Environmental impacts on grazing of different brine shrimp (Artemia franciscana) life stages

Abstract

We examined the grazing rate of brine shrimp from Great Salt Lake, Utah (USA) at different life stages under varying water temperatures, salinities, and concentrations of two of their common phytoplankton foods: Dunaliella viridis and Coccochloris elabens. Trials for a brine shrimp life stage at a specific temperature, salinity, and food concentration occurred within 50 mL test tubes for 1 h; the difference between initial and final food concentrations represented grazing rate. General trends indicated grazing rate significantly increased with progressive life stages, increased with temperature, increased with food concentration, and decreased with salinity. Grazing rates for all life stages were greater on D. viridis compared to C. elabens. Brine shrimp life stages respond differently to environmental conditions. Specifically, while juveniles and adults varied their grazing rates in response to different food concentrations and salinities, nauplii grazing rate was not affected. Only adult grazing rates increased with increasing temperature. Differences in grazing rates under varying environmental conditions have implications for brine shrimp phenology, because brine shrimp populations in the Great Salt Lake are food limited in this highly variable environment.