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MISSION DISPATCH 7 August 27, 2005 | Brian Cousin - @SEA Correspondent Port Fourchon exists to service the offshore oil patch in the north-central Gulf of Mexico. Dozens of supply boats, crew boats, seismic boats and others come and go through the channels carved into the Louisiana bayou, where it is said "there's a pretty girl standing behind every tree". Just as there no trees at Fouchon, there's no town to speak of, either. Several of us hitch a ride to the local cultural center at Anthony's Kajun Sportsman. 
Predictions for hurricane Katrina are monitored through all of the ship's watches. Last night, it appeared Fourchon might wind up in Katrina's path. Captain Aric Anderson decided we would leave Fourchon Saturday afternoon and head west to Galveston, Texas, about 24 hours away. This morning, after consulting with first mate Mike Schoeller who stood the night watch and had the latest on the storm, Captain Anderson changed the departure schedule and preparations were made for the R/V Seward Johnson to leave right away. The scene at the port can be described as controlled chaos. The channel was crowded with ships getting out to escape the storm and ships coming in with personnel from evacuated oil platforms. There is no port control, so it is up to the ships' captains to coordinate their own movements. The VHF radio buzzes with chatter as captains negotiate actions to keep the traffic moving A short while later, Port Fourchon is closed and evacuation of the entire area begins. 
A port is generally not a good place to keep ships in a hurricane, and many ports, including Fourchon, order vessels to leave in advance of such storms. Out at sea, there's not so much to run into. By staying in the navigable quadrant around a hurricane, a ship can actually use the storm's early, weaker effects to push it away from the storm's center. After that, a course can be set around the backside of the hurricane and out of its path. It's a lumpy ride, but it's the safest bet for ships that can't make it to a port well outside the storm's path. We hope Galveston remains out of Katrina's path for the obvious reason of keeping the ship and crew safe, but also because we still have a mechanical problem to solve with the tow winch. Chief Scientist Tammy Frank was able to put off delivery of parts to Port Fourchon, and we hope to receive them in Galveston. Though the JOHNSON-SEA-LINK I (JSL) is out of action for the time being, scientific work aboard ship continues nonetheless. Dr. Jon Cohen, Tammy Frank's post-doctoral fellow has just deployed a small trawl net over the side. He's after more copepods to continue his work on their optical physiology. He's joined by Dr. Mike Matz who's been looking into the fluorescent characteristics of these animals. 
Jon explains the eye physiology of a particular copepod Pontella securifer. "Copepods are fairly simple animals with simple eyes. What's really interesting is the complex optical adaptations in many copepod species. Why are there so many? This Pontellid has three eyes, one ventral and two dorsal, and each eye consists of only about six cells. The ventral eye has three lenses and a retinal surface." Light entering the eye must be focused on the retinal surface to allow the animal to perceive what it's looking at. Some animals have lens proteins called crystallins to focus the light. "The parabolic curvature and placement of the triplet lenses in this copepod gives a point of focus, presumably on the retina." It is worth noting that studying these animals is very difficult. Pontella securifer measures about 4 mm long and has an eye that measures about 100 microns across. Jon has developed a way to tether these tiny creatures and apply an electrode across the eye to measure such things as spectral sensitivity (the wavelength of light the copepod sees) and temporal sensitivity (the speed at which the eye responds to light stimulus). As part of the integrated Deep Scope mission, Jon is working with Mike Matz and Justin Marshall to create a model that incorporates physical aspects of the copepod's world with its visual morphology to answer questions about how it uses vision to survive. Pontella securifer lives near the surface, where it's bright and there's a lot of color. The male has a more elaborate eye than the female, perhaps to help it distinguish potential mates amongst the planktonic horde, and a bright orange antenna that acts a clasper to hold the female during mating. Under ultra-violet light, it fluoresces bright yellowish-green. 
"This animal has a strong blue peak and a strong ultra-violet peak in its spectral sensitivity", Jon continues. In time, models could indicate that the UV response may be a mechanism for revealing the animal's prey in the surface waters. And perhaps the orange color or the fluorescence of the antenna plays a role in attracting females of the species. Jon speaks about his work with the kind of excitement that makes others excited, too. He's really looking forward to bringing some of these microscopic animals out on the next blue-water scuba dive - just to snorkel around at the surface and see how the copepods orient themselves in the water. How he plans to follow them is a mystery, but anyone who can work with a 100-micron eye can probably do that, too. 
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