| Summary: | Ocean acidification (OA) is a symptom o f increased anthropogenic emissions and may change release and transparent exopolymer particle (TEP) formation, especially in bloom decline. Emiliania huxleyi is a major mediator o f carbon fixation and sequestration in today???s oceans. To estimate this specie???s response to ocean acidification, calcifying strains o f E. huxleyi were grown under three pC0 2 treatments (390 ppmv, 650 ppmv, and 900 ppmv) and sampled through a batch culture period of up to 39 days. In order to explore a strain based response to pC0 2, two different genetic isolates (RCC 1251 and RCC 1258) were tested under treatment conditions. RCC 1258 cultures consistently experienced higher concentrations of DOC and TEP than RCC 1251. Treatment pC0 2 did not have an effect on observed DOC for RCC 1251. In RCC 1258, pC0 2 treatment had a significant effect on observed DOC values (p-value = 0.007), with both elevated treatment cultures having higher DOC than ambient cultures. Differences between DOC concentrations in different treatment cultures were observed for RCC 1258 (p-value = 0.01). TEP concentrations were significantly different between strains (p-value = 0.03), but no differences between pC0 2 treatments were observed in either strain at any time point. The results suggest that these two strains have different strategies for coping with pC0 2 stress, and that the efficiency with which they maintain their cell structure is related to the types o f DOC released by these cells.
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