CORAL REEFS: SITES FOR INVESTMENT

Do we still have time and resources to save Tobago’s coral reefs? To pull them back from the edge of their long slow decline? Dr Anjani Ganase believes it’s not too late. There is need for everyone to understand their value, and for investments in monitoring, management, research and policy. Here is her quick survey of some strategies.

After the recent devastation of coral reefs around the world in the 3rd global bleaching event (2014-2016) - the longest and most severe yet - and with the still uncertain future of climate change, scientists are desperately working on the next steps for coral reef survival. Even with the global agreement to reduce carbon emission and curb temperature rise to less than 2 degrees, it is predicted that we will still lose between 70 – 90 % of coral reefs (Frieler et al 2013). For the millions of people that depend on coral reefs, this story will be a tragedy.

Apart from continued efforts to push governments to transition away from oil, coal and natural gas, scientists have begun working on “what if” scenarios for the future of coral reefs. 

What if we can physiologically prepare coral species to be more tolerant to rising temperatures?

At small scales, the Gates Coral Lab at the Hawai‘i Institute of Marine Biology has been experimenting with the assisted evolution of corals. Certain coral species are being selectively bred for more robust symbiosis between the corals and their zooxanthellae algae which will be more resilient to thermal stress. The task for developing these “super corals” is enormous and requires significant resources and research to understand the biology and mechanism for the process.

Extensive coral bleaching at Buccoo Reef of one of the major reef building species, boulder star coral (Orbicella annularis) Photo by Jahson Alemu I

What if we can identify coral reefs that are more likely to survive in the predicted climate conditions that might even serve as a source of repopulation for other coral reefs? 

A group of scientists from the University of Queensland decided to step up to the challenge to attempt to answer this question at a global scale. They adopted a financial investment concept known as the Modern Portfolio Theory, which allows a safe strategy for investment. Basically, scientists build an optimal portfolio of investments for coral reefs that maximises the return on investment (Beyer et al. 2018). Coral reefs were selected based on having lower risks of future impacts of climate change (stressful thermal conditions) and other major threats, such as cyclones, to ensure the greatest chance of survival. They were assessed for their recent and historical exposure to thermal stress events. Furthermore, reefs were chosen based their larval connectivity for reseeding and spatial diversity to account for other unpredictable disturbances, rather like “not having all your eggs in one basket.”

Coral reefs from at least 31 countries around the world fulfilled the suitable criteria. They included reefs of Cuba, Bahamas and Hispaniola in the Caribbean, as well as sections of East Africa, Great Barrier Reef, Philippines, Indonesia and Borneo (Beyer et al. 2018). At the global scale, according to the model, these reefs are the ones to invest in. 

What do we mean by investment? 

An investment is not solely related to funding coral reef protection and management directly; long-term investments include plans to promote social and cultural change, to educate about the value of coral reefs. (For a more detailed read, please see Beyer et al. 2018)

Conversely, the portfolio also highlighted areas at greater risk of being lost because of a combination of factors such as climate change, cyclones and poor connectivity for reseeding. Places included Hawai‘i, sections of the Mesoamerican Barrier Reef and Western Australia. Unfortunately, the Lesser Antilles are also at higher risk, not necessarily because of more severe future thermal conditions but because of the limited connectivity, hurricane risks as well as the historical and recent impact of thermal events. It must be noted that like most models there are other crucial factors that have not been considered because of the difficulty in accessing this information for many areas and at the global scale. For many places, there is little information on the current condition of the coral reef community, the degree of damage as a result of local disturbances – pollution, coastal development and over exploitation – and other ecological or small-scaled factors such as upwelling events or currents that may influence coral reefs. Additional information will certainly alter the portfolio of coral reefs (Beyer et al 2018). 

Bear in mind that these are not easy questions for marine scientists to ask, as we were not drawn to coral reefs because of their devastation but for their living curiosities and ecological wonders. The research required acknowledges that there will be considerable amount of loss in coral biodiversity. Coral reefs within our lifetime have been drastically altered by human activity and what we are working to protect for the future will never return to what many of us were introduced to  (Hughes et al 2018). Therefore, these long-sighted studies are not intended to condemn threatened coral reefs but to ensure that coral reefs of the future may be subsidised through reseeding from other less impacted coral reefs once climate begins to stabilise. 

Recovered reef at Castara post 2010 mass coral bleaching. Photo by Jahson Alemu I

So what does this mean for Trinidad and Tobago?

In T&T, while there is some awareness of the dangers coral reefs face in regard to climate change, action still remains minimal. The loss of coral reefs will be dire for Tobago.  Across both islands, we need to make a drastic investment in education, research and policy. The main factor – future thermal stress – is in our control. First, let us advocate a more drastic plan to transition away from oil and gas locally and globally; this will be in the best interest of our coral reefs; and likely in the best interest of our people. Secondly, let us invest not just in monitoring the coral reefs and the degradation, but in innovative and experimental coral reef research. Let us collaborate with the best minds in the Caribbean and the world. In the end, I believe that it will be the diversity of approaches in research and conservation efforts occurring on the small, medium and large scales that will be the best solution for saving coral reefs. 

References:

Beyer HL, Kennedy EV, Beger M, Chen CA, Cinner JE, Darling ES, Eakin CM, Gates RD, Heron SF, Knowlton N, Obura DO. Risk sensitive planning for conserving coral reefs under rapid climate change. Conservation Letters. 2018 Jun 27:e12587.

Hughes TP, Barnes ML, Bellwood DR, Cinner JE, Cumming GS, Jackson JB, Kleypas J, Van De Leemput IA, Lough JM, Morrison TH, Palumbi SR. Coral reefs in the Anthropocene. Nature. 2017 Jun; 546(7656):82.

Frieler, K., Meinshausen, M., Golly, A., Mengel, M., Lebek, K., Donner, S. D., & Hoegh-Guldberg, O. (2013). Limiting global warming to 2 degrees C is unlikely to save most coral reefs. Nature Climate Change, 3(2), 165–170