THE UNUSUAL OCCURRENCE OF ADIPOCERE SPHERES ON THE HYPERSALINE LACUSTRINE SHORELINE, SALTON SEA, CALIFORNIA

ABSTRACT The Salton Sea, California, a hypersaline, closed-system lake, experiences high wind event-associated tilapia fish kills. This study reports on the occurrence of several tons of organic spheres taphonomically associated with disarticulated tilapia skeletal parts occurring along the Salton Sea's shorelines. Chemical analyses demonstrate that sphere composition is consistent with soft tissue degradation of tilapia by anaerobic bacteria producing adipocere. Infrared spectroscopy (IR) and gas chromatography (GC) reveal the presence of both triglycerides and salts of free fatty acids. Specifically, GC-MS FAME (fatty acid methyl ester) analysis identified the presence of relatively high concentrations of palmitic, oleic, stearic, pentadecanoic, and myristic acids in the adipocere spheres which are nearly identical to the fatty acid profile of Salton Sea tilapia. SEM studies document the incorporation of fragmented fish bones and detrital grains within the spheres. Formation of adipocere masses in the Salton Sea affects the buoyancy and hydrodynamic equivalence of fish bone fragments, thereby influencing deposition of disarticulated bone materials, and may affect local redox conditions at the burial site.

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