The effects of changing salinity on communities of the Great Salt Lake: A mesocosm experiment and implication for management

Brian Barnes

Document Type

Conference Paper

Journal/Book Title/Conference

Spring Runoff Conference

Publication Date

4-2-2014

Abstract

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), and lake management decisions have remarkable control of the salinity found in the various bays of the lake. 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, but phytoplanktonbiomass was very high (>200 ?g/L chlorophyll-a) at higher salinities when the brine shrimp grazing was low or absent. Brine fly larvae survived in all but the lowest salinities. Both Artemia and Ephydra growth was stunted 30-40% at salinities >200 g/L, presumably by osmoregulatory stress and decreased feeding efficiency. TN:TP ratios indicated N-limitation of phytoplankton growth, 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. As a terminal lake, changes in water withdrawals and diking will certainly affect salinity, in turn modifying the benthic and pelagic community structure. With the recent removal of culverts in the SSPR Railroad Causeway salinities in the south basin of the lake will decrease, and in the short-term this should benefit brine shrimp and brine fly production. However, long-term modifications to the Great Salt Lake and its watershed should account for the effects of salinity on the communities found within the lake. (Willing to do either presentation or poster)

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