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THE MAINE EVENT: FALL 2004 Predation by Gelatinous Zooplankton in the Gulf of Maine MISSION DISPATCH 12 • Friday, September 26, 2004 Dispatch by Celeste V. Mosher - Harbor Branch Oceanographic Institution 
It has been a day of further discovery out here at Georges Basin as well as a day of apprehension.
Unfortunately, we can see on the satellite television that Hurricane Jeanne has pummeled the east coast
of Florida as a Category 3 storm. This is the second major storm there in less than two weeks. Most
of the submersible crew and many of the
R/V Seward Johnson II's
crew were up late into the night helplessly watching
and wishing they were able to transport themselves home to be with their families. It seems we will
be losing an unexpected number of crew tomorrow when we travel to Gloucester to drop off scientists
that were unable to stay for the second leg of the cruise. Consequently, the fate of this cruise is
unknown as we aren't sure if we will have the critical minimum of submersible and ship crew necessary
for operating the Johnson-Sea-Link.
On a more positive note, we have seen many Nanomia colonies and are working to learn more about their
ecology. Fishermen have reported menacing blooms in the past but during Maine Event cruises in the past
four years scientists have not observed what could be considered a "bloom". However,
Marsh asserts that
the abundance of colonies this year at this spot is the "closest we've come to observing a bloom". Most
of these critters, unlike those in the canyons, migrate upward during the evening and aggregate near the
surface in the particle-rich layer where chlorophyll concentrations peak. Marsh recorded such diurnal
behavior in Wilkinson Basin a few years ago but had yet to find such pronounced associations during the
Maine Event cruises until this year. During the JSL dives here we are transecting and pumping water
samples at 30-m intervals to observe, record and capture prey (=copepods, euphausiids, amphipods, and
other small zooplankton) that occur at the same depths as
Nanomia cara.
We wonder if the colonies are searching for a food resource when they migrate
and if they are reacting to physical cues (e.g., light and temperature) in their environment?
We had perfect weather to enjoy this afternoon. The sea surface was calm and, while looking into the
water during the afternoon dive, someone spotted something familiar. Ctenophores!
Calle, Francesc and
David tried in vain to use a pole net to collect at least one of the Bolinopsis floating merrily along
just under the surface. Sometimes the simplest tool will do the trick, but unfortunately, this net had a hole in it.
An abundance of tomopteriid polychaetes appeared in Georges Basin. This pelagic worm was not observed in the deep-water canyons. Although they are ubiquitous in the world's oceans, such prevalence at this location has not been seen previously during "The Maine Event" cruises. Our day ends with the satisfaction that we made headway in our explorations of the sea. We are transiting toward Wilkinson Basin now. We'll be there in about 10 hours. In the meantime, metabolic experiments, data entry and number crunching keep us busy. 
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