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Jacqueline Dabrowski - One of the best experts on this subject based on the ideXlab platform.
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Piscivory does not cause pansteatitis yellow fat disease in oreochromis mossambicus from an african subtropical reservoir
Freshwater Biology, 2014Co-Authors: Jacqueline Dabrowski, Grant Hall, Nico Lubcker, Paul Johan Oberholster, D. L. Phillips, Stephan WoodborneAbstract:Summary Pansteatitis (yellow fat disease) is ubiquitous in the free-ranging population of Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. The disease is nutritionally mediated and associated with a diet high in polyunsaturated or rancid fats, frequently of fish origin. While Piscivory has never been reported in dietary studies of O. mossambicus in their native range, their opportunistic and omnivorous feeding habits mean that Piscivory cannot be ruled out as a cause of the disease. The diet of O. mossambicus from LR (n = 91) was compared with a population from Flag Boshielo Reservoir (FBR; n = 81) located <100 km downstream, where no pansteatitis occurs. The stomach contents and stable isotope signatures (δ15N and δ13C) of fish and food sources were evaluated across four seasons. Isotope signatures were also compared over various time scales from historic samples and mortalities collected from LR. There was no evidence of piscivorous feeding behaviour in fish from either location or from historic LR samples. The results of the stable isotope analysis in R mixing model and stomach contents analysis showed that the dinoflagellate, Ceratium hirundinella, was the dominant food source followed by zooplankton, detritus and Microcystis aeruginosa in LR. The diet of fish from FBR was less diverse than fish from LR and was dominated by sediment and detritus. The distinguishing feature of the dietary comparison between reservoirs was the abundance of planktonic food items dominated by C. hirundinella in the diet of fish from LR. The lack of evidence for Piscivory among O. mossambicus from LR suggests that the classic aetiology of pansteatitis does not apply. This highlights the need to further explore direct (environmental exposure to pollutants) and indirect (dietary exposure) links to pansteatitis. This study identified the major dietary constituents for O. mossambicus, which enables future research to focus on their nutritional and chemical composition.
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Piscivory does not cause pansteatitis (yellow fat disease) in Oreochromis mossambicus from an African subtropical reservoir
Freshwater Biology, 2014Co-Authors: Jacqueline Dabrowski, Grant Hall, Nico Lubcker, Paul Johan Oberholster, D. L. Phillips, Stephan WoodborneAbstract:Summary Pansteatitis (yellow fat disease) is ubiquitous in the free-ranging population of Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. The disease is nutritionally mediated and associated with a diet high in polyunsaturated or rancid fats, frequently of fish origin. While Piscivory has never been reported in dietary studies of O. mossambicus in their native range, their opportunistic and omnivorous feeding habits mean that Piscivory cannot be ruled out as a cause of the disease. The diet of O. mossambicus from LR (n = 91) was compared with a population from Flag Boshielo Reservoir (FBR; n = 81) located
Stephan Woodborne - One of the best experts on this subject based on the ideXlab platform.
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Piscivory does not cause pansteatitis yellow fat disease in oreochromis mossambicus from an african subtropical reservoir
Freshwater Biology, 2014Co-Authors: Jacqueline Dabrowski, Grant Hall, Nico Lubcker, Paul Johan Oberholster, D. L. Phillips, Stephan WoodborneAbstract:Summary Pansteatitis (yellow fat disease) is ubiquitous in the free-ranging population of Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. The disease is nutritionally mediated and associated with a diet high in polyunsaturated or rancid fats, frequently of fish origin. While Piscivory has never been reported in dietary studies of O. mossambicus in their native range, their opportunistic and omnivorous feeding habits mean that Piscivory cannot be ruled out as a cause of the disease. The diet of O. mossambicus from LR (n = 91) was compared with a population from Flag Boshielo Reservoir (FBR; n = 81) located <100 km downstream, where no pansteatitis occurs. The stomach contents and stable isotope signatures (δ15N and δ13C) of fish and food sources were evaluated across four seasons. Isotope signatures were also compared over various time scales from historic samples and mortalities collected from LR. There was no evidence of piscivorous feeding behaviour in fish from either location or from historic LR samples. The results of the stable isotope analysis in R mixing model and stomach contents analysis showed that the dinoflagellate, Ceratium hirundinella, was the dominant food source followed by zooplankton, detritus and Microcystis aeruginosa in LR. The diet of fish from FBR was less diverse than fish from LR and was dominated by sediment and detritus. The distinguishing feature of the dietary comparison between reservoirs was the abundance of planktonic food items dominated by C. hirundinella in the diet of fish from LR. The lack of evidence for Piscivory among O. mossambicus from LR suggests that the classic aetiology of pansteatitis does not apply. This highlights the need to further explore direct (environmental exposure to pollutants) and indirect (dietary exposure) links to pansteatitis. This study identified the major dietary constituents for O. mossambicus, which enables future research to focus on their nutritional and chemical composition.
