles of 21 species of fishes that cohabit seagrass beds near Crystal River, Florida. Our analyses were based on dry weights of food items and are expressed as percent of total stomach contents. The species analyzed were Harengula pensacolae, Opisthonema oglinum, Anchoa hepsetus, Anchoa mitchilli, Synodus foetens, Strongylura marina, Hyporhamphus unifasciatus, Oligoplites saurus, Trachinotus falcatus, Eucinostomus gula, Haemulon plumieri, Orthopristis chrysoptera, Bairdiella chrysura, Cynoscion nebulosus, Diplodus holbrooki, Lagodon rhomboides, Microgobius gulosus, Chasmodes saburrae, Menidia beryllina, Trinectes maculatus, and Sphoeroides nephelus. Analyses of stomach contents taken from small, sequentially arranged size classes enabled us to delineate discrete ontogenetic changes in food habits in many of the species. In the 15 species in which planktivorous feeding stages were detected, only zooplankters were consumed in measurable amounts. Juveniles of H. pensacolae, O. oglinum, A. hepsetus, A. mitchilli, and M. beryllina were almost exclusively planktivorous throughout most of the available size ranges and exhibited a distinct selection for molluscan veliger larvae. Copepods, mysids, and larval crustaceans were the principal plankters consumed by juveniles of other species. Only three species, D. holbrooki, L. rhomboides, and H. unifasciatus, exhibited herbivorous feeding stages. In both D. holbrooki and L. rhomboides, the herbivorous habit began quite early in juvenile development and followed a preliminary planktivorous stage. Larger specimens of L. rhomboides became carnivorous, whereas adults of D. holbrooki (and H. unifasciatus) were herbivorous. Juveniles of eight species exhibited carnivorous feeding stages, consuming primarily benthic invertebrates. Of these species, O. saurus, H. plumieri, O. chrysoptera, and B. chrysura consumed primarily shrimp and mysids; E. gula and T. maculatus utilized primarily polychaetes; C. saburrae consumed primarily amphipods; and T. falcatus consumed mainly crabs after utilizing mysids, small shrimp, and fishes in earlier feeding stages. In O. saurus, an intermediate stage was apparent in which material obtained from a cleaning habit made an important contribution to the diet. Juveniles of two species, L. rhomboides and C. nebulosus, exhibited carnivorous stages in which both benthic invertebrates and small fishes were important in the diet. Specimens of S. marina and S. foetens were primarily piscivorous. Detritus was an important dietary component in six species. In S. nephelus, M. gulosus, and C. saburrae, detritus was a major food item throughout most of the available size ranges. In M. beryllina, detritus was the major food item in the smallest size class examined. Appreciable amounts of detritus were also consumed by juveniles of O. oglinum and adults of H. unifasciatus.
The Mantel test has been widely used in many areas of research in biological science since its publication in 1967 and is particularly well suited to use in dietary studies. It is a non-parametric test that has been suggested as appropriate for comparisons when sample sizes are small. The methodology is reviewed, benefits to be gained are examined, and effects of features that have considerable impact (sample-size dependence and sensitivity to inequality of sample size) are considered.
A total of 5113 fishes belonging to 91 species was collected from seagrass and unvegetated habitats at Western Port for dietary analysis between August 1989 and November 1990, with 720 animals having empty guts. None of the common species was found to have a highly specialised diet. Crustaceans were the dominant component in the diets of the majority (69%) of the 88 species with non-empty guts, with five species (a girellid, a mugilid, a monacanthid and two gobiids) consuming large amounts of algal material, and only one species [the garfish Hyporhamphus melanochir (Valenciennes)] ingesting seagrass in any quantity. In general, dietary differences between juveniles and adults of a species were as great as dietary differences between fish belonging to different species when at the same body size. Amongst the crustacean feeders, diets generally changed from predominantly copepods to predominantly peracarids (amphipods, isopods and mysids) at ≈0.1 g wet body weight, and from predominantly peracarids to predominantly crabs and shrimps at ≈100 g. Across the range of species examined, there was a close relationship between the size of ingested prey and fish biomass. Prey length averaged 7.5% of predator length. The dominant species in gillnet catches, the mullet Aldrichetta forsteri (Cuvier & Valenciennes), possessed an unusual diet because prey were smaller than for other fishes of the same body size and large quantities of algal material were also consumed.
