Scandinavian Dive Team nye samarbejdspartner Big Blue Conservation bringer os denne miljørapport om forhold der har påvirket korallerne omkring Koh Tao og dykningen i Thailand generelt. De gode nyheder er dog at vandtemperaturen i Juli er faldet igen og korallerne er begyndt at returnere ti normalt igen.
2010 Alert on Oceanic Temperatures
In 1998, oceanic temperatures reached the highest they have been for 650,000 years. 2002 was the second hottest, and 2010 could be hotter. Climate change is causing oceanic temperatures to rise, threatening the destruction of coral reefs world wide, making them now the world's oldest but most threatened ecosystem. In 1998, 60% of the worlds corals bleached resulting in many reefs seeing mass coral death.
Save Koh Tao, Marine Conservation Koh Tao and Big Blue Conservation have observed 95% bleaching in many areas around Koh Tao in 2010, and the same is being reported throughout the Gulf and Andaman Coastlines.
So what is coral bleaching and why is it happening now?
Corals are animals in the same family as jellyfish, they are very primitive and have a clear, jellylike anatomy called a polyp. When we look at a healthy coral, the colours we see are actually from millions of little algae cells that live inside the coral's tissue called zooxanthellae. Using the sunlight for photosynthesis, they provide 85% of the coral polyps nutrients which is used for skeleton growth, reproduction and to produce its protective coating. In return, the algae are given a stable place to live and steady supply of nutrients.
When the water temperature rises above 30C, the chemistry and resulting living environment within the coral polyp changes attacking the algae. In response, the algae produces chemicals to defend themselves which attacks the coral and the coral is forced to expel the algae. This results is the coral skeleton being visible through the coral polyp giving a bleached appearanced. The coral polyps are severely stressed, although not dead, as they are only able to obtain 15% of the nutrients without the algae. Should the conditions improve within 28 days, and the algae return, the corals are likely to survive the bleaching event. However, whilst bleached they are much more susceptible to disease, damage and pollutants, and many bleached corals will not survive bleaching.
Certain invertebrate and fish species will have an impact on the health of the reefs as well as indicating water quality, as the presence and absense of many essential algal grazers, predators and pests will influence reef health and shape the ecosystem. It is therefore also essential that we monitor the abundance of indicator species around Koh Tao.
As such, it is vital that we monitor the life and coral health around the island, and this is what Big Blue Conservation strives to do. Through training, education and raising general awareness, we hope that the beautiful diverse corals around Koh Tao will remain so for years to come.
