Open AccessThe Great Salt Lake Ecosystem (Utah, USA): long term data and a structural equation approach
Author(s) -
Belovsky Gary E.,
Stephens Doyle,
Perschon Clay,
Birdsey Paul,
Paul Don,
Naftz David,
Baskin Robert,
Larson Chad,
Mellison Chad,
Luft John,
Mosley Ryan,
Mahon Heidi,
Van Leeuwen James,
Allen David V.
Publication year - 2011
Publication title -
ecosphere
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.255
H-Index - 57
ISSN - 2150-8925
DOI - 10.1890/es10-00091.1
Subject(s) - phytoplankton , brine shrimp , food web , benthic zone , ecology , ecosystem , environmental science , artemia salina , salinity , biology , fishery , oceanography , nutrient , chemistry , geology , organic chemistry , toxicity
Great Salt Lake (Utah, USA) is one of the world's largest hypersaline lakes, supporting many of the western U.S.'s migratory waterbirds. This unique ecosystem is threatened, but it and other large hypersaline lakes are not well understood. The ecosystem consists of two weakly linked food webs: one phytoplankton‐based, the other organic particle/benthic algae‐based. Seventeen years of data on the phytoplankton‐based food web are presented: abundances of nutrients (N and P), phytoplankton (Chlorophyta, Bacillariophyta, Cyanophyta), brine shrimp ( Artemia franciscana ), corixids ( Trichocorixa verticalis ), and Eared Grebes ( Podiceps nigricollis ). Abundances of less common species, as well as brine fly larvae ( Ephydra cinerea and hians ) from the organic particle/benthic algae‐based food web are also presented. Abiotic parameters were monitored: lake elevation, temperature, salinity, PAR, light penetration, and DO. We use these data to test hypotheses about the phytoplankton‐based food web and its weak linkage with the organic particle/benthic algae‐based food web via structural equation modeling. Counter to common perceptions, the phytoplankton‐based food web is not limited by high salinity, but principally through phytoplankton production, which is limited by N and grazing by brine shrimp. Annual N abundance is highly variable and depends on lake volume, complex mixing given thermo‐ and chemo‐clines, and recycling by brine shrimp. Brine shrimp are food‐limited, and predation by corixids and Eared Grebes does not depress their numbers. Eared Grebe numbers appear to be limited by brine shrimp abundance. Finally, there is little interaction of brine fly larvae with brine shrimp through competition, or with corixids or grebes through predation, indicating that the lake's two food webs are weakly connected. Results are used to examine some general concepts regarding food web structure and dynamics, as well as the lake's future given expected anthropogenic impacts.