Coral around the world is getting a severe hammering from human related activity and most of the world's major reefs are under threat. These incredibly beautiful and critically important colonies of sea creatures may well become, for the most part, extinct very soon.

Not only does coral have to contend with global warming and the associated rise in sea water temperatures that is causing coral bleaching on a catastrophic proportion, but the latest known threat added to the list - pesticide runoff, mainly from agricultural sources.

What's especially disturbing is the minute about of insecticide and fungicide needed to kill young coral; levels so low they are practically undetectable.

A study by scientists at the Australian Institute of Marine Science (AIMS) have found that some insecticides and fungicides killed juvenile coral when present in water at one part per billion.

Adult coral are also affected. In a photo in this report (PDF), the control sample shows coral polyps with tentacles active and feeding, wheras in the branchlet exposed to incredibly low levels of fungicide; the tentacles were all retracted and there is substantial tissue death evident exposing the underlying coral skeleton

Just to give you an idea of how little pesticide it can take to damage or kill coral, 1 part per billion is equivalent to a teaspoon full in an Olympic size swimming pool!

Read the study on the effects of pesticide on coral (PDF)