Naked amoebae (Protozoa) of the Salton Sea, California

The Salton Sea is an inland lake in California with an average salinity of ca. 44 g l^–1. This productive water body, which supports substantial fish and migratory bird populations, is under threat because of increasing salinity levels. The present study was the first to examine the naked amoeboid protozoa of the Salton Sea and provide a first estimate of their numerical importance. Over a six-month sampling period (June–December, 1999), 45 different morphospecies (considered to be species) of amoebae were isolated. Wherever possible, isolates were identified to species or genus using diagnostic features recognizable by light microscopy. For each isolate, illustrations and brief notes on the diagnostic characters used in the identifications are given. These will allow this paper to be used as an identification guide to amoebae of the Salton Sea in future studies. Of the 45 taxa, around 18 of the isolates (i.e. 40%) are probably new to Science. Preliminary counts, based on enrichment cultivation methods, showed that amoebae in shoreline waters ranged from 14560 to 237120 cells l^–1 (mean 117312 ± 86075 S.D.). The ecological importance of high numbers and high diversity of amoebae is unknown. But it should be noted that several of the amoebae were actively grazing cyanobacterial and algal filaments and filaments of the bacterium Beggiatoa. Others were predominately associated with suspended particulates. As such, amoebae may be important in the cycling of carbon and nutrients in the Salton Sea.