| Summary: | The United States Fish and Wildlife service declared an unusual mortality event (UME) in 2006 when a high number of northern sea otters in Alaska were found dead beginning in 2002. Necropsies revealed the cause of death in 30% of cases to be septicemia with meningoencephalitis and/or vegetative valvular endocarditis (VVE) colonized by gram positive cocci, later determined to be primarily Streptococcus infantarius ss coli and Streptococcus phocae. While much work has been done to uncover the pathogenic agents responsible for these deaths in northern sea otters, the ecology of S. infantarius ss coli and S. phocae in the environment remains poorly understood. This study investigated the presence of S. infantarius ss coli and S. phocae in the marine environment by 1) developing a molecular method to detect S. infantarius ss coli 2) examining potential microbe-habitat associations in Kachemak Bay and Resurrection Bay, Alaska, and 3) determining the competency of otter prey species to act as reservoirs for these pathogens. A PCR assay was developed to detect the sodA gene of S. infantarius ss coli in both environmental and clinical samples. Water and bay mussels were collected from sites in Kachemak and Resurrection Bays and pathogen presence was determined using PCR. Habitat attributes were recorded onsite and determined using ShoreZone. Prey competency was determined via a dosing experiment in the lab. Our primer set for the S. infantarius ss coli sodA gene, as well as a previously published primer set for the S. phocae sodA gene, successfully identified our targets in clinical and environmental samples using conventional PCR. Primer sets we designed successfully quantified the sodA gene of S. infantarius ss coli and/or S. phocae in environmental samples and in dosed prey samples using qPCR. S. infantarius ss coli and/or S. phocae were present in water or mussels at 61 of 162 sites. Statistical analyses to determine bacterial correlations with habitat attributes revealed some correlations between habitat parameters selected and presence of our target bacteria in the environment. Prey competency experiments showed that bivalves were the most competent pathogen reservoirs. Results of this study will inform microbial ecologists and wildlife managers of the potential environmental risk factors for S. infantarius ss coli and S. phocae infection as well as provide information about pathogenic bacterial presence in the marine environment.
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