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Piscivory does not cause pansteatitis (yellow fat disease) in Oreochromis mossambicus from an African subtropical reservoir
Freshwater Biology, 2014Co-Authors: Jacqueline Dabrowski, Grant Hall, Nico Lubcker, Paul Johan Oberholster, D. L. Phillips, Stephan WoodborneAbstract:Summary Pansteatitis (yellow fat disease) is ubiquitous in the free-ranging population of Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. The disease is nutritionally mediated and associated with a diet high in polyunsaturated or rancid fats, frequently of fish origin. While Piscivory has never been reported in dietary studies of O. mossambicus in their native range, their opportunistic and omnivorous feeding habits mean that Piscivory cannot be ruled out as a cause of the disease. The diet of O. mossambicus from LR (n = 91) was compared with a population from Flag Boshielo Reservoir (FBR; n = 81) located
Paul Johan Oberholster - One of the best experts on this subject based on the ideXlab platform.
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Piscivory does not cause pansteatitis yellow fat disease in oreochromis mossambicus from an african subtropical reservoir
Freshwater Biology, 2014Co-Authors: Jacqueline Dabrowski, Grant Hall, Nico Lubcker, Paul Johan Oberholster, D. L. Phillips, Stephan WoodborneAbstract:Summary Pansteatitis (yellow fat disease) is ubiquitous in the free-ranging population of Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. The disease is nutritionally mediated and associated with a diet high in polyunsaturated or rancid fats, frequently of fish origin. While Piscivory has never been reported in dietary studies of O. mossambicus in their native range, their opportunistic and omnivorous feeding habits mean that Piscivory cannot be ruled out as a cause of the disease. The diet of O. mossambicus from LR (n = 91) was compared with a population from Flag Boshielo Reservoir (FBR; n = 81) located <100 km downstream, where no pansteatitis occurs. The stomach contents and stable isotope signatures (δ15N and δ13C) of fish and food sources were evaluated across four seasons. Isotope signatures were also compared over various time scales from historic samples and mortalities collected from LR. There was no evidence of piscivorous feeding behaviour in fish from either location or from historic LR samples. The results of the stable isotope analysis in R mixing model and stomach contents analysis showed that the dinoflagellate, Ceratium hirundinella, was the dominant food source followed by zooplankton, detritus and Microcystis aeruginosa in LR. The diet of fish from FBR was less diverse than fish from LR and was dominated by sediment and detritus. The distinguishing feature of the dietary comparison between reservoirs was the abundance of planktonic food items dominated by C. hirundinella in the diet of fish from LR. The lack of evidence for Piscivory among O. mossambicus from LR suggests that the classic aetiology of pansteatitis does not apply. This highlights the need to further explore direct (environmental exposure to pollutants) and indirect (dietary exposure) links to pansteatitis. This study identified the major dietary constituents for O. mossambicus, which enables future research to focus on their nutritional and chemical composition.
