Ivory tree coral (Oculina varicosa) is a deepwater, hermatypic, delicately branching coral which occurs along the continental shelf edge of the southeastern U.S. often forming large mounds, as high as 30 m off the surrounding bottom, known as the Oculina Banks off the east coast of Florida. These deep-water reefs (at depths of 70 – 100 m) are unique in that they are known to exist at high densities exclusively in this area. These deep reefs foster a diverse assemblage of fish and invertebrates including several economically important species. Spawning aggregations of gag (Mycteroperca microlepis) and scamp (M. phenax) have been observed associated with Oculina colonies, and many deepwater groupers utilize the area during their juvenile and sub-adult stages including speckled hind (Epinephelus drummondhayi), yellowedge (E. flavolimbatus), and snowy grouper (E. niveatus).
Head of live Oculina.
The Oculina Habitat Area of Particular Concern (OHAPC) was established by the South Atlantic Fishery Management Council (SAFMC) in 1984, becoming the first marine protected area closed to protect habitat in the U.S. east coast federal waters. The OHAPC consisted of a 92 square mile area where bottom gear such as trawls, longlines, fish traps, and dredges were prohibited because of the damage these gear types were having on the fragile coral. Evidence demonstrating the deleterious effects of bottom hook and line fishing on grouper populations prompted the restriction of this method of fishing in 1994 for a period of 10 years in order to experimentally test the use of a reserve to enhance grouper reproduction. The area known as the original OHAPC became the Experimental Oculina Research Reserve (EORR). Further expansion of the original OHAPC to cover 300 nmi² from Fort Pierce to Cape Canaveral, FL between 80 degrees W longitude and the 100 fathom depth contour was instated in 2000. In 2004, this closure was extended indefinitely by the SAFMC. An Oculina Evaluation Team provided the most up-to-date information on the effectiveness of the reserve to the SAFMC in 2007. This will again be completed in 2014.
Since 2001, NOAA Fisheries has been using an ecosystem based approach to monitor this area and examine the effectiveness of a marine reserve in restoring fish populations and coral habitat. The OHAPC is not an easy environment to study. It is rugged, deep (beyond normal scuba diving depths), and currents are hazardous as the banks are swept by the Gulf Stream. The most effective approach for characterizing the state of OHAPC coral habitat and fish populations is broad area mapping using acoustic survey technologies, followed by targeted exploration and assessment using in situ technologies, such as manned submersibles, remotely operated vehicles (ROVs), and mixed gas diving. NOAA Fisheries has been studying the following four research objectives:
- Objective 1: Mapping the OHAPC and surrounding areas. Multibeam acoustic bathymetry surveys were performed in 2002 and 2005, covering most of the Oculina habitat in the OHAPC. These surveys produced a high definition 3D map of the bottom, which has been crucial in locating and guiding ROV dives. An autonomous underwater vehicle (AUV) was tested in the OHAPC in 2006 and can be used to create high resolution maps of the deeper portions of the OHAPC.
- Objective 2: Monitoring fish populations and habitat changes inside and outside the OHAPC. Specifically, we want to determine fish densities within various habitats and management areas as well as examine changes in percent coral cover. Since 2001, 16 submersible dives and 55 ROV dives have been completed. Researchers are also in the process of developing an Acoustic and Listening Monitoring Station (ALMS), which will serve as a long-term monitoring station, providing continuous environmental data, pictures, and audio of the area.
- Objective 3: Habitat restoration. Over 100 artificial structures with small pieces of live Oculina attached were deployed between 1997 and 2001 to evaluate survival of coral transplants and recruitment of fish to the habitat. Several of these structures were surveyed in 2003 with the ROV, demonstrating that fish were utilizing the structure for habitat and the attached Oculina was growing, albeit slowly (Oculina grows extremely slow at a rate of about 1-2 cm per year). Florida State University (FSU) and NOAA/NURC had some success in 2008 using technical divers to examine the artificial reefs. We are hoping to survey all the artificial structures that were deployed in the near future.
- Objective 4: Outreach and public education to disperse information on the Oculina reserve and why we're trying to protect its ecosystem. A website and Geographic Information Systems (GIS) database are being developed for the Oculina MPA and are constantly updated with new information. The GIS will produce a comprehensive habitat map describing the relationship between habitat and fish assemblages. We have invited media, journalists, and teachers-at-sea on past cruises to get an inside look at current research. In addition, we held a live web cast during our 2003 cruise and a port day prior to our 2005 research cruise where we invited local school kids to come and learn about the Oculina ecosystem.