Meeting Abstract
Due to unprecedented increases in atmospheric CO2, marine organisms now face a rapid global reduction of seawater pH, or ocean acidification (OA). To date, the majority of studies on biological responses to OA are short-term and the potential for acclimation and adaptation is rarely addressed. I performed experiments on the model copepod Tigriopus californicus to investigate population level differences in the effect of pH on life history across multiple generations. Reproductive F0 females from each of 4 geographically isolated populations were allocated to 3 pH treatments: 8, 7.5, and 7. Cultures were maintained in these treatments through the F3 generation. For each generation and population, I quantified survivorship, fecundity, and development time. Initial nauplii production by F0 females was not affected by pH, however, there were large differences in fecundity among populations. Later in F1 development, population sizes and development rates were reduced in the 8 pH, for all populations. After F1 adults were isolated to start the F2 generation, copepods in the 8 pH initially produced the most nauplii. However, by week 4 of F2 development, population sizes in the 7.5 and 8 pH treatments dropped drastically, leaving few F2 adults to begin the F3 generation (experiments on survivors are ongoing). These results suggest that transitions through later developmental stages may be most sensitive to different pH treatments. There were population differences in life history throughout the F2 generation, but all populations had highest overall performance in the 7 pH. T. californicus inhabits tidepools, which undergo large diurnal and seasonal fluctuations in pH. This species may be preadapted to low pH conditions and may tolerate higher pH, but only for short-term exposure. Coastal species that currently experience extreme abiotic variability may be resilient to rapid environmental change.
