Mission Log: Sept. 10, 2007
Getting Underway
Emma Hickerson
Chief Scientist
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| The research dive team - Click here for bios of the team. (Photo: SolmarHydro/Stecher) |
Hi all!
The weather gods are looking favorably on us so far! HOORAH! After loading up the multibeam system and the science party, we headed off the dock in the Strand District in Galveston at around 6:30 p.m. on Saturday night. We steamed all night and arrived at the East Flower Garden Bank at around 10:30 a.m., all geared up ready to go diving!
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| A ridge of yellow pencil coral, Madracis mirabilis, is often coexisting with stands of purple rope sponge, Aplysina sp. (Photo: Emma Hickerson, FGNMS) |
We have five teams of divers - 10 divers all told, who will be doing three dives per day. This means that we are shooting to complete 15 habitat surveys and 15 fish surveys every day, each time in a different, randomly selected location. It's quite a process getting everyone off the boat into the three small boats each time we dive.
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This picture was taken in the middle of a large "wheat" field of the yellow pencil coral, Madracis mirabilis. Who is winning this battle for space? The barrel sponge (Xestospongia muta), or the Madracis? (Photo: Emma Hickerson, FGNMS)
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The three small boats sit on the back deck of the NOAA Ship Nancy Foster, and the it takes about six crew to deploy the boats with a crane, ropes, and a lot of skill. The Foster swings around in a tight turn and creates a "lee" - a patch of smooth water to launch each boat into. Once a boat is in the water, a ladder is dropped down, and we (the science divers), climb down and hang on. Today we've had 3-5 foot seas to contend with - lots of bouncing around in the small boats!
So, ten divers and three coxswains in three small boats are launched and head out to predetermined, randomly selected drop sites. We have programmed the latitude and longitude into the GPS (Global Positioning System) Unit and get the countdown from the coxswain, and flip backwards into the water. For safety, each team descends on a line that is tied to a float that allows the coxswain on the small boat to know exactly where the divers are - good thing! It's a LONG swim to shore!
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| During the benthic habitat transects, the divers are counting the percentage cover of both algae and coralline algae. In this picture, the reddish white components are coralline algae, both encrusting, and plating forms. You can also see some brown algae, Dictyota sp., which grows in forms that looks like the letter "Y", and flat leaf like brown algae called Lobophora sp. The coral in the picture is Madracis mirabilis, or yellow pencil coral. (Photo: Emma Hickerson, FGNMS) |
Yesterday we conducted some training dives, and started the working dives to collect data. We've completed surveys at 23 dive sites, and are aiming to collect 60 more before the end of the week. The sites have all been different - all high coral cover, but different kinds of coral assemblages. The main part of the coral cap is dominated by large brain and star corals, with intermittent sand channels. On the flanks of the coral cap we've encountered fields of a yellow pencil coral called Madracis miribilis - we sometimes refer to these fields as wheat fields because they look just like rolling hills of wheat. These Mirabilis fields seem to be pretty popular habitat with some species of juvenile fish. A purple rope sponge, Aplysina sp., is also quite conspicuous in some of these pencil coral fields, and large barrel sponges (Xestospongia muta) are prevalent. Some areas of the cap we've surveyed areas are dominated by plating mustard hill coral (Porites astreoides).
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| Symmetrical brain coral (Diploria strigosa) with three Christmas tree worms (Spirobranchus giganticus) embedded into the skeleton of the coral. The gills of the worms are what is visible on top of the coral head, and the body of the worm, which may be a foot or more long, lives in a tube burrowed into the coral skeleton. (Photo: Emma Hickerson, FGNMS) |
The fish surveyors have seen some grouper, including yellowmouth, marbled, tiger, rockhinds, and redhind, but unfortunately not as many as we saw this time last year. The fish counters are counting everything from tiny juvenile bluehead wrasse to the 5-foot barracudas that come in for a look. I'm focusing on the benthic habitat, which is quite a change for me. Despite this, I've been able to take note of a few juvenile yellowmouth and tiger grouper, which is a treat!
Visibility has been fabulous - well over 100 feet! Not much current to speak of, and a balmy 86 to 87 degrees Fahrenheit for water temperature.
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| This image illustrates the difference between the two brain corals found at the Flower Garden Banks - the boulder brain coral (Colpophyllia natans), which has larger ridges, and wider valleys, and symmetrical brain coral (Diploria strigosa). Also illustrated is "no mans land" between the two corals - this is an area of competition between two adjacent colonies. At night the corals send out tentacles like appendages called mesentarial filaments, which sort of "dissolves" the next door neighbor, and makes room for the coral to encroach on neighboring territory. (Photo: Emma Hickerson, FGNMS) |
We are using a Simrad EM 1002 to collect high resolution (3m) multibeam bathymetry in areas of the Sanctuary and surrounding areas of interest that have not been previously mapped - as I type this log, we are north of the West Flower Garden Bank mapping away! Mike Stecher, Bryan Costa and Missy Partyka are heading up the mapping project and are working in 8-hour shifts when all the divers are sleeping the night away. Talk about techno overload! They are surrounded by eight monitors and computer systems. Phew! I'm going to stick with the diving.
I'm holding out for a manta or a whale shark...good night and thanks for cruisin' with us!
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