11 research outputs found
Temperature and Resource Availability May Interactively Affect Over-Wintering Success of Juvenile Fish in a Changing Climate
The predicted global warming may affect freshwater systems at several organizational levels, from organism to ecosystem. Specifically, in temperate regions, the projected increase of winter temperatures may have important effects on the over-winter biology of a range of organisms and especially for fish and other ectothermic animals. However, temperature effects on organisms may be directed strongly by resource availability. Here, we investigated whether over-winter loss of biomass and lipid content of juvenile roach (Rutilus rutilus) was affected by the physiologically relatively small (2-5°C) changes of winter temperatures predicted by the Intergovernmental Panel on Climate Change (IPCC), under both natural and experimental conditions. This was investigated in combination with the effects of food availability. Finally, we explored the potential for a correlation between lake temperature and resource levels for planktivorous fish, i.e., zooplankton biomass, during five consecutive winters in a south Swedish lake. We show that small increases in temperature (+2°C) affected fish biomass loss in both presence and absence of food, but negatively and positively respectively. Temperature alone explained only a minor part of the variation when food availability was not taken into account. In contrast to other studies, lipid analyses of experimental fish suggest that critical somatic condition rather than critical lipid content determined starvation induced mortality. Our results illustrate the importance of considering not only changes in temperature when predicting organism response to climate change but also food-web interactions, such as resource availability and predation. However, as exemplified by our finding that zooplankton over-winter biomass in the lake was not related to over-winter temperature, this may not be a straightforward task
Otoliths as elemental tracers of walleye environmental history: insights for interjurisdictional fisheries management
Environmental DNA assays for the sister taxa sauger (Sander canadensis) and walleye (Sander vitreus)
Overwinter Habitat Use, Feeding Habits and Energetics of Juvenile Bluefish in the Northern Florida Coastal Ocean
Native fish larvae take advantage of introduced mussel larvae: field evidence of feeding preferences on veligers of the introduced freshwater bivalve Limnoperna fortunei
Regime change in a large-floodplain river ecosystem: patterns in body-size and functional biomass indicate a shift in fish communities
Niche segregation facilitates coexistence between native and introduced fishes in a deep Patagonian lake
Production and use of two marine zooplanktons, Tigriopus japonicus and Diaphanosoma celebensis, as live food for red sea bream Pagrus major larvae
We evaluated the effectiveness of two representative marine zooplankton, the harpacticoid copepod Tigriopus japonicus and the euryhaline cladoceran Diaphanosoma celebensis, as live food for red sea bream Pagrus major larvae. Chicken-dropping extract (CDE) was applied to both zooplankton cultures to improve population growth. Population growth of both zooplankton was significantly enhanced by CDE supplementation (at 1 or 2 ml/l). The highest amount of docosahexaenoic acid (DHA) and higher DHA/eicosapentaenoic acid ratio were detected in T. japonicus, whereas D. celebensis showed similar values to that of Artemia. Effectiveness of both animals as live food was tested by rearing red sea bream larvae on them for 28 days and comparing the results with those for Artemia. There were no significant differences in total length (8.6 ± 1.1?8.7 ± 0.7 mm) or wet weight (8.2 ± 0.3?9.4 ± 0.1 mg) among fish larvae feeding on the three different zooplankton. Survival rate was significantly higher with T. japonicus (39.4 ± 3.1 %) than with D. celebensis (20.8 ± 3.8 %) and Artemia (16.7 ± 9.8 %). Viability was significantly higher in fish fed with T. japonicus (60.0 ± 27.8 %) and D. celebensis (60.0 ± 32.2 %) than in those fed with Artemia (44.4 ± 12.3 %). Fish fed with T. japonicus contained higher n-3 highly unsaturated fatty acids than those fed with D. celebensis and Artemia. It is concluded that T. japonicus and D. celebensis have high potential as live food in marine fish larviculture
Size-dependent foraging niches of European Perch Perca fluviatilis (Linnaeus, 1758) and North American Yellow Perch Perca flavescens (Mitchill, 1814)
The foraging ecology of larval and juvenile fishes
Knowledge of the foraging ecology of fishes is fundamental both to understanding the processes that function at the individual, population and community levels, and for the management and conservation of their populations and habitats. Furthermore, the factors that influence the acquisition and assimilation of food can have significant consequences for the condition, growth, survival and recruitment of fishes. The majority of marine and freshwater fish species are planktivorous at the onset of exogenous nutrition and have a limited ability to detect, capture, ingest and digest prey. Improvements in vision, development of fins and associated improvements in swimming performance, increases in gape size and development of the alimentary tract during ontogeny often lead to shifts in diet composition. Prey size, morphology, behaviour and abundance can all influence the prey selection of larval and juvenile fishes. Differences in feeding behaviour between fish species, individuals or during ontogeny can also be important, as can inter- and intraspecific interactions (competition, predation risk). Temporal (diel, seasonal, annual) and spatial (microhabitat, mesohabitat, macrohabitat, regional) variations in prey availability can have important implications for the prey selection, diet composition, growth, survival, condition and, ultimately, recruitment success of fishes. For fish populations to persist, habitat must be available in sufficient quality and quantity for the range of activities undertaken during all periods of development. Habitats that enhance the diversity, size ranges and abundance of zooplankton should ensure that sufficient food resources are available to larval and juvenile fishes