Experiments were conducted to assess the pathogenicity of 2 'atypical' Aerornonas salmon~cida strains solated from ulcerated flounders Platichthys flesus for this species, rainbow trout Oncorhynchus mykiss, roach Rutilus rutilus, and bleak Alburnus alburnus. The pathogenicity of the strains was evaluated by 3 challenge methods: intraperitonea] (i-p.) injection, subdermal (S d . ) injection, and...

Several hypotheses concerning the dominance of percids under mesotrophic lake conditions were tested in five lakes of intermediate trophic state, situated in northeastern Germany. In contrast to prediction, the fish communities in four lakes were dominated by cyprinids (roach, Rutilus rutilus and bream, Abramis brama), while percids (Eurasian perch, Percafluviatilis) dominated in one lake only....

A new species of amphizoic amoeba, Nuclearia pattersoni sp. n., isolated from gills of Rutilus rutilus L. is described. It is characterised by elongate flattened trophozoites of irregular shape. The longer dimension of their bodies is 13.2 (11.0-15.7) microm. Filopodia radiating mostly from the poles are 2 to 2.5 times longer than the body. The diameter of less frequently observed spherical tro...

Biomanipulation by fish removal has been used in many shallow lakes as a method to improve lake water quality. Here, we present and analyse 30 years of chemical and biological data from the shallow and 16 ha large Lake Væng, Denmark, which has been biomanipulated twice with a 20-year interval by removing roach (Rutilus rutilus) and bream (Abramis brama). After both biomanipulations, Lake Væng s...

Wild roach (Rutilus rutilus) inhabiting UK rivers contaminated with estrogenic effluents from wastewater treatment works show altered sexual development, including intersex, and this can impact negatively on their reproductive capabilities. The molecular events underlying these disruptions in gender assignment, however, are still poorly understood. In this study, two isoforms of aromatase (cyp1...

BACKGROUND The feminization of nature by endocrine-disrupting chemicals (EDCs) is a key environmental issue affecting both terrestrial and aquatic wildlife. A crucial and as yet unanswered question is whether EDCs have adverse impacts on the sustainability of wildlife populations. There is widespread concern that intersex fish are reproductively compromised, with potential population-level cons...

We tested for facultative changes in behavior of an aquatic insect in response to cues from predation and for evolution of prey behavior in response to experimental predation regimes. Larvae of the tree hole mosquito Aedes triseriatus reduced filtering, browsing, and time below the surface in response to water that had held a feeding larva of the predator Toxorhynchites rutilus. We subjected ex...

We have examined the effects of prolonged periods of darkness on the responses of luminosity-type horizontal cells (L-HCs) in the freshwater cyprinid, Rutilus rutilus. Two groups of retinae were compared, those recorded after 10 min dark adaptation (SA) and those recorded after 3 h dark adaptation (LA). The results suggest that long-term light history does not modify the general responsiveness ...

Using three different swimming velocities and a school size of eight roach Rutilus rutilus, individual intra-school position and tail beat frequency were examined in a flume tank. Tail beat frequency was determined in defined leading and trailing positions. Individual roach showed consistent intra-school positional preferences which implied a sustained positional pattern where certain individua...