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Rudd (Scardinius erythrophthalmus) introduced to the Iberian peninsula: Feeding ecology in Lake Banyoles
Abstract
The first data on the ecology of rudd (Scardinius erythrophthalmus) introduced to the Iberian peninsula are presented. The habitat and diet variation of rudd were studied in Lake Banyoles (Spain), an oligotrophic karstic lake dominated by exotic fish species. Rudd were strictly littoral and the diet was based on detritus and plant material. The most important animal prey were the cladocerans Daphnia longispinaand Scapholeberis rammneri, amphipods and several late stages of nematoceran dipterans. Rudd were more zooplanktivorous in spring and autumn and less in summer. There was also a size-dependent diet shift, from microcrustaceans to macroinvertebrates. The diet of rudd was also distinguished by the importance of plant material and various small neustonic invertebrates, particularly S. rammneriand late stages of nematocerans, showing a strong resource partitioning with other fish species. The degree of herbivory in Lake Banyoles was lower than usual.
... Rudd, Scardinius erythrophthalmus is mediumsized freshwater cyprinid fish occurring commonly in Europe (GARCÍA-BERTHOU & MORENO-AMICH 2000;FROESE & PAULY 2019). The rudd is a strictly litoral species occurring in still-water, slow-flowing rivers, and lakes with a heavily overgrown, muddy bottom (HOLCIK 1967;KENNEDY & FITZMAURICE 1974;GARCÍA-BERTHOU & MORENO-AMICH 2000). ...
... Rudd, Scardinius erythrophthalmus is mediumsized freshwater cyprinid fish occurring commonly in Europe (GARCÍA-BERTHOU & MORENO-AMICH 2000;FROESE & PAULY 2019). The rudd is a strictly litoral species occurring in still-water, slow-flowing rivers, and lakes with a heavily overgrown, muddy bottom (HOLCIK 1967;KENNEDY & FITZMAURICE 1974;GARCÍA-BERTHOU & MORENO-AMICH 2000). They are fairly hardy and can survive up to 15-17 years in water of poor quality (KENNEDY & FITZMAURICE 1974;NURMINEN et al. 2003;TARKAN et al. 2010). ...
... Previous studies on rudd described their growth (ZIVKOV et al. 2003;TARKAN et al. 2010), feeding (PREJS 1984;GARCÍA-BERTHOU & MORENO-AMICH 2000;LAKE et al. 2002;NURMINEN et al. 2003), morphometrics (BOZNAK 2008), fertility (PAPAGEORGIOU & NEOPHYTOU 1982;TARKAN 2006), and population structure (BLACKWELL et al. 2009). The spawning period of rudd is strictly related to accessibility to sunlight and temperature (ZIVKOV et al. 2003). ...
The rudd is a common freshwater species of the European ichthyofauna, however, this species’ sexual cycle has not yet been described based on the histological analysis of its gonads. The aim of this study was to analyze the annual gonad development cycle of rudd from the watercourses of north-western Poland. Adult individuals aged 2+ to 13+, of both sexes were caught in the Oder River and Lake Dąbie. A standard paraffin technique and six-stage scales were used to assess the development of gonad maturity in both sexes. Rudd gonads developed similarly in the Oder River and Lake Dąbie. Eggs were deposited in batches from the beginning of May to the half of June. Females deposited at least two batches of eggs. In the majority of females collected from these sites, the gonads developed asynchronously throughout the year. Rudd males attained reproductive readiness in the same period as the females, but retained gametes in their gonads for a month longer than the females. Rudd avoid locations with warmer water discharged from power plants.
... Seasonal availability of macrophytes likely affected the diet composition of the rudds sampled in our study, but this was not tested. Herbivory by rudd has been reported for populations both within (Prejs & Jackowska, 1978;Prejs, 1984) and outside (Garcia-Berthou & Moreno-Amich, 2000;Hicks, 2003;Nurminen et al., 2003) its native range, but the breadth of the rudd diet varies greatly among populations and is likely influenced by macrophyte availability and water temperatures. In Lake Hiidenvesi, Finland, where the biomass and diversity of submerged macrophytes was low, rudds consumed significant amounts of detritus and invertebrates from May 15 to August 15; invertebrates composed about 50% of the diet during mid-summer (Nurminen et al., 2003). ...
... In Lake Hiidenvesi, Finland, where the biomass and diversity of submerged macrophytes was low, rudds consumed significant amounts of detritus and invertebrates from May 15 to August 15; invertebrates composed about 50% of the diet during mid-summer (Nurminen et al., 2003). The diet of rudds in Lake Banyoles, Spain, was dominated by detritus, macrophytes, and algae; the percent biomass of plant material (31.6%) in the diet was probably lower than that reported for some populations due to low availability (Garcia-Berthou & Moreno-Amich, 2000). Conversely, rudds in New Zealand are considered obligate herbivores after they reach 200 mm fork length (Hicks, 2003). ...
... The rudd is often described as a littoral species that prefers lentic habitats (Johansson, 1987;Lake et al., 2002), with few references made to rudd occupying slow-flowing lotic habitats (Cadwallader, 1978;Zerunian et al., 1986;Hicks, 2003). Furthermore, most studies of wild rudd were focused on lake populations (Prejs, 1984;Garcia-Berthou & Moreno-Amich, 2000;Vila-Gispert & Moreno-Amich, 2000;Popović et al., 2001;Nurminen et al., 2003;Tarkan, 2006). The rudd population in the upper Niagara River not only exhibited superior condition and more rapid growth compared to lentic populations, but reproduction was successful at lotic sites and very poor at sites with very low flow (immeasurable with a flow meter). ...
Feeding patterns and population structure of the non-native rudd Scardinius erythrophthalmus (Linnaeus) were examined to understand their ecology in Buffalo Harbor and the Niagara River. We hypothesized that (1) the diet of rudds would be omnivorous, but contain greater proportions of macrophytes in summer months, (2) feeding intensity would increase with water temperature, and (3) condition and growth would be similar to other populations. We collected rudds with a variety of gears in 2009 to test these hypotheses, and used data from 2007 to 2010 seining surveys to determine if the relative abundance of young-of-the-year rudd differed among sites with different flow conditions. Rudds were mostly herbivorous; they consumed aquatic macrophytes in summer and supplemented their diet with algae and fish in spring and fall. Feeding intensity was positively correlated with water temperature, but significantly reduced during spawning. Rudd condition and growth were greater than estimates from other populations, suggesting increases in abundance and range expansion are possible. Furthermore, reproduction was successful at lotic sites but very poor at sites without measureable flow, contrary to the paradigm of optimal rudd habitat. Research is needed to understand how herbivory by abundant rudd populations affects native aquatic communities.
... Finally, while the density of fish in the cage experiments was higher than that in the oxbow itself (10 ind./m 2 vs. 0.125 ind./m 2 ), and hence there may have been density dependant impacts of observed diet, the fact that a significant proportion of P. acutifolius remained in the cage at the end of each experimental run would tend supported our findings, i.e. that rudd, even at relatively high densities, were not having a significant impact on P. acutifolius. Dietary analysis indicated that rudd deliberately consumed submerged macrophytes throughout the year, as also noted by Losos et al. (1980), Prejs (1984) and García-Berthou & Moreno-Amich (2000). On the other hand, Tomec et al. (2003) noted that rudd from Lake Vrana (Croatia) mainly consumed algae, with macroinvertebrates (e.g. ...
... Several other authors have also recorded rudd diet as including macroinvertebrates, especially gammarids, Asellus and trichopteran larvae (e.g. Martyniak et al. 1996, García-Berthou & Moreno-Amich 2000. Our own data confirm that macrophytes are indeed taken alongside algae and macroinvertebrates at significant levels; however, we suggest that further studies are needed to clarify the relative importance of the three food types in rudd diet and the specific roles played by different macroinvertebrate taxa in different environments and seasons. ...
Oxbow lakes are specialised standing water bodies that often support unique macrophyte and animal communities. Between 2015 and 2016, we assessed the diet composition of adult rudd (Scardinius erythrophthalmus) in one such macrophyte-rich lake. Over 2016, we also undertook a series of feeding behaviour tests under artificial conditions, the aim being to assess whether adult rudd represent a threat to the endangered sharp-leaved pondweed (Potamogeton acutifolius). In total, we examined 100 digestive tracts of rudd feeding under natural conditions and 100 from rudd feeding under artificial conditions. Our results show that i) P. acutifolius is deliberately consumed by rudd, and ii) pondweeds, periphyton and invertebrates were the dominant dietary components in the diet. A reluctance to consume cleaned P. acutifolius suggests a link with periphyton and invertebrate consumption. While rudd clearly consume P. acutifolius, we found no evidence of any negative impact on either pondweed development or on the macrophyte community as a whole.
... Finally, while the density of fish in the cage experiments was higher than that in the oxbow itself (10 ind./m 2 vs. 0.125 ind./m 2 ), and hence there may have been density dependant impacts of observed diet, the fact that a significant proportion of P. acutifolius remained in the cage at the end of each experimental run would tend supported our findings, i.e. that rudd, even at relatively high densities, were not having a significant impact on P. acutifolius. Dietary analysis indicated that rudd deliberately consumed submerged macrophytes throughout the year, as also noted by Losos et al. (1980), Prejs (1984) and García-Berthou & Moreno-Amich (2000). On the other hand, Tomec et al. (2003) noted that rudd from Lake Vrana (Croatia) mainly consumed algae, with macroinvertebrates (e.g. ...
... Several other authors have also recorded rudd diet as including macroinvertebrates, especially gammarids, Asellus and trichopteran larvae (e.g. Martyniak et al. 1996, García-Berthou & Moreno-Amich 2000. Our own data confirm that macrophytes are indeed taken alongside algae and macroinvertebrates at significant levels; however, we suggest that further studies are needed to clarify the relative importance of the three food types in rudd diet and the specific roles played by different macroinvertebrate taxa in different environments and seasons. ...
While removing fish during reservoir biomanipulation, it was noted that the diet of normally piscivorous 5+ to 7+ perch was
dominated by macrophyte fragments, with fish eggs sub-dominant. To the best of our knowledge, macrophytes have not previously been
reported as a food item in perch. Here, we briefly discuss this finding and its significance for perch diet studies.
... Carassius auratus showed a relatively high and diffuse overlap with a number of native species, such as S. erythrophthalmus and S. squalus, and to a lower extent with A. anguilla, all known to feed mainly on benthic invertebrates [100][101][102]. C. auratus has zooplanktivorous habits yet is able to shift to a benthivorous diet depending on resource availability [103][104][105]. ...
Simple Summary
An in-depth study of the feeding habits characterizing bioinvaders may provide key information on the magnitude of their impacts on recipient communities. Specifically, if invaders’ trophic niche is superimposed on that of native species, interspecific competition may increase, resulting in negative consequences for the competing species; alternatively, trophic niche divergence may occur, facilitating the invaders’ integration into the community. In the present study, the analysis of carbon and nitrogen stable isotopes was used to investigate the trophic overlap of native and non-indigenous consumers. We found a generally low degree of isotopic overlap in both the invertebrate and fish assemblage, a condition that may facilitate coexistence and, in turn, limit the strength of invaders’ impact. The only exception was the Louisiana crayfish Procambarus clarkii, which was demonstrated to interact with a wide spectrum of native invertebrate species, confirming the necessity of guaranteeing appropriate measures of control and mitigation of its ecological impacts.
Abstract
An advanced characterization of the trophic niche of non-indigenous species (NIS) may provide useful information on their ecological impact on invaded communities. Here, we used carbon and nitrogen stable isotopes to estimate pairwise niche overlaps between non-indigenous and native consumers in the winter food web of Lake Trasimeno (central Italy). Overall, a relatively low pairwise overlap of isotopic niches was observed between NIS and native species. The only exception was the Louisiana crayfish Procambarus clarkii, which showed a relatively high and diffuse overlap with other native invertebrates. Our findings highlighted a high niche divergence between non-indigenous and native species in Lake Trasimeno, suggesting a potentially low degree of interspecific competition that may facilitate coexistence and, in turn, limit the strength of impacts. The divergent results obtained for the Louisiana crayfish indicate that additional control measures for this invasive species are needed to mitigate its impact on the Lake Trasimeno system.
