Coral Reef Denizens Part I, II & III

Focus on heat resistant coral

Lace Coral (Stylaster spp.)In a recent study to investigate which factors are most influential in coral resilience with respect to global warming, researcher Tim McLanahan and colleagues suggest that by far the most important factor is the ability of corals to withstand higher temperatures. Factors most influential in driving recovery of corals following an environmental insult are their recruitment rates and the abundance of macroalgae. From the multiple biological and physical factors they looked at, 11 were found to be particularly useful and might form the basis of a more useful coral reef assessment tool in the future. Should we try to focus our limited resources on identifying and protecting those corals already most resistant to temperature change and give up on the rest?

Read the original article online in PLOS One

Images of Sharks & Rays

Triassic-style extinction?

Tiputa Pass, RangiroaIn an article published on the 15th August, 2012  in eLS online, entitled Extinction: End-Triassic Mass Extinction,  Michael Hautmann, discusses one of the five greatest mass extinction events in Earth’s history. It occurred at the end of the Triassic, c. 200 million years ago nearly annihilating corals, sponges and ammonoids.  This event coincided with the break up of the supercontinent Pangaea. Some causes of the near extinction of these marine taxa are believed to be “sea-level changes, marina anoxia, climatic changes, release of toxic compounds and acidification of seawater”. While level-bottom communities of marine organisms recovered relatively quickly, reef systems disappeared from the geological record for nearly 10 million years. Although there are many differences, Dr Hautmann asserts that many of the global-warming like effects experienced during this extinction event are remarkably similar to those we are experiencing today.

Read the abstract of this article (subscription required to read full article). DOI: 10.1002/9780470015902.a0001655.pub3

Controlling run-off is key

Coral vistaA recent letter published in Nature Climate Change discusses the effects of nutrient enrichment on coral reef survival. 

The letter’s authors (Wiedemann, J, D’Angelo, C., Smith E.G., Hunt, A.N., Legiret, F.E., Postle, A.D. & Achterberg, E.P.) confirm that enrichment of reef waters is often associated with a significant loss of coral cover and diversity. Their study reveals, however, that increased levels of dissolved inorganic nitrogen in combination with limited phosphate concentrations result in an increased susceptibility of corals to temperature- and light-induced bleaching.  Based on these findings they suggest that controlling the balance of nutrients in coastal waters might be as important as reducing the amount of anthropgoenic run-off.

In an article by the Press Association, Dr Wiedemann is quoted as saying: “The findings suggest that a balanced reduction of the nutrient input in coastal waters could help to mitigate the effects of increasing seawater temperatures on coral reefs. However, such measures will be effective only for a short period of time, so it is important to stop the warming of the oceans, which will otherwise destroy most of the reefs in their present form in the near future.”

So addressing nutrient enrichment can help slow down damage to coral reefs but will only offer a short term solution.

Rangiroa, Tuomotus

Garuae Pass, Fakarava

Tumokohua Pass, Fakarava

Coralbots to the Rescue!

SCOTTISH scientists are developing a swarm of intelligent robots to save coral reefs.

 A team of “coralbots”, each individually working to simple rules, will piece together damaged bits of coral, allowing them to regrow. The approach is inspired by the behaviour of natural swarms of insects such as bees, wasps and termites which collectively build substantial and complex structures.

After damage, some coral fragments will regrow if reassembled on the reef framework. At present, this is done by volunteer scuba divers but the method has only limited success because they cannot spend long periods underwater nor reach depths of over 200 metres where some of the deep-sea coral grows.

Now, researchers at Heriot-Watt University in Edinburgh are developing squad of coralbots to do the work instead.

Read the full article at the Scotsman.

Parasol needed for Barrier Reef

Australian scientists have proposed covering endangered coral reefs with shade cloth during periods of thermal stress as part of “last resort” measures to protect parts of the Great Barrier Reef. They also suggest using low-voltage electrical currents to stimulate coral growth and defend against the worsening impact of heat stress.

The paper, in the journal Nature Climate Change, says the pace of global warming is unparalleled in 300 million years and has led to temperature rises of at least 2 degrees Celsius and a 60-per-cent increase in surface ocean acidity over the past three centuries.

Professor Ove Hoegh-Guldberg of Queensland University, writing with Greg Rau from the University of California and Elizabeth McLeod from The Nature Conservancy, calls for “unconventional, non-passive methods to conserve marine ecosystems”.

Read the original article in Nature Climate Change.

Read a review of this article in The Daily Telegraph.