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Sensitivity of Antarctic phytoplankton species to ocean acidification: Growth, carbon acquisition, and species interaction
Author(s) -
Trimborn Scarlett,
Brenneis Tina,
Sweet Elizabeth,
Rost Björn
Publication year - 2013
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2013.58.3.0997
Subject(s) - phytoplankton , photosynthesis , chaetoceros , total inorganic carbon , botany , mixotroph , algae , biology , chemistry , carbon dioxide , environmental chemistry , heterotroph , nutrient , ecology , genetics , bacteria
Despite the fact that ocean acidification is considered to be especially pronounced in the Southern Ocean, little is known about CO 2 ‐dependent physiological processes and the interactions of Antarctic phytoplankton key species. We therefore studied the effects of CO 2 partial pressure (P CO2 ) (16.2, 39.5, and 101.3 Pa) on growth and photosynthetic carbon acquisition in the bloom‐forming species Chaetoceros debilis, Pseudo‐nitzschia subcurvata, Fragilariopsis kerguelensis, and Phaeocystis antarctica. Using membrane‐inlet mass spectrometry, photosynthetic O 2 evolution and inorganic carbon (C i ) fluxes were determined as a function of CO 2 concentration. Only the growth of C. debilis was enhanced under high P CO2 . Analysis of the carbon concentrating mechanism (CCM) revealed the operation of very efficient CCMs (i.e., high C i affinities) in all species, but there were species‐specific differences in CO 2 ‐dependent regulation of individual CCM components (i.e., CO 2 and uptake kinetics, carbonic anhydrase activities). Gross CO 2 uptake rates appear to increase with the cell surface area to volume ratios. Species competition experiments with C. debilis and P. subcurvata under different P CO2 levels confirmed the CO 2 ‐stimulated growth of C. debilis observed in monospecific incubations, also in the presence of P. subcurvata . Independent of P CO2 , high initial cell abundances of P. subcurvata led to reduced growth rates of C. debilis . For a better understanding of future changes in phytoplankton communities, CO 2 ‐sensitive physiological processes need to be identified, but also species interactions must be taken into account because their interplay determines the success of a species.