Swamped in Sargassum

BY STEPHANIE MACDONALD

The pristine sandy beaches of the Caribbean are falling prey to our changing climate. Often when people think of climate change, the first things that come to mind are rising sea levels, ice melting, forest fires and drought, to name a few. We don’t consider the compounding effects of climate change. Here in the Caribbean the effects of climate change are making themselves known in a way many locals did not expect. Since 2011 our beaches have become increasingly smothered in Sargassum and in 2018 it reached record levels.

The Sargassum Frogfish perfectly camouflaged.

Usually contained within the Sargasso Sea, this brown macro-algae at normal levels is an ecologically important and complex source of food and shelter for many marine species . Sylvia Earle described Sargassum as a golden floating rainforest . The seaweed is home to unique species. To name a few, the sargassum frogfish perfectly mimics the seaweed pattern and coloration, while turtle hatchlings seek protection and shelter from predators in the mats it forms.

These days sargassum has been observed in the form of the Great Atlantic Sargassum belt (GASB) stretching from West Africa to the Gulf of Mexico. Spread over a very large area the GASB consists of an extremely large collection seaweed scattered loosely over 9,000 km.

Scientists believe that warming waters and changing ocean currents due to climate change are encouraging the growth of sargassum. Rising ocean temperatures help the seaweed proliferate faster. While the increased levels of nutrients resulting from the never ending Amazon deforestation, create favorable for increased growth. These factors combined cause huge blooms to form the phrase “Too much of a good thing” come to mind when looking at the current sargassum crisis.This unique ecosystem is bringing harm to the local environment where it washes up. Mangrove habitats which play host to many juvenile fish are being suffocated, beaches choked and reefs carpeted.

Many of the tourism dependent islands are not prepared for the daily influxes of seaweed intermingled with plastic washing up on their shorelines.

Huge sargassum blooms were once unique. Now we we can only assume that they will keep occurring annually. With Caribbean ecosystems already at threat from the stresses of climate change, theses additional factors are only going to lead to more devastation.

National Geographic article: https://www.nationalgeographic.com/magazine/2019/06/sargasso-sea-north-atlantic-gyre-supports-ocean-life/