Earth Today | Living resources face death by climate change

THE CARIBBEAN’S living resources – from coral reefs to seagrass, mangroves, fish and shellfish, all of which contribute to the region’s multibillion-dollar blue economy – face an uphill battle for survival in the changing climate.

This is detailed in the October 2020 book The Caribbean Blue Economy, under the chapter titled ‘Implications of climate change for Blue Economies in the Wider Caribbean’.

Authored by researchers Professor Michael Taylor, Professor Mona Webber, Dr Tannecia Stephenson and Felicia Whyte, the chapter notes that the “Caribbean has already changed in significant ways and is projected to continue changing through the end of the current century due to further global warming”.

“The overall picture is of a Caribbean already characterised by increases in storm intensity, drought risk, ocean temperatures, acidity, sea levels and wave heights. The future climate will likely see more intense storms, even higher sea levels, smaller wave heights, and warmer, more acidic oceans,” write the authors.

The negative implications for the region’s living resources are real.

For example, intense rainfall periods with increased sedimentation and nutrient inputs blanket reefs in sediments, which reduces light for photosynthesis, while there is reduced light penetration, leading to lower productivity, shoot biomass and density for seagrass.

Increased sea surface temperatures mean bleaching, which kills or weakens corals, making them more susceptible to disease.

Sea level rise drowns seagrass by a reduction in optimal depth and effective light intensity, while mangroves face coastal ‘squeeze’, or lack of space for upland migration.

Extreme weather

Increased storminess associated with more extreme weather events topple mangrove trees, while uprooting and eroding seagrass beds, leading to a reduction in the structural complexity of reefs.

“The effect of climate change will be most critical for the major coastal ecosystems (coral reefs, seagrasses and mangroves) as well as their associated organisms (fish and shellfish),” write the authors.

“Corals have received the greatest attention due to the severe decline in live coral cover over the last 30 years and the alarming bleaching events that have occurred after periods of extremely high sea surface temperatures,” they add.

“Seagrasses and mangroves have similar responses to variables like sea level rise and intense storms. Seagrasses, more so than mangroves, are also threatened by increased turbidity from land derived sediments and high sea surface temperatures,” the researchers wrote further.

These living resources, meanwhile, contribute significantly to the blue economy of the Caribbean, helping to sustain livelihoods in sectors such as tourism, agriculture and fisheries that have been high performers in their contribution to the region’s economy.

The researchers have, therefore, recommended a number of interventions to halt the loss of life from among the Caribbean’s living resources. They include giving “urgent attention” to identifying and protecting locations where organisms may be more robust, or less exposed, to climate change.

“This is in addition to restoring degraded but still existent sites. The latter may require ex situ conservation approaches,” the researchers explain.

They also note the need for “applying integrated coastal zone management which recognises the changing resources”.

“Approaches to coastal development must integrate infrastructure and other land management practices with the changing ecosystems, for example, accounting for shoreward shift or maintaining sediment supply to coastal areas to assist mangroves to keep pace with sea level rise,” they write.