Shared parasites can strongly influence the outcome of competition between congeneric, sympatric hosts, and thus host population dynamics. Parasite-mediated competition is commonly hypothesized as an important factor in biological invasion success; invasive species often experience lower infection levels and/or parasite-induced mortality than native congeneric hosts. However, variation in infec...

The effects of the environmental estrogen 17alpha-ethinylestradiol (EE) on mixed populations of 90 individual Gammarus pulex were examined following a 100-d exposure in a flow-through system. Counts of total animal numbers revealed that, in all treatment groups, population size dramatically increased due to recruitment, with neonate and juvenile gammarids the most abundant. At concentrations of...

Mercury (Hg) is a global contaminant resulting of both natural processes and human activities. In aquatic environments, studies conducted on vertebrates highlighted changes gene expression or activity antitoxic oxidative enzymes. However, although Hg highly toxic compound in only few have evaluated the lethal sublethal effects inorganic Gammarus sp. Therefore, this study aimed at evaluating (Hg...

The success of invading species can be restricted by interspecific interactions such as competition and predation (i.e. biotic resistance) from resident species, which may be natives or previous invaders. Whilst there are myriad examples of resident species preying on invaders, simply showing that such an interaction exists does not demonstrate that predation limits invader establishment, abund...

1. Daphnia pulex and Daphnia middendorffiana are commonly found in the Toolik Lake region of arctic Alaska. These two species are very similar morphologically, although their natural distributions differ markedly: D. pulex is restricted to shallow ponds, while D. middendorffiana is widely distributed and found in a variety of ponds and lakes. We compared the reproductive capabilities of D. pule...