Meeting Abstract
Trace metals, especially iron, are required for virtually all biochemical and metabolic processes. Coral thermal tolerance is attributed mostly to individuals pre-conditioned to thermal stress, access to greater nutrient reserves (from heterotrophy), and the photo-physiological capabilities of their resident algal symbiont. However, the underlying role of trace metals in these processes remains largely unknown due to several technical challenges when applying trace metal clean methods. With continued ocean warming, a possible decrease in iron availability raises questions about how this may affect reef coral physiology. To examine the importance of trace metals for Symbiodiniaceae physiology and metallome (elemental content), cultures were exposed to various (ecologically relevant) iron concentrations and temperatures. Additionally, metallomes of Symbiodiniaceae (in hospite) were compared between reefs with different thermal regimes. Sufficient iron concentrations (>50 pM Fe’), were needed by cultured symbionts to cope with heat stress. Moreover, one species that actively acquired more iron (and other metals) during thermal stress, exhibited greater thermal tolerance and cell growth. Furthermore, symbiotic algae extracted from corals living in high temperature environments exhibit different elemental compositions relative to conspecifics living in cooler habitats. Such differences in elemental composition among heat tolerant corals may correspond to increased enzymatic activity or other protective processes. The scope and significance of trace metals to biochemical pathways that support coral-algal symbioses under normal and adverse conditions deserves more attention.
