The seas are warm, too warm, as I no­ticed when my dive com­put­er read 33C in north­east To­ba­go last week. Any­body who swam in the sea would have no­ticed this: “the seas were calm and nice!” But it isn’t so nice for ma­rine life ac­cus­tomed to liv­ing in wa­ter at least 4 de­grees cool­er, and that has many im­pli­ca­tions for peo­ple’s health.

If our body tem­per­a­ture rose to 40C, we’d need im­me­di­ate med­ical at­ten­tion. While we ob­serve most corals for bleach­ing (turn­ing white as the liv­ing or­gan­isms that keep corals alive leave due to heat stress) dur­ing ma­rine heat waves, high tem­per­a­tures im­pact all life in coastal wa­ters.

Sponges, soft corals, fish, conch and lob­ster all suf­fer from heat stress. Less dead­ly im­pacts of heat stress to ma­rine life in­clude re­duced re­pro­duc­tion and poor health, while ex­treme im­pacts in­clude mass die-offs. On­ly last year, we ex­pe­ri­enced this in To­ba­go. Many coral species, ma­rine sponges and sea fans bleached and died.

A red tide (harm­ful blooms of cer­tain types of al­gae) along the At­lantic coast trig­gered by high wa­ter tem­per­a­tures re­sult­ed in mass fish death along sev­er­al beach­es. This year, tem­per­a­tures are warm­ing even faster.

Warm­ing seas al­so af­fect div­ing con­di­tions. When I start­ed div­ing 15 years ago, I wore a 5mm wet­suit and I’d be cold with­in an hour. To­day, I dive in a rash guard and tights and on many oc­ca­sions, the heat sti­fles me. At night, the air was cool­er than the wa­ter. We were re­freshed by the cool air af­ter div­ing for hours at Mt Irvine, but what about the ma­rine crea­tures that can­not es­cape the warm­ing wa­ter?

Corals as in­di­ca­tors

This year, the Na­tion­al Ocean­ic and At­mos­pher­ic Ad­min­is­tra­tion (NOAA) up­dat­ed the coral bleach­ing alert net­work, from two Lev­els of bleach­ing alerts: Lev­el 1- risk of reef-wide bleach­ing, and Lev­el 2 - mass bleach­ing and (mor­tal­i­ty) death. The new sys­tem has five lev­els which ex­plain ex­pec­ta­tions when tem­per­a­tures go be­yond Lev­el 2. With Lev­el 5 comes the risk of more than 80 per cent of the coral dy­ing.

To­ba­go’s coral reefs have ex­pe­ri­enced ma­rine heat waves an­nu­al­ly for the last six years, with the most se­ri­ous oc­cur­ring in 2023 and 2024. Sci­en­tists pre­dict­ed se­vere an­nu­al bleach­ing from 2040 on, but cur­rent trends show that this was an un­der­es­ti­mate.

Hu­man-caused cli­mate change, which has in­creased heat-trap­ping car­bon diox­ide in the air, has al­ready de­ter­mined the cli­mate con­di­tions for at least an­oth­er 10 years, and we must pre­pare for a warmer plan­et. While glob­al ac­tion is im­prov­ing, change is slow, es­pe­cial­ly for small is­lands that are both de­pen­dent on ocean re­sources and vul­ner­a­ble to the im­pacts of cli­mate.

We are part of our ocean and earth sys­tems and need to take re­spon­si­bil­i­ty for our plan­et. In fu­ture, we can ex­pect worse flood­ing and storm surge dam­age to coastal com­mu­ni­ties, and pho­tos on clas­sic sandy beach­es to be spoiled by Sar­gas­sum. Ex­pect more germs, chances for in­fec­tions, more cas­es of ciguat­era poi­son­ing (cigua­tox­ins are found in fish that eat cer­tain or­gan­isms, and are poi­so­nous when eat­en by hu­mans), and red tides with im­pacts on our seafood and tourism sec­tors. Seafood will be scarcer and more ex­pen­sive. Ex­pect the next
gen­er­a­tions to not know what a healthy coral reef looks like.

Healthy ocean, healthy is­lands

Not every­thing can be blamed on cli­mate change. We have a long his­to­ry of ma­rine over-ex­ploita­tion and min­i­mal pro­tec­tion of ma­rine habi­tats. We con­tin­ue to think the ocean is vast, end­less and un­touched, nev­er mind that we catch on­ly half the num­ber of fish at a quar­ter of the size as com­pared to 50 years ago. We need to con­nect the dots.

A good ex­am­ple is the tourism shift at Buc­coo Ma­rine Park from ex­plor­ing the ocean on glass-bot­tomed boats to par­ty tourism with raft-ups and beach par­ties in what should be a pro­tect­ed ma­rine park.

The fu­ture of life on is­lands re­quires us to adapt, and we need to care for our ma­rine do­main which makes our is­lands liv­able. Cli­mate change re­quires us to con­serve nat­ur­al bio­di­ver­si­ty to re­duce changes and avoid reach­ing points of no re­turn. Ur­gent reg­u­la­tions are need­ed to pro­tect our ma­rine parks and stop over-ex­ploita­tion of our fish­eries. Gov­ern­ments need to in­vest now in food se­cu­ri­ty and ad­vo­cat­ing ecosys­tem-based strate­gies for de­vel­op­ment.

In­di­vid­u­al­ly, we can make a dif­fer­ence to the health of the oceans by re­duc­ing fer­til­iz­er run-off, and avoid­ing oil spills. Not tak­ing an­i­mals/coral from the sea, and not walk­ing on reefs are sim­ple steps that help. A healthy body will re­cov­er quick­er from dis­ease than an un­healthy one. We need to re­store our nat­ur­al re­sources to their health­i­est state so that they – and there­fore us – will sur­vive cli­mate dis­tur­bances. Chil­dren to­day need to be taught to ap­pre­ci­ate the nat­ur­al world, to re­spect and to learn to live with wild na­ture.

Dr An­jani Ganase is a coral ecol­o­gist and works on the reefs around To­ba­go.