In this study I review the literature on resource partitioning in fish assemblages from 1940-83. Studies are grouped into seven global habitats: tropical reefs, temperate reefs, coastal marine, the Antarctic, mesopelagic/slope environments and freshwater streams and lakes. Freshwater systems first attracted the interest of resource ecologists; however, the number of studies of assemblages in all global habitats has risen sharply in the last decade. Studies treating single fish families show that resource partitioning occurs along more resource axes in more diverse assemblages. Unlike terrestrial systems, trophic separation is more important than habitat separation in fish assemblages. Based on 37 studies which concurrently examined habitat, food and temporal axes, 32% showed primary separation by habitat, 57% showed the greatest separation by food and 11% showed temporal separation to be most important. Global habitat differences in the importance of major resource axes are difficult to determine because of sampling bias; however, fish assemblages in most habitats show approximately equal importance of separation along spatial and trophic dimensions. The exceptions are marine systems, especially temperate marine reef assemblages which show greater importance of trophic separation. Global habitat differences in the amount of resource partitioning are not apparent, given the level of resolution of this study. Assemblages from all habitats show rather high separation of coexisting species along at least one resource dimension. The degree of taxonomic relatedness varies significantly over assemblages from the seven major global habitats. Investigation of tropical reef fish assemblages and also stream fish assemblages, has focused on more closely related faunas than studies of assemblages from other habitats. The degree of relatedness has a significant effect on ecological separation for both congeneric-confamilial and confamilial-conordinal species pairs, with less related pairs showing greater differences in resource use. Comparisons of niche overlap between assemblages of different taxonomic structure will thus be biased by historical effects. Unlike habitat or trophic partitioning, temporal partitioning was significantly more important in less related species pairs so that temporal partitioning, at least to a major degree, may reflect historical effects, rather than coevolution within a particular community. Few studies have attempted to deal with most or all life history stages of species in an assemblage so that our knowledge of resource partitioning is biased toward late juvenile to adult stages. The inclusion of more life history stages, the control (or awareness) of biases due to historical effects or sampling design and a more experimental approach will be important components of future studies of resource partitioning.
We visually censused fishes along transects on the back-reef and adjacent lagoons of bank-barrier reefs at 6 sites on St. Croix, US Virgin Islands, to determine the extent to which coral reef fishes use lagoon habitats as nurseries. Fishes were recorded by size class (small, 5 cm) on the back-reef, and on 5 lagoon habitat types: patch-reef, rubble, seagrass, algal plain, and sand. We examined densities of 4 focal 'species' (Acanthurus spp. (A. bahi- anus and A. chirurgus), Haemulon spp. (all species of the Haemulon genus), Sparisoma aurofrena- tum, and Scarus iserti), and densities of all species combined to determine spatial and temporal pat- terns of habitat use. Although there was a general tendency for coral reef fishes to use lagoon habitats as nurseries, we discerned 2 patterns of habitat use: 1 group, exemplified by Acanthurus spp. and Haemulon spp., use lagoon patch-reef and rubble as nurseries in preference to back-reef and other lagoon habitats; in contrast, Sparisoma aurofrenatum and Scarus iserti preferentially use back-reef and, to a lesser extent patch-reef, as nursery, juvenile, and adult habitat. Temporal variation was greatest in the small size class and least in the large size class. Most settlement occurred during summer, which is when settlement in lagoon habitats was greatest, with a little settlement in winter in the back-reef habitat. For species that use lagoons as nurseries, lagoon habitats must provide advantages that offset the additional energy expense and predation experienced by both incoming larvae, as they cross over the reef and search for patch-reef and rubble, and juveniles, as they return to the reef during the juvenile-to-adult transition. Given the use of lagoon habitats as nurseries, there is a need for inclusion of lagoons in coral reef reserves.
Fringing the southwest coast of Florida is a mangrove belt which supports large populations of birds, gamefishes, and invertebrate species of commercial importance. A study was conducted between 1967 and 1969 in the North River basin of this mangrove region to determine the energy basis for this large population of animals and to delineate the routes by which energy is transferred through the food web. This is the first of three publications summarizing the results of this study. It consists of summaries of food habits for most of the fish and aquatic invertebrate species which occur in the North River mangrove ecosystem. In addition to our data, which include in excess of 10,000 analyses of stomach contents, information from other publications has been summarized where pertinent. Finally, for most species there is an estimate of relative importance in the North River system in terms of abundance.
On the basis of the available tide gauge records over the period 1950-1956 the character of the tides in Annabaai Harbour, Curaçao, was determined. A periodic change of a diurnal and semidiurnal period, comprising 13.7 days, was observed. The average daily range between the tides in the period mentioned proved to be 29.7 cm. In relation to the currently accepted datum level, the so-called “Curaçaos Peil” (C.P.), it became obvious from the available data that the “true” mean tide level was situated 6.35 cm above C.P. A semi-annual variation in the height of the average sea level was observed; low sea level occurs during the first half of the year, and high sea level during the second half. The average percentage of submergence of different zones in the tidal region was determined.
