Last month, the Grouper Moon Project - a highly successful conservation science collaboration between REEF and the Cayman Islands Department of Environment - wrapped up its 18th year of work in Little Cayman. Because all of the field work takes place during a few weeks around the winter full moons when the Nassau Grouper aggregate to spawn, the team prepares all year to ensure success for the big event. As we reported in last month’s e-News, because of this year's moon calendar, we sent research teams to Little Cayman in both January and February. Based on our historical work, we assumed that February would be the “big” month for spawning, and it turned out we were right.
Our team consisted of twelve scientists, including two REEF staff members: Dr. Christy Semmens, REEF Director of Science, and Dr. Alli Candelmo, REEF Invasive Species Program Manager. In addition, Environmental Leadership Intern, Sophie Costa and the Grouper Moon lead educator, Todd Bohannon joined the team. The team conducted daily research dives to collect data on number and size of individuals at the spawning site. Based on preliminary results, it is estimated that roughly 6,500 individuals were seen at the spawning site in February, which is similar to the numbers documented last year. The team also documented a lot of fish that were probably attending the aggregation for the first time (Nassau Grouper are reproductive starting between 5-8 years old). Spawning was documented over three nights, starting five nights after February’s full moon.
To connect Caymanian students with the project, the team hosted live webcasts from the field with several classrooms. Students also participated in lessons about the ecological and social role of Nassau Grouper. A local news reporter, Joe Avary from Cayman27, also joined the team for several days and his extensive news stories provided coverage of the program to the public. You can check out the Cayman27 news coverage here.
The growing body of research findings from the Grouper Moon Project has supported science-based legislation passed by the Cayman government in 2016. Nevertheless, there is still much to be learned about Nassau Grouper, their spawning biology, and what components are critical to the species survival. One such question that our team is working on as we look forward is how the changing oceans and climate might impact the species. Based on our historical data, spawning tends to occur when the water temperature is 27.2 C, which is just under 81 degrees F. What will happen when global water temperatures increase over the next 100 years? Our team has been collecting eggs to determine how developing embryos and larvae may be affected by increased temperatures, UV light, and salinity. These experiments will provide a good understanding of how Nassau Grouper populations will react to a changing climate.
For more information, visit www.REEF.org/groupermoonproject to see links to videos and photos, and to read about the scientific publications and legislative actions that have been informed by our work.