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Day-night shifts of fishes between shallow-water biotopes of a Caribbean bay, with emphasis on the nocturnal feeding of Haemulidae and Lutjanidae
Abstract and Figures
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.
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... There is also the potential for limited spatial overlap in the delivering of different, complementary functions (Tebbett et al. 2017(Tebbett et al. , 2020Streit et al. 2019). This issue raises three interesting points for nocturnal reef fishes, which often migrate to forage during the night (Nagelkerken et al. 2000;Nagelkerken and Velde 2004;Hitt et al. 2011b;Koeda et al. 2021). Firstly, it is more than likely that the functional feeding impact of nocturnal predators is delivered at locations that are away from diurnal resting sites (Holland et al. 1996;Holzman et al. 2007;Meyer et al. 2007). ...
... Firstly, it is more than likely that the functional feeding impact of nocturnal predators is delivered at locations that are away from diurnal resting sites (Holland et al. 1996;Holzman et al. 2007;Meyer et al. 2007). Secondly, that feeding areas vastly exceed an individual's space use while resting (Nagelkerken et al. 2000;Hitt et al. 2011a). And, finally, that their excretion is likely to be concentrated in small resting areas during the day (Randall 1967;Francis and Côté 2018), compared to their wider ranging feeding areas at night. ...
Seascape connectivity can facilitate key ecosystem functions in complex ecosystems like coral reefs. Many reef fishes move across the seascape, bridging different ecosystems. However, their role in shaping important functions, such as biomass production and nutrient cycling, is still poorly understood. This study, therefore, assesses the extent of natural movements of cardinalfishes (Apogonidae), one of the major contributors to nocturnal fish biomass production with the potential for a major role in transferring energy and nutrients between sandy ecosystems and adjacent coral reefs. Consistent with previous work, showing their ability to move distances of 100 s to 1000 s of metres when displaced, we reveal that these small fishes undergo major voluntary nocturnal foraging forays extending up to at least 145 m from reef structures. Their estimated daily movement distances are at least 430 times greater than expected based solely on body size-home range expectations. Given their large travel distances and strong homing abilities, apogonids may provide a major conduit for material transfer between lagoonal soft sediment habitats and adjacent coral reefs. These results highlight the potential importance of apogonids in the cross-system or cross-habitat transport of energy and nutrients on coral reefs.
... This scale may vary for different species [27,28], and it can be location-or region-specific [22]. Many reef fishes exhibit regular migrations between habitats, such as emperors (family Lethrinidae) and grunts (family Haemulidae), which travel diurnally from coral reef habitats to seagrass beds to feed [6,29,30]. Perhaps the best-documented link between habitats in a tropical seascape is ontogenetic migrations, where reef fishes use non-reef habitats as juveniles before migrating to coral reefs as adults [9,[31][32][33][34]. The movement of reef fishes among benthic habitats is a major mechanism for connectivity that contributes to ecosystem processes such as nutrient transport [35], trophic transfers [36], and population replenishment [37]. ...
While benthic characteristics of coral reef habitats are a major driver of the structure of coral reef fish assemblages, non-reef habitats adjacent to coral reefs (e.g., mangroves, seagrass beds, and macroalgal beds) can affect reef fish assemblages. Here, we investigate how reef fish assemblages respond to local-scale benthic habitats within a coral reef and larger-scale adjacent seascape features (habitats within 500 m of coral reefs) on Siquijor Island in the Philippines. We examined an abundance of species for the entire reef fish assemblage and within the assemblages of parrotfishes (subfamily Scarinae) and wrasses (family Labridae). Five distinct habitat types were identified in a cluster analysis, which incorporated benthic characteristics within coral reefs and habitats adjacent to coral reefs. We found that the diversity and structure of coral reef fish assemblages were affected by benthic characteristics within coral reefs and also by benthic habitat types adjacent to coral reefs. Individual species responses and juveniles of certain species demonstrated uniquely high abundances in habitat clusters characterized by the non-reef habitats surrounding coral reefs. Considering coral reef habitats and adjacent non-reef habitats as a holistic, interconnected seascape will provide better estimations of the drivers of the structures of coral reef fish assemblages.
... The use of UVC is still the most practical and widely used method to assess coral fish fauna (Nagelkerken et al., 2000), especially since its impact on the environment is negligible (Mazzoldi and Girolamo, 1998). Such techniques have been used extensively in MPAs because they are non-destructive and guarantee that the fish community is not affected by sampling (Arcas et al., 2023). ...
