On-board Diary: Sunday, September 26, 2010

Author: Jon Warrenchuk
Date: September 26, 2010



The underwater ridge looked promising.  South of Key West, 10 miles offshore and 200 meters deep.  The bathymetric lines piled up steeply on the chart, indicating some steep relief in some otherwise flat habitat.  As far as I knew, no one had ever seen what the seafloor looked like in that area.  We deployed the ROV some distance from the site, trying to take into account the drift of the boat.

By the time the ROV reached the seafloor, we were some distance from the ridge that had caught my attention on the chart.  And according to the chart, we were going to drift over a flat featureless bottom…….boooo…..   Sure enough, the video screen showed a flat, muddy bottom and a few scattered shells.  There were probably a few worms to excite the die-hard invertebrate taxonomists in the sediment (and likely a bunch of species undescribed to science, all quaint and wonderful and weirdly unique in their own way)  but we didn’t have any slurp-up guns or anything attached to the ROV to do that kind of stuff.

But…after a few meters drifting, the lights of the ROV reflected back a bunch of eyes at the edge of the gloom.  Fish.  Many fish.  Not quite a school of fish…just kind of hanging out, spaced pretty regularly from each other.  And many different species…a large snowy grouper (Epinephelus niveatus) was prominent, and there were many other species.  Why were they hanging out there?   There was a flat old coral ledge that was lifted about a foot off the bottom of the mud, and extended into the distance as far as we could see.  This little ledge provided a foothold for gorgonian corals, antithiparian corals, and a very strange sponge of a type I’d never seen before.  Also lots of smaller invertebrates, on the corals, in the water column, in the mucky crevasses…Probably a hundred different species of animals fill one frame of that HD video… All these things taken together provide habitat and set the stage for the ecological community gathered on this small feature of the seafloor.

Just goes to show you that there’s a lot of important ecological areas out there…even if its not on the chart yet.