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Guest Column

Gulf oil spill imperils deep-water organisms

Unlike the inviting climate at the surface of the Gulf of Mexico, the waters adjacent to the devastating Deepwater Horizon oil spill — nearly a mile down — are absolutely dark and cold. The organisms in these bottom waters and sediments have adapted to live in a completely different world. To understand the spill's potentially devastating effect on them, we must see and sense the world as they do.

The vast majority of living space in the gulf is not warm and sunny but rather is a high-pressure, lightless environment, home to a diverse group of organisms that include shrimps, fishes, jellyfish and sharks. The extreme environment — the pressure at the drill site is 150 times what it is at the surface — leads to extreme adaptation: the angler fish with its long lure that can be illuminated, the black gulper, dragon fishes and bristlemouth with their extensive set of fangs, the hatchet fish with rows of tunable light pipes that are used to hide from predators, comb jellies with rapidly pulsing rows of light that glow as they move through this dark environment, and animal plankton that come in vivid shades of red.

These animals have evolved to thrive in this harsh environment by developing incredibly sensitive senses of smell to find mates as well as prey that they could never see. In fact, these creatures are far better at detecting traces of chemicals than even the most sophisticated underwater mass spectrometers used by the scientists from SRI and Woods Hole who were tracking subsurface oil in the northern gulf.

The American Naturalist points out that a goldfish — by no means the most sensitive organism studied — could detect a dissolved chemical that was 20,000 times less concentrated than what SRI's underwater mass spectrometer needs just to register the presence of methane. In other words, the well-developed noses of mid-water organisms allow them to detect, and react to, trace levels of organic chemicals in water that are so diffuse no scientist could possibly measure them. The best scientific instruments will be unable to detect chemicals that could be critical to the health of oceanic organisms. Undetectable is not synonymous with safe.

Some video footage taken in the gulf from a submarine provided a graphic demonstration of the remarkable sensory capability of deep-living golden crabs that inhabit the extensive outer shelf and upper slope off Florida's west coast. As the submersible neared the ocean bottom at 400 feet, a bag of dead fish was deposited on a flat, featureless bottom. The submersible backed away and waited. Within 20 minutes several large golden crabs appeared, seemingly out of nowhere, and set about eating the dead fish. Within 45 minutes the bag of fish was totally covered with these crabs that apparently had caught a "whiff" of the dead fish and, like well-trained hunting dogs, followed the trail.

Most members of the mid-water and deep food webs in the world's oceans — fishes, shrimps, crabs and zooplankton — would be unable to function without their chemical-sensing capability. Unfortunately, the suite of organic chemicals in the spilled crude oil not only has varying degrees of toxicity but could also compromise their sense of scent. Scientific reports from the spill leave little doubt that layers rich in microscopic droplets of oil and methane have been detected anywhere from 50 to 1,400 meters beneath the surface.

Given the importance of the issue, it is remarkable that the first expedition to study the possible interaction of oil with the mid-water food web in the northern Gulf of Mexico did not embark until early this month. Starting today, images of some of the mid-water organisms that Dr. Jose Torres and his scientific team are studying in the Gulf of Mexico can be found at www.marine.usf.edu — click on TorresOceanOil.

In sharp contrast to surface oil that was tracked with satellites, aircraft, surface vessels and sophisticated chemical fingerprinting, submerged oil is much more challenging to trace. It is understandable that our primary emphasis so far has been on the beaches, on the wetlands, on the fishing and aquaculture industries as well as on the tourism industries that are integral to the lives of so many people living near the Gulf of Mexico.

But now that the well has been sealed, we can focus on the cleanup and also on scientifically addressing and monitoring the gulf ecosystems as they recover from this assault. It is critical that these efforts include monitoring and research of the mid-water and deep food chains in the Gulf of Mexico where organisms might still be reacting to the more stable organic compounds derived from the oil.

Going forward, the public should demand that multiple safeguards be applied by any industrial group that sets out to drill and subsequently extract oil and gas from the Gulf of Mexico and, further, that an extensive set of multiyear scientific studies of the possible major transformations related to the Deepwater Horizon oil spill be made and used as a basis for evaluating future proposed uses of the Gulf of Mexico.

Peter R. Betzer, Ph.D., is president and CEO of the St. Petersburg Downtown Partnership Inc. He is the former dean of the University of South Florida's College of Marine Science.

Gulf oil spill imperils deep-water organisms 09/07/10 [Last modified: Tuesday, September 7, 2010 7:19pm]

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