The authors studied the structure of the coastal fish assemblage in a temperate coral reef within a marine protected area in order to provide a baseline information on the occurrence and temporal distribution of fish and to highlight the importance of the coral reef to ichthyofauna. The coastal fish assemblage was investigated at two sites in Veliko jezero (Mljet National Park) in the southern Adriatic Sea with a non-destructive SCUBA visual technique in the period from 2013 to 2021. Altogether, 38 fish taxa were recorded on the right bank (coral reef) and 36 species on the left bank. The presence of the coral reef at a depth range between 9 m to 12 m is the main factor differentiating the fish fauna in these two areas, which are otherwise governed by the same environmental factors. At the coral reef a decrease in fish diversity was discovered with a steady regression from 2013 to 2021.
... However, all habitats were dominated by species of low trophic level, particularly mobile invertebrate feeders such as the tomtate grunt (Haemulon aurolineatum). This grunt often dominates assemblages on coastal Brazilian reefs (Ferreira et al. 2004;present study) and, its daily migration between reef and surrounding soft bottoms to feed (Alheit 1983;Nagelkerken et al. 2000;Pereira and Ferreira 2013), probably explains its conspicuous presence in all habitats. ...
Fishes are conspicuous and threatened components of reef ecosystems. Understanding the role of the variables that shape their assemblages is important to buffer species, fishery stocks, and habitats from anthropogenic threats. So, the influence of depth and topographic complexity on trophic guilds and body size of reef fishes was assessed by underwater visual censuses (UVCs) conducted in biogenic reefs, rocky reefs, and rhodolith beds interspersed with algae, invertebrates, and sand. The study area lies in the southern continental shelf of Espírito Santo state, Brazil, a region that has lacked thorough UVC surveys of biogenic reefs and rhodolith habitats. A total of 105 species belonging to 42 fish families were registered. Among the eight trophic guilds registered, mobile invertebrate feeders and herbivores were the most representative in terms of density and biomass. Biogenic and rocky reefs showed higher biomass, density and richness than rhodolith habitats due to greater topographic complexity, which promotes more food resources and shelter. The five habitats hosted distinct fish assemblages (guilds and taxonomic diversity) probably because of the varying ability of resources they provide. Nevertheless, all habitats were dominated by species of low trophic level. Large fish, especially macrocarnivores, were mostly found in the deepest zones. This pattern is associated with ecological preferences but could also be strengthened by overfishing on shallower sites, decreasing the abundance of top predators and influencing their depth distribution. Our results provide a baseline for future studies, presenting subsidies for the management of human activities and the conservation of marine ecosystems in southeastern Brazil.
... A significant proportion of the fishes migrating from mangrove and reef to seagrass habitats at night consists of haemulid grunts and lutjanid snappers (Clark et al. 2009). By leaving the reef at night to feed (Nagelkerken et al. 2000;Clark et al. 2009), these fishes not only avoid areas where gnathiid density is highest, but they also avoid peak activity periods of gnathiids (Sikkel et al. 2006). While their exposure to gnathiids is reduced , our findings here indicate that it is not eliminated, and that the most susceptible species are also the most exploited. ...
Appreciation for the role of cryptofauna in ecological systems has increased dramatically over the past decade. The impacts blood-feeding arthropods, such as ticks and mosquitos, have on terrestrial communities are the subject of hundreds of papers annually. However, blood-feeding arthropods have been largely ignored in marine environments. Gnathiid isopods, often referred to as “ticks of the sea”, are temporary external parasites of fishes. They are found in all marine environments and have many consequential impacts on host fitness. Because they are highly mobile and only associated with their hosts while obtaining a blood meal, their broader trophic connections are difficult to discern. Conventional methods rely heavily on detecting gnathiids on wild-caught fishes. However, this approach typically yields few gnathiids and does not account for hosts that avoid capture. To overcome this limitation, we sequenced blood meals of free-living gnathiids collected in light traps to assess the host range and community-dependent exploitation of Caribbean gnathiid isopods. Using fish-specific COI (cox1) primers, sequencing individual blood meals from 1060 gnathiids resulted in the identification of 70 host fish species from 27 families. Comparisons of fish assemblages to blood meal identification frequencies at four collection sites indicated that fishes within the families Haemulidae (grunts) and Lutjanidae (snappers) were exploited more frequently than expected based on their biomass, and Labrid parrotfishes were exploited less frequently than expected. The broad host range along with the biased exploitation of diel-migratory species has important implications for the role gnathiid isopods play in Caribbean coral reef communities.
