Ocean acidification and warming alter photosynthesis and calcification of the symbiont-bearing foraminifera Marginopora vertebralis

Sutinee Sinutok, Ross Hill*, Michael Kühl, Martina A. Doblin, Peter J. Ralph

*Corresponding author for this work

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The impact of elevated CO2 and temperature on photosynthesis and calcification in the symbiont-bearing benthic foraminifer Marginopora vertebralis was studied. Individual specimens of M. vertebralis were collected from Heron Island on the southern Great Barrier Reef (Australia). They were maintained for 5 weeks at different temperatures (28, 32 °C) and pCO2 (400, 1,000 μatm) levels spanning a range of current and future climate-change scenarios. The photosynthetic capacity of M. vertebralis was measured with O2 microsensors and a pulse-amplitude-modulated chlorophyll (Chl) fluorometer, in combination with estimates of Chl a and Chl c 2 concentrations and calcification rates. After 5 weeks, control specimens remained unaltered for all parameters. Chlorophyll a concentrations significantly decreased in the specimens at 1,000 μatm CO2 for both temperatures, while no change in Chl c 2 concentration was observed. Photoinhibition was observed under elevated CO2 and temperature, with a 70-80 % decrease in the maximum quantum yield of PSII. There was no net O2 production at elevated temperatures in both CO2 treatments as compared to the control temperature, supporting that temperature has more impact on photosynthesis and O2 flux than changes in ambient CO2. Photosynthetic pigment loss and a decrease in photochemical efficiency are thus likely to occur with increased temperature. The elevated CO2 and high temperature treatment also lead to a reduction in calcification rate (from +0.1 to >-0.1 % day-1). Thus, both calcification and photosynthesis of the major sediment-producing foraminifer M. vertebralis appears highly vulnerable to elevated temperature and ocean acidification scenarios predicted in climate-change models.

Original languageEnglish
Pages (from-to)2143-2154
Number of pages12
JournalMarine Biology
Volume161
Issue number9
DOIs
Publication statusPublished - Sep 2014
Externally publishedYes

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