The assessment of the statistical significance of differences in diets is surprisingly rare. In this note we discuss a powerful randomization test, that can be applied to diets as well as well as to other patterns of resource utilization and, for example, to patterns of species composition. We argue that ecological questions often require that both between-group overlaps and within-group overlaps are compared with their expected distribution under the null-hypothesis or no differences between groups.
Stomach contents were analyzed from 144 juvenile spotted seatrout, Cynoscion nebulosus, and 215 juvenile gray snapper, Lutjanus griseus, collected by trawl or rotenone from shallow seagrass flats, deep bank channels, or mangrove prop root habitats in western Florida Bay. Both species fed almost exclusively on crustaceans and fishes. Smaller non-decapod crustaceans-copepods, amphipods, and mysids-were more abundant as measured by percent occurrence in the smallest size classes (<50 mm SL). Penaeid shrimp, the most numerous prey in both fishes, and caridean shrimp increased in percent occurrence as fish increased in size. Fish were important in the largest size classes, above 150 mm SL. Rainwater killifish, Lucania parva, was the most common fish consumed. About 20% of the trout and snapper had empty stomachs when collected in grass flats, whereas about 60% of both species had empty stomachs when taken in channels. Relatively few fish were collected in mangroves and none of these specimens contained penaeids. No prey species were identified in either gamefish that are not common in Florida Bay.
A study of the biology of the gray snapper was based on the examination of 849 fish collected primarily from the sport fishery of Everglades National Park. Gray snappers from Park waters ranged from 1 to 5 years of age, with age-groups II and III making up 62 and 29 percent of the catch. Mean lengths for each age group, age and length at recruitment into the sport fishery, length-weight relationship, and sex ratio of gray snapper are given. All Everglades Park fish were immature.The stomachs of 200 fish were examined for food contents. Crustaceans made up 61.6 percent of food items by number and 76.7 percent by volume, shrimp occurring most frequently. Fish and crabs occurred in 34 and 27 percent of the stomachs containing food.
Nekton dynamics were studied in two contrasting habitats in Terminos Lagoon, Mexico. Over an annual cycle, a total of 83 fish species used the high-salinity fringing mangrove/Thalassia testudinum habitat and biomass ranged from 0.43 to 3.43 g m−2. The highest biomass occurred during the dry season when aquatic primary production was highest (i.e. 333 g C m−2 year−1). By contrast, 65 species used the freshwater and low-salinity riverine mangrove/Crassostrea virginica/Vallisneria habitat and biomass ranged from 0.57 to 1.48 g m−2 with the highest biomass occurring during the wet season, the time of highest primary production in this habitat (i.e. 219 g C m−2 year−1). The high- and low-salinity habitats serve as ecological bridges between freshwater areas and the sea. Fish life histories have evolved to utilize these habitats for spawning, feeding and nursery grounds in a manner which generally leads to the use of different habitats during the periods of highest primary productivity.
The differential distributions of juveniles and adults of 25 species of teleost were investigated and compared from four habitat types in sub-tropical Moreton Bay, Queensland. The aim of the study was to identify factors influencing the distribution of juveniles, particularly the species which enter estuaries. The following habitats were sampled: a shallow, sheltered tidal estuary (Caboolture); a shallow, exposed bay with muddy substrates (Deception Bay); an exposed area of sandy substrates and seagrass (Toorbol Point) and a sheltered oceanic site with sandy substrates and seagrass (Kooringal). Data on diet, spawning seasons and recruitment periods of fry are presented together with measurements of salinity, temperature and turbidity. Species entering estuaries recruited mainly in summer (rainy season). The possible preference of juveniles for calm water, the roles of food and predation pressure, the effects of salinity, temperature and turbidity are discussed in relation to the biology and distribution of the fish. Salinity and temperature were probably not important to most juvenile fish. The effects of calm water, suitable food and predators vary according to species. Although all juveniles studied preferred shallow water, in the case of those entering estuaries, turbidity was the single most important factor. Juveniles of the same species occurred in both the estuary and Deception Bay where abiotic and biotic factors other than turbidity were different. During summer, turbidity gradients extended from east to west in Moreton Bay with highest turbidities in Caboolture estuary and Deception Bay. In winter, turbidities throughout Moreton Bay were low and relatively uniform. At this time many of the ‘clear water’ species occurred in Deception Bay. The influence of high turbidity on fish may be linked to reduced predation pressure and perhaps food supply in shallow water. Turbidity gradients in summer may aid fry in locating estuarine nursery grounds. It is apparent however, that juveniles of many species are probably not attracted to estuaries per se but to shallow turbid areas.