... Work in the eastern Caribbean focused on French grunt Haemulon flavo lineatum (Haemulidae), which is a well-studied and extremely common diel-migratory species in the western Atlantic (e.g. Helfman et al. 1982, McFarland & Wahl 1996, Nagelkerken et al. 2000, Clark et al. 2009). At dusk, French grunts leave the reef, where they rest during the day, and migrate to seagrass beds and sand flats (e.g. ...
While concepts of connectivity are increasingly used in determining locations for marine protected areas, they are much less applied in the management of fish stocks, which are assumed to be well-mixed populations. However, due to seascape structure and often asymmetrical dispersal, the stocks of many species are unlikely to be well mixed and there is potential to enhance management by utilising emerging ecological modelling approaches that incorporate functional connectivity. Here, we apply a new model, MerMADE, that couples biophysical modelling of dispersal with spatial population demography, to predict within-stock patterns of connectivity of sandeels in the North Sea. By deriving origin- and destination-centrality measures, we highlight a set of key origin sites within the area occupied by the stock that contribute immigrants to many other sites and also identify patches that are particularly isolated, unlikely to receive immigrants from elsewhere. We show that the connectivity characteristics of the stock have a strong impact on how rapidly it recovers following a major harvesting event that leads to a patch depletion. Furthermore, the recovery of a local population will depend on the demographic status of the sites from which it can obtain immigrants. Thus, sites that provide strong out-centrality (especially if they themselves have weak in-centrality) and sites that are especially isolated should be harvested less heavily. To reduce the potential for local or regional stock collapse, models incorporating both biophysical dispersal and local demography are needed to support spatially explicit management of commercial marine species.
... Work in the eastern Caribbean focused on French grunt Haemulon flavo lineatum (Haemulidae), which is a well-studied and extremely common diel-migratory species in the western Atlantic (e.g. Helfman et al. 1982, McFarland & Wahl 1996, Nagelkerken et al. 2000, Clark et al. 2009). At dusk, French grunts leave the reef, where they rest during the day, and migrate to seagrass beds and sand flats (e.g. ...
Connectivity between habitats and ecological communities is a critical component of trophic structure. Coral reef systems include reef, seagrass, and mangrove habitats, and the movement of fishes is a key component of habitat connectivity among them. Fishes that undergo diel migrations between habitats are among the best-studied functional groups. Studies on their role in energetic connectivity between adjacent habitats have not considered the possible contribution of parasites. Some diel-migratory species are both highly susceptible to and disproportionately exploited by gnathiid isopods, temporary, tick-like parasites of marine fishes. By leaving the reef at night, diel-migratory fishes reduce their overall exposure to gnathiids, which are more active at night and more abundant in reef habitat. Here we show that for sites in both the Caribbean and the Great Barrier Reef, gnathiids are attached to diel-migratory fishes at the time they depart reef habitat. Because gnathiids associate temporarily with host fishes, they can be acquired by hosts in one habitat and can become dislodged and deposited in another. Field experiments in the Caribbean show that gnathiids from reef habitat dislodge in seagrass habitat, where they likely remain until their next feeding. Sequencing blood meals from free-living gnathiids in seagrass beds, where they are least abundant, shows that diel-migratory and other transient fishes are the most frequently exploited hosts, confirming that deposition of gnathiids in seagrass is facilitated mainly by migratory hosts. These findings have important implications for trophic, population-genetic, and disease connectivity involving gnathiid isopods and potentially other external parasites.
... Fish species commonly occur in seagrass beds in the Philippines (Salita et al. 2003). Many of these fish species use the seagrass beds either throughout their life (residents) or only as a nursery for younger individuals of the species (Nagelkerken et al. 2000). Members of the Family Labridae and Siganidae are frequently observed in seagrass beds not only in the local area but also in other parts of the country (Salita et al. 2003). ...
