Coral Reef Evaluation and Monitoring Project 2009 Annual Report

View the Coral Reef Evaluation and Monitoring Project 2009 Annual Report (6.9 MB)

To view this PDF file, you will need Adobe Reader. To download Adobe Reader, visit http://get.adobe.com/reader/

2009 Executive Summary

The purpose of the Coral Reef Evaluation and Monitoring Project (CREMP) is to monitor the status and trends of selected reefs in the Florida Keys National Marine Sanctuary (FKNMS). CREMP assessments have been conducted annually at fixed sites since 1996 and data collected provides information on the temporal changes in benthic cover and diversity of stony corals and associated marine flora and fauna. The core field methods continue to be underwater videography and timed coral species inventories. Findings presented in this report include data from 109 stations at 37 sites sampled from 1996 through 2008 in the Florida Keys and 1999 through 2008 in the Dry Tortugas. The report describes the annual differences (between 2007 and 2008) in the percent cover of major benthic taxa (stony corals, octocorals, sponges, and macroalgae), mean coral species richness and the incidence of stony coral conditions. Additionally, it examines the long-term trends of the major benthic taxa, five coral species that are the most spatially abundant (Montastraea annularis complex, Montastraea cavernosa, Colpophyllia natans, Siderastrea siderea, and Porites astreoides) and the clionaid sponge, Cliona delitrix.

In 2008, mean benthic cover values in the Florida Keys (N=97 stations) were 13.6% for octocorals, 12.6% for macroalgae, 6.6% for stony corals and 2.2% for sponges. In the Dry Tortugas (N=12 stations) cover was 8.7% for octocorals, 12.3% for macroalgae, 10.3% for stony corals and 1.4% for sponges. From 2007 to 2008 the cover of octocorals and macroalgae increased in the Florida Keys while cover remained similar for stony corals and sponges. Cover for all taxa remained similar between years in the Dry Tortugas. No significant differences in mean coral species richness (number of species per station) were observed between 2007 and 2008 in the Florida Keys and Dry Tortugas. The long-term trends of the four major benthic taxa varied. Throughout the Florida Keys, stony coral and sponge cover has significantly declined from 1996 to 2008. During this time octocoral cover has significantly increased, and no trend has been observed for macroalgae. The trends within the Dry Tortugas mostly mirror those occurring in the Florida Keys; the lone divergence being octocoral cover has decreased there. The demise of stony corals is reflected by the declines in cover of four of the five most spatially prominent species. Overall trends in cover for M. annularis complex, M. cavernosa, C. natans, and P. astreoides were all negative. Only the trend for S. siderea indicated cover for this species remained similar. To date, the mass bleaching event during the 1997/1998 El Nino Southern Oscillation (ENSO) resulted in the most substantial reductions in cover. However, during the last decade, after effects of the 1997/1998 ENSO had dissipated, the overall trends remain negative for these four species. This is mostly attributed to a regional effect of the Lower Keys and the Dry Tortugas, whereas the sites in the Middle or Upper Keys do not exhibit this trend.

It has been widely reported that following the disappearance of stony corals on reefs in the Caribbean and Western Atlantic large-scale shifts to macroalgae or sponge dominance have occurred. While CREMP has recorded single year spikes or ephemeral blooms after major disturbances (e.g. after the 1997/1998 ENSO and 2005 hurricane season) a prolonged shift towards increased macroalgal cover has not occurred. Likewise, the slow but steady decreases in sponge cover as well as decreases in Cliona delitrix suggest that sponges may be vulnerable to the same stressors that affect stony corals. Instead, CREMP findings support a transition to octocorals at many sites in the Florida Keys. The transition is most apparent in the shallow forereef where Elkhorn coral, Acropora palmata, and the blade fire coral, Millepora complanata, were previously abundant. Although the demise of A. palmata mostly predates the implementation of CREMP, the mortality of the few remnant A. palmata colonies on shallow forereefs during or shortly after the 1997/1998 ENSO has been followed by significant increases in octocoral cover in this habitat. Considering that octocoral cover has rebounded twice following major disturbances, while little or no recovery of stony coral cover has occurred, even during intervals lacking major perturbations, reefs in the Florida Keys have likely entered into a new alternate state where octocorals are replacing stony corals as the dominant taxa.

The CREMP 2009 Executive Summary was prepared by the Fish and Wildlife Research Institute

To inquire about CREMP data please contact the Fish and Wildlife Research Institute corals group at Corals@MyFWC.com

Learn more about CREMP field and laboratory methods

Funding for CREMP has been provided by the Environmental Protection Agency and the National Oceanographic and Atmospheric Administrator