Defense Date

12-5-2024

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Biological Sciences

First Advisor

Paul Arena, Ph.D.

Second Advisor

Brian Walker, Ph.D.

Third Advisor

David Gilliam, Ph.D.

Keywords

Mesophotic, coral, ROV, dredging, refugia

Abstract

Mesophotic coral ecosystems, MCEs, are coral ecosystems found at depths between 30-150m and are divided into two zones-the upper and lower MCE. The upper MCE serves as a transitional zone between shallow water reefs (SWRs) and the lower MCE. This transition is marked by increased reliance on heterotrophy by benthic organisms. While MCEs have been of increased interest by resource managers as potential sources of resiliency for impacted benthic species, these benthic communities are understudied. Mesophotic benthic communities in close proximity of Port Everglades between 32-37m depth were surveyed using video footage recorded by a remotely operated vehicle (ROV). This area allowed investigation of previously buried stretches of these deeper reefs by dredged spoil sourced during the initial creation of Port Everglades over 100 years ago. Video transects were performed at three locations: unburied sections to the north and south of Port Everglades and an area previously buried by dredge spoil. It was found that location and depth had no effect on the substrate cover and densities of the biological communities surveyed. The surveyed depths exhibit expected trends for upper MCEs-a decrease in scleractinian coral cover that’s met with an increase in sponge and octocoral cover, however the high degree in overlap of species richness suggests the surveyed depths are deeper extensions of nearby SWR. The results from this research is significant as it has reduced the knowledge gap concerning the benthic biological community make up and effects of burial in these deeper benthic ecosystems. Results show evidence of benthic biological community resilience and overlap in benthic richness with nearby SWRs. This information provides insights into the connectivity of MCEs with SWRs. Future research is needed to determine the local transition depths between SWR and MCE, and the transition between upper and lower MCE.

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