Coral reefs are known as the providers of an intricately rich ecosystem. But in addition to this, they have many other functions. In fact, they are also important for protecting coastlines against rising ocean waves as well providing the food necessary for many fish deep at the bottom of the sea. Though mostly seen as areas in which conservation must be done, and therefore sinks for federal revenues, coral reefs actually provide billions in revenues for our government entities. Nevertheless, the threat coral reefs face from increased human activities as well as climate change in the recent decades is alarming.
Though this fact is well-established, research lacks in enough long-term monitoring studies that shed light on how reef communities respond and interact with the threats they face from human-generated activities as well as progressive changes in the climate of our globe. Especially, research on how the coral recovery process is affected by these threats is of utmost importance to come up with effective and pragmatic conservation schemes to save our coral reefs. Thus far, the implementation of “Marine Protected Areas” or MPAs to protect the coral reef systems have been followed-through with due to the idea that such areas, due strict lack of human intervention and fishing in the region, will be able to recover after major disturbances to the reef systems. In addition, bans on fishing in these specified areas increase the population of algae-eating fish and invertebrates that could also promote coral recovery.
But how effective are these efforts? That is exactly what Wilson and his team at the Marine Science Program, in the Department of Environment and Conservation in Kensington, Washington and other collaborating institutions. Interestingly, they wanted to do what is relatively uncommon—how multiple disturbance-causing factors interact together on coral reef recovery. Thus they focused on investigating the effects of protection, regions, substrates, the spread of algae, the population of herbivorous fish after perhaps the most well-known disruption of the coral reef ecosystems—the prolonged exposures to warmer waters in the Indo-Pacific Oceanic Basins due to global warming in 1998 that lead to intensive bleaching of the coral. Wilson and his team used the Seychelles island system and the neighboring coral reef systems. They compared change in the coral amounts as a function of region, management, substrates found, the biomass of the herbivorous fish, and the amount of algae over 1994 to 2011, whenever the pertinent data was accessible. They also measured the effects of multiple variables.
After extensive data analysis, they arrived at some very important findings. Firstly, for up to 7 years after the 1998 bleaching of the coral reefs, there was as strong, steady decline in the coral network from 28 to 7 percent, with losses in branching corals. These branching corals were associated with increased coral recovery. Interestingly, sites with granitic substrates had lesser decline rates. Lastly, they found that the algae cover increased hand in hand with the rate of coral recovery.
What does this all mean and more importantly, what are the implications of these findings that we can use to save future coral reef losses? As expected, reefs under protected areas, such as the MPAs, were the most strongly impacted by the bleach crisis of 1998— especially as they were located in areas where coral cover was high and composed of the branching coral, the coral that is most heavily affected the warmer waters. Over the past 17 years, using the Seychelles model island system, the protected areas has the most stable amounts of coral cover. Thus, MPAs are effective in maintaining conditions and slowing further decline in coral amounts. In general the rate of recovery was very low, only one percent per year if left to nature. Thus, it is clear that something must be done to promote coral re-growth. And, as Wilson robustly concludes, the use of the relationship between algae and coral can be used to a conservationist’s advantage. Because coral and algae both compete for space on the surface of reefs, controlling algae growth could increase coral recovery. To control algal populations, herbivorous fish can be used, though with caution for this could also inadvertently change the dynamics of the ecosystem as to promote algal domination. Wilson’s studies provides great stimulus to target coral recovery with a slightly different approach, an approach that seems to lead to a positive future for our coral reefs.
By Shachi Daru
Photo Credit: http://www.public-domain-image.com/cache/nature-landscapes-public-domain-images-pictures/underwater-public-domain-images-pictures/colorful-underwater-landscape-of-a-coral-reef_w725_h483.jpg
Source Article: Wilson, S. K., Graham, N. A. J., Fisher, R., Robinson, J., Nash, K., Chong-Seng, K., Polunin, N. V. C., Aumeeruddy, R. and Quatre, R. (2012), Effect of Macroalgal Expansion and Marine Protected Areas on Coral Recovery Following a Climatic Disturbance. Conservation Biology, 26: 995–1004. doi: 10.1111/j.1523-1739.2012.01926.x