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Piscivory does not cause pansteatitis (yellow fat disease) in Oreochromis mossambicus from an African subtropical reservoir
Freshwater Biology, 2014Co-Authors: Jacqueline Dabrowski, Grant Hall, Nico Lubcker, Paul Johan Oberholster, D. L. Phillips, Stephan WoodborneAbstract:Summary Pansteatitis (yellow fat disease) is ubiquitous in the free-ranging population of Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. The disease is nutritionally mediated and associated with a diet high in polyunsaturated or rancid fats, frequently of fish origin. While Piscivory has never been reported in dietary studies of O. mossambicus in their native range, their opportunistic and omnivorous feeding habits mean that Piscivory cannot be ruled out as a cause of the disease. The diet of O. mossambicus from LR (n = 91) was compared with a population from Flag Boshielo Reservoir (FBR; n = 81) located
A. Brabrand - One of the best experts on this subject based on the ideXlab platform.
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Piscivory in larval perch (Perca fluviatilis): mechanisms structuring larval roach (Rutilus rutilus) cohorts
Ecology of Freshwater Fish, 2001Co-Authors: A. BrabrandAbstract:– Perch (Perca fluviatilis) can act as a piscivore from larval stage VI (body size 10.3 mm) on newly hatched larval roach (Rutilus rutilus), bream (Abramis brama) and smaller siblings of its own cohort. Consumption rates at this stage were approx. 0.5 prey/perch*h at 21°C. Larval perch predation was strongly gap-limited, and the maximum size of roach consumed by perch (perch length interval 10.3–62.0 mm) under experimental conditions followed the linear regression, Pprey-max.=0.478*LPred.+1.829 (r2=0.99, P
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Piscivory in larval perch perca fluviatilis mechanisms structuring larval roach rutilus rutilus cohorts
Ecology of Freshwater Fish, 2001Co-Authors: A. BrabrandAbstract:– Perch (Perca fluviatilis) can act as a piscivore from larval stage VI (body size 10.3 mm) on newly hatched larval roach (Rutilus rutilus), bream (Abramis brama) and smaller siblings of its own cohort. Consumption rates at this stage were approx. 0.5 prey/perch*h at 21°C. Larval perch predation was strongly gap-limited, and the maximum size of roach consumed by perch (perch length interval 10.3–62.0 mm) under experimental conditions followed the linear regression, Pprey-max.=0.478*LPred.+1.829 (r2=0.99, P<0.001, n=12). Under experimental conditions, predatory 0+ perch substantially affected the size distributions of 0+ roach prey cohorts, since smaller prey individuals were predated more frequently than larger ones. In both unimodal and bimodal size distributions of prey roach, the distributions changed according to the maximum prey size consumed by the added predatory perch. Unimodal prey distributions were positively skewed when piscivorous perch were added compared with controls without predators. According to the size distributions of lake-living 0+ roach and 0+ perch and the relative size difference between prey and predator, the vulnerability of 0+ roach cohort to 0+ perch predation changed from June to September. Prey vulnerability was extremely sensitive to the relative size difference between predator and prey. Therefore differences in hatching time and growth rates between the two species will strongly influence the potential for predator-prey interactions.Note
Rob P Houthuijzen - One of the best experts on this subject based on the ideXlab platform.
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Piscivory growth and size selective mortality of age 0 pikeperch stizostedion lucioperca
Canadian Journal of Fisheries and Aquatic Sciences, 1992Co-Authors: A D Buijse, Rob P HouthuijzenAbstract:Year-class strength of pikeperch (Stizostedion lucioperca), indexed as the age 0 abundance in trawl surveys, varied 300-fold in the northern part of Lake IJssel, The Netherlands, over the period 1966–89. Both mean length and year-class strength of age 0 pikeperch in November were highly correlated with mean summer temperature. Depending on the environmental conditions, especially water temperature and availability of food, the initially unimodal length frequency distribution of age 0 pikeperch developed into a positively skewed, bimodal or negatively skewed distribution towards the end of the summer. Strong year-classes were characterised by larger mean lengths and a negatively skewed frequency distribution, while weak year-classes were smaller and positively skewed. Stomach contents consisted of zooplankton and macrofauna for the smaller specimens and of age 0 smelt (Osmerus eperlanus) for the larger pikeperch (> 10 cm). Body energy content increased with fish length, and differences in proximate analysi...