Environmental issues of Jamaica's reefs

Jamaica's coral reefs house 135 different species of fish.[6] Between 1995 and 1998, fishing licenses increased by 68 percent for the Montego Bay Marine Park where 69 percent of fishers rely on fishing as their full-time income.[7] In 1970 on Jamaica's north coast, trap fishermen set 1800 traps which was at least two times above estimated sustainability levels.[2] Fish density dwindled to 9.8 fish per 100 m² between 2001 and 2006.[8] Overfishing has reduced the herbivorous fish that keep algae populations in check and it has caused a phase shift from coral reefs to algae reefs.[3] Today, algae covers 24 percent of the reefs where corals once stood.[3] By 1960, fish biomass was reduced by 80 percent due to overfishing.[2] Fish that are vital to coral reef survival, such as the parrot fish, have been driven to near extinction in some regions.[9] In addition, overfishing has also been linked to the disappearance of the black sea urchin, Diadema antillarum, which also helped to reduce microalgal presence.[10]

Sewage pollution has led to eutrophication which results in an abundance of nutrients for microalgal populations to bloom.[11] The United Nations Environmental Program determined that 85 percent of the sewage entering the Caribbean ocean is untreated.[12] This raw sewage contains dissolved inorganic nutrients, pathogens, heavy metals, and toxins that can cause coral bleaching, disease, increased mortality, and decreased coral growth.[12] A study concluded that increased nutrients such as, inorganic nitrogen and phosphorus, doubled the probability of coral diseases and tripled the probability of bleaching.[12] An increase of inorganic nitrogen was also linked to the presence of pathogens which can lead to coral mortality.[12] The heavy metals prevent respiration and nerve communication within the coral which also leads to coral mortality.[12]

Major hurricane events include Hurricane Allen in 1980, Hurricane Gilbert in 1988, and Hurricane Ivan in 2004.[8] In 2005, there were a record breaking 26 storms recorded that caused 26 events of bleaching in 16 of Jamaica's coral reef sites.[8] The hurricanes affected 68 percent of Jamaica's coral reefs and 38 percent of those corals later died.[8] In September 2005, up to 95 percent of Jamaica's corals had bleached, but only 50 percent recovered later.[8] As a result of the 2005 hurricane, microalgal blooms took over where the corals once were.[8]

The Caribbean's coral reefs have been increasingly becoming diseased by 20 percent.[12] Coral diseases can cause tissue damage or it could even destroy the entire colony.[12] In 1980, white-band disease killed 95 percent of the Acroporid palmata and Acroporid cervicornis colonies which placed them on the Endangered Species Act.[12] A 2010 study concluded that sewage runoff was correlated to the white pox coral disease that destroyed the Acroporid palmata species.[13]