LONG-TERM MONITORING RESEARCH

Principle Investigator:

Richard B. Aronson
Dauphin Island Sea Lab
Dauphin Island, AL
raronson@disl.org

Collaborators:

Bill Precht, Ken Deslarzes, Les Kaufman

Research Assistant:

Ryan M. Moody

Research Focus:

East and West Flower Garden Bank Long Term Monitoring

Background:

Richard Aronson is a marine ecologist who combines the tools of benthic ecology and paleoecology to understand the past dynamics of coral reefs and predict their future trajectories. He and Bill Precht have been collaborating for more than twenty years, focusing on why corals declined drastically and macroalgae (seaweeds) increased on Caribbean reefs beginning in the late 1970s.

Richard and Bill have always been interested in the Flower Garden Banks because they exhibit luxuriant reef communities at the margin of corals’ tolerance for low sea temperatures. Along with Ken Delsarzes, Les Kaufman and their colleagues at the engineering and environmental firm PBS&J, they seized the opportunity to run the FGBNMS’s long-term reef-monitoring program.

Research Summary:

Long term monitoring results from the Flower Garden Banks (FGB) provide an interesting counterpoint to data that Richard and others have collected in the Caribbean. The cover of living corals at the FGB has held steady at about 50% since at least 1978, whereas average coral cover in the Caribbean declined from 50% to 10% during the same period. The explanation for this difference revolves around the species of reef corals that dominate in the Caribbean as compared to the FGB.

Until the early 1980s, Caribbean reefs were dominated by staghorn coral (Acropora cervicornis), elkhorn coral (Acropora palmata), and star corals (Montastraea annularis species complex). Outbreaks of an infectious bacterial disease called white-band disease killed almost all the staghorn and elkhorn corals around the region, drastically reducing coral cover and providing space for macroalgae to settle and grow. The Acropora corals are more cold-sensitive than other corals and, therefore, could not settle and grow at the FGB. As a result, the dominant corals at the FGB were (and still are) the star corals and several species of brain coral. White-band disease only affects Acropora corals, so the outbreaks during the 1980s and 1990s had no impact on corals or macroalgae at the FGB because there were no Acropora corals there to be killed.

Now other diseases are beginning to affect the star and brain corals at the Flower Garden Banks, which means that Richard and his colleagues are keeping a close eye on the situation. Furthermore, as sea temperatures continue to warm, elkhorn coral appears to be colonizing the FGB for the first time in thousands of years. These latest observations show how dynamic coral reefs are in an era of rapid climate change.