Scientists Develop Strategies to Help the Coral Reefs Return to Balance

Thanks to Mrs. Becker’s class for the fun teleconference Thursday; it was my last one for this trip. I really have enjoyed learning about and using the Skype technology to do live communications.

A Construction Project~

Not all of our work here has been recording data on the health of the coral reefs. Tuesday afternoon, we did a different kind of activity aimed at maintaining the coral reef ecosystem.

Some of you may remember that the Bahamian Reef Survey project has been going on for the last 15 years. During that time, the composition of the local coral reefs here have changed.

Photo credit:NOAA

When we do the underwater point-intercept survey that I described on Monday's post, we count six features of the coral reef: hard coral, soft coral, algae, sand, rock and 'other'(anything else). Over the 15 years this study has been conducted, the percentages of these features in the San Salvador reefs have changed. The percentages of hard corals have decreased and the percentage of algae has increased. Also, certain fish populations have declined.

To be in a healthy state, the coral reef must maintain a balance between all the types of organisms that live in the reef. The hard corals are necessary to maintain the health of the reef; their hard skeletons are like bricks in a wall. They are called the 'reef builders' because the rest of the creatures of the reef live on and around the hard calcium carbonate skeletons that the hard corals form. Also, the branching shape of some of the hard corals (such as the Elkhorn, Staghorn and Fire Coral species) form lots of nooks and crannies in the reef necessary for a good fish habitat.

Fire Coral - note the different structural elements present in the reef Photo credit: Annette Pennock

Variety of coral structures on the reef Photo credit: Elizabeth Brill

The hard corals are declining on the San Salvador reefs, and the healthy balance has been disturbed. In an ecosystem, any change will cause other changes to happen. Algae is covering increasing amounts of the reef, depriving the coral of needed light and nutrients, the hard corals are dying off, so the structure of the reef does not have any nooks and crannies for fish to hide. With fewer fish to eat the algae, the algae continues to multiply.

Reef species need the hiding places supplied by those nooks and crannies Photo Credit: Elizabeth Brill

A Nassau Grouper hides in the reef Photo credit: Annette Pennock

The structure of a declining reef can be replaced in two ways; one involves transplanting living coral to the reef and the other involves attaching artificial ‘corals’ to the reef to replace structural features necessary to maintain the habitat for other species, such as fish. The reef rebuilding experiments being conducted by the Bahamian Reef Survey team on San Salvador will involve the creation of artificial structures to replace hard coral sections that have died and broken away

On Tuesday, we experimented with building a simple artificial coral structure.

We made a form with a box, sand and cardboard.

We poured special hydraulic cement in the mold.

While the cement was being molded, we also built a raft for the artificial coral to float on. We planned to attach boat bumpers to make it buoyant.

Here is what our completed structure looks like. You may be thinking that this doesn't look much like a coral; it will still provide the reef with the kind of structure elements it lacks, now that so much of the Elkhorn and Staghorn coral have dissappeared. This summer's volunteer groups will develop a design that has branching features, more resembling real coral.

Celebrating a team effort Photo credit:Elizabeth Brill