This study provides information on the effects of fish grazing on a seagrass bed that was dominated by Thalassia hemprichii in Guang-guang, Dahican, Mati City, Davao Oriental, Philippines. We tested the assumption that herbivore exclusion keeps the growth of seagrass shoots up to a minimum length. Fish visual census was used to count the abundance of fish in the area during high tide at a distance of 5 m away from the treatment cages with a 15 m transect length. Among all species, Siganus fuscescens was the most abundant (499) followed by S. guttatus (153), while Thalassoma jansenii was the less abundant (13). The result of the weekly fish count in the seagrass bed showed highly significant variations in the number and census of species present in the area (df = 11, MS = 2.88, F = 30.10, p < 0.001). Analysis of shoot length measurement in treatment cages also exhibited highly significant differences throughout the sampling period (df = 11, MS = 726.71, F = 1,633.10, p < 0.001). Comparison between initial and final shoot counts also showed significant differences, with a higher shoot count in the full cage (X2 = 8, df = 2, p = 0.018; FC > PC > OP). This study raises clear evidence to support the assumption that herbivore exclusion positively influences the growth of T. hemprichii in this area.
A wide variety of species depend on mangroves, making them essential habitats in tropical and subtropical regions. While the function of mangrove habitat is well studied for taxa such as teleost fishes, limited attention has been directed towards their value for elasmobranchs. Here, we review the available literature on how and why elasmobranchs use mangrove habitats based on 65 papers identified through literature searches. The use of mangrove habitat as nursery areas in combination with other coastal habitats has been well examined, although we found taxonomic and regional biases in research. Additionally, mangrove habitats are considered to offer elasmobranchs feeding opportunities and refuge from predators, yet such functions have rarely been tested. In particular, the ecological role of elasmobranchs within mangrove habitats is poorly known; as it is difficult to study their behaviour in complex mangroves, their feeding ecology is understudied as are trophic linkages between mangrove and adjacent ecosystems. For a greater understanding of the association between mangroves and elasmobranchs, direct observations of elasmobranch behaviour in mangrove habitats are needed. Given global concern regarding mangrove loss, understanding how this affects elasmobranch populations will require long-term studies, particularly in those regions where losses are greatest. We identify 8 key research questions that will help improve this understanding.
The aim of this study was to describe the feeding ecology of predatory fishes in the inshore waters of Groote Eylandt in the Gulf of Carpentaria, a large tropical bay in northern Australia. This knowledge will increase our understanding of trophic ecology of fishes in tropical waters and, in particular, their interactions with commercially important penaeid prawns. Several structurally complex habitats, including seagrass beds, mixed seagrass/reef habitats and mangrove areas, which support a diverse marine fauna, are found in these shallow waters. Consequently the diets of most predatory fishes in the region comprise a wide variety of fish and invertebrate prey. Juveniles of several species of penaeid live in seagrasses, where they are preyed on by, especially,Scomberoides commersonianusand the common shark species. However, the impact on juvenile penaeid populations is not as high as in the tropical estuaries of north-eastern Australia where fish abundances are lower. Many predatory fishes are size-selective and, in general, larger fish eat bigger penaeids. Seasonal and diel predation on penaeids is largely density-dependent. Evidence from this and previous studies indicates that individual species of tropical marine fishes eat similar prey (taxa and proportions) regardless of their habitat; any differences are chiefly only at the level of genus or species.
A one year survey of benthic macrofauna was conducted over a series of subtidal sites characterized by different standing crops of benthic macrophytes. Since the stations had similar granulometric properties, the role of seagrass biomass in regulating community organization of benthic macrofauna could be tested independently, unlike earlier studies. The density of macrobenthic animals (N/m2) was directly related to mean macrofloral biomass as was the number of species taken over the sampling period. The unvegetated site was characterized by the highest degree of faunal dominance and a species composition distinct from that found at vegetated sites. The relative abundances of epifaunal amphipods and epifaunal polychaetes were directly related to macrophyte biomass. Abundance of deposit feeding and omnivorous polychaetes decreased as a function of macrophyte standing crop, whereas suspension feeding and carnivorous polychaetes increased with vegetation. Biomass of benthic macrophytes, independent of sediment granulometry and hydrodynamic effects, was an important regulator of species abundances, dominance, diversity, and trophic organization in macrofaunal assemblages.
An examination of macrofaunal microhabitats within a seagrass meadow was conducted in Apalachee Bay (north Florida). Core samples were taken from two substrata within the grassbed, Thalassia testudinum shoots and bare areas among the shoots, and compared with the fauna collected in randomly placed cores. Seagrass samples showed significantly greater numbers of individuals and species than the other two treatments. When compared with either bare substrate or random samples, four times the number of individuals and twice the number of species were collected in cores containing seagrass shoots. Random samples were not significantly different from samples taken on the bare substrate. Many of the species undersampled in randomly placed cores were epifaunal and closely associated with the vegetation present. Macrobenthic species were classified according to preferred microhabitat (seagrass, bare substrate or no preference). It is suggested that macrofaunal density and species richness estimates may be greatly affected by the distribution of plants within the grassbed. This study points out potential difficulties in macrofaunal estimates when the preferred microhabitat of the species under examination is undersampled.
