Scene of change

Yesterday, on our last afternoon at Navassa, I spent one dive revisiting a site along the west wall base where we marked permanent 1m2 plots in 2002. I knew that there had been a lot of change in this reef from hurricanes and coral disease in 2004 and probably from coral bleaching in 2006. I was somewhat shocked when I actually got the pictures back last night and compared them with the earlier versions of themselves. I am showing just one example here to give you the idea. This 1m2 area of reef had been home to a decent sprig of staghorn coral, as well as nine juvenile coral colonies of various species in November 2002 (left image). Today, (right image) a single live coral colony is visible in the quadrat (though it appears to have grown a bit). This colony is outlined in both photos to help convince you that it is the same area. Otherwise, it is pretty unrecognizable, with a brown leafy-looking seaweed covering most of the area. This alga, Lobophora variegata, may be somewhat seasonal, but it covers the majority of Navassa reef surfaces at the moment. It will take some time to analyze all the benthic cover data from the transects and photo-quadrats we took at the sites of the fish surveys, but my impression is that more live coral cover remains on the deep patch reefs along the shelf, than in the nearshore habitats around the wall base where these permanent quadrats are located.

Photo by Margaret Miller

--Maraget Miller