Dr Anjani Ganase, coral reef ecologist, reviews current research and activities for coral reef conservation.

Extremely warm waters have hit the Caribbean, the second year in a row. In 2023, mass bleaching was observed throughout the Caribbean then the rest of the world.

At the beginning of this year the fourth global coral bleaching event was declared, the second within the last decade. We seem to be well on our way to 99 per cent loss in coral populations by 2050 with the current trajectory of global emissions.

Since I returned to Trinidad and Tobago to study reefs here, I have been reporting on coral bleaching every year. The severe coral bleaching last year decimated reefs throughout the Caribbean including the Meso-American Barrier Reef (Mexico and Belize), Jamaica, and Bahamas.

In Tobago, many brain corals bleached and died last year, and in 2024, many colonies started to pale and bleach as early as July. The reefs have little time to recover between the hot summer months of succeeding years.

A mass coral bleaching event occurs when many colonies of corals of different species lose their colour and turn white. Corals have a symbiotic relationship with micro-algae that live in their tissue. The algae provide nutrients sourced from photosynthesis, while the coral host provides essential minerals and removes waste for the algae keeping it happy in its home. This relationship breaks down under conditions of stress, such as excess heat or cold temperatures or even with influxes of fresh water, and results in coral bleaching. Global coral bleaching – remember all oceans are interconnected – occurs when coral reefs around the world all bleach in the same year because ocean temperatures are too warm during their summer months.

Caribbean research

While widespread coral mortality can be very discouraging for us, many scientists continue to research strategies to assist coral regeneration and improve resilience. Organisations such as Secore International have worked on developing methods of enhanced coral propagation to increase coral populations through assisted fertilisation and survival in the early stages of life which can be naturally very low. Improved genetic mixing aims to create opportunities for natural adaptation in the future. This is the opposite of what we do in agriculture where we practise selective breeding for desirable traits. Instead, we try to grow corals of many different gene combinations so that through diversity, the species may be prepared for a future of unknowns.

[caption id="attachment_1112288" align="alignnone" width="1024"] Global coral bleaching occurs when coral reefs around the world all bleach in the same year because ocean temperatures are too warm during their summer months.- Anjani Ganase[/caption]

Assisted fertilisation involves the collection of coral sperm and eggs during the nights of spawning from several colonies, fertilising large batches, then allowing embryos to settle on specially designed units that can be planted on the reef to increase chances of sur