Great Barrier Reef, coral, immunity, bleaching, global warming

William Atkins
Thursday, 19 August 2010 00:21

Science - Climate

Australian researchers have studied different types of coral and their susceptibility to disease and bleaching brought on by global warming. Depending on their level of immunity, corals such as those within Australia's Great Barrier Reef may be more or less affected by global warming.

 

The Australian researchers are concerned with the health of coral reefs throughout the world. They based their research on the corals within the Great Barrier Reef.

The abstract to their paper states, 'Immunity is a key life history trait that may explain hierarchies in the susceptibility of corals to disease and thermal bleaching, two of the greatest current threats to coral health and the persistence of tropical reefs.'

Coral bleaching (thermal bleaching) is the whitening of corals from stressful conditions brought about by the removal or death of the normally golden-brown colored protozoa zooxantheliae.

The unicellular protozoa provide most of the energy requirements for corals while the corals provide protection and nutrients to the zooxantheliae.

The two live in a symbiotic relationship (both benefiting from the other).

However, when climatic conditions change, as in increased temperatures around the world, (what we call global warming), the protozoa degrade or die, turning white in the process - thus producing what is called coral bleaching.

However, the researchers found that only a few studies have been made into the 'immunity mechanisms' at work within corals.

Thus, these researchers decided to look two orders of corals: Scleractinia (hard or stony coral, reef-building corals) and Alcyonacea (soft coral, non-reef-building corals).

Within these two coral orders, the researchers investigated such immunity factors as 'melanin, size of melanin-containing granular cells, and phenoloxidase (PO) activity, as well as concentrations of fluorescent proteins (FPs).'

The Australian researchers - Caroline V. Palmer and John C. Bythell (both from the School of Biology at Newcastle University), and Bette L. Willis (from the Australian Research Council Centre of Excellence for Coral Reef Studies and School of Marine and Tropical Biology at James Cook University, Palmer is also associated here) - published their study in the June 2010 issue of The FASEB Journal.

Their paper is entitled 'Levels of immunity parameters underpin bleaching and disease susceptibility of reef corals'.

Page two continues with specifics on the study of corals and their susceptibility to global warming.