In a study announced today by the Wildlife Conservation Society* (WCS) at the International Coral Reef Initiative** (ICRI) meeting in Thailand, researchers show that some coral reefs located off East Africa are unusually resilient to climate change. The high resilience is believed to be caused by geophysical factors in combination with improved fisheries management in these waters.

After studying corals off the coast of Tanzania, researchers found that these coral reefs has made an incredibly speedy recovery from the 1998 bleaching event that wiped out up to 45 percent of the region’s corals. The authors of the study attribute the swift recovery to a combination of reef structure and reef management.

Compared to many other coral reefs around the world, Tanzania’s reefs are used to considerable variations in both current and water temperature which has turned these reefs into an unusually complex web of different coral species. This bio-diverse ecosystem includes several different species known to quickly re-colonize an area after a bleaching incident.

The authors of the study believe that reefs in other parts of the world subjected to similarly diverse environmental conditions might have the same high ability to recover from large-scale climatic and human disturbances. The study provides additional evidence that such “super reefs” can be found in the triangle from Northern Madagascar across to northern Mozambique to southern Kenya and the authors suggest that these reefs should be a high priority for conservation efforts since they may come to play an important global role in the future recovery of coral reefs worldwide.

“Northern Tanzania’s reefs have exhibited considerable resilience and in some cases improvements in reef conditions despite heavy pressure from climate change impacts and overfishing,” says Dr. Tim McClanahan***, the study’s lead author. “This gives cause for considerably more optimism that developing countries, such as Tanzania, can effectively manage their reefs in the face of climate change.”

The study also stresses the impact of direct management measures in Tanzania, including closures to commercial fishing. Algae is known to easily smother corals, but researchers found how areas with fishery closures contained a rich profusion of algae eating fish species that kept the corals clean. The few sites without any management measures remained degraded, and in one of them the population of sea urchins had exploded. Sea urchins feed on corals and can therefore worsen the problem for an already suffering reef.

The study has been published in the online journal Aquatic Conservation: Marine and Freshwater Ecosystems.

Authors of the study include Tim McClanahan and Nyawira Muthiga of the Wildlife Conservation Society, Joseph Maina of the Coral Reef Conservation Project, Albogast Kamukuru of the University of Dar es Salaam’s Department of Fisheries Science and Aquaculture, and Saleh A.S. Yahna of the University of Dar es Salaam’s Institute of Marine Sciences and Stockholm University’s Department of Zoology.

* The Wildlife Conservation Society is an institutional partner to ICRI and is actively conserving tropical coral reef species in priority seascapes in Belize, Indonesia, Papua New Guinea, Fiji, Kenya and Madagascar. Along with monitoring reefs, WCS also trains of park staff in protected areas.

** The International Coral Reef Initiative (ICRI) is a global partnership among governments and organizations working to stop and reverse the degradation of coral reefs and related ecosystems. This ICRI General Meeting was convened by the joint Mexico – United States Secretariat.

*** Dr. McClanahan’s research regarding ecology, fisheries, climate change effects, and management of coral reefs at key sites throughout the world is supported by the Western Indian Ocean Marine Science Association (WIOMSA) and The Tiffany & Co. Foundation.

Good news from Queensland: Certain reefs in Australia’s Great Barrier Reef Marine Park seem to have undergone a remarkable recovery since the devastating Keppel Islands coral bleaching event of 2006.

In 2006, massive and severe coral bleaching occurred around the Keppel Islands due to high sea temperatures. After being bleached, the reefs rapidly became overgrown with a species of seaweed and scientists feared this would be the end of the corals.

Picture is not from Keppel Island. It is another part of the Great barrier reef

Earlier studies have indicated that reefs that do manage to recover from catastrophes like this one need at least a decade or two to bounce back. However, a lucky combination of three previously underestimated ecological mechanisms now seems to have made it possible for the Keppel Islands reefs to make an amazing recovery, with large numbers of corals re-establishing themselves within a single year.

“Three factors were critical,” says Dr Guillermo Diaz-Pulido, from the Centre for Marine Studies at The University of Queensland and the ARC Centre of Excellence for Coral Reef Studies (CoECRS). “The first was exceptionally high regrowth of fragments of surviving coral tissue. The second was an unusual seasonal dieback in the seaweeds, and the third was the presence of a highly competitive coral species, which was able to outgrow the seaweed.“

Dr Diaz-Pulido also stresses that the astonishing recovery took place in a well-protected marine area where the water quality is at least moderately good.

Surviving tissue, not sexual reproduction

“The exceptional aspect was that corals recovered by rapidly regrowing from surviving tissue,” explains Dr Sophie Dove, also from CoECRS and The University of Queensland. “Recovery of corals is usually thought to depend on sexual reproduction and the settlement and growth of new corals arriving from other reefs. This study demonstrates that for fast-growing coral species asexual reproduction is a vital component of reef resilience.”

Buying time

According to Professor Ove Hoegh-Guldberg, also of the CoECRS and The University of Queensland, understanding the different mechanisms of resilience will be critical for reef management under climate change. “Clearly, we need to urgently deal with the problem of rising carbon dioxide in the atmosphere, but managing reefs to reduce the impact of local factors can buy important time while we do this. Our study suggests that managing local stresses that affect reefs, such as overfishing and declining water quality, can have a big influence on the trajectory of reefs under rapid global change.”

Dr Laurence McCook from the Great Barrier Reef Marine Park Authority agrees. “As climate change and other human impacts intensify, we need to do everything we possibly can to protect the resilience of coral reefs. This combination of circumstances provided a lucky escape for the coral reefs in Keppel Islands, but is also a clear warning for the Great Barrier Reef.“

You can find out more about the remarkable recovery in the paper “Doom and boom on a resilient reef: Climate change, algal overgrowth and coral recovery”, published in the journal PLoS ONE, by Guillermo Diaz-Pulido, Laurence J. McCook, Sophie Dove, Ray Berkelmans, George Roff, David I. Kline, Scarla Weeks, Richard D. Evans, David H. Williamson and Ove Hoegh-Guldberg.

Many of us may think about clown fish as commonly found reef fish but the fact is that many clownfish species might becoming endangered in some areas such as of the coast of Australia at least if we should believe Dr Billy Sinclair, University of Cumbria.. A big culprit is the aquarium trade. Just five years ago there were still plenty of clownfish out there but than come the very popular movie finding Nemo from pixar. The movie which was a success in theatres and have sold over 40 million DVDs created an instant demand for clown fish species looking like Nemo. (like the Percula clownfish) Even though a lot of clownfish is being bred in captivity each year the captive bred stock couldn’t satisfy the demand and therefore over-harvesting of wild specimens became a reality. Many (most) marine biologists agree with the effect the movie has created.

A problem is that people who buy them don’t know how to manage a marine aquarium and just set one up like they would a goldfish bowl. This often leads to death of the fish as the owners don’t know how to care for them or a saltwater tank.

Clownfish sales have gone up eight-fold since the movie was released and not only biologist like Dr Billy Sinclair see a decline in the wild populations. Divers also reports how much rarer it has become to see clownfish. It has also become much rarer for clownfish to be caught accidentally by commercial fishermen

The study done by Dr Billy Sinclair shows that shoals that used to number dozens of clownfish now only contain a few specimens. This makes it harder for the species to breed. In some area they are more or less gone completely. Hopefully however populations can recover quickly if the pressure from the collection of clownfish from the pet trade can be reduced. The pet trade is however not the only culprit in the population declines. Coral bleaching and die off (caused by rising temperatures) is also believed to play a role.