Exposure of the toxigenic dinoflagellate Alexandrium catenella to variations in pCO₂/pH, comparable to current and near-future levels observed in Southern Chilean fjords, revealed potential functional adaptation mechanisms. Under calculated conditions for pH_{(total scale)} and pCO₂ ranging from 7.73–8.66 to 69.7–721.3 μatm, respectively, the Chilean strain Q09 presented an optimum growth rate and dissolved inorganic carbon (DIC) uptake at near-equilibrium pCO₂/pH conditions (∼8.1). DistaLM analysis between physiological relevant carbonate system parameters (CO₂, HCO as the unique variable explaining a significant portion of the physiological response. Estimations of equivalent spherical diameter (ESD) and chain-formation index (CI) revealed reduced cell size and enhanced chain formation at high pH/low pCO₂ conditions. Light intensity as co-factor during experiments (50 vs. 100 μmol photons m⁻² s⁻¹) produced no effect on ESD and CI. Cells exposed to low light; however, had reduced cell growth and DIC uptake especially at high pH/low pCO₂. We suggest that A. catenella Chilean strains are highly adapted to spatio-temporal pCO₂/pH fluctuations in Chilean fjords, becoming a resilient winner from expected climate change effects.

Item Type:	Refereed Article
Keywords:	Alexandrium catenella, cell size, chain-forming, Chilean fjords, DIC uptake, harmful algal blooms
Research Division:	Biological Sciences
Research Group:	Ecology
Research Field:	Marine and estuarine ecology (incl. marine ichthyology)
Objective Division:	Environmental Policy, Climate Change and Natural Hazards
Objective Group:	Adaptation to climate change
Objective Field:	Ecosystem adaptation to climate change
UTAS Author:	Mardones, JI (Mr Jorge Mardones)
UTAS Author:	Hallegraeff, GM (Professor Gustaaf Hallegraeff)
ID Code:	114548
Year Published:	2017
Web of Science® Times Cited:	10
Deposited By:	Fisheries and Aquaculture
Deposited On:	2017-02-17
Last Modified:	2018-03-21
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