Date of Award

Fall 2013

Project Type

Dissertation

Program or Major

Natural Resources and Environmental Studies

Degree Name

Doctor of Philosophy

First Advisor

Marianne Klauser Litvaitis

Abstract

Blue mussels create extensive aggregations on intertidal and low subtidal shores in the Gulf of Maine, in which they modify habitat, trap sediments and create microclimates for many organisms. Mussels are an important aquaculture species worldwide, and play a major part of the economy of New England. Blue mussels produce collagenous byssal threads to anchor themselves to the substrate on wave swept shores. Byssogenesis, growth and movement abilities of mussels are influenced by a host of biotic and abiotic factors. In this dissertation I quantified byssogenesis and growth of the blue mussel, Mytilus edulis, affected by wave exposure, temperature, and epibiont fouling. Byssogenesis and movement abilities of two size classes of mussels were also quantified in relation to epibiont fouling and predator presence. Results from a series of short- and long-term field experiments indicate that more byssal threads were produced by fouled mussels at sheltered sites during summer, while stronger byssal threads were produced by epibiont-fouled mussels during winter. Although mussel growth was greater at wave-exposed sites in the summer, epibiont fouling did not influence growth. My experiments also revealed that fouling results in increased byssal thread production and attachment strength in large mussels, whereas movement ability in small mussels is reduced in the presence of epibionts. Upon exposure to crab effluent, mussels produced more byssal threads while mussels exposed to effluent of injured conspecifics began depositing threads more quickly than in any other treatment. Large mussels produced stronger attachments while small mussels were quick to begin depositing and releasing byssal threads, indicating increased movement.

These studies indicate that byssogenesis is influenced by abiotic factors such as temperature, artificial epibiont fouling, and wave exposure, and biotic variables including mussel size and exposure to predators and injured conspecifics. Mobility of mussels is influenced by factors which include predator presence and artificial epibiont fouling. This dissertation highlights the variety of adaptive abilities of mussels, whose presence shapes intertidal and subtidal zones. It is important to understand the biological and ecological processes of mussels especially in light of environmental changes, including increased wave activity due to seasonal storms and fouling by invasive epibionts.

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