Forereef and backreef corals exhibit different responses to anthropogenic stressors in Belize

Sara Fowell1, Gavin L Foster2, Karl Castillo3, Justin B Ries4 and Toby Tyrrell2, (1)University of Southampton, Southampton, SO14, United Kingdom, (2)University of Southampton, Ocean and Earth Science, Southampton, United Kingdom, (3)UNC Chapel Hill, Chapel Hill, NC, United States, (4)Northeastern University, Department of Marine and Environmental Sciences, Nahant, MA, United States
Abstract:
The health of coral reefs is threatened by simultaneous anthropogenic impacts, namely ocean acidification, ocean warming, elevated nutrients (nutrification) and sedimentation. These processes have been shown to reduce the ability of corals to grow, but culturing experiments have previously demonstrated this response to vary across different reef environments and between different taxa. The absence of in-situ pH data, records of nutrient evolution and limited sea surface temperature (SST) measurements prior to the 1980s, has prevented the extent of either ocean acidification, nutrification or ocean warming to be quantified in Belize. Here, we have applied a multi-proxy approach (Li/Mg, Sr/Ca, Ba/Ca, δ11B, δ13C) to reconstruct these variables in corals from across the southern Mesoamerican Barrier Reef System over the last 100 years. We find that although the warming signal is spatially coherent, significant spatial variability exists in the extent of acidification and sediment input. Further investigations into the impact of such variability, and possible changes in net primary production must be conducted before we can conclude which anthropogenic stressor is responsible for the decline in forereef coral extension rates.