Seriously Bad News for Caribbean Ecosystems

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I scanned it, but I wasn't sure if it says why exactly this is happening. Did I misread it? does anyone have a solid reason why?

Dear Jack,

Bleaching events can be caused by a number of factors. Thermal stress seems to be the highest correlative factor, possibly because it makes it more possible for bacterial infections etc.

No one quite knows why it happens, but when the stress level reaches certain measures, the corals either release or metabolize their symbiotic Zooxanthellae algae. These algae are important for a couple of reasons. Their micrometabolism creates an Eh/pH environment in which the coral skeletons can be precipitated, and they contribute to the food supply of the corals.

According to the article, it is thermal stress that is causing this event. See Paragraph 4 of the article.

Anyway, I don't know to what to attribute the stress; however, the environmental effect can be absolutely devastating.



Anyway, I don't know to what to attribute the stress...

I had caught the thermal stress; my question was meant more as to what causes that: general global warming trends? human activity in the Caribbean? Your answer clarifies that, thanks!

Here's another question: is this a downward spiral? that is, if the coral die, does that increase the thermal stress, and thus worsen the problem?

Dear Jack,

No, the death of the corals will probably not feed back into the loop of thermal stress, but it does have some fairly severe ramifications for ecosystem dynamics in general.

What people often fail to realize is that coral reef ecossytems are peculiar little oasesin a vast desert of relative lifelessness. The reason water is so blue around areas of coral reefs is that it is relatively devoid of nutrients that feed phytoplankton. As a result the water remains clear and corals can develop. When this happens a kind of oasis develops wherein there is the greatest diversity of life on Earth. (Speculated to be even greater diversity than tropical rainforest.) In addition, coral reefs are speculated to be large organic carbon sinks that help to regulate CO2 partial pressures, etc.

Anyway, the death of the coral often results in ecosystem breakdown and the nurseries that are coral reefs begin to depopulate. For peoples dependent upon the richness of the reefs for much of their food supply this is disastrous and leads to overfishing of the remaining populations, etc.

Anyway, this is one of the worst episodes I've seen detailed in twenty years. I have my doubts about the human cause but we will have to wait and see the ultimate effect.





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