The decline of sea urchins (Diadema antillarum) and parrotfish (Sparisoma viride) across reefs in the Caribbean could lead to the loss of coral reefs in the Caribbean, according to the study “Status and Trends of Caribbean Coral Reefs: 1970-2012” released last week by the Global Coral Reef Monitoring Network and the International Union for the Conservation of Nature.
In the report, scientists cite the loss of parrotfish and sea urchins, herbivorous species that graze on algae build up on coral reefs.
When the algae get out of control, the corals die off. Parrotfish, according to the report have suffered serious declines due to overfishing in certain areas in the Caribbean, including the entire Florida reef tract, (Miami to Key West), Jamaica, and the U.S. Virgin Islands. These areas show serious coral reef declines, according to the report. While not always a targeted species, according to the report, the wide body of the parrotfish causes them to easily become ensnared in nets that are cast for foodfishes. Commercial harvesting of three parrotfish species in U.S. Caribbean waters was made illegal in 2011, and recreational harvesting of parrotfish was restricted.
In areas of the Caribbean where large populations of parrotfish are protected, such as the U.S. Flower Garden Banks national marine sanctuary, Bermuda and Bonaire, the reefs are thriving and are considered some of the healthiest in the region. The sea urchin suffered a massive die off in 1983, wiping out huge populations of the important algae grazer throughout the region, While some areas in the Caribbean have recovered, many areas have not, which has led to rampant algae growth.
“The rate at which the Caribbean corals have been declining is truly alarming,” said Carl Gustaf Lundin, director of IUCN’s global marine and polar program. “But this study brings some very encouraging news: the fate of Caribbean corals is not beyond our control and there are some very concrete steps that we can take to help them recover.”
In addition to overfishing that has decimated the parrotfish populations in certain areas, excessive coastal pollution, tourism, and coastal development are significant contributing factors to the decline of this algae grazing fish.
Reefs that are protected from overfishing, as well as other threats such as excessive coastal pollution, tourism and coastal development, are more resilient to pressures from climate change, according to the authors.
The full report can be downloaded from the IUCN website.