Research Projects > Environmental Physiology of Corals

We have been involved in collaborative studies of how corals respond to thermal stress, including investigations at all levels of the coral-algae-microbial symbiosis. While there are no active ongoing coral projects at present, we remain interested in coral environmental biology.

Our projects have mainly focused on the massive reef building coral Porites lobata from a lagoon in American Samoa that routinely experience thermal conditions that would result in bleaching (the loss of photosynthetic endosymbionts, and a "unhealthy" condition for corals). Yet, the corals in those lagoons do not bleach. We have used a protein biomarker approach to understanding how coral hosts modulate their cellular physiology in response to the levels of environmental variation between benign forereef and thermally-stressful lagoon habitats. We performed a lagoon-forereef reciprocal transplant experiment where we monitored HSP70 and SOD (proteins involved in thermal and oxidative stress responses) and protein markers of protein damage (ubiquitin and 4-HNE). In addition to biomarkers, we are also genotyping both host and symbiont in order to assess which member of the holobiont may be genetically distinct among source populations. Our results, which are accepted for publication in the journal Molecular Ecology, indicate that in Porites lobata, local adaptation in the cnidarian host is driving population physiological differentiation (Barshis et al., 2010 Molec. Ecol.).

In addition to field-based experiments, we performed a laboratory thermal acclimation experiment in my laboratory in San Francisco to simulate lagoon and forereef thermal conditions on the same corals from American Samoa. From these samples we performed protein analyses of the same four sets of biomarkers, as well as photophysiology experiments. Those results demonstrate the range of responses due to local adaptation as well as to plastic responses.

At present, our coral projects mainly involve a display reef aquarium (pictured here). But, performing coral experiments remain a distinct possiblity in our laboratory if funding should become available in the future.