Richard B. Gump South Pacific Research Station

12 Jan, 04 AM - 02 Feb, 04 AM

Rising sea surface temperatures (SST) and ocean acidification (OA) threatens the ability of calcified organisms to build carbonate reefs. Current understanding of the effects of OA on coral reefs originates from static laboratory studies largely focused on growth of corals. But tropical crustose coralline algae (CCA) have been proclaimed as the canary on the coral reef because some species dissolve in these OA shock experiments. The exact physiological mechanism is unknown, but may be related to the magnesium content of the skeletal tissue, which renders the calcite more soluble in acidified conditions. The mole fraction of Mg in CCA in situ is subject to temperature and salinity and is positively correlated with warmer SST. This relationship has been exploited for climate reconstruction studies, but has not yet been considered in the context of OA. If CCA are not phenotypically plastic for Mg fractionation, then warming may exacerbate the response of these species to OA. The overall objective is to examine the ecological importance of Mg content in recently deposited skeletal tissue of common, pantropical CCA across a wide latitudinal range that encompasses natural spatio-temporal gradients in carbonate saturation and SST. The proposed research includes three specific objectives: 1) Describe the biogeographic and fine-scale patterns of Mg content in the carbonate skeleton of several species of common tropical CCA. 2) Explore the relationships of temperature and seawater carbonate chemistry with Mg content in several species of CCA. 3) Test whether Mg content alters the biological response (e.g. species-specific net calcification rates and community composition) of CCA to global warming and/or ocean acidification. Both powdered X-ray diffraction analysis and laser ablation inductively coupled plasma mass spectrometry will be used to quantify Mg2+ content relative to Ca2+ in the calcite lattice of CCA skeletal tissue; growth increment patterns will pinpoint the timing of deposition. For the first time, high frequency time-series seawater pH or pCO2, salinity, and SST data, complimented by discrete sampling for the remaining carbonate parameters (from established OA monitoring programs), will resolve daily, tidal, and seasonal cycles and be related with coincident biological data (calcification and production rates and Mg content) in situ.

Visit #37659 @Richard B. Gump South Pacific Research Station

Approved

Under Project # 29720 | Research

Mineralogy of coralline algae and global change

faculty - Bigelow Laboratory of Ocean Sciences

Reservation Members(s)

Emily Donham Jan 12 - Feb 2, 2015 (22 days)
Maggie Johnson Jan 12 - Feb 2, 2015 (22 days)

Reserve Resources(s) | Create Invoice

Dorm 1 2 Jan 12 - Feb 2, 2015
Full Use/Person - Waterfront Bungalow 2 Jan 12 - Feb 2, 2015