Graduation Year

2005

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Marine Science

Major Professor

Dr. Pamela Hallock Muller.

Keywords

Bioerosion, Cliona delitrix, Coral reefs, Monitoring

Abstract

In 2001, the Coral Reef Evaluation and Monitoring Program (CREMP) began monitoring the abundance and area covered by three clionid sponges (Cliona delitrix, C. lampa, and C. caribbaea). Subsequently, monitoring has been conducted annually at all 40 CREMP sites throughout the Florida Keys National Marine Sanctuary (FKNMS) and the Dry Tortugas. Between 2001 and 2002, mean clionid area decreased significantly from 7.6 cm2/m2 to 4.6 cm2/m2 (Wilcoxon; p= 0.035). Between 2002 and 2003, the decline to 4.5 cm2/m2 was not significant. Approximately 80% of all clionid colonies recorded at the CREMP stations covered less than 50 cm2. Among all recorded stony coral species, Montastraea annularis, M. cavernosa, and Siderastrea siderea were the most frequently and extensively invaded by clionid colonies. However, the vast majority of clionid colonies occurred in substrata not associated with a live coral colony.

The mean percent cover for the four coral species identified to be most susceptible to clionid invasion had the greatest decline in the Dry Tortugas deep stations between 2001 and 2003. At Lower Keys patch-reef stations, mean percent cover showed a small, steady decrease, while at Upper Keys patch-reef stations, a small steady increase occurred. Fifteen water-quality parameters collected by the Water Quality Monitoring Network (WQMN) were analyzed to determine if clionid distributions correlated with water quality. When patch-reef sites were analyzed as a subset of sites, clionid area and abundance correlated strongly ( 0.65) with water-quality parameters that indicated higher nutrient flux and food resources. However, the correlation was weak when all 39 CREMP sites were considered ( 0.10). Clionid sponges are well known to be aggressive and successful bioeroders on coral reefs.

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