Diurnal and nocturnal habits of some inshore fishes were observed in the southern Gulf of California. Certain patterns of behavior within and between species were consistently observed, and permit a number of tentative generalizations regarding feeding habits, schooling, and other activity in relation to time of day. Species with predominently diurnal foraging habits include: Mycteroperca rosacea (Streets), Epinephelus labriformis (Jenyns), Chromis atrilobata (Gill), Eupomacentrus rectifraenum (Gill), Abudefduf troschelii (Gill), Bodianus diplotaenia (Gill), Thalassoma lucasanum (Gill), Scarus californiensis (Pellegrin), Heniochus nigrirostris (Gill), Prionurus punctatus Gill, Runula azalea Jordan and Bollman, Balistes verres Gilbert and Starks, and Balistes polylepis Steindachner. Species obtaining most of their food at night include: Holocentrus suborbitalis (Gill), Myripristis occidentalis Gill, Rypticus bicolor (Valenciennes), Lutjanus argentiventris (Peters), Apogon retrosella (Gill), Microlepidotus inornatus Gill, Anisotremus interruptus Gill, Haemulon sexfasciatum Gill, Selar crumenophthalmus (Bloch), and Pareques viola (Gilbert). A number of other species are introduced as their activity relates to the discussion. The nocturnal species are predators, while the herbivorous and omnivorous fishes show predominantly diurnal feeding habits. Those species schooling in dense, relatively inactive schools inshore during the day are nocturnal feeders and the school functions in defense against diurnal predators. Members of these schools disperse to feed at night, often after moving a considerable distance offshore.
The species composition and biomasses of fishes in the tropical seagrasses of Groote Eylandt, northern Australia, were studied in 1989 and 1990. A total of 156 species was recorded. Tall dense seagrass, short seagrass and control (no seagrass) sites in different depths were compared. Shallow (<1 m) sites were dominated by small resident species and juveniles of non-resident species, while deeper waters (to 7 m) were dominated by larger species. Species composition was not significantly different between sites, but species diversity (H) and evenness (E) were higher in non-vegetated areas. In slightly deeper water (<2 m) species composition was different between habitats and species diversity was highest in tall seagrass and least in open areas. Most species were more abundant in tall seagrass and least abundant in open areas. Most of the larger fishes, including 11 species of sharks, are piscivores, and most move into shallow sea-grass areas at night, irrespective of tide height. Only five species showed abundance patterns related to tide height and there were no significant seasonal patterns of abundance in any of the communities. The biomasses for all sites and sampling methods were mostly from 1 to 2 g m-2, which is low relative to other inshore tropical areas. The possible causes-the characteristics of adjacent habitats (coral reefs and mangroves) and the role of seagrasses in the life cycle of fishes are discussed. It is suggested that habitat structure is a major determinant of the species composition of fish in tropical seagrass areas, primarily because it affects food availability, both for small residents and juveniles, and for visiting predators.
Visual censusing was used to investigate diel, lunar, and seasonal variations in abundance and composition of a fish assemblage inhabiting a mangrove key off the southwest coast of Puerto Rico. Forty-one species were visually identified among the mangrove prop-roots duing designated census periods: 0700, 1200, 1700, 2200. Statistical analysis indicated distinct trends in diurnal, day versus night, and seasonal abundances. Although diurnal variability was evident, the most pronounced feature was nighttime declines in species abundance. All species present during the day showed marked reduction in numbers or complete absence at night. Unlike coral reef habitats, there was no evidence for a diurnal-nocturnal changeover of species assemblages in the mangroves. Low nighttime abundance was partly due to twilight migrational activities. Movements away from the mangrove prop-root habitat at dusk were observed for a variety of fishes, particularly haemulids. Predictable, well ordered migrations were observed for juvenile French grunts (Haernulon flavolineaturn) and sub-adult bluestriped grunts (H. sciurus). Timing, duration, and pre- and post-migratory behaviors differed among species. Seventy-six% of species examined showed significant (P < 0.05) seasonal differences between Oct/Nov 86 (rainy season) and Apr/May 87 (dry season). Lunar periodicity had no obvious effect on species abundance in this mangrove fish assemblage.