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MISSION DISPATCH 11 September 11, 2005 | Brian Cousin - @SEA Correspondent It was a normal day until someone called out 'shark!'. The blue water dive team had just rolled into the water from the small boat about a quarter mile from the R/V Seward Johnson . Up on the bridge of the research vessel, chief scientist Dr. Tammy Frank, Dr. Edie Widder, Dr. Mike Matz and ship's captain Aric Anderson were engaged in a ship-to-shore news conference to discuss Ocean Exploration's Deep Scope 2005. While Aric was speaking, Mike and OE's Cindy Renkas noticed a large, slow-moving shadow just under water, and a dorsal fin and tail periodically breaking the surface. Small boat driver Christian Knapp took the radio message from the Seward Johnson and relayed it to the divers who had not yet disappeared below the waves. Diver Dr. Sonke Johnsen spoke first. "Dive cancelled. Back in the boat." 
Off came the tanks, buoyancy compensators and weight belts to be handed
up to the boat tender. The divers hauled themselves out of the water and
Sonke pulled in the blue-water rig. While waiting for more information
from the ship, the divers agreed to cancel the dive. Under normal
blue-water conditions where visibility can be unlimited, the odd shark
swimming around in an unthreatening manner is not cause for real
concern. Considering the poor visibility we were experiencing yesterday and
today, we made the safe decision not risk a last second encounter or a case of
mistaken identity in the murky water.
We did not hear what kind of shark it was, only that it was larger than our 21-foot small boat. That leads us to believe it may have been a species or basking shark, perhaps a whale shark. Basking sharks are filter feeders that screen large amounts of plankton from the water for their nutrition. Humans aren't on their menu. 
Earlier in the day, Sonke dove in the submersible on what he describes as the second best JOHNSON-SEA-LINK I (JSL) dive he has ever made. "The best one was last year, right here, only the visibility was much better." Hurricane Katrina has made her effects felt from the surface to the bottom of the gulf. "There was an amazing amount of animals around the Lophelia coral - four to five species of crabs, shrimps, urchins, starfish, a bunch of different kinds of fish, scallops, squid. There were all the things you ever see down there, but all together. Tremendous diversity - it was like diving on a shallow water reef for that. The only bad thing was the visibility." Sonke says the water was full of ground up zooplankton that not only cut visibility around the sub, but also prevented downwelling light from reaching anywhere near the depth they were diving. Before the storm, it would have been possible to record irradiance at their working depth, but not today. "It was pitch black down there - like diving in coastal water." He did acquire lots of video that he can analyze over the coming months, splitting color channels to see how animals appear, or disappear, in the different colors of the spectrum. Sonke is collating the proposal for Deep Scope 2006. If it is funded, he will perform the duties of chief scientist on that mission. 
Justin Marshall took to the sphere with pilot Hugo Marrero for this afternoon's dive to recover the Eye-in-the-Sea (EITS) and Tammy's benthic trap. Hugo describes it as the toughest he has made. Visibility was poor and the current very strong. "You couldn't see the Eye from 10 feet away." The current actually swept the sub into the EITS, knocking it over for the third time this mission. Edie was relieved to see her instrument safely back on deck. It won't be deployed again this mission, but Edie and Erika Raymond have plenty of images to download and filter through during their last day at sea. Justin and Hugo collected a few samples to bring back to the surface that the science team is checking for fluorescent activity in the wet lab. Tammy's trap came back, not with the kind of crab she was seeking, but a pasty white specimen with barely-discernible eyes. Instead, its legs are covered with sensory hairs, demonstrating another sensory adaptation for this dim light environment. Rather than relying onvision to find prey and mates, this crab probably relies on chemoreception, the ability to detect chemical trails in the environment. This crab's most distinguishing feature is a very large claw, easily ten times the size of the other claw which tucks under its body. 
Tomorrow is the last day of this mission. There'll be two dives in the JSL, and a blue-water dive is planned. We'll take full advantage of the day that would have been our transit day had our time at sea not had a hole punched out of the middle of it. The scientists will continue to look into how light and vision affect marine animals in the shallows and the depths - and perhaps peer into the future as well, envisioning Deep Scope 2006. 
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