Improving Grades for the Mesoamerican Reef

Fish swimming in waters of Bay Islands, Honduras
Fish swim in protected waters off the Bay Islands of Honduras.  (Francesca Diaco Pargos)

Report cards are useful in school because they help students and teachers keep track of how students are doing. Good grades show that a student is on the right track, while bad grades mean more work is needed. But school’s not the only place where report cards come in handy. Most jobs require employees to go through performance reviews, and some scientists and resource managers are even using the concept to keep an eye on ecosystem health and recovery.

That’s where the Smithsonian Healthy Reefs for Healthy People Initiative (HRI) comes in. Roughly every two years they release a report card for the Mesoamerican Reef—a barrier reef that stretches along the Atlantic coasts of Mexico, Belize, Honduras and Guatemala, the largest such reef in the Americas.

And it turns out that this year its grades are up! Despite several bleaching events in the Caribbean, coral cover increased by an average of 38 percent at more than 100 sites that have been monitored from 2006 to 2016.

There is no doubt that the world’s coral reefs face unprecedented stresses. Climate change is causing mass bleaching events and ocean acidification is slowing down the growth of calcium carbonate structures of corals. So, why is this region’s coral cover improving while coral reefs around the world struggle?

The answer might lie in regional protections that provide the reef with the ability to be resilient in the face of bleaching and ocean acidification. Studies have shown that protecting fish species, such as parrotfish, that like to munch on algae paves the way for reducing algal invasions on reefs. The Healthy Reefs Initiative actively assists countries to safeguard their parrotfish populations—the fish are protected now in Belize, in the Bay Islands of Honduras, and Guatemala. In Mexico, a law for their inclusion as a protected species is in the works. Other animals can help reduce algae cover as well, and HRI will begin pilot studies this year to determine if restoring populations of the Caribbean King crab and the Diadema sea urchin, both important algae eaters, can help increase grazing and reduce macroalgae.

Preview Cover of 2018 Mesoamerican Reef Report Card
The 2018 Mesoamerican Reef Report Card from the Healthy Reefs for Healthy People Initiative.

Protected areas are another piece of the puzzle. Forty-seven Marine Protected Areas (MPAs) now cover over 34,000 square km (13,127 square miles) and protect roughly 57 percent of the territorial seas of the Mesoamerican Reef. However, only three percent of the area is completely closed off to fishing. These fully protected areas seem to work—they are home to nearly all the big fish found during monitoring, with closer to six mature fish per site compared to an average of one and a half outside MPAs and in MPA zones where fishing is allowed. These protected areas also safeguard places where some fish species come together in large groups to reproduce. Some of these spawning aggregations, for example of the Nassau grouper, are starting to recover after nearly being destroyed by overfishing. When the babies produced by fish in MPAs grow up, they not only help keep the reefs healthy, they also feed local people.

It’s not just protecting animals that is important - reducing the input of nutrients that encourage algae growth also helps. Strong wastewater quality standards have been established in the Bay Islands of Honduras and initiatives are helping inform local communities about the connection that human sewage systems and runoff have to coastal algae growth.

The HRI reports from the last decade emphasize two things—successfully protecting reefs requires a collaborative, multi-pronged approach, and with hard work you can see improvement. HRI helps to identify the most urgent threats and feasible solutions, and their report cards help us see how the reefs are doing in response to the actions that are taken. It turns out that it’s not time to give up on coral reefs.

March 2018