Sunday, April 23, 2017

Earth Sciences Colloquium | Rob Eagle Tripati from UCLA

Rob Tripati (UCLA) will be coming tomorrow to speak about "Cross-disciplinary approaches to understand the response of marine organisms to changing oceanic conditions in a high CO2 world”.

Abstract: The growth response of calcium carbonate mineralizing organisms to elevated CO2 conditions is extremely diverse. Some organisms are negatively influenced by CO2-induced seawater carbonate system perturbations and associated pH decline, producing less calcium carbonate in their shells or skeletons. Yet, other organisms are resilient and positive growth response for some species has been observed in culture experiments. Many organisms produce their shells and skeletons from an internal fluid pool that is chemically distinct from seawater. Here we address the hypothesis that an organism’s ability to regulate the pH and carbonate chemistry of their internal calcification fluid and their ability to buffer internal pH from changes in external seawater chemistry is a significant factor in the observed diversity of organismal responses to increasing CO2 conditions. To address this we combine approaches from geochemistry and cellular biology, using measurements of δ11B and pH microelectrodes to probe the calcification site pH of a range of different marine calcifying organisms cultured across a range of CO2 levels. Our data shows an extremely diverse range of isotopic and microelectrode signatures. In some cases this diversity is coupled to net calcification response, suggesting a primary internal pH control over shell growth, and in other cases it is decoupled suggesting additional complexity in organismal calcification responses to CO2.

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