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Seafloor Characterization of the U.S. Caribbean |
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« Cruise Intro
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Day 12: 04/01/2006:
For the first survey of the day the ROV targeted a submarine ridge protruding from the shelf slope at 650 m. The ROV began on the eastside of the north-south oriented ridge, ascended to the ridge’s peak and then followed the contour on top of the ridge several hundred meters. On its ascent the ROV encountered a solitary fish the team had not seen before. It looked like a hybrid between a filefish and jack. It had sleek reflective silvery scales, a laterally compressed oval-shaped body, and a filefishes’ broom like tail. It did not move its position when closely approached, but kept its dorsal and anal fins undulating in a sculling motion. The bottom was typically mud, but several large rocks were scattered about. Large stands of coral, the most dense we had seen at this depth, were on top of several rocks, but for the most part very little biotic cover was observed over the different types of substrate.
The second transect of the day and last of the mission was to survey an area characterized by jagged contour lines at 440 m. It was hypothesized that the area would have a large amount of boulders and deep crevices in contrast to the typical flat expanses of mud seen at these depths. This hypothesis was confirmed after only a few minutes on the bottom when a large 5 m high boulder was sighted. The majority of the benthic habitat was mud, but large rocks were seen wherever the bathymetric data showed a bumb. The bathymetry quickly became more complex. Deep crevices and irregular protrusions were spotted frequently. The ROV moved slowly so that it could navigate among the profuse pinnacles, ledges and overhangs. These features were extremely dangerous for navigation because the ROV or downweight could easily get stuck between rocks. At one point the terrain became so dangerous the ROV had to leave the transect and restart it 100 m away at a safer place. The last transect ended without incident, except for a poor squid who got so scared and lost all its ink.
The ROV team was happy they had completed their requirements, but would miss the interesting fish and habitats they had become accustomed to during their daily routine. It was an exciting unique experience the team would always remember. Now, the team is packing and getting ready to leave the tantalizing deep underwater world so that they may venture back to their normal lives on terra firma. Maybe next year they will travel deeper.
A cloud of sediment stirred up by the ROV and the red ink emitted by a frightened squid. The squid’s outline and reflective eyes can be seen through the obscuring particles in the water towards the center-right of the image.
Two crabs (taxa unknown) rest on the surface of the seafloor. The crab on the left had jumped one meter into the water column from its hiding place in the mud.