Bacterial communities endemic to healthy corals could change depending on the amount and type of natural and man-made dissolved organic matter in seawater, report researchers from The University of Texas at Austin Marine Science Institute and Mote Marine Laboratory in Sarasota, Florida.
Healthy corals naturally exude a surrounding mucous layer in which a complex population of bacteria exists. Recent studies have indicated that some coral diseases may be linked to community shifts in this bacterial population.
In experiments with a common reef building coral in the Florida Keys, Chris Shank of the University of Texas Marine Science Institute and Kim Ritchie of Mote Marine Laboratory found an obvious shift in the composition of the coral bacterial community resulting from changes in the pool of surrounding dissolved organic matter.
Dissolved organic matter in the water column near Florida Keys coral reefs comes from a variety of natural sources, including coastal mangroves, seagrasses, and plankton, as well as man-made sources, including sewage effluent. The composition of dissolved organic matter surrounding Florida Keys coral reefs has likely changed in recent decades due to growing coastal populations.
“When coastal ecosystems are physically altered, the natural flow of dissolved organic material to nearby coral ecosystems is disrupted with potentially harmful consequences for the corals,” said Shank, assistant professor of marine science.
Shank and Ritchie, manager of the Marine Microbiology Program at Mote, placed Montastraea faveolata coral fragments in aquaria filled with water collected from either Florida Bay or from an offshore bluewater site.
Dissolved organic matter concentrations are much greater in Florida Bay than in offshore waters and typically have different chemical characteristics. Water collected from these distinct locations used for the coral incubation experiments represented the variable nature of dissolved organic matter experienced by corals in the middle and lower Florida Keys.
They found that the microbial community of healthy corals shifts measurably when exposed to water from Florida Bay, suggesting the microbes that normally play a role in coral immunity may be out-competed by potentially problematic bacteria. In combination with increased water temperatures, this is an example of the type of compounded stressors known to cause health problems in corals, or “reef deterioration.”
The scientists reported their results today at the Ocean Sciences Meeting in Orlando, Florida.
The scientists’ research is part of their larger effort to investigate the link between alterations to the south Florida ecosystem and Florida Keys coral ecosystems. Coral reefs there, as with coral reefs around the world, are increasingly threatened by rising water temperatures, advancing ocean acidification and rapidly rising coastal populations.
Corals are especially susceptible to coastal alterations because they commonly exist in shallow waters at the interface of land and sea.
Shank and Ritchie are planning a series of experiments to more closely evaluate the chemical nature of the water column dissolved organic matter surrounding the corals in the Florida Keys and identify shifts in potentially harmful bacterial populations.
Source: University of Texas at Austin
Related stories:
UCR professor studies engineering and invention on the half-shell
Marine snails, sea urchins, and other animals from the sea are teaching researchers in UC Riverside’s Department of Chemical and Environmental Engineering how to make the world a better place.
No-fishing zones studied for ecosystem protection
(AP) -- Reeling in a 45-pound grouper used to be just an average day on the water in the Florida Keys. The abundance of behemoth fish attracted anglers from around the world in the early 1900s, including adventurers such as Ernest Hemingway and Zane Grey, who pulled in monsters from the clear, warm depths off Key West.
Dry Tortugas show positive trends: Protected area slowly rebounding
Multi-agency effort a collaborative success in integrated ecosystem assessment
A team of 38 research divers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, NOAA Fisheries Service, the Florida Fish and Wildlife Conservation Commission, the National Park Service, REEF, and the University of North Carolina at Wilmington recently completed a successful 20-day biennial census to measure how the protected status of the Florida Keys National Marine Sanctuary's Tortugas Ecological Reserve and Dry Tortugas National Park's Research Natural Area are helping the regional ecosystem rebound from decades of overfishing and environmental changes.
8-day undersea mission begins experiment to improve coral reef restoration
Scientists have begun an eight-day mission, in which they are living and working at 60 feet below the sea surface, to determine why some species of coral colonies survive transplanting after a disturbance, such as a storm, while other colonies die.
Ancient deep-sea coral reefs off southeastern US serve as underwater 'islands' in the Gulf stream
Largely unexplored deep-sea coral reefs, some perhaps hundreds of thousands of years old, off the coast of the southeastern U.S. are not only larger than expected but also home to commercially valuable fish populations and many newly discovered and unusual species. Results from a series of NOAA-funded expeditions to document these previously unstudied and diverse habitats and their associated marine life have revealed some surprising results.
New Window Opens on the Secret Life of Microbes
Nowhere is the principle of "strength in numbers" more apparent than in the collective power of microbes: despite their simplicity, these one-cell organisms -- which number about 5 million trillion trillion strong (no, that is not a typo) on Earth -- affect virtually every ecological process, from the decay of organic material to the production of oxygen.
Coral Reefs Unlikely to Survive in Acid Oceans
Carbon emissions from human activities are not just heating up the globe, they are changing the ocean’s chemistry. This could soon be fatal to coral reefs, which are havens for marine biodiversity and underpin the economies of many coastal communities.
Immediate action needed to save corals from climate change
The journal
Science has published a paper today that is the most comprehensive review to date of the effects rising ocean temperatures are having on the world’s coral reefs. The Carbon Crisis: Coral Reefs under Rapid Climate Change and Ocean Acidification, co-authored by seventeen marine scientists from seven different countries, reveals that most coral reefs will not survive the drastic increases in global temperatures and atmospheric CO2 unless governments act immediately to combat current trends.