Published in the Marine Technology Society Journal, Winter 2000/2001: Volume 34(4): 69-74
Dr. Steven L. Miller and Craig Cooper
UNCW Center for Marine Science
National Undersea Research Center
515 Caribbean Drive
Key Largo, Florida 33037
Aquarius is a national asset that supports scientists in their efforts to better understand our oceans and coastal resources. An open and competitive peer–review process is used to select proposals that are submitted to the program on an annual basis. Proposals target science and management issues of highest merit and relevance to NOAA, and in particular the Florida Keys National Marine Sanctuary. Over the course of almost 50 missions more than 200 scientists participated directly in the program, representing over 90 organizations including universities from across the U.S. and several foreign countries.
Aquarius scientists work to understand our changing ocean and the condition of coral reefs. Unfortunately, coral reefs are threatened worldwide by increasing amounts of pollution, overharvesting of fisheries, disease, and global climate change. Science achievements from Aquarius include discoveries related to the damaging effects of ultraviolet light on coral reefs, geological studies that use fossil reefs to better understand the significance of present–day changes in coral reefs, research that is rewriting the book on how corals feed, water quality studies that evaluate sources of pollution, and long–term studies of reefs to help distinguish between changes caused by natural system variability and humans (due to pollution and overharvesting). A few examples follow.
Coral Reef Assessment and Monitoring using saturation techniques
Aquarius provides the bottom time necessary to make detailed studies of deep coral reefs. A 1998 Aquarius mission evaluated the relative condition of corals at depths to 120 feet. The team found that hard coral colonies at the deeper depths were in better shape than corals in shallower (60 feet) water. This is significant because a substantial amount of deep–reef resource is found in the sanctuary, but little is known about its condition. Interestingly, high recruitment levels (the observance of new individuals) were noted at all study sites. This is a positive sign for reef condition and recovery — at least in deeper water. Soft corals and sponges dominated recruitment at the deeper sites, while hard corals dominated at the shallow site. Fish surveys resulted in abundance estimates for 111 species (132 fish species were documented). The benthic and fish data will be compared with baselines established in 1994 as part of a deep coral reef monitoring program in the Florida Keys National Marine Sanctuary. A mission conducted in August 2000 expanded the monitoring and assessment effort, including more detailed biodiversity studies on sponges, gorgonians, and gastropods. Since the Aquarius site is now a marine protected area (commercial and recreational fishing and collecting are not allowed) the fish surveys provide valuable information for managers about how “no–take” strategies are affecting reef dynamics.
Water quality and nutrient pollution
Extended bottom times and the ability to deploy sophisticated sampling devices on reefs during missions have helped scientists to understand factors that affect water quality on reefs in the Florida Keys National Marine Sanctuary. Water quality research conducted using the Center’s shore–based research programs previously confirmed that sewage disposal practices used in the Keys contaminate nearshore waters (Paul et al. 1995). This information has helped politicians and managers to balance the costs of modifying sewage disposal practices in the Keys (measured in the hundreds of millions of dollars) with the costs of possibly losing nearshore resources to polluted water. However, documenting offshore nutrient pollution, and tying pollution to reef decline has not been easy. Offshore of the Keys, using the Aquarius underwater laboratory, scientists documented changes in water quality caused by natural events — related to the reefs close proximity to the Gulf Stream and upwelling events — that deliver substantial amounts of nutrients, plankton, and particles to the reef (Leichter and Miller 1999, and the June 2000 mission). Understanding and quantifying this substantial natural system variability provides important perspective on the potential for sewage to be a significant offshore problem. Aquarius scientists have also searched for (by drilling monitoring wells at the Aquarius site to sample potentially contaminated groundwater that could be moving through the reef), and continue to seek, the “smoking gun” that could conclusively tie nutrient pollution to the demise of reefs in Florida. So far, evidence remains inconclusive. The research results illustrate the complexity that defines factors that affect how reefs look and function in Florida.
The mysteries of coral feeding biology — revealed
This project used video and other techniques to study the small–scale mechanisms that affect how corals feed and capture prey (Sebens et al. 1998, Heidelberg 1999). Usually, this work is conducted in the laboratory, but Aquarius provided computers, power, and the necessary bottom time to conduct this work directly on the reef (July 2000 mission). The advantage is that measurements are made under natural conditions, and the corals are not stressed by removing them from the reef for study. It is well known that water motion impacts coral biology, affecting processes such as coral growth, competition, larval dispersal, fragmentation, and sedimentation. However, even at short distances, the rate of flow over and around corals can change dramatically. Water motion also delivers prey to corals and enhances the uptake and exchange of nutrients, oxygen, and carbon dioxide. The aquanaut team built and deployed sophisticated instruments to measure current speed and direction at the site, as well as flow over and around individual corals. Combined with high resolution infra–red video cameras, that were cabled from Aquarius, interactions among plankton and coral tentacles were documented that allowed the scientists to calculate coral feeding rates — the first measurements ever made under natural conditions.
© All Rights Reserved | | maintained by Thomas Potts (pottst@uncw.edu)