... It is proved that the peculiarities of food, in particular, the change of the diet of rudd at different stages of life affects the growth processes of fish (Horppila & Nurminen, 2009). It has been established that in the early stages of development rudd consume phytoplankton, young individuals give preference to microcrustaceans, and adults to macrocrustaceans; S. erythrophthalmus eat more zooplankton in spring and autumn and less in summer (García-Berthou & Moreno-Amich, 2000). ...
Studying fish growth is a complex task because growth depends on many factors. The process of fish growth is influenced by ecological factors of the water environment. Each species of fish has growth characteristics and characteristic changes in this process as a result of the action of natural and anthropogenic factors. We investigated the morphometric features of Scardinius erythrophthalmus in the hydroecosystem conditions of the Horyn River. Fish were caught by amateur fishing methods during 2018–2021 in the section of the hydrographic system of the Horyn River within the Rivne Plateau, which is the northern part of the Volhynian Upland , namely the Horyn River and its tributaries – the Zamchysko River, the Ustia River, and the Stubelka River. The catches included fish aged from 0+ (one-year-olds) to 5+ (five-year-olds). Growth variability was studied for fish aged 1+ to 4+ because their numbers were sufficient for statistical evaluation. We noticed clear features of the morphometric variability of the fish. According to the coefficient of variation for the general populations of S. erythrophthalmus from different rivers, there was mostly significant variability of such growth characteristics as the largest and smallest fish body height, total length, Smith length and short body length of fish. We also noticed the similarity of the morphometric variability of fish of different ages for the Horyn River and Stubelka River and Zamchisko River and Ustia River. The analysis and evaluation of the surface water quality of these rivers was also similar. Thus, Horyn and Stubla districts had a transitional state from II to III quality class, and the Zamchysko River and Ustya River districts had a transitional state from III to IV quality class. We conducted a multivariate regression and it revealed statistical significance and a close correlation between the coefficients of variation of the growth characteristics of fish with the phosphate content in the water (with an average value of the weighting coefficients of 0.50 ± 0.06), nitrite nitrogen (0.39 ± 0.10) and nitrate nitrogen (0.84 ± 0.34). The calculation of the specific growth of fish by full length revealed that the intensity of growth is the highest between the first and second year of life of fish for small rivers (Zamchysko River, Ustya River, Stubelka River) and between the second and third year for the Horyn River. The results presented in the article are valuable and describe the local variation in the morphometric variability of S. erythrophthalmus. This expanded the understanding of the influence of ecological factors of the aquatic environment on the formation of growth characteristics of this species of fish. In the future, our research will continue and study the linear growth of natural fish populations against the background of changes in the ecological and hydrological conditions of the studied region
... Northern pike is described as a cool-water and temperature-tolerant species (i.e., with a wide range of suitable temperatures) (Nordahl et al., 2020;Pierce et al., 2013). Likewise, rudd are considered a temperature-tolerant species (García-Berthou & Moreno-Amich, 2000;Hicks, 2003;Kottelat & Freyhof, 2007), while wels catfish and tench are documented as species that prefer warmer water (Capra et al., 2018;Cucherousset et al., 2018). It can be assumed that species-specific temperature preferences influence the response to seiche dynamics; temperature-tolerant species are likely to respond less strongly than warm-water species to the upwelling cold water, or cool-and coldwater species to downwelling warm water. ...
Internal seiches are common in stratified lakes, with significant effects on stratification patterns, hydrodynamics and vertical nutrient transport. In particular, seiches can change the vertical distribution of the thermocline and the cold hypolimnetic and warm epilimnetic water masses by several metres on a timescale of a few hours, leading to rapid and strong changes in temperature profiles and oxygen availability, with profound effects on mobile and sessile organisms. This could affect fish communities directly, through physiological stress and elevated mortality, and indirectly, through prey distribution.
The aim of this study was to analyse the effects of internal seiche dynamics on lacustrine fish behaviour, and to characterise fish reaction patterns, with the main focus on vertical movement of fish in the vicinity of a shifting thermocline, and avoidance of cold hypolimnetic water.
The analysis was based on acoustic telemetry data from Lake Milada, a post‐mining lake in the Czech Republic, with a total of 61 tracked individuals of four species: northern pike ( Esox luciu s), wels catfish ( Silurus glani s), tench ( Tinca tinc a) and rudd ( Scardinius erythropthalmu s).
The effects of seiche dynamics on the four species studied were weak but significant during the day, while at night they affected only rudd. Upward seiches elicited stronger responses in fish than downward seiches, and the impacts occurred only during the strongest seiche events.
Thermocline shifting during seiche events may induce a transient reduction in habitat for seiche‐reacting species, and thus affect predation and other inter‐ and intra‐specific interactions, as well as fish community dynamics.
... Most of the species recorded in the two lakes were flexible predators or meso-predators such as M. salmoides (Lorenzoni et al., 2002;Marinelli et al., 2007;Feiner et al., 2013;Costantini et al., 2018), P. fluviatilis (Lorenzoni et al., 2007;Svanbäck et al., 2015;Linzmaier et al., 2018), L. gibbosus (Osenberg et al., 1988;Godinho et al., 1997) and A. melas (Kline and Wood, 1996;Leunda et al., 2008), able to shift their diet from macro-invertebrates to prey fish of different size class (including larvae), according to prey availability or shifting with ontogeny as demonstrated by the significant relationships found in this study between nitrogen ratios and body size for most of these species. Other fishes included omnivorous species such as the littoral S. hesperidicus that feeds on macrophytes, zooplankton and zoobenthos (Ravera and Jamet, 1991;Garcìa-Berthou and Moreno Amich, 2000), and A. arborella, an epipelagic zooplanktivore feeding also on algae (Giussani and Ruffoni, 1985;Soric, 2006), which had similar δ 15 N values to meso-predators. Fishes with lower nitrogen ratios were also omnivorous and included the NNS R. amarus that forages on filamentous algae, organic material, and zooplankton (Koutrakis et al., 2003;Bo et al., 2012;Moreva et al., 2017) similarly to the NS R. aula (La Porta et al., 2010). ...
The introduction and establishment of non-native fish species is a widespread phenomenon in freshwater ecosystems, including small and shallow lakes. However, these ecosystems are often not considered in conservation and ecological studies and a few information is available on their fish communities and the impacts of biological invasions. Here, standardized fish surveys (gillnetting and electrofishing) and stable isotopes analysis (SIA) of carbon and nitrogen (δ¹³C and δ¹⁵N) were combined to assess fish community composition, trophic structure and trophic diversity, and to characterize the interspecific trophic interactions (as isotopic niches and their relative asymmetric overlap) of the native and non-native species (NS and NNS, respectively) found in two protected small and shallow lakes, San Michele and Campagna (northern Italy). In San Michele, 92 % of the fish caught were NNS and both the individual and biomass per unit effort were dominated by NNS, particularly by the invasive Lepomis gibbosus L. and Ictalurus punctatus (Rafinesque, 1818). In Campagna, 5.6 % of the fish in the total catches belonged to NNS and the numeric and biomass abundances of the assemblage were dominated by the NS Alburnus alborella (Bonaparte, 1841). SIA revealed that NNS had greater trophic structure and were exploiting a wider range of resources (as per Layman metrics) and had a higher asymmetric overlap than NS assemblages in both lakes. This was also evident when species-specific isotopic ecology was considered, underlining that, in both lakes, NNS (particularly the NNS Ameiurus melas (Rafinesque, 1820)) may have a competitive advantage over NS in case of limiting resources. The results thus pointed to a worrying conservation status of these lakes that may mirror the condition of other Italian shallow and small lakes highlighting the need to implement management actions to preserve these valuable ecosystems.
... Northern pike is described as a cool water species, with a wide range of preferred temperatures (Nordahl et al., 2020;Pierce et al., 2013). Similarly, rudd is considered to be temperature-tolerant species (García-Berthou & Moreno-Amich, 2000;Hicks, 2003;Kottelat & Freyhof, 2007), while wels catfish and tench are documented as species preferring warmer water (Capra et al., 2018;Cucherousset et al., 2018). Species-specific temperature preferences can be assumed to affect response to seiche dynamics, and a lower intensity of responses to seiche dynamics can be expected for temperature-tolerant species than for warmwater species. ...
Internal seiches are common in stratified lakes, with significant effects on stratification patterns, hydrodynamics and vertical nutrient transport. In particular, seiche can change the vertical distribution of the thermocline and the cold hypolimnetic and warm epilimnetic water masses by several meters on a timescale of a few hours. The results are rapid and strong changes in temperature profiles and oxygen availability that can have profound effects on vagrant and sessile organisms. Internal seiche dynamics could therefore affect fish communities directly through physiological stress and elevated mortality, and indirectly through prey distribution.
The aim of this study was to analyze the effects of internal seiche dynamics on lacustrine fish behaviour, and to characterize fish reaction patterns, with the main focus on vertical movement of fish in the vicinity of a shifting thermocline, and avoidance of cold hypolimnetic water.
The analysis was based on acoustic telemetry data from Lake Milada, a post-mining lake in the Czech Republic, with a total of 55 tracked individuals of four species: northern pike ( Esox luciu s), wels catfish ( Silurus glani s), tench ( Tinca tinc a) and rudd ( Scardinius erythropthalmu s).
The effects of seiche dynamics on the four species studied were weak but significant during the day, but only on rudd during the night. Upward seiche produced stronger reactions in fish than downward seiche, and the effects were manifested only during the strongest seiche events.
Thermocline shifting during seiche events may induce a transient reduction in habitat for seiche-reacting species, thus potentially affecting predation and other inter- and intra-specific interactions, and probably affecting fish community dynamics.
Graphical abstract
... erefore, these relatively high concentrations of Hg in the muscles of these fish may not be directly related to their concentrations in water but are due to the phenomena of bioaccumulation and biomagnification [51]. e lowest contents of Hg were found in the muscle of S. erythrophthalmus, whose diet consists mainly of water plants, insects, and crustaceans [52]. Journal of Toxicology e general order of metal bioaccumulation measured in the muscles of the different fish species studied was Hg > Pb > Cd. ...
This study aims to assess the degree of metal contamination (mercury (Hg), cadmium (Cd), and lead (Pb)) in the muscles of five species of fish Esox lucius, Sander lucioperca, Micropterus salmoides, Lepomis macrochirus, and Scardinius erythrophthalmus, from the Mechraâ-Hammadi Dam between July 2017 and May 2018, and to conduct a risk assessment for human consumers. Trace metals were determined by Graphite Furnace Atomic Absorption Spectrometry for the Pb and the Cd and by Cold Vapor Atomic Absorption Spectrometry for the Hg. The results gotten from the study of the muscles of the different fish species show that the higher mean amounts of Cd and Hg were determined in E. lucius, and the maximum mean levels of Pb were detected in S. erythrophthalmus. Results suggested that demersal fishes inhabiting near the sediments and piscivorous fishes with higher trophic level were likely to accumulate higher trace metal concentrations. The general order of bioaccumulation of the trace metals measured in the muscles of the fish species is as follows: Hg > Pb > Cd. Therefore, the bioaccumulation of Hg in fish studied is more important than that of Cd and Pb. Furthermore, these concentrations are higher in summer than in winter for all trace metals. All the values of the trace metals in the muscle tissues are below the maximum limits recommended by the European Community (EC) N° 1881/2006. However, estimation of noncarcinogenic health risks by the target hazard quotient indicated no obvious noncarcinogenic risks to humans that consume those fishes (THQ
... The results presented in this study are in agree with the previous studies which reported that the feeding of both of the species can be characterized as omnivorous (Ravera & Jamet, 1991;García-Berthou & Moreno-Amich, 2000;Okgerman et al., 2013). The high proportions of the empty stomachs for both species can be explained by the fact that the fish specimens remain alive for a while after being caught in gillnets and, the loss of dietary information due to post-capture digestion (Hammerschlag et al., 2010). ...
