Coral pH regulation and climate change: using novel tissue cultures to assess the future of key habitat forming species

Over 500 million people worldwide rely upon coral reefs for their livelihoods; either for food or through tourism. Consequently, threats to these reefs are of global concern, and the recent consensus statement signed by over 3000 international coral scientists on the threat of Climate Change to Coral Reefs highlights growing evidence and awareness of this. These coral reefs are found throughout the world's oceans and include the well-known tropical reefs, and the lesser-known cold-water coral reefs, which are found between 30 and 3000 m deep. All of these complex ecosystems support high amounts of life, and as such have been referred to as the 'rainforests of the seas'. Unfortunately, predicted rises in atmospheric carbon dioxide may have dire consequences for these key ecosystems, as increased carbon dioxide contributes to global warming and ocean acidification.
The problem is that the oceans absorb atmospheric carbon dioxide, and this causes a change in the carbon chemistry of the water, leading to a drop in pH. Currently, seawater pH is around 8.1, but this is projected to drop to around 7.8 by the end of the century. While this is not acidic, it is more acidic than it is now - hence the term 'ocean acidification'. This drop in pH affects the amount of calcium carbonate in the water; the same mineral that coral skeletons are made from. As the concentration of calcium carbonate drops, corals will find it harder to calcify, and any exposed skeleton could even dissolve. However, corals can increase their pH inside their tissue to prevent these effects, but the extent of this process, i.e. how much can corals increase their pH by, whether this is the same across all species, and how this changes under different conditions, remains unknown. To understand this, I will grow corals without skeletons as tissue cultures in environmentally controlled flasks. Cell tissue culture research has revolutionised bio-medical and pharmaceutical research. Their novel use here to address key research questions marks the start of a new and exciting direction in the field of coral biology. The use of tissue cultures to study pH regulation in this fellowship will also contribute to fundamental coral biology research about the specifics of coral calcification, which, after decades of intensive research, remain debated. To understand the extent to which corals can regulate their pH, I will use pH sensitive dyes and microscopes capable of generating 3D images to examine the calcifying area within organised coral cells. I will also look at the composition of new skeleton produced, in particular the boron content. The quantity of specific types of boron within the skeleton is pH dependent, so by analysing this in conjunction with pH sensitive dyes, coral internal pH regulation can be accurately calculated. This will also validate the technique for use in determining past ocean pH values by looking at the boron in fossilised corals.
This fellowship thus seeks to use boron and pH-sensitive dyes as tools to assess the future of coral reefs, but also to increase our understanding of how we can use them to study our past. By understanding how well (or poorly) different coral species can alter their internal pH across a variety of different conditions, we can begin to see which coral species will be 'winners or losers' in the face of future climate change, crucial for effective coral conservation efforts.

Outside of academia, the main impact will be with the general public, school children, professional aquarists and policy makers.

For the general public and for schoolchildren, this will include knowledge exchange on the threats that coral reefs face (ocean acidification and warming) and on the cutting edge research that is being done (through this fellowship) to assess how corals will fare in the face of future climate change. This would raise awareness of the threats that coral reefs face. This will be achieved through an agreed outreach programme with The Deep (Hull) and the Horniman Museum (London) - see Pathways to Impact.

For professional aquarists and their associated industry, outreach will include live information on how different coral species will fare in predicted future conditions through CARN and the "Big Experiment" (see Pathways to Impact).

For policy makers, reports of key findings will be submitted to the IPCC working group II and the Convention of Biological Diversity expert panel on ocean acidification for the production of policy guiding documents. Additionally, reports will be submitted to local government representatives as local causes for ocean acidification can also be mitigated within existing laws (Kelly et al. 2011). Outputs from this fellowship would thus feed into influencing government policy and legislation. Modification of legislation to better protect the reefs of the future will impact and improve upon the future quality of life.