New genetic approaches unveil cryptic microbial algae in reef coral


AIMS researcher observing the 2006 bleaching event at the Keppels.
Photo: AIMS

July 11, 2007

"This work shatters the popular view that only a small percentage of corals have the potential to respond to warmer conditions by shuffling live-in algal partners…" van Oppen

Coral geneticists from the Australian Institute of Marine Science (AIMS) are closer than ever before to unravelling the ‘hidden' microscopic dynamics of reef coral.
Dr Madeleine van Oppen and Jos Mieog (PhD student) from AIMS say their new highly sensitive genetic technique- 100 times more powerful than conventional methods - has provided the first evidence that many corals store several types of algae, which can improve their capacity to cope with warmer water temperatures.

"Simply, when conditions warm the more heat tolerant algae provide back-up, become more abundant. Some algal types impart greater resistance to environmental extremes," says Mr Mieog.
Since the discovery of this ‘shuffling' effect some years ago there has been much debate amongst marine scientists, many suggesting it is an infrequent event due to the small number of corals that were shown to host several types of algae.

But this is where the high-powered genetic investigations of Dr van Oppen's team (in collaboration with the Netherland's University of Groningen) reveal the contrary.

Their study shows that most common corals on the Great Barrier Reef harbour more than one type of algae, and that conventional genetic methods have failed to detect some types which occur in low abundance.

"The potential for this hidden back-up type (algae) to step in and provide nutrition to coral during heat stress is far greater than currently thought," Mr Mieog added.

The ability of reef corals to adapt or acclimatise to projected climate change is critical, but it has been an incredibly controversial question in contemporary coral reef science and conservation.

"It is clear now that the previous techniques were unable to detect symbionts (algal partners) at low abundance."

Since the 1980s, reefs around the world have been devastated by bleaching, where temperature increases of just 1°C above the long-term average can cause coral animals to expel the photosynthetic algae that keep them supplied with nutrients.

"This flexibility discovered in our research is important in understanding the past evolutionary success of these coral species and their future survival capacity in the face of a changing climate," Dr van Oppen adds.

This work is published in the journal Coral Reefs, DOI: 10.1007/s00338-007-0244-8.

Media contacts:

Madeleine van Oppen
Telephone: 07 4753 4370
Email: m.vanoppen@aims.gov.au

Jos Mieog
Telephone: 07 4753 4113
Email: j.mieog@aims.gov.au

Wendy Ellery, AIMS Media Liaison
Telephone: 07 4753 4409
Mobile: 0418 729 265
Email: w.ellery@aims.gov.au