نتایج جستجو برای: perca
تعداد نتایج: 652 فیلتر نتایج به سال:
The widespread occurrence and accumulation of plastic waste in the environment have become a growing global concern over the past decade. Although some marine organisms have been shown to ingest plastic, few studies have investigated the ecological effects of plastic waste on animals. Here we show that exposure to environmentally relevant concentrations of microplastic polystyrene particles (90...
Over the recent years, growing number of studies suggests that intensive size-selective fishing can cause evolutionary changes in life-history traits in the harvested population, which can have drastic negative effects on populations, ecosystems and fisheries. However, most studies to date have overlooked the potential role of immigration of fish with different phenotypes as an alternative plau...
Using the widespread Eurasian perch Perca fluviatilis as a model organism, feeding ranges were investigated using stable-isotope ratios (δ15 N and δ13 C) and body condition. Differences were found between closely located sampling sites in a littoral area without obvious migration barriers, indicating that individual fish had small feeding ranges. Body condition differences between sampled stati...
Tissue samples from 1,117 fish of 25 species were collected from 1991 through 1996 at 13 locations along the River Elbe. The principal indicator species were perch (Perca fluviatilis) (n=118), chub (Leuciscus cephalus L.) (n=113) and roach (Rutilus rutilus) (n=138). Mercury (Hg) concentrations in muscle and liver were determined by atomic absorption spectrometry. The liver/muscle index in three...
The latest results about the evolutionary, biogeographic, and population genetic relationships of the three species comprising the percid fi sh genus Perca are presented, explained, and discussed. New analyses from new data dated the origin of the genus to an estimated 19.8 million years ago (mya) during the early Miocene Epoch, and the distribution of ancestral Perca likely extended across the...
The effect of group size on routine metabolic rate (RMR) and activity of the two shoaling percids Eurasian perch (Perca fluviatilis) and ruffe (Gymnocephalus cernuus) was studied using twin flow intermittent respirometry and time-lapse video techniques. In both species, we found a clear group effect. In isolated fish, oxygen consumption was up to two times as high as in groups of eight fish, wi...
The objective of this study was to examine if individual variation in morphological characters is related to swimming costs in wild and domestic brook charr, and in wild yellow perch. Our results indicate that absolute swimming cost was higher in wild and domestic brook charr individuals having a stout body shape, and these individuals are therefore less efficient swimmers. These results are co...
The study of animal behaviour is important for both ecology and ecotoxicology, yet research in these two fields is currently developing independently. Here, we synthesize the available knowledge on drug-induced behavioural alterations in fish, discuss potential ecological consequences and report results from an experiment in which we quantify both uptake and behavioural impact of a psychiatric ...
Little is known about how hatch phenology (e.g., the start, peak, and duration of hatching) could influence subsequent recruitment of freshwater fishes into a population. We used two commonly sympatric fish species that exhibit different hatching phenologies to examine recruitment across multiple life stages. Nine yellow perch (Perca flavescens) and bluegill (Lepomis macrochirus) annual cohorts...
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