Topic: Phytoplankton and Cloud Formation 3.Coral bleaching and DMS production
Background: Symbiosis refers to the relationship between two organisms living together. For example, marine algae that live in corals (called zooxanthellae) have a symbiotic relationship, where both organisms benefit from the association. When a coral is under stress from factors such as increased light and temperature, it may push the zooxanthellae with the result that the coral turns white. This is called coral bleaching, and it can cause the coral to die.
Fast facts:
. Coral reefs are sources of high DMS (dimethylsulphide) production, which comes from the algae living inside (see Fact Sheet 8). When DMS reaches the atmosphere it forms clouds over the reefs and coast.
. The light from the sun is reflected off the clouds, reducing the amount of light reaching the coral reefs. This means that the corals experience less light and heat, decreasing the likelihood of bleaching occurring.
. Coral bleaching may cause fluctuations in DMS production, for example: if the zooxanthellae pushed out of the coral die and the DMS they contain is released, a high production of DMS occurs. However, this could be followed by a low period of DMS production since the zooxanthellae would be absent from the coral, or the coral died.
. However research on the Great Barrier Reef has shown that when coral bleaching occurs because of an increase in sea temperature, the corals stop producing DMS, thus compounding the situation.
Photos of bleached coral on the Great Barrier Reef; (a) a close-up and (b) an aerial view of a mass coral bleaching event. (Photos from the Great Barrier Reef Marine Park Authority)
Did you know…
Rainforests receive precipitation from the clouds produced by
coral reefs during some seasons!
Learn more: Links/References
1. Hill RW, Dacey JWH, Krupp DA (1995) Dimethylsulfoniopropionate in reef corals. Bulletin of Marine Science 57: 489-494
2. Jones GB & Trevena AJ (2005) The influence of coral reefs on atmospheric dimethylsulphide over the Great Barrier Reef, Coral Sea, Gulf of Papua and Solomon and Bismarck Seas. Marine and Freshwater Research 56: 85-93
3. Jones G, Curran M, Broadbent A, King S, Fischer E, Jones R (2007) Factors affecting the cycling of dimethylsulfide and dimethylsulfoniopropionate in coral reef waters of the Great Barrier Reef. Environmental Chemistry 4: 310- 322
Web Great Barrier Reef Marine Park Authority