Coral bleaching creates ecological, economic problems

The reefs in Tobago, particularly the Buccoo and Speyside reefs, have undeniably been affected by coral bleaching since 2005, and maybe even before that. The vibrant colours of the reefs that once drew locals and foreigners alike, seem to be a thing of the past and in some areas, the characteristic white colour (or absence of colour) of the bleached coral is evident. Sanjiv Ramcharan, senior lecturer in the Natural and Life Sciences Department at College of Science Technology and Applied Arts of Trinidad and Tobago explained to Newsday, if not dealt with, coral bleaching can introduce serious ecological and economic issues to the nation. The reefs, which surround most of Tobago, protect the small island from such threats as storm surges, hurricanes and coastal erosion by dissipating the wave energy (Institute of Marine Affairs Coastal Conservation Project 2010). The absence of these reefs therefore means that Tobago will be more vulnerable to environmental degradation and natural disasters. It goes without saying that Tobago thrives on tourism. The reefs are a major tourist attraction and according to Ramcharan, also supply the island’s southwestern beaches with their white sand.

Although coral reefs occupy less than one per cent of the ocean, he said, “Coral reefs in general support the lives of approximately 25 per cent of all marine species either by acting as a shelter for some species and/or a nursery for others.

The reefs are also important to support Tobago’s fishery.” As a result, he sees monitoring and managing the reefs as “important for the maintenance of these ecological and economic functions.” According to the Institute of Marine Affairs’ Coastal Conservation Project 2010, if the reefs do not recover within a month or two, they could die. Death for the corals could therefore mean death for Tobago’s tourism and a large part of its marine ecosystem as well.

Ramcharan said that for reefs to recover, monitoring, educating and conservation are required.

He said corals are made up of polyps on a calcium carbonate or limestone substrate, and/or skeleton produced by the polyps and receive their nutrition in two ways. However, the method that accounts for 98 per cent of the corals’ nutritional needs is one in which a symbiotic relationship is formed with photosynthetic algae known as zooxanthellae.

In this mutually beneficial relationship, the algae is incorporated into the coral’s body tissue which protects the algae while they in turn produce food for the corals. The algae are what give corals their colour.

“Coral bleaching occurs when the corals undergo periods of stress which can be triggered by increased oceanic temperatures, freshwater dilution, invasive species and environmental contaminants,” said Ramcharan. He further clarified that after being under prolonged stress by any of these conditions, the corals respond by ejecting the algae from their bodies. Consequently, the corals’ white bodies (bleached bodies) are what is left. The absence of algae renders them colourless.

“At this point,” Ramcharan said, “the coral isn’t dead and it could, after time, reincorporate the microscopic algae into its body tissues. However, if the stressors remain, for example increased oceanic temperatures, the coral can die over time. Death usually occurs as a result of the coral bodies being overgrown by much larger, external macro algae.” The length of time that coral bleaching has been impacting reefs globally is unknown, but the first documented major global coral bleaching occurrence was in 1998 due to a massive underwater heatwave.

In Tobago, there were events of bleaching in 2008 and 2010, but the reefs have been under monitor since its first documented mass bleaching in 2005 where the Buccoo reef was especially susceptible. Ramcharan said that some of the reefs that had been affected in the 2010 global bleaching event were the Speyside Reef, Buccoo Reef and reefs in Bon Accord and Culloden. He added, “The only established reef in Trinidad is off the coast of Salybia and there was no great bleaching found there.” When asked about the main causes for coral bleaching in Trinidad and Tobago, Ramcharan said, referring to the Institute of Marine Affairs’ Coastal Conservation Project Nov/Dec 2010, “The data suggests increased oceanic temperatures as well as the expansion in developmental activities in the associated catchments (for reefs in Tobago) mainly for resorts and houses.”

“Monitoring the reefs for direct and indirect threats, damage and bleaching events. Educating the population on threats to the reefs as well as their role in contributing to the protection of the reef. Conservation methods by both public and private sector participants,” he said, are some of the ways in which bleaching can be controlled. He also shared that the reefs in Tobago are already being monitored for further events of bleaching and oceanic temperatures are also being recorded. He pointed out that the Institute of Marine Affairs has projects for the monitoring and conservation of the health of the coral reefs and by large the country’s coastal ecosystem.

“It is with no doubt that land activities also affect the health of the coastal waters of Trinidad and Tobago. Therefore, it is my opinion that the protection of our coastal waters has to be a holistic approach and ensures that all stakeholders both private and public, terrestrial and marine; are part of the protection and conservation efforts. Not only to our coral reefs but also for our wetlands (such as mangroves), seagrass beds and coast lines.”

Citizens of Trinidad and Tobago can also assist with combating the issue. Ramcharan believes that sensitising the public to the threats faced by coral reefs as well as their contribution to those threats is important. It’s crucial to recognise that there are other factors that cause coral bleaching and that we can help alleviate the impact of coral bleaching by reducing those activities. Ramcharan explained, “We as citizens can help by reducing pollution, decrease deforestation thereby reducing the amount of sediments being washed into oceans, do not damage the reefs when we visit them etc. This not only applies to all citizens of Trinidad and Tobago but to those who visit as well.” Earlier this year, scientists declared that Australia’s Great Barrier Reef (the largest coral reef in the world) could not be saved anymore. Due to the rise in oceanic temperatures, the reef was severely damaged and a reported 95 per cent of the reef was bleached. In order to save Tobago’s reefs from having a similar fate, authorities and locals need to be proactive in taking measures to protect their gems.