Some factors affecting distribution and productivity in the estuarine amphipod Anisogammarus pugettensis

Factors affecting the distribution and productivity of the benthic estuarine amphipod Anisogammarus pugettensis (Dana) were examined. Data were obtained from field samples taken from Crescent Beach, British Columbia, between May 1973 and September 1974. Tolerances to selected physical factors, growth rates, oxygen uptake, and assimilation efficiency were measured in the laboratory. This species is present and appears to reproduce throughout the year at Crescent Beach. Distribution is affected by: avoidance of temperature extremes and desiccation, which restrict the species to the middle intertidal zone and deeper at low tide; avoidance of anoxic and low oxygen waters; salinity intolerances, which restrict the species to outer estuarine areas; and food availability. Productivity within inhabited areas is affected mainly by temperature, and food quantity and quality. Productivity will be greatest in warm months. Growth rates, growth efficiencies, and reproductive ability are high compared to values reported for other species. A. pugettensis is an omnivore, capable of eating a wide variety of foods. These data indicate that this species is an important consumer organism in the estuarine environment. The wide tolerances to physical factors, broad diet, and high productivity will make it suitable for mariculture impoundments, if it can be shown that the cultured fish will show high growth rates when feeding on these amphipods.Science, Faculty ofZoology, Department ofGraduat