The selection of spawning depth by Eurasian perch Perca fluviatilis was investigated in an experiment using artificial substrata in Lake Constance during the spawning season of 2007. The experiment compared spawning behaviour at substrata between 0.5 and 15 m depth at two sites exposed to different regimes of ship-generated wave action. The total abundance of egg ribbons did not differ signific...

Standardized ecotoxicological tests still constitute the fundamental tools when doing riskassessment of aquatic contaminants. These protocols are managed towards minimal mortality in the controls, which is not representative for natural systems where mortality is often high. This methodological bias, generated from assays where mortality in the control group is systematically disregarded, makes...

Usually, the origin of a within-cohort bimodal size distribution is assumed to be caused by initial size differences or by one discrete period of accelerated growth for one part of the population. The aim of this study was to determine if more continuous pathways exist allowing shifts from the small to the large fraction within a bimodal age-cohort. Therefore, a Eurasian perch population, which...

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...

Abstract Sperm handling procedures and its usage for in vitro fertilization are crucial standardized experimental operations on evaluation of reproductive performance, gamete quality, optimization protocols. In our study, the changes perch sperm motility parameters within 6-h chilled storage using 4 different activating solutions were compared. Eight sperm-to-egg ratio was also compared during ...

Vertebrates harbour diverse communities of symbiotic gut microbes. Host diet is known to alter microbiota composition, implying that dietary treatments might alleviate diseases arising from altered microbial composition ('dysbiosis'). However, it remains unclear whether diet effects are general or depend on host genotype. Here we show that gut microbiota composition depends on interactions betw...