Mineralogical response of the Mediterranean crustose coralline alga iLithophyllum cabiochae/i to near-future ocean acidification and warming

摘要

pstrongAbstract./strong Red calcareous coralline algae are thought to be among the organisms most vulnerable to ocean acidification due to the high solubility of their magnesium calcite skeleton. Although skeletal mineralogy is proposed to change as COsub2/sub and temperature continue to rise, there is currently very little information available on the response of coralline algal carbonate mineralogy to near-future changes in ip/iCOsub2/sub and temperature. Here we present results from a 1-year controlled laboratory experiment to test mineralogical responses to ip/iCOsub2/sub and temperature in the Mediterranean crustose coralline alga (CCA) iLithophyllum cabiochae/i. Our results show that Mg incorporation is mainly constrained by temperature (+1span class="thinspace"/spanmolspan class="thinspace"/span%span class="thinspace"/spanMgCOsub3/sub for an increase of 3span class="thinspace"/span?°C), and there was no response to ip/iCOsub2/sub. This suggests that iL. cabiochae/i thalli have the ability to buffer their calcifying medium against ocean acidification, thereby enabling them to continue to deposit magnesium calcite with a significant molspan class="thinspace"/span% MgCOsub3/sub under elevated ip/iCOsub2/sub. Analyses of CCA dissolution chips showed a decrease in Mg content after 1??year for all treatments, but this was affected neither by ip/iCOsub2/sub nor by temperature. Our findings suggest that biological processes exert a strong control on calcification on magnesium calcite and that CCA may be more resilient under rising COsub2/sub than previously thought. However, previously demonstrated increased skeletal dissolution with ocean acidification will still have major consequences for the stability and maintenance of Mediterranean coralligenous habitats./p.