Meeting Abstract
Trace metals are critical to the persistence of micro-algae (e.g. phytoplankton). Mutualistic endosymbionts, Symbiodiniaceae, deliver and receive nutrients from their reef-building hosts, stony corals. Linking the connection between macro (carbon, nitrogen, phosphorus) and micro-nutrient (trace) quotas in relation to energy cycling between host and symbiont is pertinent to understanding the holobiont’s ability to withstand stress events. It is hypothesized that exposure to increased iron availability (and subsequent iron sequestration) may enhance the organism’s ability to maintain homeostasis during stress events. To test this hypothesis, Breviolum spp. (formerly Symbiodinium clade B) cultures were exposed to a full-factorial set of temperatures and iron concentrations. During exponential growth, cultures were sampled for nutrient content (trace metals and major nutrients), chlorophyll, pigments, and photosynthetic physiology to evaluate Breviolum spp. condition. Preliminary results indicate that heat stress halts growth and photosynthesis at cultures exposed to low iron concentrations whereas counterparts at higher iron concentrations are able to persist. By combining a broad suite of physiological approaches, we have created the baseline for a Breviolum spp. iron stress index to assess the compounding effects of iron limitation and heat stress on the stability of coral-algal symbioses.
