Differential effects of ocean acidification on carbon acquisition in two bloom‐forming dinoflagellate species. Issue 4 (24th January 2014)

• Record Type: Journal Article
• Authors: Eberlein, Tim; Van de Waal, Dedmer B.; Rost, Björn
• Is Part Of: Physiologia plantarum. Volume 151:Issue 4(2014:Aug.)
• Page Start: 468
• Page End: 479
• Publication Date: 2014-01-24
• Subjects: Plant physiology -- Periodicals; 571.2
• DOI: 10.1111/ppl.12137
• Languages: English
• ISSNs: 0031-9317

Abstract

<abstract abstract-type="main" id="ppl12137-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="ppl12137-para-0001">Dinoflagellates represent a cosmopolitan group of phytoplankton with the ability to form harmful algal blooms. Featuring a Ribulose‐1, 5‐bisphosphate carboxylase/oxygenase (RubisCO) with very low CO<sub>2</sub> affinities, photosynthesis of this group may be particularly prone to carbon limitation and thus benefit from rising atmospheric CO<sub>2</sub> partial pressure (<italic>p</italic>CO<sub>2</sub>) under ocean acidification (OA). Here, we investigated the consequences of OA on two bloom‐forming dinoflagellate species, the calcareous <italic>Scrippsiella trochoidea</italic> and the toxic <italic>Alexandrium tamarense</italic>. Using dilute batch incubations, we assessed growth characteristics over a range of <italic>p</italic>CO<sub>2</sub> (i.e. 180–1200 µatm). To understand the underlying physiology, several aspects of inorganic carbon acquisition were investigated by membrane‐inlet mass spectrometry. Our results show that both species kept growth rates constant over the tested <italic>p</italic>CO<sub>2</sub> range, but we observed a number of species‐specific responses. For instance, biomass production and cell size decreased in <italic>S. trochoidea</italic>, while <italic>A. tamarense</italic> was not responsive to OA in these measures. In terms of oxygen fluxes, rates of photosynthesis and respiration remained unaltered in <italic>S. trochoidea</italic> whereas respiration increased in <italic>A. tamarense</italic> under OA. Both species featured efficient carbon concentrating mechanisms (CCMs) with a CO<sub>2</sub>‐dependent contribution of HCO<sub>3</sub><sup>−</sup> uptake. In <italic>S. trochoidea</italic>, the CCM was further facilitated by exceptionally high and CO<sub>2</sub>‐independent carbonic anhydrase activity. Comparing both species, a general trade‐off between maximum rates of photosynthesis and respective affinities is indicated. In conclusion, our results demonstrate effective CCMs in both species, yet very different strategies to adjust their carbon acquisition. This regulation in CCMs enables both species to maintain growth over a wide range of ecologically relevant <italic>p</italic>CO<sub>2</sub>.</p> </abstract>