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2004 Daily Log

06/11/04 - Crabs & more crabs

 

Time: 3:11 am  
Lat: 30° 48.5 min N
Long: 79° 38.0 min W

Neuston net towDuring the night we moved about 18 miles (29 km) from our previous location and put several Neuston nets in the water. A Neuston net is made of a big metal frame that floats right at the surface as it is pulled along by the ship. We use it most frequently in areas rich with Sargassum seaweed, though we did not come across much last night. Still, we wanted to see if there was anything else in the upper part of the water column, but pickings were slim and we only caught a nudibranch and a Sargassum fish.

Bathynectes longispinus crabFor the morning dive, Steve Ross was in the bow and Cheryl Morrison of the USGS in the stern. This new area did not have as much coral diversity as previous sites and was more of a rocky outcrop. Steve and Cheryl collected two different kinds of crabs. One, named Bathynectes longispinus, is shaped like a blue crab and remains closer to the bottom. The specimens we collected were about 4 inches (10 cm) from side to side.

Laemonema melanurum, coral hake fishThe other type of crab we saw during yesterday's dive, but were not able to catch any samples. Today we were more successful and collected a crab in the genus Munida. Its shape is similar to a galatheid, but it has white bands across its body and its claws are completely red (as compared to the ones we are accustomed to seeing with white tips). This dive also brought up a Laemonema melanurum fish sometimes called a "coral hake".

We decided to steam back to our previous site for the afternoon dive. Liz Baird was in the bow and Alan Brooks from the USGS in the stern. They were primarily interested in collecting sediment samples and using traps to catch fish and invertebrates. When the sub neared the bottom, the scientists saw they happened upon a beautiful area blanketed with several types of sponges and corals. The location was so densely covered it was difficult to find a spot to land the sub. They set out wire traps baited with cat food and almost immediately crabs began moving towards the bait. The scientists also tried to get sediment samples in the area, but the sediment was so fine it streamed out of the collecting tubes. They moved to a different area with practically no coral, a few sponges, and a lot of debris. Here they collected a very large crab, about 12 inches (30.5 cm) across. When they returned to the traps they found several crabs hanging around the outside of the traps, but nothing in them. Still, it was a very successful dive.

We are now steaming to an area off the coast of South Carolina. We should arrive about 1:30 am on 6/12, and will conduct some surveys when we get there. We are also modifying the traps and sediment tubes in hopes of using them on the next dive. This truly is an around-the-clock enterprise!

06/11/04 Research Data

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