Sixty genera of coral have a symbiotic relationship with the algae zooxanthellae. Only some deep water and cold water corals can survive without them. This symbiotic relationship benefits both organisms, the zooxanthellae provides the coral with glycerol, glucose and alanine. The coral provides the zooxanthellae with nitrogen and protection against predators. The degree to which the organisms depend on one another varies between species. (Rupert and Barnes, 1994).
Coral bleaching occurs when the zooxanthellae dies and the coral expels it. This causes the coral to lose the yellow brown or dark brown colour that the zooxanthellae gives the coral. Coral bleaching can occur for a variety of different reasons such as a change in sea temperature …show more content…
Even coral that fully recovers after bleaching may have a reduced rate of reproduction In the following years. After the 1987-88 bleaching in the caribbean the species of coral Montastraea annularis did not produce any gametes (Szmant and Gassman, 1990). Another long term effect of coral bleaching is on fish populations. The size of fish populations that depend on the coral will shrink and there will be a decrease in local biodiversity. The local decline of coral in Papua New Guinea caused 75% of fish species populations to fall, 50% of the species declined to half or less than half of their original numbers and some species became locally extinct. There was a shift from a large diversity of coral dwelling fish to a small number of fish preferring rubble or algae habitats (Jones et al., 2004). One positive effect of coral bleaching is that the coral may become more resistant as after some coral bleaching the coral will recover by acquiring a new species of zooxanthellea with a higher thermal limit or a different strain of the original species.This will mean that coral bleaches less often and becomes more resilient to higher temperatures. This only usually occurs on coral that bleaches seasonally when not all coral within the population is bleached so does not protect against mass bleaching events. The resistance of the coral may only be increased a small amount.
Coral bleaching occurs when the zooxanthellae dies and the coral expels it. This causes the coral to lose the yellow brown or dark brown colour that the zooxanthellae gives the coral. Coral bleaching can occur for a variety of different reasons such as a change in sea temperature …show more content…
Even coral that fully recovers after bleaching may have a reduced rate of reproduction In the following years. After the 1987-88 bleaching in the caribbean the species of coral Montastraea annularis did not produce any gametes (Szmant and Gassman, 1990). Another long term effect of coral bleaching is on fish populations. The size of fish populations that depend on the coral will shrink and there will be a decrease in local biodiversity. The local decline of coral in Papua New Guinea caused 75% of fish species populations to fall, 50% of the species declined to half or less than half of their original numbers and some species became locally extinct. There was a shift from a large diversity of coral dwelling fish to a small number of fish preferring rubble or algae habitats (Jones et al., 2004). One positive effect of coral bleaching is that the coral may become more resistant as after some coral bleaching the coral will recover by acquiring a new species of zooxanthellea with a higher thermal limit or a different strain of the original species.This will mean that coral bleaches less often and becomes more resilient to higher temperatures. This only usually occurs on coral that bleaches seasonally when not all coral within the population is bleached so does not protect against mass bleaching events. The resistance of the coral may only be increased a small amount.