Mission Log: Sept. 11, 2007
Fish Stories & Corals
Mark Monaco
FGNMS Mission Team Member
Hello All,
It is Day 3 of field operations off the NOAA Ship Nancy Foster on a discovery mission at the Flower Gardens Bank National Marine Sanctuary!
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| Goldentail eels |
On this day we were able to conduct two of three of our planned SCUBA dives for the day as the waves became too large to launch the Nancy Foster small boats. Nevertheless, the team of 10 scientists and crew from the Nancy Foster collected data at 10 stations during the morning dives. At each of the stations data were collected by writing on underwater paper the types of fishes, their size, and abundance by one diver. The other diver followed the “fish counter” and they collected information on the types of habitat found on the seafloor and its condition or “health”.
Fish Stories
The size of fishes ranged from tiny juvenile bait fish to the large Marbled Grouper that was about 2.5 feet long! We continue to see relatively large size fish when compared to other coral reef ecosystems in the Atlantic region. For example, one team of divers encountered four big tiger groupers and a smiling goldentail eel!
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| A large Marbled Grouper poses for his picture! (Photo: Chris Caldow) |
Also, check out the Ocean Trigger Fishes which we have encountered on each dive, who usually escort us down and up the dive. Near the end of each dive the divers hang in the water at depth about 15-20 feet for a dive safety stop and often during this time we encounter curious barracuda and small juvenile jacks.
Healthy Corals?
A very important component of the mission is the information being collected on the health of the corals and other habitat such as the extent of algae and sand habitats. In addition, the divers are on alert to find evidence of coral bleaching associated with high water temperatures and/or disease.
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| Bleached Coral (Photo: Bruckner/NOAA Fisheries) |
Corals have very pretty colors due to the algae that live inside the coral skeleton. Under high stress conditions the algae is expelled and only the white coral skeleton is shown and thus the corals appear “bleached”(see picture) Fortunately, the habitat divers have found minimal incidence of bleaching in specific types of corals.
Another set of divers stopped to document the scraping of coral by the stoplight parrotfish, which is a natural feeding behavior that occurs on coral reefs by parrotfish. Although the scraping kills the coral tissue, in healthy coral ecosystems like the FGBNMS the corals appear to recover from the parrotfish bites.
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| Diseased Coral (Photo: Bruckner/NOAA Fisheries) |
Unfortunately since 2005 a disease currently known as “white plague like” has infected some of the FGBNMS corals. The picture above is an example of the evidence of disease found during the ongoing cruise. Although the FGBNMS corals tend to recover from this disease and isolated cases of coral bleaching, these stressors must be continued to monitored and studies conducted to determine the impacts of bleaching and disease on the FGBNMS.
How deep is the Flower Garden Banks National Marine Sanctuary?
In order to get a better understanding of the ocean floor’s structure, 50 km2 of bathymetry (or information about depth) have been collected north of the
West Flower Garden Bank. It was collected using SONAR or Sound Navigation and Ranging, which calculates depth by timing how long a pulse of sound takes to travel from the ship to the ocean floor and back again.
This information helps scientists to better understand the environment in which fish and corals live. The depths in the FGBNMS range from about 23m to180m.
So now it is late on Tuesday night and the coral and fish scientists head off to their bunk beds hoping for calm seas and light winds the next day. For the multibeam team it means working throughout the night to continue to map the bathymetry of the FGBNMS!
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