Macroal­gae Threaten Coral Reefs

The Playa Times Riviera Maya's English Newspaper - - Discover Mexico - BY JOE MAL­DON­ADO

From 2006 to 2014, the macroal­gae cov­er­age over the coral reefs al­most dou­bled, go­ing from 13 to 23 per­cent. It is be­com­ing a very prom­i­nent threat not only to the coral reefs of the Riviera Maya but to the whole Me­soamer­i­can Reef. The ex­ces­sive growth of al­gae blocks sun­light from reach­ing the reef and can af­fect the re­pro­duc­tion of corals and pho­to­syn­the­sis of zoox­an­thele (mi­croal­gae that lives in­side corals’ polyps and gives them their color and other ben­e­fits).

The main prob­lem, ac­cord­ing to Marisol Rueda Flores, Mexico’s Co­or­di­na­tor for the Healthy Reefs Ini­tia­tive, is closely linked to the de­cline in her­biv­o­rous fish of sizes big­ger than 40 cen­time­ters, such as par­rot­fish. Par­rot­fish spend the vast ma­jor­ity of their day eat­ing al­gae grow­ing on corals.

Rueda clar­i­fied that 78 per­cent of the par­rot­fish at sea were less than 20 cen­time­ters. As a re­sult, they don’t grow to more than 40 cen­time­ters, the point at which they would be able to re­pro­duce and in­crease the pop­u­la­tion.

Macroal­gae in­creases due to an ex­ces­sive amount of nu­tri­ent runoff into the sea (pri­mar­ily from fer­til­iz­ers, waste­water, or storm wa­ter), com­bined with sun­light and warm tem­per­a­ture. Some other al­gae species can have an al­gae bloom, be­ing of par­tic­u­lar con­cern as they re­lease neu­ro­tox­ins and can have se­vere bi­o­log­i­cal im­pacts on or­gan­isms.

“In Quin­tana Roo, Cozumel has the high­est coral cover, at 24 per­cent, which is very high com­pared to other ar­eas where there is only be­tween 16 and 18 per­cent coral cover. If the macroal­gae con­tin­ues to grow, the coral will suf­fo­cate,” Rueda ex­plained.

Be­sides hav­ing the macroal­gae in­hibit­ing the growth of the coral, we can have coral bleach­ing due to the in­crease of wa­ter tem­per­a­ture, and it causes zoox­an­tha­lae mi­croal­gae to leave the coral, which is what gives corals their orig­i­nal color.

Healthy Reefs has made an al­liance with the Mex­i­can Cen­ter for En­vi­ron­men­tal Rights (CEMDA) and the State En­vi­ron­men­tal Sec­re­tary to cam­paign about the im­por­tance of the par­rot­fishes.

“We have a group work­ing to kick start this cam­paign, we are go­ing to hang posters with in­for­ma­tion to dis­trib­ute to the fish­ing com­mu­ni­ties and Healthy Reefs will make in­for­ma­tive videos about the im­por­tance of hav­ing laws to pro­tect this specie of fish.”

Although the in­ten­tion is to take the pro­posal to law­mak­ers for anal­y­sis and ap­proval, they will first start the aware­ness cam­paign to cre­ate a bet­ter strat­egy.

In Quin­tana Roo, Cozumel has the most cov­er­age of coral, at 24 per­cent, which is very high com­pared to other ar­eas where there is only be­tween 16 and 18 per­cent coral cover. If the macroal­gae con­tin­ues to grow, the coral will suf­fo­cate.”

Marisol Rueda Flores Mexico’s Co­or­di­na­tor of Healthy Reefs Ini­tia­tive

Shi­zothrix

/ Photo: Ian Drys­dale

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