Five-Year Wellwood Restoration Assessment Completed

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The M/V Wellwood aground on Molasses Reef. Photo courtesy of the FKNMS.
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A REEF diver conducts an RDT survey at the Restoration Site in October 2002, with several restoration modules in view.
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Location map showing areas of fish monitoring effort.
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Transplanted specimens of Sstaghorn coral on one of the restoration modules (colonies were transplanted in 2004, photo taken August 2007). Photo by Ken Nedimyer.
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Wellwood AAT Team, Summer 2007

REEF has just completed our final assessment report for our five-year Wellwood Restoration Site monitoring project. Before I share some results from our study, let me give you a little background information and please visit our website to view our full report http://www.reef.org/programs/monitoring/wellwood. The M/V Wellwood, a 122-meter Cypriot-registered freighter, ran aground on August 4, 1984, on Molasses Reef off Key Largo, Florida, part of the Florida Keys National Marine Sanctuary (FKNMS). The ship impacted the reef’s upper fore reef and subsequently remained aground for 12 days. The grounding destroyed 1,285 square meters of living coral reef and injured 644 square meters of coral reef framework. Prior to the grounding, the area was a transition zone with high relief coral formations. The grounding transformed the area into a flattened, barren pavement covered with coral rubble. 

The study area of this project included a portion of the grounding area that is being restored and two adjacent reference sites. The Restoration site surveyed included restoration modules and contiguous low profile hardbottom areas adjacent to and in between the restoration modules. Nearby high profile reef, ledges, and undamaged/unrestored reef were not included as part of the Restoration Site. A north and south undamaged reef area were both used as two control sites to compare fish sighting data between the Restoration area and the natural (control) reefs.

REEF’s study focused on fish assemblages and not the coral and invertebrate communities. A team of Advanced Assessment Team REEF Experts conducted Roving Diver Technique (RDT) surveys in addition to belt transect surveys on the Wellwood restoration site and two adjacent natural reef sites seven times during Year 1. The team visited the sites once prior to restoration (May 2002) and 13 times after restoration was completed, monthly for the first three months, quarterly for the following year and semi-annually thereafter. An average of 12 surveys of each survey type was conducted during each survey effort. While REEF surveyors used the RDT surveys to collect sighting frequency and abundance data on fishes over all three reef areas, the belt-transect method was used to collect density and biomass data on fish taxa. These two methods used together give us a snapshot of how the restoration site is recovering in terms of fish assemblages as compared to the two non-impacted, adjacent reef areas.

Obviously, the most notable observation a diver makes when diving on the Restoration site is one of just how long it takes coral reefs to recover after devastating ship impacts. The Restoration site shows little resemblance to the surrounding non-impacted reef sites. The areas surrounding the Restoration site are high relief reef areas dominated by reef building corals with some very old colonies of Star coral (Monastrea annularis) and Elkhorn coral (Acropora palmata), old to the tune of thousands, not hundreds of years old. Age is important here since it takes a long time for coral colonies to rebuild structure and relief that attract different fishes over time. The smaller overall fish populations and absence of many species of fish on the damaged site are both conspicuous and the lack of coral structure makes it easy to destinguish the Restoration area from the surrounding reefs even 23 years after the initial ship grounding. However, there are signs that fishes are very slowly recruiting onto the Restoration site.

During the monitoring period (2002 - 2007), a total of 165 species were recorded at the Restoration site, 189 species at the North reference site and 207 species at the South reference site. The Restoration site recovery is clearly aided by the addition of restoration modules (2002), increasing the amount of available habitat suitable for reef fish communities, think vertical habitat here, and recessed areas underneath these modules for fish to shelter. At the Wellwood grounding site, the overall fish diversity as well as density and biomass of most key fish families continue to be less than that of the two nearby, non-impacted reefs that were selected as monitoring reference sites. Parrotfish and surgeonfish appear to be responding the quickest to the restoration efforts, grazing along a recovering hard coral landscape currently dominated by soft corals (Gorgonians). Nearly absent today on the damaged area are sightings of grunts and snappers, both of which are seen in high frequency and abundance on surrounding reef sites with plenty of relief for them to take cover. Residency of fish, movement patterns and habitat usage are all important indicators of reef recovery. So are linking coral, invertebrate, and fish studies to see a more complete picture of how the Restoration site is improving. There are signs outside of the slowly improving trends the data show such as a little Redspotted hawkfish that has taken residence on one of the modules with lots of Ken's Staghorn coral affixed.

Many more studies are necessary to properly evaluate recovery dynamics for reefs and since most reef recoveries worldwide are hampered by other anthropogenic impacts such as overfishing, excessive nutrient loading from human pollutants, and global warming stresses, these case studies are critically important in developing mitigation strategies for damaged reefs. For the full report on our Wellwood findings, please visit our website http://www.reef.org/programs/monitoring/wellwood. REEF would like to thank the many individual REEF members who dived on this project over the past 5 years, as well as Quiesscence Dive Shop in Key Largo for dive support, and Ken Nedimyer for photos and his ongoing coral replenishment work. And finally, our thanks to the Florida Keys National Marine Sanctuary for contracting REEF for this project. We hope that this work will continue in order to monitor the long term changes in fish assemblages on the Restoration site.

 

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