Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

2005

Thesis Director

Charles Pederson

Thesis Committee Member

Robert Fischer

Thesis Committee Member

Scott Meiners

Abstract

Largemouth bass in the Fish River watershed of coastal Alabama are known to contain relatively high concentrations of mercury (>1 µg g¹). g the source of which is unknown. I used benthic microalgal assemblages in effort to assess spatial distribution of mercury in the Fish River and its tributaries. Artificial substrates were deployed for 3-week exposure periods at 13 sites on 4 separate occasions. When analyzed by cold vapor atomic absorption spectroscopy. mercury concentrations in periphyton ranged from 0.066 µg g (Pensacola Branch) to 0.493 µg g¹ (Barner Branch). Principal component analysis indicated that physical and chemical environments among the sites are mostly homogeneous and are correlated with agricultural and urban land use categories. Mercury content in periphyton is reflected in the diatom assemblages which were found to characterize each site. Fact that diatoms do respond to this toxicant suggests that benthic algal communities are suitable for assessment of mercury contamination in aquatic ecosystems. Gomphonema parvulum was cosmopolitan throughout the watershed and therefore deemed suitable for assessment of mercury contamination in individual diatom cells. Failure to detect mercury in G. parvulum via SEM-EDS suggests that the method is insensitive to presence of the element in unicellular organism or that G. parvulum does not bioconcentrate mercury. Cultured diatoms did not grow at 1 µg g mercury concentration in agar (content that is very close to mercury concentration in Fish River periphyton) suggesting possible adaptation of Fish River diatoms to mercury in the ecosystem.

Download

Included in

Biology Commons

Share

COinS