title: Decreased photosynthesis and growth with reduced respiration in the model diatom Phaeodactylum tricornutum grown under elevated CO2over 1800 generations.
abstract: Studies on the long-term responses of marine phytoplankton to ongoing ocean acidification (OA) are appearing rapidly in the literature. However, only a few of these have investigated diatoms, which is disproportionate to their contribution to global primary production. Here we show that a population of the model diatom Phaeodactylum tricornutum, after growing under elevated CO2(1000 μatm, HCL, pHT: 7.70) for 1860 generations, showed significant differences in photosynthesis and growth from a population maintained in ambient CO2and then transferred to elevated CO2for 20 generations (HC). The HCL population had lower mitochondrial respiration, than did the control population maintained in ambient CO2(400 μatm, LCL, pHT: 8.02) for 1860 generations. Although the cells had higher respiratory carbon loss within 20 generations under the elevated CO2, being consistent to previous findings, they downregulated their respiration to sustain their growth in longer duration under the OA condition. Responses of phytoplankton to OA may depend on the timescale for which they are exposed due to fluctuations in physiological traits over time. This study provides the first evidence that populations of the model species, P. tricornutum, differ phenotypically from each other after having been grown for differing spans of time under OA conditions, suggesting that long-term changes should be measured to understand responses of primary producers to OA, especially in waters with diatom-dominated phytoplankton assemblages.
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China.
authors.forename: Futian
authors.initials: F
authors.lastname: Li
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China.|School of Biological Sciences, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Beardall
authors.affiliation: Ashworth Laboratories, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, EH9 3FL, UK.
authors.forename: Sinéad
authors.initials: S
authors.lastname: Collins
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China.
authors.forename: Kunshan
authors.initials: K
authors.lastname: Gao
mesh_terms: D002245:Carbon Dioxide; D017377:Diatoms; D006863:Hydrogen-Ion Concentration; D010788:Photosynthesis; D012623:Seawater
chemical_list: D002245:Carbon Dioxide
keywords: 
  Phaeodactylum tricornutum
  ; CO2; diatom; growth; ocean acidification; photosynthesis; respiration