Robert E Tripati

Biogeosciences and Geobiology

Historically our group has diverse interests, but our current research efforts are focussed in two main areas funded by the LabEx program at IUEM in France, and the National Science Foundation in the US that are focussed on biological responses to high carbon dioxide concentrations and ocean acidifiction.

1. LabEx Mer Funded Projects at IUEM on the adaptive evolutionary response of calcifying phytoplankton to high carbon dioxide conditions.

We hypothesize that these two populations will have different adaptations to temperature and ocean pH change. Therefore in both short term and long term culture experiments we intent to explore this hypothesis. Long-term culture experiments will be run for 8-12 months in order to allow adaptive evolutionary responses to high carbon dioxide levels to occur and therefore study the importance of pre-apatation in determining evolutionary  responses to a future high carbon dioxide world.

Principle collaborators: Luc Beaufort, Ian Probert, Vianney Pichereau

2. Understanding the divergent responses of marine calcifying organisms to elevated carbon dioxide conditions. LabEx and National Science Foundation funded projects.

This project primarily draw on samples cultured by collaborator Justin Ries during his 2009 study where he showed remarkably divergent responses of marine calcium carbonate form organisms in culture experiments where carbon dioxide concentrations were elevated. Samples are also supplemented by new culture experiments on diverse coral species funded by our National Science Foundation Biological Oceanography project.

Genetically distinct populations of the coccolithophore Emiliania huxleyi have been identified from a transect off the coast of Peru. One group of strains isolated from the coastal upwelling zone are highly calcified, while other strains isolated from the open ocean are less calcified.  

In order to test the hypothesis that different species ability to regulate internal pH and carbonate chemistry to one of the principle factors governing this divergent response we are combining ceullar biological approaches like pH microprobes with geochemical approaches such as the boron isotope composition of carbonates in order to determine the internal pH of the fluids each organism used to produce calcium carbonate and how the extent to which it is buffered from seawater across a range carbon dioxide concentrations.