Bleaching Reported in the Seychelles

Conditions are worsening in the Seychelles, as is indicative of a transition from a bleaching warning to an Alert Level 1 [4]. Figure 1 shows that two monitoring stations in the Seychelles have reported high and extreme bleaching events [3]. A reef in Cousin that had only showed 1% incidence of bleaching back in January is now faring worse in this month [1, 4]. In order to monitor the situation for the rest of the year, Nature Reef Rescuers scientists paired up with Nature Seychelles staff to survey the reef in Cousin and record its response to rising thermal temperatures [1]. It will be interesting to hear their reports in the next few months.

What’s notable about the reef at Cousin is that many colonies that were transplanted there were grown from corals that survived the 1998 bleaching event [1]. It is highly probably and entirely possible that these transplanted colonies will exhibit higher levels of stress tolerance [2]. Research has shown that corals exposed to high temperature stressors that survive are less likely to bleach in future events [2]. It is also becoming evident that these adaptations to a high thermal stress environment can pass along to the next generation [2]. Even though bleaching has occurred in Cousin, the single source I could gather information from did not indicate exact locations of bleaching or whether it was patchy bleaching as opposed to widespread occurrence. Thus, it is still possible that transplanted colonies may not have bleached. The bad news is that temperatures are likely to become hotter in the next 1-4 weeks, with stress levels projected to rise to Alert Level 2. From the graph below, Figure 2, you can see that the Seychelles are experiencing their sixth degree heating week, and widespread bleaching and mortality is expected at only eight degree heating weeks. Stress is expected to dissipate in 5-8 weeks to a watch level [4]. The good news is temperatures are expected to drop during the month of May, as previous SST data from previous years have suggested [4]. Still, it may be too late for some reefs in the Seychelles. It has taken 10-15 years for some reefs in the Seychelles to recover from 1998, and with a greater likelihood of more bleaching events, the Seychelles could be slammed again before the reefs have adequate time to recover.

The outlook for the future of reefs is grim. Humans have disrupted the natural flux of the earth’s climate and sped up rates of warming to a level where biological systems can’t acclimate and adapt to these changes. Coral reefs are some of the most complex, if not beautifully intricate, ecosystems that exist and they are the most visible indicator of climate change. By jeopardizing the health of these ecosystems, humans are inadvertently causing humanity’s own demise. There is hope left, and this hope lies in the fragile symbiotic relationship between a coral and its dinoflagellate algae. If these algae can acclimate or adapt quickly enough to higher thermal tolerances, perhaps with assistance from scientists, then it could be possible to buy time for reefs [2]. After all, reefs are not only faced with the threat of higher ocean temperatures, but also from a decreasing aragonite saturation level caused by the acidification of the oceans, increased fishing pressure, increased levels of bioerosion, mass influxes of nutrients that favor algal domination, and increased infrastructure along the coasts.

Nick Graham. [6] A healthy coral reef on the left and a macroalgal covered reef on the right. Both images were taken in the Seychelles. Reefs in the Seychelles will probably look more like the image on the right in the near future due to the effects of climate change and a greater occurrence of bleaching events.

The number one threat to the Seychelles as assessed by the Seychelles Foundation is climate change [5]. It is time that concerned citizens and national leaders bring themselves together to seriously discuss the impact of destroyed reef ecosystems due to climate change and how to combat local stressors that harm reefs. The most obvious wide-scale option is to lower carbon emissions collectively and turn to cleaner renewable resources such as solar. Another sure-fire option is to create Marine Protected Areas, places where there is zero extraction and zero tolerance for poachers. Less pronounced but equally important measures would be to slowly eliminate human obsession with plastics and waste, curbing the growth rate of the human population, and creating more effective waste water treatment options on islands that are home to large populations of people and reefs. This is my last blog post, but I certainly hope that all you continue to read about this massive bleaching event. I have found that the easiest way to do so is to follow Coral Reef Watch on Facebook in order to receive current updates.

1. Malaisé, Louise. “Coral bleaching, again!” Saving Paradise. Wildlife Direct Feb 4, 2016. Web. April 18, 2016.
2. van Oppen, M. J., Oliver, J. K., Putnam, H. M., & Gates, R. D. (2015). Building coral reef resilience through assisted evolution. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1422301112
3. “WIO Coral Bleaching Alert.” Cardio East Africa. Web. 18 Apr. 2016.
4. “Western Indian Ocean 5-km Coral Bleaching Data Products/Seychelles 5-km Bleaching Thermal Stress Gauges.” Coral Reef Watch. NOAA Satellite and Information Service. Web. 18 Apr. 2016.
5. “Impacts of Global Warming on Corals.” WWF. Web. 18 Apr. 2016
6. Hajira, Amla. “Seychelles Coral Reefs Just Beginning to Show Signs of Recovery, Says Researchers.” Seychelles News Agency. 14 July 2014. Web. 18 Apr. 2016.