The biology and energetics of Eogammarus confervicolus (Stimpson) (Amphipoda, Anisogammaridae) at the Squamish River Estuary, B.C.

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Abstract
Data on the biology and energetics of the gammarid amphipod Eogammarus confervicolus (Stimpson) are presented from the Squamish River estuary in southwestern British Columbia. At low tide, E. confervicolus was most abundant under cover material, especially sedge rhizomes (Carex lyngbyei) and rockweed (Fucus distichus). Maximum biomass was observed in spring under the sedge mat (16.1 g dry weight m−2) and rockweed (16.8 g dry weight m−2). The minimum sized female bearing eggs was observed to be approximately 7 mm and egg number ranged up to 75. Incubation time (10 °C, 15‰) was 17 days. In 2 years of data, mature females were most abundant in samples from October to December and July to August. Oxygen consumption rates at 5 and 10 °C were lowest in fresh water and increased with higher salinities. At 15 °C, lower salinities increased consumption rates. Net growth efficiency (K2) was calculated from growth rates on four diets used in a previous study and for respiration under prevailing environmental conditions. The following are ranked diets: Enteromorpha linza (51.2%), Pilayella littoralis (44.2%), Navicula spp. (42.7%), and Carex lyngbyei debris (22.4%). The central sector of the estuary showed the highest K2 values when averaged over diets (53.2%).