Date of Award

12-2015

Degree Type

Thesis

Degree Name

Master of Science

Department

Biology

Program

Biology

First Advisor/Chairperson

Mac Strand

Second Advisor

Alan Rebertus

Third Advisor

Erich Ottem

Abstract

Although little is known about primary productivity in wave zone habitats of very large lakes, it is presumably dominated by microalgae that attach to mineral substrates. Watershed energetics are linked with these wave zones through river mouth habitats, which provide nutrient and organismal input to lake systems. In this study, I assessed the abundance, productivity, and community composition of epipsammic diatoms in river mouth and beach habitats along the south-central coast of Lake Superior. Chlorophyll a concentrations were more than three-fold greater in river mouths (mean ± 1SE = 1.17 ± 0.45 mg/m2), than in wave zone (0.36 ± 0.07) or beach sites (0.39 ± 0.07). Richness was lower in isolated beach sites (28.72 ± 1.07 species) than in river mouth (34.06 ± 1.53) and wave zone (31.17 ± 0.92) habitats. Habitat specificity was evident for 22% of beach species and 16% of river mouth species identified, suggesting that these habitats are biologically distinct and that river mouths are productivity hot spots in wave zone environments. Wind data were used to quantify wave exposure in sites along Lake Superior’s south-central coast. Species richness was greater in low (35.06 ± 1.15 species) than in medium (28.39 ± 1.23) or high-exposure (30.50 ± 0.99) sites, indicating that wave exposure strongly influences richness of epipsammic diatom communities in locations on the south-central shore of Lake Superior.

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