Date of Award

Fall 2015

Project Type

Thesis

Program or Major

Zoology

Degree Name

Master of Science

First Advisor

Larry G Harris

Second Advisor

Jennifer A Dijkstra

Third Advisor

James F Haney

Abstract

Driven by the rising global population and shoreline development, man-made marine structures are becoming ubiquitous in coastal areas. These alterations may have enormous ecological consequences, as anthropogenic structures provide novel habitat for marine organisms and often host communities that differ from those on natural substrates. These community differences are frequently driven by non-native species, which can be more prevalent on man-made marine structures than on adjacent natural surfaces. Although multiple factors, including light intensity, surface orientation, predation exposure, and habitat type, are known to contribute to these patterns, relatively few studies have directly examined the influence of substrate material on fouling community development and non-native species abundance.

I conducted laboratory and field studies examining larval settlement preferences and fouling community composition on commonly occurring natural (granite) and man-made (concrete, high-density polyethylene, and PVC) marine materials. During laboratory trials, I quantified larval substrate preferences of two introduced species of ascidian, Botrylloides violaceus and Ciona intestinalis. In the field, I sought to determine if observed differences in community composition on man-made and natural substrates resulted from differential organism settlement, or variation in post-settlement survival and growth, on different substrate materials.

Results indicate that the effects of substrate on fouling community composition are material-specific; assemblages on concrete differed significantly from those on all other surfaces. These differences appear to result from variation in both organism recruitment and survival on different materials. Notably, I found that material classification, as “man-made” or “natural,” was not a reliable predictor of either species composition or non-native species abundance. Larval substrate preferences were also observed in B. violaceus and C. intestinalis during lab trials. However, these laboratory settlement patterns did not match those observed in the field, indicating the importance of real-world studies when seeking to answer more applied ecological questions. The effects of material on both settlement and community development most likely resulted from variation in chemical leaching or surface pH, as roughness did not seem to explain the observed differences among plate types.

Information gained through these studies may help us to understand how substrate features can contribute to differences in fouling community composition and species abundance, and may inform decisions regarding material usage in marine construction. These results also highlight the importance of settlement plate material choice in experimental marine biology research, as plate material may influence experimental conclusions.

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