Increased coral biomineralization due to enhanced symbiotic activity upon volcanic ash exposure - dataset
Abstract Coral reefs, which are among the most productive ecosystems on earth, are in global decline due to rapid climate change and associated ocean-warming. Volcanic activity also results in extreme environmental changes at local to global scales, and may have the greatest impact on coral reefs compared to other natural disturbances. During explosive eruptions, large amounts of volcanic ash are generated, significantly disrupting ecosystems close to a volcano, and depositing ash over distal areas (10s to 1000s of km depending on eruption size, wind intensity, and direction). Once volcanic ash interacts with seawater, the dissolution of metals leads to a rapid change in the geochemical properties of the seawater column. Here, we report the first known effects of volcanic ash on the physiology of a symbiotic scleractinian coral under laboratory conditions. Nubbins of the branching coral Stylophora pistillata were reared in aquaria under controlled conditions (light intensity, temperature, and pH), while environmental parameters, effective quantum yield, and skeletal growth rate were monitored. Half the aquaria were exposed to volcanic ash every other day for 6 weeks (250 mg L-1 week-1), which induced significant changes in the fluorescence-derived photochemical parameters (ΦPSII, Fv/Fm, NPQ, rETR), directly enhanced the efficiency of symbiont photosynthesis (Pg, Pn), and lead to enhanced biomineralization rates. Enhancement of symbiont photosynthesis is likely induced by the supply of essential metals, derived from volcanic ash leaching. The beneficial role of volcanic ash as an important micronutrient source is supported by the fact that neither photophysiological stress nor signs of lipid peroxidation or protein damage were detected. The implication of this beneficial interaction remains to be tested for the more complex coral reef ecosystem as it holds the potential to offset external stresses such as those caused by climate change, or volcanic eruptions themselves.