Meeting Abstract
Atmospheric carbon dioxide levels have risen at an unprecedented rate in the last 250 years, resulting in increasing global temperatures. By acting as a sink for atmospheric CO2, in addition to becoming warmer, oceans are becoming more acidic. Extensive research has documented major changes between individuals and their physical environment under ocean acidification, less attention has focused on the effects of ocean acidification on species interactions. In this study, we test how ocean acidification influences an important species interaction between the stony coral Porites furcata and the excavating sponge Cliona varians, species that have opposing ecosystem roles on Caribbean coral reefs: P. furcata creates reef structure through the accretion of calcium carbonate, while C. varians overgrows live corals and bioerodes calcium carbonate substrates. We collected RNAseq data from corals and sponges exposed to ambient or low pH conditions, both in isolation and in treatments where corals were overgrown by sponges. Previous work demonstrated that increased ocean acidification reduced calcification in the coral and increased bioerosion rates in the sponge. Using transcriptomic data, here we will identify the genomic mechanism of sponge bioerosion and test whether bioerosion rates in the sponge increase under ocean acidification due to a physiological change in the sponge or a weakening of the coral skeleton. We will also test whether decreased calcification in the coral is driven by the stress of low pH or the reallocation of resources to fight sponge overgrowth. Our results will inform models predicting ecosystem-level responses to future conditions by providing important data about species interactions under global change.
