At­tish Kan­hai

Re­search Of­fi­cer, In­sti­tute of Ma­rine Af­fairs

“Look a tur­tle!”

Al­ways the in­evitable cry of first-timers who ac­com­pa­ny me on my sam­pling trips in the Bon Ac­cord La­goon. On my fre­quent vis­its to the sea­grass beds in To­ba­go’s south­west, tur­tles are some of the more promi­nent guests, un­mis­tak­able by their re­mark­able speed un­der­wa­ter or their cau­tious heads peek­ing above the sur­face.

Tha­las­sia tes­tudinum, known by the com­mon name tur­tle grass, de­rives its name from be­ing the meal of choice for tur­tles, most­ly green tur­tles Ch­e­lo­nia my­das. The feed­ing of tur­tles on tur­tle grass, apart from pro­vid­ing nour­ish­ment for tur­tles, is al­so ben­e­fi­cial to the sea­grass­es. The graz­ing of tur­tles on the beds is a nat­ur­al source of trim­ming, which then en­cour­ages new sea­grass growth. No weed whack­ers need­ed here! Tur­tles are not the on­ly an­i­mals that like to nib­ble on sea­grass­es, as oth­er ma­rine mam­mals such as man­a­tees al­so make use of the ocean’s sal­ad bar.

As we com­mem­o­rat­ed World Sea­grass Day on March 1st, it was im­por­tant to re­mem­ber that sea­grass­es are more than just a food source in the ocean. They pro­vide im­por­tant nurs­eries for com­mer­cial fish and shell­fish such as snap­pers, grunts, groupers lob­sters, conch and shrimp, there­by con­tribut­ing to the liveli­hoods of fish­er­men and to food se­cu­ri­ty. At the same time, this di­verse ecosys­tem pro­vides the nat­ur­al in­fra­struc­ture for coastal tourism and con­tribute sands to our beach­es.

How­ev­er, even more tan­gi­ble eco­nom­ic val­ue ex­ists from sea­grass­es, for ex­am­ple, the role they play in the main­te­nance of the glob­al car­bon bal­ance. Through the up­take and stor­age of car­bon in their bio­mass and soils by ex­ten­sion, they can con­tribute to achiev­ing net-ze­ro emis­sions by 2050.

In fact, stud­ies sug­gest that coastal wet­lands-man­grove, marsh and sea­grass­es se­quester car­bon at a rate ten times greater than ma­ture trop­i­cal ter­res­tri­al forests each year. They al­so have the ca­pac­i­ty to store three to five times more car­bon than ter­res­tri­al forests of a sim­i­lar size. The val­ue of this ser­vice alone has been es­ti­mat­ed at US$190 bil­lion per year.

While blue car­bon gets most of the head­lines, there are still more valu­able ecosys­tem ser­vices pro­vid­ed by sea­grass­es. They are se­mi-per­me­able fil­ters that sta­bilise bot­tom sed­i­ments, slow/re­duce cur­rent flow, pre­vent coastal ero­sion and fil­ter sus­pend­ed solids and nu­tri­ents from coastal wa­ters. These at­trib­ut­es help in the pro­tec­tion of valu­able coastal in­fra­struc­ture – hous­es and ho­tels, for ex­am­ple – with­out the need for ex­pen­sive hard en­gi­neer­ing struc­tures.

Sea­grass­es con­tri­bu­tion to en­hanc­ing bio­di­ver­si­ty, se­ques­ter­ing car­bon, sup­port­ing liveli­hoods and pro­vid­ing coast­line pro­tec­tion all fall un­der one um­brel­la term known as “nat­ur­al cap­i­tal.” Nat­ur­al cap­i­tal, in its broad­est sense, is the world’s stock of nat­ur­al re­sources, such as plants, an­i­mals, air, wa­ter, soil, and min­er­als, that pro­vide ben­e­fits to peo­ple and the econ­o­my. It in­cludes ecosys­tems like forests, oceans and sea­grass beds, which of­fer ser­vices like clean air, food, and cli­mate reg­u­la­tion.