The feeding habits of two omnivorous fish species, Vimba vimba (L., 1758) and Scardinius erythrophthalmus (L., 1758) from the Büyükçekmece Reservoir (Turkey) were investigated through stomach content analyses. Samplings were carried out monthly to describe the dietary composition of two species and to assess whether it overlapped. The diet spectrum of V. vimba consisted of eight prey categories: Diptera, Insecta extremities, plants, Cladocera, Bivalvia, Ostracoda, Pisces and detritus. Detritus has the highest value in terms
of modified index of relative importance and it was followed by Insecta. The diet composition of S. erythrophthalmus consisted of four prey categories: Insecta extremities, plants, Bivalvia and detritus. Plant has the highest value in terms of modified index of relative importance and it was followed by detritus. No dietary overlap was detected, except for the fish collected in spring. Fractional trophic level (TROPH) and its standard error (SE) were estimated as 2.62±0.25 for V. vimba and 2.45±0.19 for S. erythrophthalmus.
... Tench is reported to primarily feed on benthos (Perrow et al., 1996). Roach and Rudd additionally forage throughout the water column, with Rudd being best adapted to feeding on prey at the water surface (Kennedy and Fitzmaurice, 1974;García-Berthou and Moreno-Amich, 2000). Their feeding behavior may vary in relation to temperature and according to the seasonal and spatial availability of food (e.g., Brabrand, 1985;Jamet, 1994;Michel and Oberdorff, 1995;Guinan et al., 2015). ...
Whether fish mediate plant dispersal in temperate freshwaters is largely unknown. A prerequisite for successful dispersal is ingestion and surviving the journey in the intestinal tract. This study asks whether plant propagules are being ingested under field conditions and what factors shape dispersal potential, focusing on differences across plant species and propagule form (seed or fragment), seasonal differences and plant and fish traits that facilitate dispersal. We focused on three common fish species reported to differ in foraging strategy. Fish were caught monthly over a 1-year period in a Dutch lowland stream. Before they were returned to the stream, fish were kept in water for 26 h and their feces were collected, resulting in 150 fecal samples. Excreted animal remains and plant propagules were identified and enumerated. Plant propagules were tested for viability. In total, 88,579 vegetative fragments of vascular plants, 316 of mosses and 14 of charophytes were identified. Viability was low (<<1%) except for mosses (53.5%). Roach (Rutilis rutilis) and Rudd (Scardinius erythrophthalmus) displayed a preference for filamentous algae and certain plant species (i.e., Elodea nuttallii and Lemna sp.), likely because they were more palatable. Of the 1,787 generative propagules of vascular plants that were identified, 120 germinated (6.7%), representing 15 species. Betula pendula, Juncus effusus, and Poa trivialis were most abundant. Tench (Tinca tinca) egested most seeds, despite being the least herbivorous species. Particularly, germination was high for seeds that were light (<1.07 mg) and that floated for a long time. Our results show that fish do ingest plant propagules under field conditions and that fish can contribute to vegetative dispersal of vascular plants and several aquatic and riparian moss species. Ingestion of propagules is affected by water temperature and season, their availability in the propagule bank, and their palatability. Both seed traits (related to buoyancy, size and hardness) and fish traits (related to size and identity) were important. Despite substantial dietary overlap, the three fish species displayed subtle differences in their diet, and together can act as vectors for the dispersal of a range of plant and moss species of freshwater systems.
... They are small to medium size fishes adapted to temperate waters with submerged vegetation, such as lowland lakes, and lentic parts of rivers and streams (Valic et al. 2013). According to Berthou and Amich (2000), they are littoral species, and closely associated to vegetation related to their high degree of herbivory (Niederholzer and Hofer 1980; Prejs 1984). The genus Scardinius consists of approximately 10 species (Eschmeyer et al. 2016) that 2 of them are found in Turkish inland waters. ...
This study was conducted to report five new localities out of its type locality for Scardinius elmaliensis in the Western Mediterranean Basin of Turkey by providing their morphological characteristics, and their phylogenetic relationship based on mtDNA Cytb region. The results revealed significant differences of all studied populations in terms of the morphometric characters despite their low genetic differences, but their meristic characters were not different. All six studied populations of S. elmaliensis including that of type locality formed a monophyletic group with S. erythrophthalmus as sister group. The molecular result confirmed distinction of S. elmaliensis from S. erythrophthalmus based on Cytb genetic distance of 1.6-1.8%. The occurrence of S. elmaliensis out of type locality was firstly reported in this study. Such knowledge is important for future conservation strategies and habitat management of this species.
... This finding was similarly observed for the non-native zooplanktivorous rudd Scardinius erythrophthalmus (L. 1758) introduced into Iberian lakes, where this cyprinid displays higher levels of herbivory and detritivory than con-specifics from the native range (García-Berthou & Moreno-Amich, 2000a). River ecosystems are structurally more complex than nearby reservoirs. ...
The bleak Alburnus alburnus (L., 1758) is a limnophilic fish native to most of Europe. This cyprinid species is a successful invader in the Iberian Peninsula, where it threatens the highly endemic fish fauna. However, studies on bleak autoecology are scarce in this region, with few data on foraging strategies. The aim of this work was to compare the dietary traits of bleak populations between contrasting habitats in Iberian fresh waters. For this purpose, bleak were seasonally collected from the small River Gévora and the Sierra Brava Reservoir (Guadiana River Basin, southwestern Spain). As percentages of occurrence and ingested mass, plant material and planktonic Crustacea were the most important food categories in the river and the reservoir, respectively. The intake of pelagic prey was higher in the reservoir, especially during summer. Benthic prey, plant material and detritus were more consumed in the river, especially benthos and detritus during spring, whereas plant intake decreased during this season. Shannon index, as a measure of trophic diversity, was higher in the reservoir, except for spring. Overall results suggest that this wide trophic plasticity will facilitate the bleak invasion process throughout Mediterranean Europe, which poses a serious risk to its highly valuable native fish fauna.
... Roach (Rutilus rutilus) have a similar diet to carp but is more zooplanktivorous (Garc ıa Berthou 1999Berthou , 2001Horppila & Nurminen 2009) and also feed on zebra mussels depending on fish size (Prejs, Lewandowski & Sta nczykowska-Piotrowska 1990). Rudd (Scardinius erythrophthalmus) usually feeds on plants and with less extent on detritus and small invertebrates (Garc ıa Berthou & Moreno-Amich 2000;Horppila & Nurminen 2009). We will show that stable isotopes alone can hardly reproduce these feeding patterns and that the use of trace metal markedly improves the estimations. ...
Food web structure is a fundamental feature of ecosystems. Stable isotopes ( δ ¹⁵ N and δ ¹³ C) are used to estimate the relative contribution of food sources to consumer's diets (e.g. mixing models).
In complex food webs, the use of δ ¹⁵ N and δ ¹³ C measurements cannot always solve trophic interactions and distinguish among aquatic organisms with different feeding habits if little intra‐ and interspecific isotopic differentiation occurs.
We have developed a method to characterize trophic relationships using Bayesian stable isotope mixing models in combination with trace metal data as prior information. Trace metal information is useful because of the high correspondence between trace metal profiles in consumers and their food sources, as we show here in an example of concentrations of fish and their expected dietary items.
Trace metal concentration allows a more accurate estimation of relative contributions of food sources to consumer species compared to estimates based only on stable isotope values. We show the improvement of the procedure using four freshwater fish species with well‐known feeding habits. The method provides a better estimation of the inter‐ and intraspecific dietary variability and correspondence with the feeding habits of these species.
The approach described shows a considerable potential as a tool to assess trophic links in situations in which stable isotope methods are not conclusive. The method can be applied using other compounds that bioaccumulate in consumers (e.g. persistent organic pollutants).
... Moreover, the shrimp has been observed in the stomach contents of different fish species, namely Scardinius erythrophthalmus (L., 1758) (cf. García-Berthou & Moreno-Amich, 2000a) and Lepomis gibbosus (L., 1758) (cf. García-Berthou & Moreno-Amich, 2000b), as well as in Squalius pyrenaicus (Günther, 1868) (cf. ...
This paper reports population dynamics, growth, and reproductive features of Atyaephyra desmarestii (Millet, 1831) from the estuary of the River Minho. Also, data were compared to information available from its distribution range. Samples were taken monthly between October 2010 and September 2011. Males were less abundant and smaller than females. The growth pattern showed hardly any increase during the autumn and winter, but a fast increase in size was recorded in spring, followed by slower growth in summer. The life span was 11-12 months. The reproductive period was from April to August, and mean fecundity reached 643 ± 254 eggs/female. Juveniles started to appear in July and a strong recruitment occurred in summer and autumn. The ecological relevance of the shrimp supports the need of obtaining further and more specific knowledge on the relationship between geographical distribution and water quality. Our results coupled with longer time series in different localities will be essential to the conservation of the species.
... Second, our sampling gears were restricted to relatively shallow waters (≤3 m) of Buffalo Harbor and the upper Niagara River. The rudd is typically described as a littoral species (Johansson, 1987;Lake et al., 2002), and García-Berthou and Moreno-Amich (2000) reported only capturing rudd in trammel nets set at 0-2 m in Lake Banyoles, Spain, despite sampling to depths of 20 m. Although we sampled optimal habitats, our estimates may have been too low if we failed to sample rudd in deeper waters. ...
The invasive rudd and grass carp consume aquatic macrophytes, thereby altering important habitat, creating novel trophic pathways, and adversely affecting indigenous species. We estimated the abundance and biomass of rudd and their consumption of macrophytes in Buffalo Harbor (northeastern Lake Erie) and the upper Niagara River during 2012–2013. We also estimated consumption of macrophytes by hypothetical populations of grass carp equal in biomass to rudd populations. Using mark-recapture methods, we estimated that 2571 (95% CI: 2362–2821) rudd were present in Buffalo Harbor and 142,957 (95% CI: 135,127–151,751) were present in the upper Niagara River. Biomass of rudd was estimated at 1.89 mt (95% CI: 1.73–2.07) in Buffalo Harbor and 100.21 mt (95% CI: 94.72–106.38) in the upper Niagara River. Using observed water temperatures and published consumption rates, we estimated that (1) rudd could have consumed 98 mt of macrophytes in Buffalo Harbor and 5210 mt in the upper Niagara River, and (2) hypothetical populations of grass carp equal in biomass to rudd could consume 96 mt of macrophytes in Buffalo Harbor and 4941 mt in the upper Niagara River. Rudd abundance and biomass are substantial in these two waters, and consumption of aquatic macrophytes by rudd may threaten existing aquatic habitat and restoration projects. Annual standardized surveys of fish and macrophyte assemblages would provide data necessary to monitor rudd populations, detect invasion and reproduction by grass carp, and assess habitat changes resulting from herbivory by these two invasive fishes.
... Empirical evidence for these hypotheses was provided by studies of non-native cyprinids feeding on larvae of endangered native fish species in the U.S. (Bestgen and Beyers, 2006;Carpenter and Mueller, 2008), of minnows Phoxinus phoxinus (L.) predating on vendace larvae Coregonus albula (L.) at low zooplankton densities (Huusko and Sutela, 1997), and of accidental observations of fish in the diet of planktivorous species such as rudd Scardinius erythrophthalmus (L.) (Garcia-Berthou and Moreno-Amich, 2000), ide Leuciscus idus (L.), and roach Rutilus rutilus (L.) (Brabrand, 1985). ...
