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THE MAINE EVENT: FALL 2002 Predation by Gelatinous Zooplankton in the Gulf of Maine MISSION DISPATCH 6 • 09/14/02 Today's Weather - images courtesy of NOAA & RSMAS Dispatch by Harry Breidahl - Marine Education Society of Australasia [MESA] 
Earlier in the week the threat of major storms put a temporary halt to the Fall 2002 Maine Event
research program in the Gulf of Maine. On Wednesday night it was reluctantly decided to take
the long trip back to Woods Hole to sit out the storms. Two days later conditions had improved
enough for the R/V Seward Johnson II to head out to sea again. At 7 am on Friday 13th we left
the Woods Hole Oceanographic Institution dock and began a 12-hour transit to Atlantis Canyon on
Georges Bank.
As we sailed through lumpy seas it was a matter of adjusting again to rolling decks and swaying rooms (I still haven't got the hang of using a mouse on a computer that refuses to stay still). Nevertheless, after a couple of quiet days ashore we were happy to be underway and eager for the now familiar shipboard routine. Upon arrival at Atlantis Canyon the initial plan was to pick up the research program with a Johnson-Sea-Link I (JSL) night dive. However, rough seas soon ruled this dive out and we were back to the waiting game and hoping that the wind will moderate and the seas abate. The rough seas didn't prevent deployment of the MOCNESS multi-net system but they did make this task a challenge. 
At times the crew deploying and retrieving the net were battling knee deep in water
as foamy waves washed over the aft deck. Considering the unsettled conditions, the safe retrieval
of the net system at 12.30 am on Saturday 14th was a job well done.
As one component of the Maine Event research program, the MOCNESS net system deployed last night is being used to quantify species diversity, vertical distribution and relative abundance of planktonic animals in the mesopelagic zone of the ocean. By the way, mesopelagic is a term used by scientists to describe the mid section (zone) of the ocean (meso is Latin for middle). This zone starts at 600 feet (200 meters) below the surface and descends to 3,000 feet (close to 1,000 meters) in depth. That's why the research team has been concentrating on canyon sites. These underwater valleys provide access to water that reaches 1,000 meters in depth. As well as being the lower boundary of the mesopelagic zone, this is also the depth limit of the submersible Johnson-Sea-Link I (JSL). The ocean is a fascinating but alien environment to humans. The invention of scuba gear about 50 years ago has allowed us humans to easily access the first 150 feet (50 meters), usually close to shore. However, waters below the sun-lit zone of the open ocean can only be explored in person with submersibles. While submersibles, such as JSL, have been available for almost as long as 
scuba gear, the use of these amazing subs is limited by time, funds and other factors, such as
the weather we are currently experiencing. As a result, direct human exploration of the
mesopelagic zone is still in its infancy. Incidentally, the average depth of the ocean is 4,000
meters and the upper 1,000 meters constitutes only 12% of this vast environment.
The mesopelagic zone is also called the twilight zone. For anyone with a lifelong curiosity about things unknown, this deep ocean environment truly is a fascinating place to explore and study. Many animals that live in this regime seem bizarre to us, partly because they have adapted to environmental conditions that are incredibly different from those we experience on land. There is almost no light (certainly not enough for human eyes). It's bitterly cold and the pressure increases 14.7 lbs/in2 every 33 ft (for the metrically minded that's 100 kilopascals for every 10 meters). Most of the deep-living plankton and nekton must rely on food that drifts down from the productive sunlit waters above. The fact that there is any life here at all seems remarkable but the diversity of life now being discovered in the deep ocean is truly astounding.  |  |
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