干旱区生态环境知识资源中心

Field distributions of benthic and hyporheic invertebrates are dynamic and are influenced by many physical and chemical factors. A laboratory flume containing natural gravel substrates was used to test the hypothesis that the amphipod Gammarus roeseli Gervais actively selects habitat based on two important environmental variables, dissolved oxygen concentration and direction of water flow. Under homogeneous oxygen concentrations throughout the flume, amphipods accumulated downstream. During trials with uniformly hypoxic conditions throughout the flume, G. roeseli moved to stones and screens at the water surface and above, into the zone normally saturated with humidity. This behavior, termed aquatic surface respiration, may enhance survival during periods of oxygen deficiency. Oxygen gradients were created in the flume by injecting water of differing oxygen concentrations into the head and the center of the channel. A statistically significant response to these gradients by G. roeseli demonstrates active selection of regions with more favorable oxygen concentrations.