Predation by zooplanktivorous cyprinids was hypothesized as substantially contributing to larval fish mortality. To test this assumption, potential predators were sampled by electric fishing at sites and times of high fish larvae densities in the lower Oder River, Germany, in 2002 and 2003. At ten sites with high prey fish densities, all fishes ≥1+ and 0+ pike – all considered potentially predating on fish larvae – were captured, anaesthetised, and fixed. In the laboratory, 982 guts, respectively, stomachs were dissected and checked for fish larvae and larvae remains. Predation on 0+ fish was detected in the primary piscivorous fishes Esox lucius L. and Aspius aspius (L.), and facultative piscivorous Perca fluviatilis L., whilst none of the other nine species examined consumed fish. These findings implicate that predation by planktivorous cyprinids did not explain the typically strong decline in larval fish densities in the first weeks after hatching.
... Because of the high ecological adaptability and the small interest by commercial fishermen, the species is able to acclimatize successfully in new environments and can become predominant in fish community. R. rutilus can competes with other species such as S. erythrophthalmus (Niederholzer and Hofer, 1980;Volta and Jepsen, 2008) more sensitive to environmental changes ( Garcia-Berthou and Moreno-Amich, 2000;Ravera and Jamet, 1991). In Piediluco lake the population of R. rutilus has significantly increased in recent years: in 1999 the species was absent in the lake; in 2004 it represented only 4.82% ), while in the present research R. rutilus reached 35.20% of total biomass captured. ...
The analysis of catch selectivity of fishing equipment is a crucial step for the management of alien species in freshwater ecosystems. Roach Rutilus rutilus was introduced in many waterways in Italy often becoming the dominant species of the fish community and it is now considered potential pest. In Piediluco lake the species was first found in 2004 and its abundance has increased at a level that creates concern for the other fish species present in the lake. The growth of R. rutilus and the selectivity of gill-nets on its population were examined in Piediluco lake by analysing the selectivity of gill-nets of different mesh size. Sampling was conducted from January 2011 to October 2012 by means of gill-nets of different-sized mesh (8, 10, 12.5, 15.5, 19.5, 24, 28, 35, 45 and 55 mm). The results showed that R. rutilus in Piediluco lake had a growth faster and higher than in many other lake environments. The results of gill-nets selectivity gave important information to design a plan to control this species and confirmed that the use of suitable fishing techniques could be useful to manage the population of this alien species in Piediluco lake as well as in other similar environments
... A pesar de la importancia ecológica que todos estos hechos podrían conferir al camarón de río, los datos sobre su distribución en España son en general escasos, conociéndose su presencia en el río Támega en Orense (FERNÁNDEZ DE LA CIGOÑA & OUJO, 2001), así como en el lago de Bañolas por ser presa de distintas especies de peces (GARCÍA-BERTHOU & MORENO-AMICH, 2000a, 2000bGARCÍA-BERTHOU, 2002). Con esta nota se pretende aumentar el conocimiento sobre la presencia de esta especie en la cuenca del Ebro, poniéndola, además, en relación con la calidad del agua. ...
... It feeds on zooplankton and filamentous algae (Johansson, 1987). The foraging habitat is close to the water surface , also in newly colonised habitats (Garcı´a-Berthou & Moreno-Amich, 2000) where neustonic prey is included in the diet. Dragonflies and other macroinvertebrates are usually lacking in the diet. ...
1. Freshwater communities are often structured by predation. In permanent lentic freshwater habitats dragonfly larvae are major predators which, in return, suffer predation by fish. Antipredator traits vary between the dragonfly species, and the dragonfly communities are therefore shaped by the presence of fish. But fish communities vary, and as different fish species affect dragonflies in different ways, the species composition of the fish community may affect the composition of the dragonfly community.
2. We sampled dragonfly larvae in 24 lakes with a known fish stock in south-western Sweden, and explored the impact of fish as well as vegetation structure on dragonfly communities by means of multivariate analyses.
3. We found that the presence of four fish species affected the community structure of dragonflies. The impact strength depended mainly on the abundance of Perca fluviatilis, with which most dragonfly species were negatively correlated. Many dragonfly species were also positively correlated with the occurrence of at least one fish species, which may reflect similar habitat requirements or imply indirect positive effects of these fish species.
4. Of the 24 recorded dragonfly species, four did not occur in lakes dominated by P. fluviatilis, whereas only one species was lacking in lakes dominated by Rutilus rutilus. The dragonfly species diversity was higher in R. rutilus lakes than in P. fluviatilis lakes.
5. Our results suggest that the fish species composition is a major determinant of the dragonfly community, which in turn will influence the lower trophic levels.
... Even if the real effect of most exotic fish introductions on Iberian fish species is still unknown (Elvira & Almod´ovar, 2001), a growing research effort in recent years is contributing to the quantitative information available. In particular, feeding studies based on stomach content of some exotic fishes have already been carried out in Iberia (Garc´ıa-Berthou, 1999a, b;Garc´ıa-Berthou & Moreno-Amich, 2000a;Garc´ıa-Berthou, 2001), some of them showing clear negative interaction through predation on native fishes Nicola et al., 1996;Dom´ınguez & Pena, 2000;Garc´ıa-Berthou & Moreno-Amich, 2000b;Dom´ınguez et al., 2002;Garc´ıa-Berthou, 2002;Rinc´on et al., 2002). The goal of the present research was to evaluate for the first time the threat of the exotic black bullhead by direct predation on and competition with the native ichthyofauna through dietary analyses. ...
The feeding ecology of the exotic invasive black bullhead Ameiurus melas was conducted in the Iberian Peninsula for the first time. Dietary analysis based on the stomach contents of individuals caught in several Iberian basins was carried out as a first step to evaluate its potential threat for the native Iberian ichthyofauna. Aquatic macroinvertebrates (mainly Chironomidae) dominated the black bullhead's diet in all size-classes and sites, irrespective of natural riverine or artificial lentic habitats. Secondary prey items were responsible for the observed between-sites (microcrustaceans in artificial lentic habitat; oligochaeta and caddisfly larvae in natural riverine habitats) and ontogenetic diet differences (from microcrustaceans to larger prey). These diet variations were also detected in trophic diversity values and feeding strategy plots. Black bullheads consumed plant material, terrestrial prey and co-occurring fish species (native or exotic) and thus they could be considered as generalist or opportunistic, foraging on the most abundant and available prey. There was no positive relationship between black bullhead size (total length) and fish prey size, probably indicating piscivory on dead or dying vulnerable fishes as well as predation on smaller-sized active fishes. The results showed that the black bullhead could negatively affect native Iberian ichthyofauna throughout direct predation and competition. Aspects of potential conservation and management implications of fishes resulting from the undesirable presence of the black bullhead in Iberian water bodies are discussed.
... obs.). This gives the roach an advantage against the rudd which is a typical phytophilic fish species (Niederholzer & Hofer 1980; Ravera & Jamet 1991; Garcia-Berthou & Moreno-Amich 2000). Moreover, roach spawn between March and late May, at least one month earlier than rudd and bleak. ...
Very recently, a common cyprinid fish species at northern latitude, the roach (Rutilus rutilus L.) has been observed in the large south-alpine Lago Maggiore for the first time. The colonization of the lake has the characteristics of an invasion. In order to investigate this new fish population, benthic multi-mesh and commercial gill nets were used to sample fish in a wide gulf in the central part of the lake (Golfo Borromeo) from February to October 2006. In total 779 roach (TL: 5.5 – 38.8 cm) were caught, aged, sexed and stomach analyzed. Fecundity was assessed by counting the eggs in ripe gonads of females of age 3 and 4. The roach have become clearly the dominant species in the catches, constituting over 70% of the biomass and 70% of the numbers caught. None of the roach exceeded 8 years in age. They grow very fast (Φ' = 2.55) and have high fecundity (F abs = 13740 ±4700 S.D. at age 3 and F abs = 14768 ±5642 S.D. at age 4). The diet spectrum is wide and characterized by a strong seasonality. In early spring algae (benthic and planktonic algae), benthos and detritus prevail, whereas in summer zooplankton is the most frequent food item. In autumn roach switch back to benthos and detritus. Algae occur more frequently in young specimens while zooplankton, benthos and detritus in adults. The roach population is practically unimpacted by fishing. The minimum legal mesh size (25 mm) of gillnets, used by commercial fishermen, selects roach at the mean L T of 21.2 cm, which is over its length at maturity. The results suggest that roach established a viable population in Lago Maggiore less than a decade ago and rapidly became one of the dominant (if not the dominant) fish species. The possible consequence for the fish fauna in general and for the ecological status of the whole lake is briefly discussed.
... Average THg concentrations (in ww) in muscle of European catfish (n ¼ 9), common carp (n ¼ 30), rudd (n ¼ 20), and roach (n ¼ 5) were 0.848 AE 0.476 mg/g; 0.333 AE 0.155 mg/g; 0.283 AE 0.163 mg/g; and 0.217 AE 0.199 mg/g, respectively. The relative trophic level of the analyzed species is based on a generalized knowledge of the species and stomach contents of the studied adult fish populations [56,60,62,71]. ...
It is well known that chlor-alkali industry has traditionally used the mercury (Hg)-electrolysis process to produce mainly chlorinated solvents. Unfortunately, a fraction of the Hg used during production is released through drainage into the aquatic environment where it can be incorporated to biota. In Europe, Spain and Germany are leading in the number of plants which still use this technology. Moreover, it should be highlighted that three out of the eight chlor-alkali plants in Spain which are still operating with this process are located in the Ebro River basin in the proximities of Sabiñánigo and Monzón cities – along the tributaries Gállego and Cinca Rivers, respectively – and Flix along the Ebro River. Therefore, the mid-low Ebro River watershed might be considered as a hot spot of aquatic mercury pollution in Spain.
This chapter focuses on all the information published up to date about total mercury (THg) and organomercury, with special emphasis on methylmercury (MeHg), in different aquatic organisms sampled along the Ebro River.
First, a brief explanation of the current knowledge regarding the sources and cycling of Hg and its transformation into MeHg is presented. Later, in this chapter, THg and limited data on organomercury levels in aquatic organisms of the Ebro River basin are detailed. The aquatic organisms most commonly studied in the Ebro River basin are zebra mussel, red swamp crayfish, and different fish species, namely European catfish, northern pike, common carp, rudd, roach, barbell, and bleak.
According to the different sentinel species analyzed, THg levels in specimens collected downstream from the impacted areas are 10–20 times greater than upstream levels. It clearly points out the relevance of chlor-alkali plants in terms of mercury river pollution.
Graphical Abstract
... Rudd are not highly selective feeders; on the contrary, they eat most suitable-sized submerged macrophyte species that are available (Prejs & Jackowska, 1978). Filamentous algae (mostly Con-jugales algae) are especially important in the rudd diet (García-Berthou & Moreno-Amich, 2000). In Kirkkojärvi, the submerged macrophyte community is composed of a mixed vegetation of e.g. ...
The role of rudd (Scardinius erythrophthalmus) herbivory was studied in Kirkkojrvi, a shallow and turbid basin in Lake Hiidenvesi, Finland. The submerged species dominating in the rudd diets were Potamogeton obtusifolius, Ranunculus circinatus, Sparganium emersum, bryophytes, and filamentous algae. Plant consumption estimated with bioenergetics modelling increased with fish age, being highest in late summer concomitant with the macrophyte biomass peak. Depending on the age structure, a rudd biomass of 20 kg ha–1 consumes 18–23 kg of macrophytes ha–1 a–1, while a rudd biomass of 100 kg ha–1 results in plant consumption of 92–115 kg ha–1 a–1. Although, rudd seemed to feed rather unselectively on suitable-sized and edible plants, some species abundant in the littoral, such as Myriophyllum verticillatum and pleustophytic Ceratophyllum demersum, were not found in rudd guts, indicating selective plant consumption. In Kirkkojrvi, selective grazing by rudd and increased turbidity and high nutrient levels partly caused by bottom dwelling cyprinid fish, may promote the inedible and pleustophytic macrophytes, which have increased in Kirkkojrvi during the past decades.
