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Click below to go to the Cruise Logs - (photo credit: Lophelia Coral - Open-File Report 2008-1148 & OCS Study MMS 2008-015)

DISCOVRE 2009



Cruise Log: 9/18/2009    



The West Florida Slope

Steve W. Ross, Cheryl Morrison, Andrea Quattrini, and Amanda Demopoulos

A goosefish (Lophoides beroe) on dead Lophelia coral rubble. A red octocoral (Anthomastus sp.) is visible in the foreground, along with orange cup corals - click to enlarge
A goosefish (Lophoides beroe) on dead Lophelia coral rubble. A red octocoral (Anthomastus sp.) is visible in the foreground, along with orange cup corals - click to enlarge
This region, roughly 140 nautical miles off Fort Myers, Florida, represented a new study area for our team. Only a few people had explored this area before, reporting rare occurrences of few coral colonies. If corals were prevalent here, however, this area would be one of our most important sites as it links our studies in the Gulf of Mexico with our datasets from the Atlantic. Last year, in preparation for this year's field work, we mapped a large part of the area with multibeam sonar, and discovered many interesting targets. Our colleagues on the cruise that preceded this cruise made one ROV dive to a part of the area, but mostly found rocky bottom with few attached organisms (see http://oceanexplorer.noaa.gov/explorations/09lophelia/logs/aug21/aug21.html). While any unexplored region of the sea floor is interesting and gives us important information, we were concerned that we may not address many of our deep coral objectives in this part of the Gulf of Mexico. But, that was not the case.

Two species observed at the rock wall habitat, the gaper (Chaunax sp.) and the squat lobster, Eumunida picta - click to enlarge
Two species observed at the rock wall habitat, the gaper (Chaunax sp.) and the squat lobster, Eumunida picta - click to enlarge
In our three Johnson-Sea-Link dives here, we targeted three different areas that looked interesting. These sites were south of explorations in this area several years ago and ca. 1.5 km north of the ROV dive in the August 2009 cruise. Two offshore mounds that were 30-40 m tall looked promising as did an area to the east that exhibited complex topography and a wall that ran in an east-west direction. The two mound areas were a diverse mixture of habitats. They both exhibited a series of ridges and valleys as the mound rose from the seafloor. There were large, rocky outcrops at the base of the southern mound, but then the mound rose steeply and exhibited the type of structure common to other coral mounds. That is, the mound was soft sediment mixed with coral rubble with the tops of the mound covered in large, mostly living Lophelia pertusa coral. The northern mound was similar but we did not find the large rocks there. As far as we know these are the largest stands of living Lophelia pertusa between the Straits of Florida and the north-central Gulf (Vioska Knoll area). At these two coral mounds, we observed a diverse and abundant fauna. Midwater fishes, usually high off the bottom, were common down to the bottom at these sites, and we observed some of them being eaten by bottom fish. Goosefish (see picture) were found resting on the bottom. Swarms of planktonic tomopterid polychaetes, chaetognaths, and squid also were abundant, providing a dramatic visual display for the submersible occupants. Crabs, including Eumunida picta and Golden crabs were very abundant, situated on top of coral thickets and located within the coral matrix. Golden crabs also appeared to be mating.

Four golden crabs (Chaceon fenneri) at a Lophelia reef on the West Florida Slope - click to enlarge
Four golden crabs (Chaceon fenneri) at a Lophelia reef on the West Florida Slope - click to enlarge
Although we did not find coral built mounds on the eastern dive site, this area was very unique and provided a good comparison site. We first explored three tall, rocky outcrops in an area south of the rock wall similar to those we had seen in deeper waters. There were some corals attached to the hard substrata, including stylasterid (lace) corals, small L. pertusa colonies, and the black coral, Leiopathes sp, yet the rocks were mostly barren. Other sessile species were observed, including soft corals, crinoids, and anemones. Mobile invertebrate fauna was dominated by the decapods crustaceans Eumunida picta, and the golden crab Chaceon (see picture). Diversity and abundance of all organisms increased once we reached the rock wall. We observed many fish species that are often found on deepwater reefs throughout the region, including the gaper, Chaunax (see picture).

These sites were particularly interesting compared with the sites we had just surveyed in August off Cape Canaveral, FL. Aside from the rocky areas, the coral/sand mounds were very similar between off the West and East coasts of Florida. Having such comparisons over wide geographic areas is critical to making sense of the data we collect. Many months of analyses back in our labs after these cruises will allow us to reach some conclusions about how these systems are connected and how they support a variety of animals. We are off to a good start.



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