Dependency drives Conservation of Earth's Coral Reefs

Credit: IUCN

More than 275 million people are dependent on coral reefs for food, coastal protection and livelihoods.

Saviour of the Coral Reefs: Sea Cucumbers

Sea cucumbers can save coral reefs from the impact of ocean acidification on their growth, a group of scientists working on the impact of climate change on coral reefs have revealed in a recent study.

The research, published in the latest issue of the Journal of Geophysical Research, suggests that calcium carbonate released from the digestion of sand by sea cucumbers, one of the largest invertebrates found on tropical reefs, is a key component for the survival of coral reefs.

Maria Byrne, professor and director, One Tree Island Research Station of the University of Sydney on the Great Barrier Reef, said that coral reefs must accumulate CaCO3 at a rate greater than or equal to the CaCO3 that is eroded from the reef to survive.

Byrne, who is the lead author of the research, writes in the journal: "The research at One Tree Island showed that in a healthy reef, dissolution of calcium carbonate sediment by sea cucumbers and other bio-eroders appears to be an important component of the natural calcium carbonate turnover."

How The Coral Reef Wildlife Trade Is Degrading Coral Reefs .wmv - YouTube

Research explains mystery of ocean sediment

A discovery, made by a team of scientists from the UK and US, helps explain the origins of a key component of marine sediments, fine-grained carbonates, the origins of which are often problematic to resolve.

Published in The Proceedings of the National Academy of Science (PNAS), the study describes the discovery of an entirely new source of marine carbonate and one that has major implications for understanding the origins of the sediments that form ancient limestone and chalk deposits.

Until now it was believed that the fine-grained carbonates that constitute a major component of marine carbonate sediments were derived primarily from either direct precipitation out of seawater or from the breakdown of the skeletons of marine invertebrates and algae.

This study, funded by the UK's Natural Environment Research Council (NERC), shows that large volumes of carbonate crystals are precipitated inside the intestines of marine fish and are then excreted at very high rates, releasing this lesser-known, non-skeletal carbonate into the marine environment.

Although this material comes from the guts of marine fish, it is derived from calcium in the seawater they drink rather than any undigested product of their food.

However, the form and fate of these crystals after excretion by the fish was unknown. The researchers therefore conducted a "needle in a haystack" search, to look for microscopic crystals that are unique to fish within areas that are already rich in carbonate crystals from other organisms.

The study was undertaken in The Bahamas, famous for its white carbonate sands and muds, where the preservation of such crystals in shallow sediments was predicted to be good.

Measurements made on fish that were local to The Bahamas yielded conservative estimates that they produce in excess of 6 million kg of carbonate each year across the region, equivalent to an estimated 14% of its total carbonate mud production.

NASA MODIS Image: Australia's Great Barrier Reef

Colonies of coral appear vibrant blue green in this Moderate Resolution Imaging Spectroradiometer (MODIS) image of Australia's Great Barrier Reef, the largest coral system on Earth

Picture: NASA

Global Warming: Protecting the Maldives

Global Warming holds the greatest threat for these idyllic atolls in the Indian Ocean