With only about one-sixth of the orig�i�nal cor�al cov�er left, most Car�ib�be�an cor�al reefs may dis�ap�pear in the next 20 years, ac�cord�ing to a re�port. The study in�di�cates that glob�al warm�ing alone is�n't to blame for a pre�cip�i�tous de�cline in cor�al area-the main prob�lem is a loss of graz�ing fish, which ...

With only about one-sixth of the orig�i­nal cor­al cov­er left, most Car­ib­be­an cor­al reefs may dis­ap­pear in the next 20 years, ac­cord­ing to a re­port.

The study in­di­cates that glob­al warm­ing alone is­n't to blame for a pre­cip­i­tous de­cline in cor­al area-the main prob­lem is a loss of graz­ing fish, which eat the al­gae on the reefs.

“The rate at which the Car­ib­be­an cor­als have been de­clin­ing is truly alarm­ing,” said Carl Gus­taf Lundin, Di­rec­tor of Glob­al Ma­rine and Po­lar Pro­gramme for the In­tern­ati­onal Un­ion for Con­serv­ati­on of Na­ture, which con­tri­but­ed to the re­port. But “the fate of Car­ib­be­an cor­als is not be­yond our con­trol and there are some very con­crete steps that we can take to help them recov­er.”

“Even if we could some­how make cli­mate change dis­ap­pear to­mor­row, these reefs would con­tin­ue their de­cline,” added Jer­e­my Jack­son, lead au­thor of the re­port and the un­ion's sen­ior ad­vi­sor on cor­al reefs. “We must im­me­di­ately ad­dress the graz­ing prob­lem for the reefs to stand any chance of sur­viv­ing fu­ture cli­mate shifts.”

Car­ib­be­an cor­als have de­clined by more than 50 per­cent since the 1970s, the study found, but re­stor­ing par­rot­fish popul­ati­ons and im­prov­ing oth­er man­age­ment strate­gies, such as protecti­on from over­fish­ing and ex­ces­sive coast­al polluti­on, could help the reefs recov­er.

The re­port is the re­sult of the work of 90 ex­perts over three years. It con­tains the anal­y­sis of more than 35,000 sur­veys con­ducted at 90 Car­ib­be­an loc­ati­ons since 1970, in­clud­ing stud­ies of cor­als, sea­weeds, graz­ing sea ur­chins and fish.

The re­port, Sta­tus and Trends of Car­ib­be­an Cor­al Reefs: 1970-2012, from the Glob­al Cor­al Reef Mon­i­tor­ing Net­work, the In­tern­ati­onal Un­ion and the Un­ited N­ati­ons En­vi­ron­ment Pro­gramme, was re­leased July 2 in Gland, Switz­er­land.

Cli­mate change has long been thought to be the main cul­prit in cor­al de­grad­ati­on. While it does pose a se­ri­ous threat by mak­ing oceans more acid­ic and caus­ing cor­al “bleach­ing,” the re­port says that the loss of par­rot­fish and sea ur­chin – the area's two main “graz­ers” – has been a worse prob­lem.

An un­iden­ti­fied dis­ease led to a mass death of the sea ur­chin in 1983 and ex­treme fish­ing through­out the 20th cen­tu­ry has brought the par­rot­fish popul­ati­on to the brink of extincti­on in some regi­ons, the re­port added. The loss of these spe­cies breaks the del­i­cate bal­ance of cor­al ecosys­tems and al­lows al­gae, on which they feed, to smoth­er the reefs.

Reefs pro­tected from over­fish­ing, as well as oth­er threats such as ex­ces­sive coast­al polluti­on, tour­ism and coast­al de­vel­op­ment, are more re­sil­ient to pres­sures from cli­mate change, ac­cord­ing to the au­thors.



Source: http://www.world-science.net/

 

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worldscience, "Caribbean coral reefs disappearing, study says", MachPrinciple, July 02, 2014, https://machprinciple.com/post/caribbean-coral-reefs-disappearing-study-says