The Spaanse Water is a relatively turbid, 3.19 km2 inland bay of virtually oceanic salinities and contains the largest seagrass, algal and mangrove areas of the Curaçao Underwater Park. During 1989 and 1990, a quantitative community assessment of the larger attached flora and fauna of the seagrass and algal meadows of the bay was conducted at 151 6 m2 stations using a quadrat sampling technique.A total of 13 different assemblages were distinguished. Shallow assemblages were dominated by Thalassia testudinum and Halimeda opuntia. As depth increased and light levels decreased, Thalassia gave way to increased coverages of especially H. opuntia, H. incrassata, Cladophora sp. and Caulerpa verticillata. In areas with significant availability of hard substrate an assemblage characterised (though not dominated) by corals was found at depths of 0–2 m, while sponges were concentrated at depths of about 4 m. The richest assemblages were found in shallow areas with high light levels and where a mix of both hard and soft substrate occurred. Assemblages with the lowest species richness were typically associated with low light intensities, soupy muds or homogeneous sandy sediments of high grain size.
Analysis of the fish faunas of Lake Opinicon and other small, cold temperate Ontario water bodies shows that the component species differ in body size, morphology, abundances, habitats, diurnal and seasonal habitat utilization patterns, diets, dietary changes with age, reproductive strategies, and population turnover rates. These differences are detailed.
The number of species occurring in a lake is partly due to historic factors, the number of habitats available, and morphological, behavioral and ecological adaptations that, by channelling their owners towards alternative resources, permit species to co-occur. Diet overlap values between most species are low except for the congeneric bluegill and pump-kinseed sunfishes, where values are moderate. These are the two commonest species in the lake and other parameters must increase the ecological differences between these two species.
Lake Opinicon is a highly variable ecosystem. Part of this variability stems from the seasonal nature of the environment and the fact that different resources reach their peak abundance at different times of the year. Ecological overlap levels between fish species fluctuate greatly in the course of the season as species switch from, or move on to, different resources. Population levels in different habitats also vary seasonally. Species adaptations and interaction patterns were presumably evolved over a long period; most of these adaptations undoubtedly developed before the component species colonized the lake.
Diet overlap measures, commonly used in studies of resource partitioning and competition in fish, are too often treated as fixed values; in fact, they are random variables. Two methods for estimating the variance of some overlap measures using stomach content data are examined here: the jackknife and the bootstrap. Simulation results indicate that the methods work well. In addition, they are valid for either continuous (biomass, percent volume) or discrete (abundance) data. Applications indicate that outliers, such as a stomach much different than others, may have large influence in determing the overlap value.
The dietary compositions and breadths of sequential 50 mm size classes of the six whiting species found in nearshore (<1.5 m),
shallow inner-shelf (5 to 15 m) and/or deep inner-shelf (20 to 35 m) waters of the lower west coast of Australia were determined.
Comparisons between the results of principal components analysis of head and mouth dimensions and the dietary compositions
of Sillago bassensis, S. vittata, S. burrus, S. schomburgkii, S. robusta and Sillaginodespunctata suggests that any differences in the dietary composition of similar-sized representatives of different species, when they
occur in the same habitat, are more likely to be due to differences in foraging behaviour than mouth morphology. Classification,
ordination and Schoener's overlap indices showed that, in nearshore waters, the juveniles of Sillago bassensis, which colonise relatively exposed areas, have a different diet to those of the smallest representatives of the other whiting
species that occupy more sheltered habitats. S. bassensis consumes mainly amphipods, whereas the smaller representatives of S. vittata, S. burrus, S. schomburgkii and Sillaginodes punctata ingest large volumes of copepods, which are typically abundant in protected nearshore waters. Although the mouth dimensions
of S. punctata tend to be smaller than those of Sillago schomburgkii, the larger individuals of the former species ingest greater quantities of larger prey, such as crabs and carid shrimps.
As S. bassensis, S. vittata and S. burrus increase in size and migrate out into shallow inner-shelf waters, the latter two species tend to concentrate more on benthic
prey, while the former species ingests fauna that is more epibenthic. The largest S. bassensis subsequently migrate out into deep inner-shelf waters, where they co-occur with S. robusta, which is restricted to those waters. In these waters, S. bassensis feeds to a far greater extent on large benthic prey, whereas S. robusta consumes a greater quantity of small epibenthic crustaceans, differences that reflect the far larger lengths of the former
species in that region. The above data emphasise that the distribution and ontogenetic movements of the six abundant species
of whiting play a major role in facilitating a partitioning of food resources amongst these species found in coastal waters
of the lower west coast of Australia.