Understanding the Effect of Salinity Change on Community Structure in The Great Salt Lake, Utah


Brian Barnes

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Journal/Book Title/Conference

USU Student Showcase

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Faculty Mentor

Wayne Wurtsbaugh


Salinity is a driving force for change in hypersaline community structure. The Great Salt Lake is populated at high salinities by the salt-tolerant brine shrimp (Artemia franciscana) and brine fly (Ephydra gracilis). In a 30-day, 12-L bucket mesocosm experiment using seed water and sediment from the lake and its estuary, community composition changed radically as salinities increased from 10 to 275 g/L. Fish, copepods, and rotifers dominated at salinities _ 25 g/L. Artemia were abundant at salinities between 25-225 g/L, but biomass decreased distinctly above 125 g/l. At salinities < 200 g/L zooplankton grazing controlled phytoplankton and periphyton was dominant, while phytoplankton growth was remarkably high (>200 ug/L chlorophyll-a) at higher salinities. Brine fly larvae survived in all but the lowest salinities. Both Artemia and Ephydra growth was stunted 30-40% at salinities >200 g/L by osmoregulatory stress and decreased feeding efficiency. TN:TP ratios indicated N-limitation, and there was a marked decrease in this ratio as salinities decreased. Additional 48-hr bioassays indicated good Artemia adult and nauplii survival at salinities between 100-225 g/L, and essentially Ephydra survived up to 322 g/L. This data will help us understand how external changes influence the aquatic food web of the lake and inform management decisions for the lake concerning future diking, water withdrawals, and climate change.

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