Dissolved organic matter in the water column may influence coral health

Mar 04, 2008

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

Explore further: Chemical spill had 'no impact on health': Costa Rica

Related Stories

FAA's Airworthiness Directive issued to avoid power loss

21 hours ago

A fix for a software problem that could possibly result in power loss in Boeing 787s has been ordered. Federal Aviation Administration officials adopted a new airworthiness directive (AD), effective as of ...

More than 2,200 confirmed dead in Nepal earthquake

Apr 26, 2015

A powerful aftershock shook Nepal on Sunday, making buildings sway and sending panicked Kathmandu residents running into the streets a day after a massive earthquake left more than 2,200 people dead.

Recommended for you

Australia—riding on the insect's back

10 minutes ago

As you may have spotted, the title of this article is a cheeky reference to the famous saying that Australia rides on the back of a particular woolly ruminant. The reference dates back to 1894, when the wool ...

Behind the scenes with a Los Angeles mountain lion expert

50 minutes ago

When LA's Griffith Park mountain lion crawls under someone's house, or a brother-and-sister pair become the first mountain lions with tracking collars to cross a freeway since 2009, Seth Riley is at the top ...

Student dig uncovers hundreds of rare moa bones

1 hour ago

Māori Studies staff and students from Victoria University of Wellington have excavated hundreds of moa bones from a central North Island site where few moa remains were known to exist.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.