 |
|
 |
 |
 |
|
 |
|
 |
|
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
SHARK SENDOFF Mission Dispatch 6 - April 9, 2005 | Mark Schrope - @SEA Correspondent Elbow Cay, Cay Sal Bank 
Today was our last day off Elbow Cay. Thankfully, the winds and seas died down today making for excellent
working conditions, and a number of neighborly sharks came around to send us off. For this morning's scuba
dive we went to a patch reef about 60 feet deep. We were farther east than during past dives and the current
wasn't nearly as strong, so the team had a much easier time working.
The scientists were no doubt already looking for good samples as we descended in the crystal-clear water, but I was scanning the horizon of the 100 or so foot visibility. Out on the edge of the reef I saw another reef shark, perhaps six feet long, but it swam off before I got a close look. Please don't get the impression that this is death-defying stuff as sharks' bad reputation is largely undeserved. Attacks are rare despite the huge number of people that enter the water each year, and they tend to be in situations where sharks mistake something like an arm for their normal prey. In clear waters this is especially rare (and sharks would have a really difficult time getting into the sub). After lunch, some of the sub crewmembers took a quick jaunt to the island to have another look around. While snorkeling they came across the wreck of an old paddle wheel steamer in shallow water with its wheels still plainly visible. At another spot, pilot Phil Santos found what looks like an old musket ball. No archaeologists here, so no telling its age, so I'm free to assume it was one the Spanish used when they came round surveying in the 1500s. 
Today's real shark show was in the deeper waters a mile or so from the islands. During the first submersible dive,
Amy Wright
and pilot Hugo Marrero saw a group of about 15 sharks, including a mako. On the second submersible dive
a pair of large makos twice made passes at the submersible. I was in the back of the sub, and the second time they
passed I got to watch them in the dim blue light at about 700 feet.
DEEP EXPERIENCE The Johnson-Sea-Link (JSL) submersible has a clear front sphere that holds a pilot and a lead scientist, and there is also an aft chamber that holds another sub crewmember and an observer. This back area is separate from the sphere but has two portholes. The view is nothing compared to that from the front, but still a spectacular and rare opportunity to see the deep sea up close. Either Amy Wright or Shirley Pomponi is typically in the front because they have the extensive experience needed to pick out the best organisms to sample, but the back slot is typically open. We drew names at the beginning of the trip to determine when each person who wanted a spot would dive. That second sub dive began at 1,200 feet on a gently sloping sediment plane. Soon after we reached bottom we began to see a number of sponges not yet encountered on the trip. Each was about the size of a laptop computer and attached to the bottom all along its base. Like trees at the beach permanently bent by the wind the sponges were all oriented perpendicular to and slightly bent from the nearly constant force of the ripping current, which again made sample collections difficult. 
DIVE ME TO THE MOON
The slope gradually became steeper as we progressed and by 900 feet or so the terrain became rockier, taking on the look of a moonscape. The current also increased to about a knot as we got shallower, which is close to the speed of the sub. At 1,200 feet it was pitch black save for the sub's lights, but in the 800 foot range enough blue light started to filter through to illuminate the scene. At about the same time we came upon a large rock outcropping and Hugo fought the current to collect several samples. Working against the current forces the pilots to use the thrusters much more than on dives elsewhere, so the batteries run down more quickly. On our dive, the batteries were down enough after less than three hours on the bottom that it was time to head for the surface. Typical dives would last three and a half hours or more. 
SAMPLES EVERYWHERE With at least two days of work remaining, the sample tally, including specimens from shallow and deep water, is up to 165. All of these have been subsampled for processing in various lines of research. There is still plenty left to explore here at Cay Sal, but our time is short and we want to make it to at least one other section of the Bank. So, tonight we will run east to the next group of islets, called the Dog Rocks. We should be there by morning ready to get in the water. 
|  |
| ||