The effects of multiple experimental floods in the same year on the ecology of a river (River Spöl) below a large reservoir were investigated. In the flood year (2000), three floods of different magnitude (10 m/s on 15 June, 25 m/s on 5 July, and 10 m/s on 10 August) were implemented, each lasting 7–8 h. Regulated baseflow discharge was maintained at less than 2.5 m/s. Samples of macroinvertebr...

concentration of heavy metals in aquatic ecosystems is considered as an important environmantal issue. in this study, the namrood river located in firoozkooh (tehran province, iran) was assessed for the existence of heavy metals. the namrood river is situated by the main road being by pollutants from tourism and recreational centers, gas stations, sewage of villages, agricultural wastewater and...

Rapid and extensive genetic introgression has occurred between Pecos pupfish (Cyprinodon pecosensis) and sheepshead minnow (Cyprinodon variegatus) in the wild. We studied both female mate choice and male-male competition for mates among C. pecosensis, C. variegatus, and their F1 hybrids to determine what role these behaviours played in the formation of the hybrid swarm. Female C. pecosensis pre...

The well known rhythmically active pyloric neural network in intact and freely behaving lobsters Homarus gammarus was monitored prior to and following ecdysis. Despite long-lasting hormonal and metabolic alterations associated with this process, spontaneous pyloric network activity remained largely unaltered until the last 12-48 h before exuviation. At this time, the most notable change was a p...

1. Reduced metabolic rate among cave organisms compared with surface species has long been suggested as an adaptation to food shortage in cave environments. However, comparisons of metabolic rates between species have not often included closely related surface and cave species. By measuring metabolic rate across three seasons and over a range of body sizes, we examined the hypothesis that the r...

Age-0 yellow perch (Perca flavescens) were collected during October 1998 and age-1 yellow perch were collected during June 1999 from southeastern Lake Michigan off St. Joseph and Muskegon, Michigan, to evaluate diets relative to recent ecosystem changes. Size range of yellow perch examined was 72 to 118 mm. In October at a 15-m site off Muskegon, both Gammarus spp. and Isopoda were found in nea...

SUMMARYVertically transmitted parasites may have positive, neutral or negative effects on host fitness, and are also predicted to exhibit sex-specific virulence to increase the proportion or fitness of the transmitting sex. We investigated these predictions in a study on the survival and sex ratio of offspring of the amphipod Gammarus roeseli from females infected by the vertically transmitted ...

A laboratory-based study was performed to assess the impact of climate warming on the recruitment of the endangered population of the European lobster (Homarus gammarus) at Helgoland (North Sea, German Bight). Egg-bearing females collected in situ just after spawning in late summer were subjected to various seasonal temperature regimes. Regimes with elevated temperatures (mild winters) resulted...