Error processing SSI file
Flower
Garden Banks National Marine Sanctuary SSE
Accomplishments Report
On August
29, DeepWorker pilots Steve Gittings, Edie Widder,
Peter Vize, and Emma Hickerson departed Key West on
board the NOAA Ship Ferrel and steamed towards the
Flower Garden Banks National Marine Sanctuary.
Flat, calm seas and dolphin and whale spottings
brought hopes for good weather during the missions.
Unfortunately, the sea state took a downward turn
about the time the Flower Garden Banks hit the
radar screen. Although faced with unpredictably bad
weather, and certain logistical problems, a total
of 12 DeepWorker dives were conducted in the short
time nature cooperated.
Coral
Spawning
|
A
remotely operated vehicle is deployed to
document spawning. Weather and sea
conditions did not permit scuba or
DeepWorker dives to be conducted during
this event. (Photo credit:
FGBNMS)
|
On the peak spawning night for several species of
coral, scuba and submersible operations were
canceled due to weather conditions and sea states.
Fortunately, an S2 Phantom remotely operated
vehicle (ROV) could be deployed to document this
event. Phil Otalora, Nuytco, flew the ROV for
several hours as others crowded around the screen
to witness the beauty of the "snowstorm" occurring
beneath the water. Dr. Peter Vize, the principle
investigator of the coral spawning project, made
several good observations using the ROV as his
window to the spawning. He recorded the deepest
spawning observation to date, Montastraea
cavernosa (a star coral) at 43
meters.
Unfavorable
sea states disrupted submersible diving operations
for the remainder of the first week, so scuba and
ROV operations were continued. Spawn collections
were made using scuba. Samples from blushing star
coral, Stephanocoenia sp., verified that
this species' eggs are fertilized prior to release
from the female coral.
Geological
Exploration
|
Emma
Hickerson, research coordinator for the
sanctuary, prepares for a dive. (Photo
credit: Frank Burek)
|
During dives, DeepWorker pilots reported changes
in topography to topside. The vertical incline of
the reef crest on the west bank varied from around
50-80 degrees. Some portions were densely covered
with well developed boulder and star corals. In
other areas, it was clear that the reef had
collapsed and toppled down to the sandy bottom.
What was left was just rubble. On two occasions,
pilots Emma Hickerson and Laddie Akins observed
small canyon like formations with reef structures
forming the canyon walls. These areas had sandy
bottoms, as if some force had been moving down the
crest like a river. Emma and Laddie followed the
"rivers" up to 90 feet (30 m) to a sunken "bowl"
shaped depression, approximately 30 feet (10m)
across, with the "river" of sand forming a
horseshoe around the top side, and returning down
the crest on the other side of the "bowl". In the
middle of the depression was well formed reef -
star and brain coral - just lower than everything
around it. This area appeared to have sunk,
probably due to dissolution of the salt dome
underneath. Hence, somewhere below, a brine seep
like that on the east bank may exist.
On the
east bank, Jim Gardner and Dave Lott used
technology provided by the U.S. Geological Survey
to navigate the ROV to points of interest in and
around the brine seep. The ROV was also used to
explore the north ridge of a graben area. The U.S.
Geological Survey mapped the Flower Gardens in the
winter of 1998 using high resolution multibeam
sonars. The images were taken originally to test
equipment but were spectacular and informative,
stimulating further interest. A paper on this work
was published in the recent dedicated issue of the
journal Gulf of Mexico Science (for copies, email
emma.hickerson@noaa.gov).
(top)
Fish
Censuses
|
The
nurse shark (G. cirratum) was one
of several shark species seen during the
Expeditions. (Photo credit: Frank
and Joyce Burek)
|
Emma and Laddie simultaneously piloted the two
DeepWorker submersibles while conducting REEF (Reef
Environmental Education Foundation) censuses of the
fish they encountered in different zones. They
began their surveys in the zone where the coral
stops, between 150 and 170 feet (50-57 m). Red hind
(Epinephelus guttatus), not often seen on
top of the reef crest, were abundant, propped up on
their pectoral fins on top of coral heads. A
dynamic school of cottonwick (Haemulon
melanurum) congregated in a particular location
of the reef edge and it was realized that it was a
large cleaning station. Numerous juvenile Spanish
hogfish (Bodianus rufus) flitted around the
school cleaning one fish, then the next. A large
school of horse eye jacks (Caranx latus)
took time out of their transit to swirl several
times around Laddie's submersible. Emma recorded a
total of 40 fish species during her survey around
this small portion of the base of the west bank,
including sunshinefish (Chromis insolata),
large amberjack (Seriola dumerili), tiger
grouper (Mycteroperca tigris), and green
razorfish (Hemipteronotus splendens).
Several carcharinid sharks were seen, but their
species could not be identified.
Next
Laddie and Emma headed west over the sand, which
was filled with yellow-headed jawfish
(Opistognathus aurifrons) dancing over their
holes. As they descended, the terrain changed to
rubbly chunks of drowned reef. Several very large
circular piles of rubble revealed large sand tile
fish (Malacanthus plumieri) busily picking
up chunks of the rubble and moving the rubble to
the perimeter of their territory. With continued
descent, the rubble turned to algal nodules, hiding
all sorts of cryptic species. Emma hopes to return
to this zone next year to collect some of these
nodules to assess the contents -- likely
micromolluscs, sponges, etc. The deepest depth
reached by Emma and Laddie was about 260' (87m)
where there were large outcroppings. A roughtongue
bass (Holanthias martinicensis) was seen
among the outcroppings.
|
Tiger
grouper, Mycteroperca tigris, and
several other grouper species were seen
around piles of reef rumble, perhaps
preferred habitat. (Photo credit: Frank
and Joyce Burek)
|
On another DeepWorker dive, Emma and Laddie
circumnavigated the west bank crest at 150-170 feet
(50-57 m) and while surveying fish using the REEF
roving diver technique they noted a healthy
population of groupers -- tigers (Mycteroperca
tigris), yellowmouths (M.
interstitialis), blacks (M. bonaci), and
yellowfins (M. venenosa) -- and a comb
grouper (M. rubra), rarely seen on the east
and west banks. Piles of reef rock, which had
perhaps tumbled from the reef crest, seemed to be
the preferred habitat for groupers. About a half
dozen reef sharks were also observed in the area.
Forty fish species were recorded during the
dive.
One
limitation of the DeepWorker, discovered during
REEF roving diver surveys, is that it cannot get
close enough to the substrate to allow the pilot to
see the cryptic species.
Georeferencing
One of
the major accomplishments of the missions at the
Flower Garden Banks was the use of the tracking
system. This system allowed pilots and topside
technicians to georeference notable observations,
such as the cleaning station with the cottonwicks,
an anchor, a cable, or a particularly large
congregation of grouper, so that in future
expeditions pilots and scientists will know where
they have been and what to look for.
|
This
water spout was only one of the weather
hazards that plagued the Expeditions
during its first week at the Flower Garden
Banks National Marine Sanctuary. (Photo
credit: FGBNMS)
|
return
to overview
(top)
|