As an intermediary connection between primary producers and higher trophic levels, zooplankton are important component of the aquatic food chain, contributing significantly to biological productivity. This study describes diversity community structure, as well their relationships with ecological factors, in homestead ponds a coastal district along northern Bay Bengal region. Significant differe...

In this study, laboratory experiments have addressed the acute toxicity of two common mycotoxins, deoxynivalenol (DON) and zearalenone (ZON), in a range freshwater organisms (including rotifers Brachionus calyciflorus, insects Chironomus riparius (larvae), crustaceans Daphnia pulex Thamnocephalus platyurus, cnidarians Hydra vulgaris, molluscs Lymnaea stagnalis (embryos) Protozoa Tetrahymena the...

The uptake of resources from the environment is a vital process for all organisms. Many experimental studies have revealed that the rate at which this process occurs depends critically on the resource concentration, a relationship called ‘‘functional response.’’ However, whether the concentration of the consumer normally affects the functional response has been the subject of a long-standing, p...

The freshwater chlorophyte Scenedesmus obliquus (Turpin) Kützing produces colonies as an inducible defence against herbivores. We investigated the dynamics of Scenedesmus colony formation and disintegration in response to the density of the herbivorous rotifer Brachionus calyciflorus in large-scale mesocosms. Additional bioassays were performed to investigate Scenedesmus colony disintegration u...

Brachionus calyciflorus typically develops long, defensive spines only in response to a kairomone from the predatory rotifer, Asplanchna. However, in the absence of any environmental induction, females of some clones produce daughters with increasingly long spines as they age; late-born individuals can have posterolateral spines as long as those induced by Asplanchna: up to 50% or more of body ...

BACKGROUND Asexuality has major theoretical advantages over sexual reproduction, yet newly formed asexual lineages rarely endure. The success, or failure, of such lineages is affected by their mechanism of origin, because it determines their initial genetic makeup and variability. Most previously described mechanisms imply that asexual lineages are randomly frozen subsamples of a sexual populat...

Transitions to obligate asexuality have been documented in almost all metazoan taxa, yet the conditions favoring such transitions remained largely unexplored. We address this problem in the rotifer Brachionus calyciflorus. In this species, a polymorphism at a single locus, op, can result in transitions to obligate parthenogenesis. Homozygotes for the op allele reproduce strictly by asexual repr...

In periurban zones, urban wet weather discharges have been recognized as the most significant vector of pollution in aquatic environments. The discharge of this water without treatment into the aquatic environment could present an ecotoxicological risk for biocenosis. The aim of the INVASION project is to assess the potential ecotoxicological impact of a combined sewer overflow (CSO) on a peri-...

Current theory proposes that sex can increase genetic variation and produce high fitness genotypes if genetic associations between alleles at different loci are non-random. In case beneficial and deleterious alleles at different loci are in linkage disequilibrium, sex may i) recombine beneficial alleles of different loci, ii) liberate beneficial alleles from genetic backgrounds of low fitness, ...