Symbiont acquisition in Caribbean coral recruits
The early life stages of corals are crucial.
Since coral spawning and settlement in the Caribbean coincides with the warmest ocean temperatures of the year, and because corals in their early life stages are particularly vulnerable to environmental stress and high mortality, it is important to understand how coral juveniles might become more thermally resilient from the start.
Most Caribbean corals take up new algal symbionts (family Symbiodiniaceae) through horizontal transmission from the environment upon larval settlement to the reef. Warming ocean temperatures may favor initial uptake of the thermally tolerant symbiont Durusdinium (Abrego et al. 2012), although this process is not well understood in Caribbean coral recruits. Moreover, nearby adult corals may influence symbiont availability by continuously discharging symbionts into the environment (Hoegh-Guldberg & Smith 1989), where they may persist in the sediment and water column (Cunning et al. 2015) and increase the rate of symbiont acquisition by newly settled recruits (Nitschke et al. 2015). Therefore, as symbionts like Durusdinium become more prevalent on reefs due to increasingly frequent thermal stress and mass bleaching events, they may accelerate the positive feedbacks of thermally tolerant symbionts at the ecosystem level. Such dynamics have significant implications for reef performance and responses to environmental change.
Since beginning my Ph.D. in August 2017, I have been evaluating metacommunity feedbacks in coral symbiosis ecology by studying whether differences in the local availability of different types of Symbiodiniaceae influence the composition of symbiont communities populating juvenile corals. Focusing on key reef-building species including Orbicella faveolata (mountainous star coral) and Diploria labyrinthiformis (grooved brain coral) collected from various sites across the Caribbean, I am conducting larval settlement and symbiont uptake experiments in the presence of adult corals with different symbiont assemblages in order to quantify the degree to which the existing symbiont metacommunity on a reef influences the establishment of symbiosis in coral recruits. My goal is to elucidate potential intergenerational feedbacks that may drive the future trajectory of coral symbiosis ecology in the Caribbean.
I am working with partners including SECORE International, the Perry Institute for Marine Science, The Nature Conservancy, Shedd Aquarium, and NOAA's Southeast Fisheries Science Center to collect and rear coral juveniles.