Theses and Dissertations

Defense Date

4-21-2016

Document Type

Thesis

Degree Name

M.S. Marine Biology

First Advisor

Nicole D. Fogarty

Second Advisor

Cliff Ross

Third Advisor

Kenneth Banks

Abstract

This study examined the effect of a growing environmental stressor, sedimentation, on the physiology and oxidative stress throughout the different life stages of two common scleractinian corals Montastraea cavernosa and Porites astreoides. Physiology, oxidative stress, and settlement success of newly released P. astreoides larvae were measured after exposure to various turbidity treatments. No significant effects were seen on larval settlement and photosynthetic efficiency, however carbonyl content and catalase activity were significantly higher in 2015 compared to 2014; highlighting a possible inter-annual variability in susceptibility. Larval settlement deterrence in the presence of a layer of accumulated fine- or coarse-grained sediment was examined and showed significant differences between treatments but not between sediment grain sizes. Ultimately showing that any sediment can deter settlement. The deleterious effects of sediment accumulation on the survival of newly settled spat was examined by smothering with varying layers of fine- or coarse- grained sediment. Survival was significantly different by treatment with coarse-grained sediment showing decreased survival with increasing accumulation. In adult P. astreoides fragments photosynthetic efficiency significantly decreased after being exposed to layers of accumulated sediment, with recovery monitoring after exposure revealing that over time photosynthetic efficiency did not recover to pre-exposure levels. However, in M. cavernosa the photosynthetic efficiency of fragments exposed to high sedimentation saw significant recovery after exposure. Significant differences among oxidative stress biomarkers (catalase activity and carbonyl content) were seen among exposed P. astreoides fragments, however no significance was seen in M. cavernosa. Tissue mortality was also assessed with P. astreoides fragments having significantly higher mortality compared to M. cavernosa. These results highlight the negative effects of sedimentation on scleractinian corals throughout their life history stages, increasing our need for a more thorough understanding of this growing environmental stressor.

Available for download on Friday, May 19, 2017

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