This is far from an ex­haus­tive list, as nat­ur­al cap­i­tal refers to any val­ue pro­vid­ed by an ecosys­tem. Sea­grass­es al­so pro­vide oth­er less im­me­di­ate­ly ob­vi­ous ben­e­fits such as sci­en­tif­ic re­search, which in turn con­tributes to ed­u­ca­tion, yet an­oth­er ex­am­ple of nat­ur­al cap­i­tal.

From per­son­al ex­pe­ri­ence, snor­kel­ing in sea­grass­es pro­vides much calm and re­lax­ation, while en­coun­ter­ing many of na­ture’s less­er-known ma­rine won­ders such as feath­er duster worms, sea urchins, and sea cu­cum­bers, in ad­di­tion to the afore­men­tioned tur­tles and ar­rays of fish. The con­tri­bu­tion to re­lax­ation and men­tal health im­prove­ment is an­oth­er in­tan­gi­ble ben­e­fit that can be con­sid­ered nat­ur­al cap­i­tal.

How­ev­er, de­spite all of these ben­e­fits pro­vid­ed by sea­grass­es, these ecosys­tems are un­der threat world­wide. Phys­i­cal dam­age from boat an­chors, scar­ring of sea­grass leaves by pro­pellers, phys­i­cal re­moval of sea­grass­es, poor wa­ter qual­i­ty from in­land ac­tiv­i­ties, com­pe­ti­tion for coastal re­sources and coast­line de­vel­op­ment all play a role in the dis­ap­pear­ance of sea­grass beds from our coastal wa­ters glob­al­ly.

Nat­ur­al cap­i­tal is on­ly ben­e­fi­cial if the ecosys­tems pro­vid­ing the cap­i­tal re­main in good shape. One method of de­ter­min­ing this for sea­grass­es is us­ing satel­lite im­agery to de­ter­mine the ex­tent and changes in ar­eas of sea­grass beds. This is fol­lowed by ground truthing to en­sure that sea­grass­es were cor­rect­ly iden­ti­fied from the satel­lites. Ad­di­tion­al­ly, growth and bio­mass mea­sure­ments de­ter­mine whether sea­grass beds are healthy or in need of in­ter­ven­tions.

The In­sti­tute of Ma­rine Af­fairs has em­barked on ex­per­i­men­tal ef­forts to in­ves­ti­gate how best to re­store sea­grass­es in ar­eas where they once ex­ist­ed. A glob­al ef­fort is cur­rent­ly un­der­way in ar­eas such as Aus­tralia, New Zealand, the Unit­ed King­dom, Be­lize and the Unit­ed States to re­store var­i­ous species of sea­grass. How­ev­er, this is no sim­ple task. As I have out­lined above, there are many stres­sors that play a part in their de­struc­tion. Un­til these stres­sors have been re­moved, sea­grass­es will not thrive in their pre­vi­ous habi­tats. This re­quires co­op­er­a­tion among all stake­hold­ers, in­clud­ing gov­ern­ment, pri­vate sec­tor and civ­il so­ci­ety. Ap­pro­pri­ate plant­i­ng tech­niques and site se­lec­tion are al­so cru­cial to suc­cess­ful­ly re­store sea­grass ecosys­tems.

Through con­ser­va­tion and restora­tion, ecosys­tem ser­vices from sea­grass­es will con­tin­ue to pro­vide ben­e­fits for the en­tire plan­et. How­ev­er, it takes more than just sci­en­tists en­gag­ing in restora­tion ef­forts for it to be a suc­cess. Pub­lic sup­port and aware­ness are cru­cial to the long-term suc­cess of con­ser­va­tion and restora­tion ef­forts, as they are labour-in­ten­sive and time-con­sum­ing. The more avail­able hands, the greater the chances of suc­cess for these ef­forts. More­over, lo­cal com­mu­ni­ties are able to func­tion as en­vi­ron­men­tal stew­ards to spread knowl­edge and look af­ter the en­vi­ron­ment where they live once they are in­clud­ed in these ef­forts.

When we take care of the en­vi­ron­ment, the en­vi­ron­ment takes care of us. If con­ser­va­tion and restora­tion ef­forts con­tin­ue to be suc­cess­ful, then maybe many more first-timers will be able to shriek with joy as they see not just one but bales of tur­tles dart­ing by on their dai­ly vis­it to have their meals in their favourite sea­grass mead­ow.