The Caribbean in Hot Waters

The ocean around the Caribbean is in hot waters, and we mean that in the literal sense. We already reported on warning signs that predict mass coral bleaching in the tropics. Scientists have monitored concerning changes in the coral reefs off South Florida, USA. In the last 50 years we have seen a steep decline of Staghorn and Elkhorn corals. Once an abundant reef builder, these species have been decimated and replaced by algae and soft coral. It is estimated that we see 90 % lees of these today and in some locations they seem to have almost disappeared altogether.

Diego Lirman is a researcher with the University of Miami and has been researching the reefs in the region for the last 3 decades. His focus is on Disturbance Ecology, research on forces that can wipe out whole ecosystems. In the past he observed a surface coverage of 20 % hard coral on the typical reefs. Today that density is down and coral can only survive on about 5% of all reef surfaces in the area. Those changes in the ecosystem have widespread effects on complex symbiotic relationships withing the reefs ecosystem. It changes breeding grounds, changes the food chain and leaves less shelter for species that rely on coral for their survival.

The dangers reefs face are plentiful. From boat anchors to fishing lines, pollution and commercial dredging, overfishing and changes in water acidity, the list is long. For decades, activists and local governments seek to curb the effect human activity has on the reefs. In 1990 a 3,843 square-mile protected area was established. The Florida Keys National Marine Sanctuary reaches from the Biscayne National Park to the Dry Tortugas and encompass many reefs beneath shallow ocean waters. Preservation efforts included the installation of mooring buoys, and the establishing of no fishing zones around the largest reef structures. But also education efforts and training of the crews of tourist tour operators were part of the efforts to protect fragile environments.

The biggest threat of all is the unprecedented rise of ocean temperatures. In August 2023 NOAA’s Atlantic Oceanographic and Meteorological Laboratory on Virginia Key recorded record high sea temperatures in their 174 year history. In the Florida Keys some shallow areas recorded more than 38 degree Celsius.

Scientists are scrambling to come up with measures to preserve biodiversity among coral species and to assist ailing reefs with the recovery despite the high temperatures. One Strategy is the “Noahs Arc concept” where the staff at the Coral Restoration Foundation pulled coral from the ocean based field nurseries and relocated them to land based operations to shield them from the warm waters. The aim is to preserve biodiversity and keep enough stock to be able to repopulate the reefs at a later point in time. Another different approach by the NOAA’s Experimental Reef Laboratory on the campus of UM’s Rosenstiel School of Marine, Atmospheric, and Earth Science together with other research institutions to grow more resilient species of coral that can withhold higher temperatures while resisting disease. The idea would be to use those specimen in propagation and reforestation efforts. While there is no universal answer to the mounting challenges presented by climate change, the best solution for now might be an ‘all hands on deck’ approach. It may take unified efforts by various leadership organizations and real political will to address the source of the problem. In addition we will need creative scientific efforts to minimize the devastating effects we already see. There is a lot to loose and reefs are much more that pretty underwater gardens. They are vital to a vast majority of life in the oceans. We are just now starting to understand the far reaching inter-dependencies of marine life as we broaden our knowledge of the mysteries that lies beneath the blue waters.

Healthy coral