The provided information outlines a study conducted on the diet and feeding relationships of two species, Sarmarutilus rubilio (near threatened) and Scardinius erythrophthalmus, in the largest water reserve in Tunisia, Sidi Salem. Both species are introduced and are the most abundant in the reservoir. They share the same food resources, with macrophytes being the primary component of their diet, especially for S. erythrophthalmus, Macrophytes accounting for 77.78% of its diet.
The second most important prey category for both species is Arthropoda. Additionally, there are other prey categories such as Cyanobacteria, Microalgae, Nematoda, and Sand, but these are ingested by both species in lower proportions (%PV < 1.5).
S. rubilio, outside its native area, maintains its feeding plasticity
The study revealed some differences in the diet of the two species. For S. erythrophthalmus, variations in diet were observed among seasons, while for S. rubilio, variations were observed among different stations within the reservoir. Both species were found to have narrow niche breaths, indicating specialized feeding habits. Despite these variations, the diets of the two species showed significant overlap.
The research highlights the feeding ecology of S. rubilio and S. erythrophthalmus outside their native range. This information can be valuable for developing future fishery management plans and biodiversity preservation strategies in Tunisian freshwater systems. Understanding the feeding preferences and interactions between these introduced species can aid in maintaining a balanced ecosystem and conserving the native species in the region. Considering that S. rubilio is categorized as near threatened, such knowledge becomes even more crucial for effective conservation efforts.
Over recent decades, many Mediterranean and Ponto-Caspian aquatic invertebrate species have dispersed northwards and
established as non-native species in colder regions. We hypothesized that these species have cold-tolerant traits, which facilitate
dispersal into colder climates. Thanks to these traits, Southern European aquatic species are able to cross biogeographic
boundaries. We downloaded the list of all alien invertebrate species that were fully aquatic (i.e. lacking terrestrial adults) from
the GRIIS database and picked out those Mediterranean and Ponto-Caspian species that have undergone northwards range
expansion. We identified traits that may facilitate dispersal to colder climates including the following: small size; capacity
for behavioural thermoregulation; feeding habit (omnivorous, filter-feeders, food generalists); quiescence and dormancy
(or diapause); freezing avoidance (presence of cryoprotectants); tolerance to low temperatures or eurythermicity; active
dispersal; and enhanced reproduction. We statistically tested the null hypotheses that Mediterranean and Ponto-Caspian
alien aquatic invertebrate species that dispersed into the north have all of these traits. We used contingency tables populated
with raw frequency data with χ2—tests and assessed statistical significance at α of 0.05. We identified 95 Mediterranean and
Ponto-Caspian alien aquatic invertebrate species that have shown northwards range extension, 10 (10%) of which were of
Mediterranean origin and 85 (90%) of Ponto-Caspian origin. We found that this northwards dispersal from Southern Europe
is mainly limited to a few following groups of aquatic invertebrates: small crustaceans, molluscs, cnidarians and annelids.
Ability to go to diapause, hibernation or resting period, temperature tolerance and small size were the traits most commonly
shared by these organisms. We conclude that Mediterranean and Ponto-Caspian aquatic invertebrate species showing northwards
range expansion have cold-tolerant strategies. The traits analysed can favour the establishment of the species.
Le présent rapport dresse un profil des proies recensées dans les contenus stomacaux examinés des poissons du Réseau de suivi ichtyologique du fleuve Saint-Laurent (RSI) de 2016 à 2019 et présente la contribution des espèces exotiques envahissantes dans leur régime. Durant cette période, les poissons ont été échantillonnés dans sept secteurs du fleuve Saint-Laurent et de ses tributaires, soit le lac Saint-Louis, le lac Saint-Pierre, le tronçon situé entre Bécancour et Batiscan, le lac des Deux Montagnes, la rivière Richelieu dans les secteurs de la baie Missisquoi et du Haut-Richelieu.
Au cours des quatre années d’inventaire, 3 019 estomacs ou tractus digestifs ont été prélevés et examinés chez 10 espèces de poissons. Les espèces dont l’estomac a été examiné sont : le grand brochet (Esox lucius), le maskinongé (Esox maskinongy), les achigans à petite et grande bouche (Micropterus dolomieu, Micropterus salmoides), le baret (Morone americana), le bar rayé (Morone saxatilis), la perchaude (Perca flavescens), les dorés jaune et noir (Sander vitreus, Sander canadensis) ainsi que le gardon rouge (Scardinius erythrophthalmus).
Une grande diversité de proies a été répertoriée dans les contenus stomacaux des poissons du RSI. Des analyses classiques comme le calcul de la fréquence d’occurrence des estomacs vides, le nombre moyen de proies ainsi que leur fréquence d’occurrence dans les estomacs examinés ou pour un nombre donné d’estomacs chez certaines espèces sont présentées.
Plusieurs espèces exotiques et envahissantes ont été détectées dans les contenus stomacaux des poissons capturés au cours de cette période. La présente étude a permis de confirmer que le gobie à taches noires représente une proie importante pour la majorité des espèces piscivores, et ce, dans tous les secteurs étudiés du système du Saint-Laurent qu’il fréquente et où il abonde. L’examen des contenus stomacaux d’espèces exotiques et envahissantes, telles que le gardon rouge, permet d’apporter les premières précisions sur sa niche alimentaire, du moins à l’automne, et d’anticiper ses répercussions potentielles sur les herbiers aquatiques. L’exercice réalisé au cours de la période 2016-2019 a aussi révélé deux nouvelles espèces aquatiques envahissantes dans le régime alimentaire des poissons du fleuve Saint-Laurent et de la rivière Richelieu, soit la crevette rouge sang et la tanche.
Resum El professor Ramon Margalef és l'ecòleg més important que ha tingut l'Estat espanyol. Va inspirar i formar més d'una generació d'ecòlegs ibèrics i llatinoamericans, ja fos directament a través dels seus consells, classes i conferències com, encara avui, a través dels seus articles o llibres, especialment els tractats monumentals Ecología i Limnología. Revisem, breument, el coneixement de la limnologia i especialment de l'ecologia dels peixos de l'estany de Banyoles. La limnologia més clàssica i l'ecologia de peixos continentals sovint han anat poc lligades per diversos motius, essencialment pels mètodes emprats, les aproximacions conceptuals i les diferents escales espacials i temporals utilitzades. L'estany de Banyoles també reflecteix aquest fet: un dels primers treballs que Margalef va publicar (1946) va ser sobre l'Estany i hi va dirigir dues de les seves primeres tesis doctorals, però no va ser fins a finals dels anys vuitanta que s'hi van iniciar els primers estudis de peixos. Des de llavors, s'hi han realitzat quatre tesis doctorals centrades en els peixos i se n'han publicat nombrosos articles a revistes internacionals, que aquí intentarem breument resumir. També plantejarem algunes preguntes que ens semblen interessants per a futurs estudis. Abstract Professor Ramon Margalef was the most important Spanish ecologist. He inspired and trained more than a generation of Iberian and Latin American ecologists, either directly through his advice, conferences and lectures or, even today, through his articles or books, especially the monumental treatises Ecología and Limnología. We briefly review the knowledge of limnology and especially of the ecology of fish in Lake Banyoles. Classical limnology and ecology of inland fish have often been poorly linked for various reasons, essentially by many differences on their techniques needed, conceptual approaches, and spatial and temporal scales. Lake Banyoles also reflects this: although Margalef published one of his first works (in 1946) and directed two of his first doctoral theses on it, it was not until the late 1980s that the first research on fish started. Since then, four doctoral theses focusing on fish have been written and numerous research articles have been published in international journals, which we will briefly summarize here. We also suggest some questions for future research in Lake Banyoles.
This study was conducted to determine age and growth features of 1329 rudd,
Scardinius erythrophthalmus (L., 1758) individuals caught from Lake Ladik between
November 2009 and December 2010. A total of 260 samples collected in February
and March 2010 was used to estimate the reliable bony structure for ageing. Five
hard parts such as scale, vertebra, opercle, lapillus and asteriscus were aged three
times by one reader. Age data obtained from different bony structures were
compared using the percent agreement (PA), average percent error (APE) and
coefficient of variation (CV). The hard structure indicating the highest PA and the
lowest APE and CV values was preferred to others for age determination. The von
Bertalanffy equation parameters of growth in length and weight were calculated
according to ages of the reliable bony structure. Length-weight relationship and
condition factor were examined.
Lapillus was found as the most reliable hard part for age estimation. Age
distribution of sampling was 2-7 years and sex ratio (F/M) was 1/0.16. The von
Bertalanffy growth equation parameters were calculated as L∞=39.32 cm,
W∞=1504.92 g, K=0.08 (year-1
), t0=-1.08 (year) for females and L∞=28.19 cm,
W∞=448.03 g, K=0.13 (year-1
), t0=-1.19 (year) for males. Length-weight
relationships of females and males were obtained as W=0.0060 FL3.386 and
W=0.0078 FL3.282, respectively. Condition factor in both sexes displayed an upward
trend with age and length groups. Mean condition factor values of females, males
and all specimens were computed as 1.737, 1.667, and 1.727, respectively.
Consequently, it is suggested that rudd population inhabiting L
Într-un ecosistem lentic, ce apare ca un adevărat microcosmos, ca o lume în miniatură formată din compartimente bine evidenţiate legate unele de altele printr-o reţea complicată, orice factor perturbator cu acţiune asupra unei singure specii va afecta, mai devreme sau mai tîrziu, întregul ansamblu. Zooplanctonul, prin structura şi funcţiile sale, este indispensabil desfăşurării normale şi eficiente a circuitului materiei şi energiei într-un bazin acvatic de tip lentic. Cuprinzînd grupuri taxonomice diverse, cu cerinţe şi valenţe diferite, zooplanctonul reprezintă într-adevăr veriga de legătură între toate celelalte compartimente ale ecositemelor lentice, asigurîndu-le supravieţuirea şi autosusţinerea.
Acesta este motivul pentru care una din componentele zooplanctonului, aceea a microcrustaceelor, a fost aleasă pentru studiu în teza mea de doctorat, ce este concretizată în lucrarea de faţă.
Lacul Ştiucii a fost declarat Rezervaţie Naturală încă din anul 1966, statutul său fiind reconfirmat în 1974 iar suprafaţa iniţială propusă pentru conservare fiind ulterior extinsă în 1994 şi 2004. Lacul Ştiucii este din 2001 inclus în reţeaua EMERALD şi mai mult, este una dintre Ariile de Importanţă Avifaunistică (A.I.A.). Din 2011 Lacul Ştiucii este inclus în următoarele situri Natura 2000: ROSPA0104 Valea Fizeşului-Sic-Lacul Ştiucilor şi ROSCI0099 Lacul Ştiucilor-Sic-Puini-Valea Legiilor, a căror custozi sunt Asociaţia Educaţional Ecologică ECOTRANSILVANIA şi Asociaţia ECOCHOICE. Aceste organizaţii mai au în custodie rezervaţiile naturale Lacul Ştiucilor, Stufărişurile de la Sic, Pădurea Ciucaşului şi Valea Legiilor.
