Today began with a little reconnaissance. With the help of our captain, Amaury, and fellow students Sandra and Francisco, we snorkeled the reef to get our bearings. Since we’ll be diving at night and spending all of our energy trying to collect spawn, we need to be able to find the coral colonies blindfolded. Here’s just one example:

Hopefully the fin at the top of the picture gives you a sense of scale. Some of these formations are huge! It’s really encouraging to see that large stands of Acropora palmata, a threatened species, can still be found in the Caribbean.

Which brings us to the question of why we’re here in Mexico. What’s the point? What are we hoping to accomplish? We actually have a lot of experiments lined up for this summer, all designed to answer different questions. In the first installment of a multi-part series, we’ll first address the one that’s been going on the longest–close to five years!

Corals are very sensitive to high temperatures, and the oceans have been getting warmer and warmer. One life stage where this change might be really important is larval dispersal. When some corals reproduce, they release millions of gametes into the water, where they mingle and form larvae. These larvae are transported on the currents and eventually settle down and begin to grow into adult colonies. We want to know how temperature is affecting this process. Is it hurting the larvae? Do they travel shorter distances? Do they settler faster?

To get at these questions, we’ve been attending annual spawning events for years, raising collected larvae in special aquaria where we control the temperature, and seeing how the larvae develop in stressful conditions compared to normal ones. So far we’ve documented several differences in gene expression, including greater production of heat-shock proteins in stressed larvae, as well as atypical morphologies (strange shapes) that likely reduce larval duration (time spent traveling in the water).

To make things more interesting, we can control which corals reproduce with one another, giving us insight into genetic mechanisms for such characteristics. We’ve found that certain coral families perform better than others. These would make great targets for protection. Such natural differences provide hope that there is enough standing genetic variation in current populations for adaptation to climate change to be possible. Still, the corals are in a sorry state, and things will continue to get worse before they get better. With any luck, our research can help.