Reef and Fishery Assessment of Navassa Island National Wildlife Refuge

On April 23, 2009 scientists from the NOAA's Southeast Fisheries Science Center in Miami Florida (SEFSC) departed from San Juan, Puerto Rico aboard the NOAA Ship Nancy Foster. Their destination: the Navassa National Wildlife Refuge. Along with the NOAA scientists are researchers from the University of Miami's Rosenstiel School of Marine and Atmospheric Science (UM/RSMAS), the US Fish and Wildlife Service (FWS), and the Director of the Fondation pour la Protection de la Biodiversité Marine (FoProBiM), an NGO based in Haiti.
This work is funded by the NOAA Coral Reef Conservation Program.

Sunday, April 26, 2009

Walls of coral

The underwater sides of the island are nearly vertical from the surface down to about 80 feet (25m) and the water is incredibly clear making for some spectacular vistas! It is hard to tell from a photograph, but the lower part of this frame is at about 30ft deep. Where I do most of my diving in the Florida Keys the visibility is probably half of what you see in this picture taken in Navassa in 2006. Aside from making for awesome scenery, it also means that sunlight reaches deeper than at home. Elkhorn coral generally does not have enough light to grow below 30ft in Florida however we have found small colonies living at nearly 70 feet in Navassa!

Since most of the shallow area is wall, all of the corals that usually live on the shallow part of a typical reef have to find a way to live and grow sideways! In past years we have found Elkhorn coral growing and thriving in this environment. However, rather than growing up like a tree as it usually does, it encrusts the walls of Navassa forming a carpet of Elkhorn with stubby branches!

In 2006 I snorkeled around two thirds of the island (about 10hrs in the water!) and marked each colony with a GPS point so that we could record where they were located and how many there were. The blue line on the map is where I snorkeled and each orange dot is a colony of Elkhorn coral! I counted approximately 1800 colonies in the nearly 7km of coast I was able to snorkel. It is extremely hard to count them because they grow very close together but the GPS makes it a little easier!
This year we hope to repeat this survey but it will depend on the weather conditions while we are there. To do this survey I have to swim very close to the rocks and big waves can make it a little dicey to say the least! --Dana

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