The study was conducted in an artificial reservoir, adjacent to a nuclear power plant, in which water temperatures are cool in the winter (8.2 – 12.4°C) and rise early in the spring (April : 14.7°C) nearly 5°C and 3°C over the temperature of its tributary (Moselle river), respectively. The absence of stratification (neither thermocline nor oxycline exist) and the constant water level provided a unique opportunity to observed fish distribution with low abiotic constraints. In one hand, temporal and spatial distributions of the fish community were studied in both littoral and pelagic area. The time survey separated two major groups of young of the year (YOY) according to their time of appearance; the first represented the progeny of early-spring spawning species whereas the second resulted from later-spawning species. Ontogenetic niche shifts of coexisting species were appreciated and for example during late spring and summer, the smallest white bream YOY (LT < 20 mm) were restricted to complex habitats whereas those of pumpkinseed occupied all available habitats. Growing white bream progressively migrated to open water before reaching pelagic areas. There, the vertical distribution of fish was studied using gill net time series. Seasonal and species-specific distribution patterns were highlighted. During the autumn, many species were sampled in deeper water whereas pumpkinseed was the only one sampled in abundance in the littoral zone. Pumpkinseed introduction success might be explained by both its late hatching and its opportunistic strategy in habitat selection enabling it to exploit space left vacant. In the other hand, life history reactions of fish exposed to heated waters were studied particularly in the pumpkinseed population. Fast growth among young of the year, precocious maturity and short life-span were observed, in contrast to related studies. The short life span appeared to be the price paid for early maturity in breeding fish, which suffered high mortality rates just after their first reproduction. These findings should prove helpful in predicting ecological responses to climatic change.
Dietary shifts of invasive rudds Scardinius erythrophthalmus (Linnaeus, 1758) and food web structure of the upper Niagara River were examined. Stable isotope analysis (SIA) of liver tissue was used to test the hypothesis that rudds shifted their diets from piscivory during early spring months when macrophyte availability was low towards herbivory when macrophytes were abundant and warmer water temperatures facilitated digestion. Muscle tissue was used to evaluate the trophic position of rudds and other invasive species relative to native species. SIA revealed enriched δ15 N and depleted δ13 C in liver tissue of rudds during early spring months, suggesting a mostly piscivorous diet of pelagic origin when macrophyte availability was low, and depressed δ15 N and elevated δ13 C values during warmer summer months when littoral macrophytes were abundant. Analysis of muscle tissue from late summer indicated that rudds and other invasive fishes, including common carp Cyprinus carpio (Linnaeus, 1758) and goldfish Carassius auratus (Linnaeus, 1758), had similar trophic positions that may be attributed to their omnivorous feeding strategies. The ability of rudds to shift their diets from feeding on fishes of pelagic origin towards consuming littoral macrophytes is an adaptation that is likely to both facilitate invasion and create novel pathways of nutrient transfer among habitat types. Our results provide an increased understanding of the feeding ecology of the rudd and the role of this invasive species in the food web of the upper Niagara River.
The invasive, omnivorous rudd Scardinius erythrophthalmus is abundant in the upper Niagara River, a Great Lakes Area of Concern. Invasive species can alter trophic and contaminant pathways, but complex ontogenetic and seasonal diet shifts by rudds make it difficult to predict their chemical burdens relative to other fishes. We quantified concentrations of chemical residues in rudds and compared them to six fish species from various trophic levels. Rudds contained low concentrations of total dichlorodiphenyltrichloroethane (mean = 0.02 μg/g), Hg (mean = 0.03 μg/g), and polychlorinated biphenyls (mean = 0.06 μg/g); these concentrations were among the lowest for all species examined. Concentrations of aldrin, heptachlor, hexachlorobenzene, total hexachlorocyclohexanes, mirex, and total chlordanes were less than the method detection limit for all rudds examined. If reducing rudd biomass is determined to be beneficial, resource managers could consider targeted harvest, given the low concentrations of contaminant in rudds and their susceptibility to capture.
The present work is the first integral analysis of the influence of different types anthropogenic pressure and impact on the freshwater ecosystems in our country. A total of 173 samples of benthic macroinvertebrates, zooplankton and fish from specially selected 17 lentic and 31 lotic sampling points at water bodies of diverse type of pressure are studied. The taxonomic composition and trophic structure of the three communities are defined. The functioning of the aquatic ecosystems is analyzed by using the trophic webs modeled by using a qualitative modeling software. The main hypothesis for depending the taxonomic structure and functioning of the freshwater ecosystems by the
type and special feautures of the anthropogenic pressure is confirmed. The formation of the taxonomic and trophic structure of the fish and invertebrate communities is considered to be a direct biotic response to anthropogenic pressure applied to the objects studied. Three main types of effects on α-and β-diversity are registered in response to anthropogenic pressure:
a) significant changes in the composition of zooplankton, benthic macroinvertebrates and fish in the lotic and lentic water bodies studied;
b) development of scarce limnophilic macrozoobenthos on one hand and diverse zooplankton on another characterize the impact of changing the lotic to lentic conditions in artificial water bodies;
c) specific spatial distribution of the bottom macroinvertebrates and fish. The most common anthropogenic impacts on the trophic structure of zooplankton communities studied is the change in the relative importance of the phytoplanktonivorous and detritivorous zooplanktonic goups. As an impact the changes in the trophic structure lead to trophic disorders in the adequacy of the riverine macrozoobenthic communities. Increasing the proportion of omnivorous fish is common impact on ichthyocenoses. Complementary effect of natural and anthropogenic environmental factors provide trophic
niches with specific parameters that are occupied by species with opportunistic feeding.
The lenght and the horizontal conectivity in the trophic webs are found to be the key features, influenced by the pressure. One of the main anthropogenic impacts on the trophic webs is associated with the formation of numerous horizontal links, leading to decreasing the efficiency of energy transfer within and through the trophic webs.
The analysis of the main parameters of the trophic webs is considered to be a suitable tool for assessing anthropogenic pressure and impact on freshwater ecosystems. It could be usefull for fulfilling the missing information in the analysis algorithm (Driving force - Pressure - State - Impact - Response), which is an essential element of the Common Implementation Strategy of the WFD (2000/60/EC).
The ecology of largemouth bass (Micropterus salmoides) is one of the best known for freshwater fish, though largely through studies within its native range (North America). I studied the habitat and diet of a bass population introduced into a Mediterranean lake. The bass displayed strong ontogenetic diet shifts as follows: young-of-the-year 300 mm, on crayfish and large fish. The diet showed several differences from most previous studies: importance of freshwater shrimp instead of insects, low piscivory, and a delay in the ontogenetic shift to piscivory. Moreover, the ontogenetic shift to piscivory was interrupted at 250–300 mm, with consumption of shrimp and crayfish. This interruption of piscivory has been largely unreported and seems a consequence of the size-structure and species composition of the fish assemblage. A review of the literature suggests that piscivory by largemouth bass might be generally lower in populations introduced outside North America.
Gut contents of rudd, Scardinius erythrophthalmus L. (age group 3+), which represents a dominant fish species in the oligotrophic karstic Vrana Lake, Cres Island, Croatia, were examined. Benthic micro- and mac - roalgae (Cyanobacteria, Dinophyceae, Bacillariophyceae, Chlorophyceae, Xanthophyceae) constituted the major food items of the species while macrophytes (mostly Potamogeton), zooplankton (Cladocera and Copepoda) and detritus were also recorded. Over the period of study, diatomaceous Bacillariophyceae were observed in all samples, contributing up to 79% of dietary intake during February. An increased variation of food in gut contents, associ- ated with elevated gut lipid and protein presence, was observed in May and June. During this period, total energy or nutritive values were increased when compared with other months.
In the south of Portugal there are only two species of strictly freshwater decapods: the
native freshwater shrimp Atyaephyra desmarestii and the exotic crayfish
Procambarus clarkii. The aim of this study is to understand if the
exotic crayfish acts as river shrimp predator and if both species share the same type of
microhabitat. We performed laboratory experiments to study predation and conducted field
work in the river Sorraia to verify the microhabitat distribution of both species.
Laboratory experiments demonstrated significant predation on river shrimp for crayfish
with a cephalothorax length (CT) over 24 mm. The average daily
consumption increases with crayfish CT to a maximum of 0.8 shrimps at 44
mm. Field work confirmed that both species share the same microhabitats although with
small differences e.g. on the water quality variables such as
conductivity and the percentage of oxygen saturation. These microhabitats are shallow
pools with abundant aquatic vegetation with no preference for the type of substrate. In
the field, both crayfish density and its cephalothorax length are negatively correlated
with shrimp densities. In conclusion, P. clarkii can predate
A. desmarestii and the major impacts are expected at high densities of
large sized crayfish.
The river shrimp Athyaephyra desmaresti is a Mediterranean species which in recent years expanded its distribution, colonizing rivers of central Europe. The purpose of this study was to investigate the possibility of passive external dispersal of the river shrimp Athyaephyra desmaresti by waterfowl. We performed experiments testing shrimp desiccation survival, probability of attachment to waterfowl, and probability of successful transport. We found that in the laboratory 10% of the river shrimps can survive out of water for up to 90.1 min, but this period was reduced to 18.5 min under simulated bird flight conditions. Two different outdoor experiments simulating bird flight conditions indicated a 50% probability of successful transport on flight distances over 15 km. Our results using dead ducks show evidence that small, large or ovigerous river shrimps can attach to and be transported by ducks and that this capacity is affected by water depth. This study demonstrated that waterbird-mediated passive dispersal of river shrimps can occur and may be important for genetic flows between populations and for the colonization of new sites.
This article provides a literature review about the distribution of the freshwater shrimp, Atyaephyra desmarestii (Millet, 1831) in Portugal. The information obtained shows that A. desmarestii has been found in many Portuguese watercourses, including reservoirs, rice fields, coastal lagoons and temporary streams. Despite the ecological relevance of this shrimp in aquatic communities, scientific information about its distribution in the country is still fragmentary and scattered. Thus, in view of its potential use as a test organism for the biomonitoring of anthropogenic stress imposed on aquatic ecosystems, there is a need for further investigations so as to account for a complete picture of the area of distribution of the species in Portugal.Dieser Artikel gibt einen Überblick über die derzeit bekannte Verbreitung von Atyaephyra desmarestii (Millet, 1831) in Portugal. Daraus folgt, dass A.desmarestii in Portugal in vielen langsam fliessenden Gewässern, Reservoirs, Reisfeldern, temporären Gewässern und sogar in Küstennähe in Lagunen vorkommt. Die bisherigen Verbreitungsdaten sind jedoch als lückenhaft und verstreut zu bezeichnen. Diese Tatsache, sowie die potentielle Bedeutung dieser Art im Biomonitoring von anthropogenem Stress in Gewässerökosystemen verlangen nach weiteren Untersuchungen.
Recent studies suggest that stable hydrogen isotope ratios (delta D) of fish can be used to track their watershed origin and the relative contributions of source material. Both applications assume that there is no metabolic or trophic effect on tissue delta D. We studied the local variation of delta D values in four fish species of contrasting size and feeding habits in an isotopically homogenous reservoir (Flix, Spain). Other isotopic values (delta(15)N, delta(13)C) and trace metal content were measured as indicators of trophic and bioaccumulation patterns. In addition, isotopic values (delta D, delta(15)N, delta(13)C) of other food web components were measured for comparison. Muscle delta D values differed greatly among fish species: European catfish, Silurus glanis (-131 parts per thousand); common carp, Cyprinus carpio (-141 parts per thousand); rudd, Scardinius erythrophthalmus (-158 parts per thousand); and roach, Rutilus rutilus (-163 parts per thousand). The influence of fish size and trophic position affected the fish delta D values. Possible mechanisms that drive delta D variation among fish might be a metabolic effect and (or) the compounding effect of ambient water delta D on exchangeable H at each trophic stage. Our findings showed that size and feeding habits are factors that should be controlled when tracing origins of fish or their dependence on nutrient inputs using delta D measurements.
