title: Swimming behaviour in Monoporeia affinis (Crustacea: Amphipoda) - dependence on temperature and population density.
abstract: Swimming speed and swimming activity of the nocturnally active benthic amphipod Monoporeia affinis were measured in water temperatures from 3 to 18 degrees C and different population densities in the laboratory. Swimming speed increased with increasing temperature. Increasing water temperature reduced the percentage of active animals in the population, as measured by a "freeze frame" technique. At 7 and 10 degrees C a higher percentage of the population was active in higher animal densities. In all tested conditions swimming activity was highest at about 1 h after light-off and lowest shortly before the predicted time of light-on. The consequences of the documented behavioural responses to environmental stimuli are discussed in relation to population dynamics.
authors.affiliation: Tvärminne Zoological Station, University of Helsinki, FIN-10900, Hanko, Finland
authors.initials: M
authors.lastname: Lindström
authors.initials: W
authors.lastname: Fortelius