16 February, 1998
Last night and today have both been relatively calm. It was certainly not the harsh sea that were predicted. Many of the scientists have been using the time to enter data into their computers for analysis or just catching up on their sleep. (An option they haven't exercised much on this cruise.)
I had a opportunity to talk to Dr. Deneb Karentz, a professor who teaches General Biology, Oceanography, and Environmental Science at the University of San Francisco. She had been at Palmer Station since September studying the affects of ozone depletion on sea urchins, sea stars, and limpets. They chose those three to study because the adults are benthic (bottom dwellers) , but their larval stages live in the water column where they are exposed to ultraviolet (UV) light. Deneb and her co-workers, Mario Pineda, and Will Jaeckie, have been studying the UVB tolerance of the larval forms to see how it affects morphology deformities (body shape alterations), death, DNA damage, and time it takes to develop from one stage to the next. They suspended fertilized eggs into the water column at different depths with different types of coverings that went from no light, to UV filtered light, and to full exposure. They also took advantage of the movement of the ozone hole. The ozone hole rotates so sometimes the exposure to UVB is no greater than it is on other places on the globe. They have found that the organisms as adults have minimal natural sunscreens in their bodies, but do concentrate it in the eggs and ovaries. Why do you think that would be an advantage to the species? Another idea brought up by the study was that before photosynthesis produced the protective layer of gases around the Earth, primitive organisms would have had to develop with a natural UV protectant just to survive normally. Is this a remnant of that old protectorate being called upon again from deep in the DNA of these marine organisms? Interesting questions to a rising problem.
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