Coral reefs in Tobago are under threat after experiencing their fourth consecutive year of coral bleaching.
The National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch has placed most of the Caribbean on Coral Reef Bleaching Alert. T&T is under a Level 2 alert for the next three months for widespread bleaching and mortality.
The alert comes as corals in Florida are being bleached at alarming rates as a result of this year’s historic heatwaves and rising sea temperatures.
Above average sea temperatures are being recorded in T&T and the wider Caribbean according to Dr Anjanie Ganase, Coral Reef Ecologist at the Institute of Marine Affairs (IMA).
“The IMA was out in the field for our annual monitoring over the last couple weeks and the waters have been exceptionally warm,” she said. “We’ve clocked temperatures around 31 degrees at some reef sites, at least two degrees above what is typical for this time of year. We have asked our stakeholders to report any signs of bleaching to us.”
Dr Ganase added: “We will be promoting this reminder over the next month or so. We will be back in Tobago in the beginning of September and will continue to monitor and will likely do a bleaching assessment in October/November.”
In 2022, the IMA team observed pale and partially bleached corals in Charlotteville, northeast Tobago. Reports of coral bleaching were received from reefs in southwest Tobago, including Buccoo Reef, Store Bay Reef, Flying Reef and Mt Irvine Reef. Several species, including brain, mountainous star, staghorn, fire and even soft corals were affected.
In Trinidad at Saline, Salybia Bay, bleached coral fragments have been reported.
In 2005, marine scientist Dr Stanton Belford began mapping and researching Trinidad’s corals with Dr Dawn Phillip of the UWI.
“I’m not sure if these fragments came from finger coral colonies further out at the reef crest, where scuba is needed for further investigate,” he said.
“Fragments from finger corals break off as a result of the heavy pounding by the waves at the reef crest. However, the fragments that break off are usually still alive (in this case they maintain their brown colour). What I saw at the reefs were bleached (white) fragments, which are a bit unusual.”
The Salybia Bay reef is the only fringing reef in T&T.
It extends 200 meters parallel to the shoreline and about 1.5 km in length. There you can find large colonies of reef-building finger corals (Porites porites), boulder star corals, and the occasional brain coral. Additionally, large beds of brown encrusting zoanthid (Palythoa spp.) and green mat zoanthid (Zoanthus spp.), with purple octocrals interspersed.
Hope for coral and seagrass
The coral reef and seagrass beds that are part of Tobago’s marine ecosystem have suffered degradation over decades from a combination of climate change and human impact. One of the most notable effects was the loss of up to 50 per cent of hard coral cover due to global bleaching in 2010.
Seagrass beds along the island’s southwest coast have not escaped, facing land-based pollution, coastal developments such as land reclamation and events such as Sargassum influx.
Often called the rainforests of the sea, the diverse ecosystems are home to 25 per cent of marine life and are essential to many sectors, including food production and tourism. In fact, Tobago’s coral reefs support the livelihood of the island’s fishermen and tour operators.
Alex Nedd, founder of Waterholics, expressed concern about the bleaching alert. His water sport business offers activities including jet skiing, wake boarding, water skiing, paddle boarding, dolphin watching tours and trips to two major attractions, Buccoo Reef and Nylon Pool.
“The Buccoo Reef heavily contributed to Tobago’s tourism sector,” said Nedd.
“It is the most popular glass bottom tour on the island. Tourists and visitors love the close distance of the Buccoo Reef from the shoreline. It takes about 10-15 minutes to get there. Tour boat operators can make two to three trips daily.”
With current climate change projections for island nations, including sea-level rise, an increase in extreme storms, global warming and ocean acidification, there is an urgent need to boost the resilience of crucial marine ecosystems to reduce their vulnerability.
The IMA, in partnership with bpTT, launched the Marine Resilience Initiative (MARIN) Tobago last year. The 18-month pilot seeks to determine appropriate and feasible rehabilitation strategies for the coral reef and seagrass beds that surround Tobago.
“There is an urgency to build capacity with respect to coral reef management,” explained Dr Ganase.
“Our first restoration will take place in 2024. We will be collecting the sperm and eggs for fertilization. We will feed them on specialised tiles and grow them, then try and outplant them to increase the amount of next generation.
“This is very important in terms of climate change. The outcome is that you will have some species, which will become more resilient to coral bleaching.”
As the pilot wraps up in September, bpTT has committed to the main phase according to Vice President, Corporate Operations and Head of Communications and Advocacy Giselle Thompson.
“We are pleased that based on the success of the pilot, we have secured funding as the project moves from pilot into the main phase.
“MARIN will become one of the sustainability initiatives that bp supports at a global level. Among the benefits will be the opportunity to share the learnings from MARIN with similar projects in other parts of the Caribbean and the world.”
The project aims at building resilience in coastal ecosystems as one of the strategies to mitigate climate change.
Record high temperatures
Record high air and sea temperatures were recorded in July.
On Thursday a maximum high temperature of 33.8°C was recorded at Piarco, while a maximum high of 31.8°C was recorded at Crown Point according to the T&T Meteorological Service (TTMS). Earlier in the month, the Copernicus Climate Change Service (C3S) reported record highs of global air and ocean temperatures in July.
Global average sea surface temperatures continued to rise after a long period of unusually high temperatures since April 2023, reaching record high levels in July. For the month as a whole, global average sea surface temperatures were 0.51°C above the 1991-2020 average.