Lake Banyoles is the second largest lake in the Iberian Peninsula. It is usually considered oligotrophic because of the low nutrient concentration and phytoplankton biomass, although it is rather mesotrophic based on its primary production and its benthic community. Knowledge of the fish assemblage of the lake and the conservation problems due to a long history of fish introductions is reviewed. Before 1910, only five or six native species were present. Since that time 12 alien species have been introduced, leading to the apparent loss of two native species (three-spined stickleback Gasterosteus aculeatus L. and, possibly introduced several centuries previously, tench, Tinca tinca (L.)), and the decline of three others (eel Anguilla anguilla (L.), chub Leuciscus cephalus (L.), and barbel Barbus meridionalis Risso). The current fish assemblage is dominated by alien species, particularly the largemouth bass, Micropterus salmoides (Lacépède), and the pumpkinseed sunfish, Lepomis gibbosus (L.), in the littoral zone, and roach, Rutilus rutilus (L.), in the limnetic zone. Management strategies for the conservation and rehabilitation of the lake are discussed.
The pumpkinseed sunfish Lepomis gibbosus introduced into Lake Banyoles (Spain) were predominantly littoral but there was a tendency of large fish to use deeper zones. Their diet was dominated by littoral macrobenthos, particularly amphipods (Echinogammarus sp.). There was ontogenetic variation in the diet, with small young-of-the-year (LF<4 cm) feeding on several littoral microcrustaceans, especially the cladoceran Ceriodaphnia reticulata, whereas larger fish shifted to a freshwater shrimp (Atyaephyra desmaresti), snails and damselfly larvae. Seasonal variation in diet was linked to resource availability, with consumption of fish eggs and plant debris in spring and summer. In autumn, pumpkinseeds were partially zooplanktivores, preying on the cladoceran Daphnia longispina. The diet of pumpkinseeds in Lake Banyoles and other Iberian populations shows less molluscivory than North American populations. The potential ecological impact of this successful exotic species involves mainly predation on fish eggs and molluscs.
The ecological impact of fish introduced to Catalonia. We review the invasive fish species introduced to Catalonia (Spain) and their mechanisms of ecological impact. Catalonia has about 15 established foreign fish species and many other that have been translocated. These fish species are the same that have been introduced worldwide (thus contributing to biotic homogenization), such as common carp (Cyprinus carpio), largemouth bass (Micropterus salmoides), eastern mosquitofish (Gambusia holbrooki) and many European cyprinids that are not native to the Iberian Peninsula. There are some well known impacts on the native fauna, such as the impact of mosquitofish on endangered, endemic cyprinodonts. The illegal introduction by anglers continues to be one of the main drivers of this environmental issue, barely addressed by the administration.
The Iberian Peninsula contains a highly endemic freshwater ichthyofauna that is being homogenized and threatened by an increasing number of non-native fishes. Here, in this paper, I reviewed the literature on the impacts of fish introductions and translocations on the native Iberian ichthyofauna. The aims of the present review were (1) to provide an overview of the already studied and proven impacts as well as of the suggested potential impacts that remain to be tested, (2) to synthesize the current knowledge in the Iberian Peninsula and (3) to suggest future research approaches. Despite some well-documented impacts, an increasing number of non-native fish species and a wide range of diverse ecological situations uncover knowledge gaps which hamper conservation and management efforts. Since the introduction of species is often pointed out as a major cause of extinctions, I encourage research groups and funding agencies to devote more resources to the study of interactions between non-native and native fishes in order to develop evidence-based species-specific impact assessments.
The fish assemblage and limnological features along twelve sites from the Terri River basin (Catalonia, Spain) were sampled
quarterly from August 1999 to May 2000. Twelve fish species were captured, of which four were native and eight exotic. Correspondence
analysis revealed that spatial variation accounted for most of the variation (73.7%) in fish species composition. The upstream,
urban area was dominated by chub (Leuciscus cephalus) and common carp (Cyprinus carpio) with some exotic species coming from nearby Lake Banyoles, whereas Mediterranean barbel (Barbus meridionalis) predominated in the rest of the Terri River. Along the longitudinal gradient, fish assemblage displayed discontinuous variation
and disappearance in more polluted areas. Fish abundance was significantly correlated with summer oxygen concentration and
decreased in downstream sampling sites. Species richness was higher in downstream sampling sites due to the proximity of the
Ter River. Common carp size increased progressively along the course of the Terri River, whereas the pattern for the eel was
the opposite, with the smallest found in downstream sampling sites and a gradual increase in size in the upper reaches. The
natural zonation in the fish assemblage of the Terri River is presently altered to a high degree by habitat degradations,
pollution, and dispersal of exotic species.
We collected the first rudd, Scardinius erythrophthalmus (Cyprinidae), from the New (Kanawha) River drainage, West Virginia. The rudd has now been reported from 12 states (Arkansas, Kansas, Illinois, Massachusetts, Maine, Missouri, New York, Oklahoma, Virginia, Wisconsin, and West Virginia) and several major river systems. The rapid spread of the rudd has apparently been facilitated by bait dealers. Despite its widespread distribution, there have been no investigations of potential interactions with native aquatic fauna.
The hybrid golden shiner Notemigonus crysoleucas × rudd Scardinius erythrophthalmus is the first known nonsalmonid, intergeneric hybrid of an exotic species and a North American native species. The cross is also the first valid record of a viable hybrid involving the native golden shiner. Meristic and mensural characters of 30 artificially produced hybrids of male golden shiners and female rudds were analyzed. Forty-seven percent of the meristic traits exhibited character states intermediate between those of parents. Twenty-seven percent of the meristic characters were supernumerary, suggesting developmental instability of the hybrid genome. Mensural hybrid characters were significantly skewed to the golden shiner phenotype. The skewed mensural inheritance and other skewed patterns of morphological inheritance also suggest problems in canalization of the hybrid phenome or atypical patterns of dominance. All hybrids were identifiable by intermediate squamation of the cultrate abdomen: the keel was mostly scaled but exhibited a small fleshy ridge posteriorly. This minnow hybrid allows general inferences to be made about the phylogenetic affinity of the golden shiner to other cultrate cyprinids of Eurasia. The hybrid cross has important management and conservation implications for fishes in North America. The hybrid is an example of how an exotic species may negatively affect a native species.
1. The life cycles and annual production of the eight most abundant species of chironomids (Prodadius cf. choreus, Tanypus punctipennis, Chironomus bernensis, Chironomus gr. plumosus, Cladopelma virescens, Microchironomus tencr, Tanytarsus gr. lestagei, and Cladotanytarsus atridorsum) were studied from sublittoral and profundal samples taken monthly in Lake Banyoles during 1987 at five sampling stations (depths ranging from 5 to 20 m).
2. The number of generations per year deduced from instar-frequency data varied from one to four, depending on the species, lake basin and depth. Annual temperature range, dissolved oxygen in the stratified period and presence of sulphide are the key factors that may explain the differences in the number of generations.
3. Production estimates were calculated using the size-frequency (SF) method corrected for the number of generations (SFG), and the increment-summation method (IS) when cohorts could be clearly deduced.
4. Production calculated with the SFG method gave results which were comparable with those of the IS method using smoothed-survivorship curves in the three species for which the use of the IS method was possible (C. virescens, M. tener and C. atridorsum). Using these methods production was estimated to range from 23–70 mg AFDW (ash-free dry weight) m−2 yr−1 at 12 m to 74–275 mg AFDW m−2 yr−1 in the sublittoral zone of the lake (5-m depth).
5. Calculation of production for the other five species using the size-frequency method with the number of generations (SFG) deduced from monthly instar-frequency data gave values ranging from 12 mg AFDW m−2 yr−1 (Chironomus bernensis at 20 m depth) to 3.75 g AFDW m−2 yr−1(Prodadius cf. choreus at 12 m).
6. Total chironomid production (with the SFG method) varied from 0.8 to 5 g AFDW m−2 yr−1 in the profundal and sublittoral, respectively. At each sampling station two species groups accounted for most of the production: Prodadius cf. choreus and Chironomus spp. Annual production/biomass ratio (P/B) varied from very high values for Prodadius (between 11 and 27, as four generations completed each year) to very low values for Chironomus gr. plumosus (2.20), which completed only one generation each year. The annual production of P. cf. choreus in Lake Banyoles is higher than any reported in the literature due to the completion of four generations and to the high densities of this species.
Niche relationships of fishes can be inferred from dietary analysis. Individual fish and their prey can be ordered along an underlying continuum that has ecological relevance, The specific arrangement is a function of the predator's behavior and the prey's spatial distribution. This distribution of prey eaten by predators conforms to the underlying assumptions of detrended correspondence analysis. This multivariate technique, designed specifically for discrete data, uncovers underlying resource gradients in the dietary data. We used it to analyse dietary information collected from banded sunfish Enneacanthus obesus and bluespotted sunfish Enneacanthus gloriosus and compared then the results with analyses by discriminant analysis, factor analysis, and principal component analysis. Detrended correspondence analysis was as effective in discriminating among species on the basis of diet as discriminant analysis, and was much better than either factor analysis or principal component analysis in producing a small number of interpretable resource axes.
Is concerned with the identity, distribution, feeding rates and growth of herbivorous freshwater fishes, as well as with the identity and nutritional quality of plants fed upon by these fishes. -from Author
Underwater observations of the three common fish species Alburnus alburnus (L., 1758), Rutilus rutilus (L., 1758) and Scardinius erythrophthalmus (L., 1758) in a small part of the Danube flood area near Vienna have been made from June to October 1985 and 1986. Particular emphasis has been laid on the partitioning of feeding resources and habitat. It has been established that these species prefer different water zones. Alburnus a. and Scardinius e. are “obligate” schoolers (BREDER, 1967) whereas Rutilus r. is a facultative schooler. While feeding Rutilus r. and Scardinius e. form “aggregations” (BREDER, 1959) and both adopt equivalent feeding techniques. Furthermore Alburnus a. is a quick moving species living near the surface and chasing mostly in schools. While inter- and intraspecific aggression is rarely observed for Rutilus r. and Scardinius e., Alburnus a. often show interspecific actions.
Habitat and diet variation of roach (Rutilus rutilus) were studied in Lake Banyoles (Spain), an oligotrophic karstic lake with strong spatial heterogeneity in food resources. In addition to seasonal variation in diet, roach displayed an ontogenetic shift from zooplanktivory (dominated by the cladoceran prey Daphnia longispina) to benthivory (based on detritus, plant debris, amphipods, algae, and other invertebrates). Strong patterns of spatial heterogeneity in roach diet were detected for this lake. Firstly, there was a winter aggregation of smaller fish in the deepest basin, where benthos was scarce but a patch of copepods had been previously described. These fish displayed a high condition and fed on zooplankton, particularly those copepods. Secondly, meiobenthos, mainly ostracods and other microcrustaceans, was more important in the diet in the shallowest basin. The ontogenetic diet shift was also mediated by spatial heterogeneity, because in basins where benthos was scarce, larger roach continued to feed on zooplankton.
The impact of exotic species is a neglected, worldwide ecological problem, particularly for freshwater fish. Examples of historical changes in southern Europe due to fish introduction are rare. Lake Banyoles, the second largest lake of the Iberian Peninsula, has suffered a long history of fish introductions. We reviewed the historical changes in the fish assemblage and assessed its current state in a field study. Before 1910, only five or six native species were present. During this century up to 12 exotic species were introduced, leading to the apparent loss of two native species (three-spined stickleback Gasterosteus aculeatus and, possibly introduced several centuries ago, tench Tinca tinca) and the decline of three others (eel Anguilla anguilla, chub Leuciscus cephalus, and barbel Barbus meridionalis). The current fish assemblage is dominated by exotic species, particularly the largemouth bass (Micropterus salmoides) and the pumpkinseed sunfish (Lepomis gibbosus) in the littoral zone and roach (Rutilus rutilus) in the pelagic zone. The only native species still common nowadays is the freshwater blenny (Salaria (= Blennius) fluviatilis).
