Physiological and Behavioral Responses, and their Variability, in Squid, Doryteuthis Pealeii, Embryos and Paralarvae Reared Under Chronic Ocean Acidification

Casey Zakroff, Ph.D., 2019
T. Aran Mooney, Advisor
Ocean acidification (OA) and warming are occurring rapidly in coastal systems, potentially impacting the early development of species that use the nearshore as nursery habitat. The inshore longfin squid, Doryteuthis pealeii, annually lays its eggs in the nearshore benthos during summer. This thesis sought to characterize morphological, physiological, and behavioral responses of D. pealeii embryos and paralarvae to OA. Initially, I exposed squid eggs to a range of acidification levels (400 – 2200 ppm CO¬2) to uncover the dosage where impacts first appear (1300 ppm¬). Compiling experiments from 2013 – 2016, I show that seasonal temperatures impact the baseline state of the paralarvae through parental condition, while acidification sensitivity appears driven by year class. Finally, I examined the interaction of acidification stress with warming, demonstrating an antagonistic relationship between these stressors. These data indicate that acidification stress builds over time, impacting late embryonic development, while warming impacts early development. Warming appears to reduce acidification impacts by increasing development rate and decreasing exposure time. This dissertation demonstrates that while the embryonic and paralarval stages can be sensitive to acidification, high fecundity and variable resistance across multiple temporal scales