Coral Bleaching Alert for Tobago
In September, the National Oceanic and Atmospheric Administration (NOAA), Coral Reef Watch has placed Trinidad and Tobago under Bleaching Alert Level 2, where severe, widespread bleaching and significant coral mortality are very likely. Reports of moderate coral bleaching have been received from several sites around Tobago including Store Bay, South Coast, Mt Irvine, and Englishman’s Bay by marine users.
Bleached boulder brain coral at Castara in August
Bleached grooved brain coral at Mt Irvine in September
As part of Tobago’s Bleaching Response Plan, the Institute of Marine Affairs has alerted all stakeholders that work in the marine environment, and have made an appeal for any observations of coral bleaching. As a partner in Bleaching Response Plan Network, IMA has sought assistance from the Division of Food Security, Natural Resources, the Environment and Sustainable Development, the Department of Marine Resources and Fisheries to conduct bleaching assessments in Tobago, and notify marine resource users of coral bleaching threat and give guidelines to curtail the potential threat of disease outbreaks in the aftermath of a mass bleaching event, and to facilitate reef recovery.
Here are some frequently asked questions on Coral Bleaching
(sourced from IUCN, WWF and Reef Resilience)
What is Coral Bleaching?
Corals form a symbiotic relationship with microscopic algae that lives in its tissues. The algae photosynthesize using sunlight and then feeds the coral. The algae give the corals their amazing bright colours. In return, the coral provides the algae with all essential nutrients and removes the waste. The amount of food provided allows corals to grow to enormous rocky skeletons which are used by other marine organisms for shelter. However, if waters get too warm the relationships between the coral and the algae break down and the algae get expelled from the coral. This results in coral bleaching where the coral eventually turns white because they lose all their colour.
What is Mass Bleaching?
Mass bleaching events occur when sea temperatures remain unusually high for extended periods resulting in bleaching of several species of coral over a large areas at the same time. Three mass global bleaching events have occurred in recent history (1997 to 1998, 2010, and 2014 to 2017) where coral reefs around the world bleached as ocean temperatures exceeded their thermal tolerance threshold.
What causes coral bleaching?
Today, global warming is the main driver of coral bleaching and die-off, but pollution and over exploitation limit natural reef recovery. In the last 40 years, coral reefs around the world have suffered from global and regional coral bleaching events, where large sections of reef turned white as summertime sea temperatures became too warm because of global warming. Coral reefs of Tobago have also suffered from multiple bleaching events in the past including 2005 and 2010, and these have significantly degraded reef health. Corals that survive coral bleaching become vulnerable to diseases that also result in coral mortality.
How does coral bleaching impact wildlife?
Coral reefs are home to diverse marine life, including sea turtles, fish, crabs, shrimp, jellyfish, sea birds, starfish, and many other. Reefs offer shelter, a safe place for reproduction, and protection from predators. They also form the foundation of ocean food chains. If coral reefs deteriorate, it could lead to the extinction of vulnerable species, and loss of habitat for many marine organisms.
How does coral bleaching impact humans?
Coral bleaching has significant consequences for people’s well-being, food security, and safety. Coral reefs act as natural barriers that absorb the impact of waves and storm surges, safeguarding coastal communities. Without them, we are forced to depend on costly, less effective, and environmentally harmful man-made seawalls. This is especially important in low-lying areas of southwest Tobago. Additionally, bleached coral exacerbates the overfishing problem by disrupting the food chain and depriving certain fish and crustacean species of a breeding and development environment. Those who rely on these creatures for their income or on reef habitats to support their livelihoods will face challenges. Lastly, reef-based tourism generates billions of dollars annually and supports numerous jobs. Bleached coral reefs, stripped of their magnificent marine life, put all of this at risk.
Why should people care about mass coral bleaching?
Coral bleaching harms reefs in multiple ways. It makes them less attractive to tourists, reduces their ability to support fishing, and provides less protection to coastal communities from storms and waves. According to the International Union for Conservation of Nature (IUCN), “Recovery of degraded reefs can take decades, and the social and economic impacts can be long-lasting. In Tobago, for example, most of the corals still have not recovered from the 2010 bleaching event. One study in Australia has estimated that coral bleaching on the Great Barrier Reef could cost the regional economy approximately US$100-300 million over 20 years. In addition, reefs damaged by coral bleaching have lowered biodiversity and, quite simply, are less beautiful.”
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