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THE MAINE EVENT: FALL 2002 Predation by Gelatinous Zooplankton in the Gulf of Maine MISSION DISPATCH 3 • 09/06/02 Today's Weather - images courtesy of NOAA & RSMAS Dispatch by Harry Breidahl - Marine Education Society of Australasia [MESA] Yesterday brought us much finer weather and the Fall 2002 Maine Event was now in full swing. The R/V Seward Johnson II was still positioned over the deep water of Oceanographer Canyon and the morning program began at 
7.30 am with the deployment of a MOCNESS net system. Stay tuned for details of this multi-net gear in future
dispatches.
At 1 pm sub crew persons Dan Boggess (subpilot) and Hugo Marrero (aft operations technician) took Chuck Jacoby and Marc Picheral on the day's first dive in the submersible Johnson-Sea-Link I (JSL). The JSL carries a crew of four in two separate chambers - the front chamber is a clear acrylic sphere and the rear chamber is an aluminum cylinder with hemispherical ends and three small acrylic portholes. 
Most of the 'action' happens in front of the sphere. Here the sub pilot and a scientist sit side by side with
a nearly uninterrupted view all around. This level of visibility is ideal for the study of midwater animals,
especially gelatinous animals, such as siphonophores, ctenophores and medusae (what many people call jellyfish).
The sub pilot is responsible for maneuvering the JSL to track, video tape and often to the capture these fragile
creatures. For this very purpose JSL has a nifty pair of 'critter gitter' suction tubes that lead to 24
collecting buckets.
Specimens captured in these buckets and immediately preserved in situ allow Marsh Youngbluth and his colleagues to study the diet Nanomia cara and other pelagic fauna in the lab aboard the R/V Seward Johnson II. Thus far they've learned that Nanomia cara consumes mostly copepods (only the resting diapause phase Calanus finmarchicus stage V). Some colonies captured euphausiids (at least three species in different genera Meganyctiphanes, Nematoscelis, and Stylocheiron). One big siphonophore with more than 50 gastrozoids ( = stomachs) had eaten a chaetognath (an arroworm, genus Sagitta). 
The aft operations technician, is responsible for monitoring levels of carbon dioxide and oxygen inside the two
habitable sections of the sub. In an emergency the occupants of the rear chamber can also take the JSL to the
surface by using a small red control panel.
A big Maine Event highlight came for me when Marsh asked me to take part in the second dive for the day. This time a night dive commencing at 9.30 pm. Exploring the deep sea in a submersible is something I have read a great deal about but never dreamed I would be fortunate enough to experience in person. Our dive was number 4473 for JSL. Well and truly rugged-up against the cold that would be transferred into the rear chamber through its aluminum walls, I entered through a small hatch. After closing and sealing the hatch 
behind us, Hugo gave me a safety briefing then ran me through the emergency procedures. The safety briefing was
easy to follow but I must admit that my technical ineptitude soon cut-in. I tried to look as if I was taking it
in but don't think I was all that convincing.
The dive was simply stunning. Reading other people's words or watching videos can only convey part of an experience like this. It is a head down - backside up and face pressed against the window kind of ride. We were submerged for a little over three hours and arrived at the sea-floor at 2100 feet (that's 700 meters for my dive buddies in Australia). Through my small window JSL's lights allowed me to see perhaps 15 feet (5 meters) into the dark and yet I saw so much life - most of it gelatinous. The deep ocean environment is truly an alien world and one that mankind has only just begun to explore or comprehend.  |  |
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