Formation of Alewife Concretions in Polluted Onondaga Lake

Abstract

The previously reported finding of alewife concretions along the shores of Onondaga Lake in Upstate New York prompted investigation of the field conditions necessary for their formation and laboratory simulation of these conditions to induce concretion formation. Onondaga Lake is shown to be calcium-polluted and continuously supersaturated with respect to CaC03• Anaerobic conditions exist in the hypolimnion in approximately eight months of every year. In controlled laboratory experiments, formation of structure-retaining alewife concretions was successful under anaerobic conditions, and was enhanced by elevated calcium concentrations. Additional chemical analyses of fresh alewives, natural concretions and laboratory-formed concretions were performed. A previously proposed mechanism for concretion formation is evaluated with respect to the presented results. The common occurrence of alewife concretions in Onondaga Lake is a manifestation of the unique polluted state of the ecosystem, combined with the invasion of the lipid-rich alewife.