Physical Sciences and Mathematics Commons^™

Implications Of Natural Variation Of Fish Assemblages To Coral Reef Management, Lance K. B. Jordan, Richard E. Spieler

Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

In order to evaluate the impact of a planned beach renourishment project we obtained baseline data on hardbottom coral reef fish assemblages adjacent to the beach. During the summers of 2001 and 2003 we conducted 92 and 89 visual transect-counts, respectively, each 30x2x1m. Fish were recorded by species, abundance, and size class. Fish exhibited a 62.8% decrease in abundance between the 2001 and 2003 surveys. Juvenile Haemulon spp. (<5cm total length, TL) alone decreased 72.8% in abundance and, due to their predominance, primarily drove the decrease seen for total abundance. The second most abundant species Halichoeres bivittatus, also primarily juveniles (<5cm TL), contributed 8% of the total abundance and also showed a significant decrease between the 2001 and 2003 surveys. Even after removal of the two most abundant taxa, total abundance remained significantly lower the second survey year, suggesting the possibility of a community-wide decrease in abundance. However, the decrease between years was mainly due to a decrease in juveniles. When fish less than 5cm TL were removed from the dataset, no significant difference in abundance between years was detected. Species richness also declined significantly with fewer species noted in 2003 and eight fewer total species between years. Nonetheless, multivariate examination of assemblage structure did not indicate a difference between years. These results have important implications for determining potential anthropogenic change in fish assemblages (e.g. caused by beach renourishment).