Access Type

Open Access Thesis

Date of Award

January 2014

Degree Type

Thesis

Degree Name

M.S.

Department

Biological Sciences

First Advisor

Donna R. Kashian

Abstract

Occurrence of the filamentous cyanobacteria Lyngbya wollei has become an increasing concern in the Great Lakes region. Prior to the early 1900's, L. wollei had been occasionally documented in the Great Lakes region, but in the last decade it has been observed with increasing frequency. In the Great Lakes L. wollei has been proliferating, fragmenting, and accumulating ashore, where it decays forming thick detrital mats harboring potentially harmful bacteria such as Escherichia coli and enterococci. While the filamentous green algae species Cladophora glomerata has been well studied in this region, very little research has been done on the cyanobacteria L. wollei and the potential for it to harbor and transfer fecal microbes to the water column and underlying sand on beaches. Complementary laboratory and field experiments were performed to quantify the transfer of E. coli and enterococci to the water column from L. wollei mats and to the beach sand underlying the mats. Laboratory microcosm experiments demonstrated significant concentrations of E. coli (p = 0.005) and enterococci (p = 0.007) were transferred to the water column from L. wollei mats, and from the sand collected immediately beneath the mats (p= 0.008 for E. coli and p = 0.005 for enterococci) after a 24 hour exposure. Field mesocosm experiments conducted for one week on a publicly accessible beach showed that L. wollei mats can persistently transfer E. coli (p < 0.005) and enterococci (p > 0.008 for the first five days) to underlying beach sand. Our results indicate that surface waters as well as the sand on public beaches can be negatively impacted by harmful bacteria where decaying mats of L. wollei persist along the shoreline, resulting in potential human health risks.

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