Mission Log Aug. 12, 2008
Geoff Cook, Co-Principal Investigator
George Mason University
Let your body relax in its weightlessness.
Check your air pressure.
What’s my depth?
Check out the neck on that Loggerhead turtle!
Where the heck is the survey stake?
Are those corals glowing fluorescent orange?
This place is amazing!
These are but a few of the thoughts running through the minds of the research scientists aboard the NOAA Ship Nancy Foster as they descend into the crystal clear, azure waters within the Tortugas Ecological Reserve (TER), North. Today’s survey site, dubbed “Sherwood Forest”, the deepest of the 44 areas we’ll be collecting data from during this week’s cruise, poses one of the more unique hazards associated with deep diving: nitrogen narcosis. Often used as an anesthetic in dental and medical offices across the country, nitrogen gas (N2) serves to block synaptic processes in the brain and create a sense of general well being. While this state of mind might be considered a pleasant experience on land, diving on an anesthetic can be quite dangerous.
|FKNMS Associate Science Coordinator, and this year's cruise Chief Scientist, Scott Donahue, points at the R/V Nancy Foster from Ft. Jefferson, Dry Tortugas National Park. (Photo: Kathy Morrow)
During this morning’s briefing, our divemaster, Sarah Fangman, conveyed the potential hazards of nitrogen narcosis: “At high concentrations, like those encountered when diving deep, nitrogen can sometimes cause one to experience a sense of euphoria…an altered sense of perspective that can impair judgment. It is often compared to drinking a martini in one swift gulp. You wouldn’t drive a car in this condition, nor should you continue collecting data.” Fortunately, nitrogen narcosis is easy to remedy: ascend slowly to a shallower depth. With these warnings in mind, our survey teams gaze over the seemingly endless expanse of sapphire-colored water inundating Sherwood Forest, beckoning us to take the plunge. And so, as the sun breaks free from the shackles of the horizon, we willingly obey Mother Nature’s request.
The Tortugas Ecological Reserve (150 nm2) was formally established in 2001and is the largest no-take area in NOAA’s Florida Keys National Marine Sanctuary (2,900-nm2). The TER is comprised of two, non-contiguous areas TER North, and TER South. The only activities permitted within TER North are diving and, well, more diving. Leave only bubbles; take only data. We have come here to collect information on the health and overall condition of corals inhabiting this stretch of reef. Our surveys are conducted by recording the general condition of every species of coral inhabiting a 113 m2 of reef located within a large circle. At the center of these circles are survey stakes. These “markers” are actually steel rods that had been installed into the seafloor approximately 10 years ago. Needless to say, finding a 1-inch diameter steel pipe encrusted in algae and the ever-painful “fire coral” at the bottom of the ocean is quite an adventure.
As our teams, clad in wetsuits and SCUBA gear, roll backwards off the rigid hull inflatable boats (RHIB) we immediately thrust our faces in the water to look down at the site. Even from the surface we can see clear to the bottom, some 80 feet away. “It’s beautiful”, says Lauri MacLaughlin, resource manager for the FKNMS. It’s hard not to agree. While floating on the surface we easily spot large and colorful coral colonies peppering the ocean’s bottom in a manner reminiscent of a cartoon landscape. “I think the recreational dive community first named this site ‘Alice in Wonderland’”, Laurie continues. The bright oranges, purples, greens, and browns being reflected by the corals, sponges, algae and fish make it easy to understand why.
|Kathy Morrow, Lauri MacLaughlin, and Sarah Fangman pose for a pre-dive photo. (Photo: Kathy Morrow)
As we begin our surveys one thing becomes clear: there is more live coral in Sherwood Forest relative to those sites already surveyed in the upper, middle, and lower Keys. Not only does there seem to be more coral colonies, the colonies also appear to be larger in size. These anecdotal reports imply that the reefs within the TER might be in better overall health than those situated closer to the Keys. However, where there are more corals there are also more potential hosts for disease. Much like the common flu can infect large numbers of people in a congested urban center, diseases affecting coral populations, such as white plague and black band, have more potential to affect a greater number of individual colonies. Our surveys confirm these suspicions.
As we finish our day’s work and return to the NOAA Ship Nancy Foster the research teams begin to convey both positive and negative feelings about the status of coral reefs sampled within the FKNMS. Although Sherwood Forest appears to have more coral, those that inhabit this site are still not exceptionally healthy. We can’t help but ponder whether or not the Tortugas Ecological Reserve is really effective at protecting coral reefs and their inhabitants from regional and global coral reef stressors. However, if it is, can we ensure the same degree of relative health for the corals reefs within the entire FKNMS? If not, what causes coral diseases on reef systems that are both protected and relatively far removed from dense human populations?
A few scientists joke about possibly transplanting corals from Sherwood Forest to other areas within the FKNMS. The reefs in Sherwood Forest are, relative to other areas we sampled in the FKNMS, rich in corals. Nevertheless, we all agree that playing Robin Hood would do more harm than good. So the quest continues for a better understanding of what causes disease in coral populations and communities and how we can minimize the damage to these beautiful and important ecosystems for further generations to use and enjoy.