TY - JOUR

T1 - Impacts of ocean acidification on growth and toxin content of the marine diatoms Pseudo-nitzschia australis and P. fraudulenta

AU - Ayache, Nour

AU - Lundholm, Nina

AU - Gai, Frederik

AU - Hervé, Fabienne

AU - Amzil, Zouher

AU - Caruana, Amandine

N1 - Funding Information: The authors acknowledge Ifremer and the Regional Council of the ?R?gion des Pays de la Loire? for the PhD funding of Nour Ayache. The authors would like to thank Audrey Duval and Nicolas Chom?rat from Ifremer, Concarneau, France for providing and identifying the French Pseudo-nitzschia australis IFR-PAU-17 strain, and Deon Louw and Cecilie Hedemand for providing the Namibian Pseudo-nitzschia australis L3-100, L3.4 and L3-30 strains. Thanks are also due to Juliette Fauchot from UMR BOREA, Normandy University, France, for providing the two P. fraudulenta strains PNfra167 and PNfra169. The authors thank Georges-Augustin Rovillon for his invaluable help for technical assistance in toxin analysis. Publisher Copyright: © 2021 Elsevier Ltd

PY - 2021

Y1 - 2021

N2 - This paper present the effects of ocean acidification on growth and domoic acid (DA) content of several strains of the toxic Pseudo-nitzschia australis and the non-toxic P. fraudulenta. Three strains of each species (plus two subclones of P. australis) were acclimated and grown in semi-continuous cultures at three pH levels: 8.07, 7.77, and 7.40, in order to simulate changes of seawater pH from present to plausible future levels. Our results showed that lowering pH from current level (8.07) to predicted pH level in 2100 (7.77) did not affect the mean growth rates of some of the P. australis strains (FR-PAU-17 and L3-100), but affected other strains either negatively (L3-30) or positively (L3.4). However, the growth rates significantly decreased with pH lowered to 7.40 (by 13% for L3-100, 43% for L3-30 and 16% for IFR-PAU-17 compared to the rates at pH 8.07). In contrast, growth rates of the non-toxic P. fraudulenta strains were not affected by pH changing from 8.07 to 7.40. The P. australis strains produced DA at all pH levels tested, and the highest particulate DA concentration normalized to cell abundance (pDA) was found at pH 8.07. Total DA content (pDA and dissolved DA) was significantly higher at current pH (8.07) compared to pH (7.77), exept for one strain (L 3.4) where no difference was found. At lower pH levels 7.77–7.40, total DA content was similar, except for strains IFR-PAU-17 and L3-100 which had the lowest content at the pH 7.77. The diversity in the responses in growth and DA content highlights the inter- and intra-specific variation in Pseudo-nitzschia species in response to ocean acidification. When exploring environmental responses of Pseudo-nitzschia using cultured cells, not only strain-specific variation but also culturing history should be taken into consideration, as the light levels under which the subclones were cultured, afterwards affected both maximum growth rates and DA content.

AB - This paper present the effects of ocean acidification on growth and domoic acid (DA) content of several strains of the toxic Pseudo-nitzschia australis and the non-toxic P. fraudulenta. Three strains of each species (plus two subclones of P. australis) were acclimated and grown in semi-continuous cultures at three pH levels: 8.07, 7.77, and 7.40, in order to simulate changes of seawater pH from present to plausible future levels. Our results showed that lowering pH from current level (8.07) to predicted pH level in 2100 (7.77) did not affect the mean growth rates of some of the P. australis strains (FR-PAU-17 and L3-100), but affected other strains either negatively (L3-30) or positively (L3.4). However, the growth rates significantly decreased with pH lowered to 7.40 (by 13% for L3-100, 43% for L3-30 and 16% for IFR-PAU-17 compared to the rates at pH 8.07). In contrast, growth rates of the non-toxic P. fraudulenta strains were not affected by pH changing from 8.07 to 7.40. The P. australis strains produced DA at all pH levels tested, and the highest particulate DA concentration normalized to cell abundance (pDA) was found at pH 8.07. Total DA content (pDA and dissolved DA) was significantly higher at current pH (8.07) compared to pH (7.77), exept for one strain (L 3.4) where no difference was found. At lower pH levels 7.77–7.40, total DA content was similar, except for strains IFR-PAU-17 and L3-100 which had the lowest content at the pH 7.77. The diversity in the responses in growth and DA content highlights the inter- and intra-specific variation in Pseudo-nitzschia species in response to ocean acidification. When exploring environmental responses of Pseudo-nitzschia using cultured cells, not only strain-specific variation but also culturing history should be taken into consideration, as the light levels under which the subclones were cultured, afterwards affected both maximum growth rates and DA content.

KW - Amnesic shellfish poisoning

KW - Domoic acid

KW - Harmful algae

KW - Ocean acidification

KW - Pseudo-nitzschia

U2 - 10.1016/j.marenvres.2021.105380

DO - 10.1016/j.marenvres.2021.105380

M3 - Journal article

C2 - 34146891

AN - SCOPUS:85108087646

VL - 169

JO - Marine Environmental Research

JF - Marine Environmental Research

SN - 0141-1136

M1 - 105380

ER -