The seasonal changes of proteolytic activity in the gut content of roach R. rutilus and rudd S. erythrophthalmus in four Tyrolean lakes and the adaptation of the proteases to constant temperatures and different natural diets were studied. In rudd proteolytic activity remains nearly constant throughout the year. In roach proteolytic activity increases and then decreases during the first three months after the thaw in spring. This period appears to be endogenously controlled and is followed by a second stage in which proteolytic activity is influenced by environmental factors. Under natural conditions both species have a higher proteolytic activity when feeding on animals than on detritus. Under laboratory conditions there is a slight maximum at an environmental temperature of 16° C when the fish had been fed on meal worms. With plant food a significant dependence of proteolytic activity on environmental temperature was only found in roach.
Pike preferred the soft-rayed rudd over the spiny-rayed perch in open water. At low vegetation density the prey species were selected equally and at dense vegetation the more available perch were selected over rudd. In the low productivity Lake Ornanas, Sweden, rudd were mainly found in the inner part of the littoral zone, while perch were found in the outer part and in the pelagic zone. The main potential piscivore found in the littoral zone was pike. This suggests that rudd and perch habitat distribution is influenced by pike predation where the prey species either can use physical complexity or morphological defence as antipredator devices. Consequently rudd is expected to take cover in the vegetation to which it seems to be better adapted while the spiny-rayed perch can withstand pike predation and stay in the more open habitat. -from Authors
The feeding of the endemic freshwater fish Scardinius acarnanicus Stephanidis, 1939 has been studied from the content of its intestine and from the results of feeding experiments in the laboratory. This species appears to be phytoplanktophagous when young, whereas as an adult, it becomes macrophytophagous. No difference was observed in the diet of males and females.
The pumpkinseed sunfish Lepomis gibbosus introduced into Lake Banyoles (Spain) were predominantly littoral but there was a tendency of large fish to use deeper zones. Their diet was dominated by littoral macrobenthos, particularly amphipods (Echinogammarus sp.). There was ontogenetic variation in the diet, with small young-of-the-year (LF<4 cm) feeding on several littoral microcrustaceans, especially the cladoceran Ceriodaphnia reticulata, whereas larger fish shifted to a freshwater shrimp (Atyaephyra desmaresti), snails and damselfly larvae. Seasonal variation in diet was linked to resource availability, with consumption of fish eggs and plant debris in spring and summer. In autumn, pumpkinseeds were partially zooplanktivores, preying on the cladoceran Daphnia longispina. The diet of pumpkinseeds in Lake Banyoles and other Iberian populations shows less molluscivory than North American populations. The potential ecological impact of this successful exotic species involves mainly predation on fish eggs and molluscs.
Seasonal changes of the amylolytic activity in the gut content of roach and rudd in four Tyrolean lakes and the adaptation of the amylase to four acclimation temperatures and to different natural foods were studied. In roach amylolytic activity varied with the environmental temperature. Between September and October, however, enzyme activity shifted to a higher level where it remained for the entire cold season. In rudd, which has almost the same seasonal pattern of amylolytic activity as the roach, the activity of the enzyme is independent of environmental temperature. This suggests an endogenous rhythm of enzyme activity. Under natural conditions the roach, but not the rudd, has a higher amylolytic activity when feeding on animals and a lower activity when feeding on detritus. The laboratory experiments revealed no significant differences in amylase activity between fish feeding on animals and those feeding on plants, although in both species the enzymatic activity was lowest when Chara served as food.
The mosquitofish Gambusia holbrooki of Lake Banyoles, Catalonia, Spain, were strictly littoral. Their population was dominated by females throughout the year, except in spring when males were more common. Their diet was based on littoral cladocerans, particularly Chydorus sphaericus, Scapholeberis ramneri, Ceriodaphnia reticulata, and Pleuroxus laevis, and nematoceran (basically chironomid) adults. There was a large variety of prey of terrestrial (collembolans, ants) or aquatic neustonic origin (S. ramneri, emerging nematoceran adults), showing the microhabitat of mosquitofish closely linked to the water surface. In contrast to other studies, terrestrial insects were not especially important in summer. In addition to seasonal and between-site variation, there was an ontogenetic diet shift from microcrustaceans, particularly cladocerans (smallest fish also using diatoms and copepod nauplii) to larger prey, namely nematoceran adults. However, there was an unusual, inverse relationship between fish length and the size of two prey (S. ramneri and the collembolan Sminthurides sp.), paralleling the overall increase in mean prey size.
The annual limnological dynamics of two meromictic basins of Lake Banyoles (C-III and C-IV) have been studied and compared
on the basis of their physical, chemical and biological characters. Stability values calculated for both basins gave 865 g
cm cm−2 and 495 g cm cm−2 for C-III and C-IV respectively. These values are in agreement with the fact that C-IV was almost completely mixed during
winter. In this basin, during stratification, the monimolimnion increased in thickness as the stability increased. Isolation
of the respective monimolimnia resulted in the development of anoxic conditions and the accumulation of sulphide in both C-III
and C-IV, which favoured the development of dense populations of sulfur phototrophic bacteria. The purple sulphur bacterium
Chromatium minus and the green sulphur bacterium Chlorobium phaeobacteroides were identified as the main components of these photosynthetic populations. The different depths at which the O2/H2S boundary was situated in both basins (and consequently the different light intensity reaching this zone) determined the
growth of these bacteria. Light intensities at the chemocline of C-IV reached values up to 5% of surface incident light. In
contrast, in C-III this variable was sensibly lower, with values depending on season and seldom reaching 1%. Phototrophic
bacteria were consequently found earlier in C-IV than in C-III, where no significant concentrations were found until August.
Finally stability is discussed as an important factor controlling chemical and biological dynamics in meromictic lakes.
Studies of the plant contribution to the food of fish in eutrophic lakes in Poland show that roach (Rutilus rutilus) and rudd (Scardinius erythrophthalmus), which frequently dominate in biomass and numbers, are the main plant consumers. Submerged macrophytes and filamentous algae are the most important plant food. The fish examined feed selectively on macrophytes and show a preference for species with low cost/ benefit ratio. The variability of plant ingestion according to temperature and the size of fish is discussed, and estimates of the annual consumption of algae and macrophytes by fish in the lakes examined are given. The possibility and effectiveness of mechanical and enzymatic processing of the ingested plants are presented. Qualitative and quantitative descriptions of faeces as well as their possible impact on the lake system are given. The herbivorous fish studied were found to be relatively efficient grazers but inefficient assimilators, thus they play a significant role in initiating the internal, biologically mobilized, nutrient sources.
Because of the difference in morphometry and in the underground heating of the two lobes of Lake Banyoles there is a differential cooling that causes a density current — the denser water of the shallower lobe plunging into the deepest lobe forming a bottom current — which redistributes water between the lobes and replaces that of the northern lobe about every 5 days. This current has been studied during the mixing periods of the years 1989–1991 from temperature and current measurements and it has been found that it increases or slows down depending on the direction of the wind. Furthermore, it is observed that it mainly flows along the west shore of the lake, deflecting towards the right as an effect of the bottom morphometry. However, due to the long time scale of the density current the influence of the earth''s rotation should not be neglected in advance. Finally, a simple numerical model has been used to corroborate the magnitude of this current — whose velocity has been directly measured — which is found to be the most important in the lake during the mixing period and so, it dominates the lake-wide circulation
The competitive interactions between roach (Rutilus rutilus) and rudd (Scardinius erythrophthalmus) were investigated in two habitats, the open water and the waterlily zone. The growth rates of both species in enclosures were lower when confined together than when alone, demonstrating interspecific competition. Allopatric roach had the highest growth rate in both habitats although the open water was preferred. The diets of both species were dominated by zooplankton in both the open water and waterlily zones. In laboratory experiments, roach had significantly higher feeding rates than rudd when fed D. magna and Cyclops sp. The impact of roach on the mean sizes and densities of zooplankton in the enclosures, together with the results from the laboratory study, indicate that roach were competitively superior in the open water. Because of high mortality in the sympatric waterlily enclosure, no conclusions about interspecific competition in this habitat could be drawn. The observed habitat segregation between roach and rudd was at least partly interactive.
A new bathymetric map of the Lake of Banyoles (NE-Spain) is presented. Echo-sounding transects identified new bathymetric features. The map locates the 13 bottom springs that are presently known and shows a configuration of the lake in six basins. A morphometrical study based on the new bathymetry is also presented.
García Food of introduced mosquitofish: onto-genetic diet shift and prey selection Introduction of exotic fish into a Mediterranean lake over a 90-year period
- Hydrobiol
- E Berthou
Hydrobiol. 146: 239–256. García-Berthou, E., 1999b. Food of introduced mosquitofish: onto-genetic diet shift and prey selection. J. Fish Biol. 55: 135–147. García-Berthou, E. & R. Moreno-Amich, 2000a. Introduction of exotic fish into a Mediterranean lake over a 90-year period. Arch
Ecologia alimentària de la comunitat de peixos de l’Estany de Banyoles
- García
- E Berthou
García-Berthou, E., 1994. Ecologia alimentària de la comunitat de peixos de l’Estany de Banyoles. Ph. D. dissertation, Univ. of Girona, Girona, Spain: 288 pp
Food of intro-duced pumpkinseed sunfish: ontogenetic diet shift and seasonal variation Com-parative study of two meromictic basins of Lake Banyoles (Spain) with sulphur phototrophic bacteria Detrended correspondence analysis of dietary data
- Hydrobiol García
- E Berthou
- R Moreno
Hydrobiol. 149: 271–284. García-Berthou, E. & R. Moreno-Amich, 2000b. Food of intro-duced pumpkinseed sunfish: ontogenetic diet shift and seasonal variation. J. Fish Biol. 57: 29–40. Garcia-Gil, L. J., X. Casamitjana & C. A. Abella, 1996. Com-parative study of two meromictic basins of Lake Banyoles (Spain) with sulphur phototrophic bacteria. Hydrobiologia 319: 203–211. Graham, J. H. & R. C. Vrijenhoek, 1988. Detrended correspondence analysis of dietary data. Trans. am. Fish. Soc. 117: 29-36
Distribución en el espacio y en el tiempo de las especies del zooplancton del lago de Banyoles
- M R Miracle
Miracle, M. R., 1976. Distribución en el espacio y en el tiempo de las especies del zooplancton del lago de Banyoles. Monografías ICONA 5: 1–270.
Life history of the rudd – Scardinus erythrophthal-mus (Linnaeus, 1758) in the Klícava reservoir
- J Holč
Holč, J., 1967. Life history of the rudd – Scardinus erythrophthal-mus (Linnaeus, 1758) in the Klícava reservoir. Vest. Cs. Spol. Zool. 31: 335–348.
Ecologia alimentària de la comunitat de peixos de l'Estany de Banyoles. Ph. D. dissertation, Univ. of Girona Spatial heterogeneity in roach (Ru-tilus rutilus) diet among contrasting basins within a lake
- E García-Berthou
García-Berthou, E., 1994. Ecologia alimentària de la comunitat de peixos de l'Estany de Banyoles. Ph. D. dissertation, Univ. of Girona, Girona, Spain: 288 pp. García-Berthou, E., 1999a. Spatial heterogeneity in roach (Ru-tilus rutilus) diet among contrasting basins within a lake. Arch. Hydrobiol. 146: 239–256.
Seasonal growth of the fry of rudd (Scardinius erythrophthalmus) in the Musov reservoir. Folia zool
- M Prokes
- M Rebickova
Prokes, M. & M. Rebickova, 1987. Seasonal growth of the fry of rudd (Scardinius erythrophthalmus) in the Musov reservoir. Folia zool. 36: 73-83.
The feeding of roach (Rutilus rutilus L.) and rudd (Scardinius erythrophthalmus L.). I. Studies on natural populations
- R Niederholzer
- R Hofer
Niederholzer, R. & R. Hofer, 1980. The feeding of roach (Rutilus rutilus L.) and rudd (Scardinius erythrophthalmus L.). I. Studies on natural populations. Ekol. pol. 28: 45–59.
L'estany de Banyoles
- J Vidal
Vidal, J., 1925. L'estany de Banyoles. Tipografía La Económica, Girona: 153 pp.