STRESS CONDITIONING TO HYPERCAPNIC SEAWATER IN THE PACIFIC GEODUCK PANOPEA GENEROSA

• Main Author: Gurr, Samuel J.
• Format: Text
• Language: unknown
• Published: DigitalCommons@URI 2021
• Subjects: Pacific; Ocean acidification
• Online Access: https://digitalcommons.uri.edu/oa_diss/1275; https://doi.org/10.23860/diss-gurr-samuel-2021; https://digitalcommons.uri.edu/context/oa_diss/article/2292/viewcontent/Gurr_uri_0186A_12733.pdf

Expansion and enhancement of sustainable shellfish production is necessary to prevent overexploitation of wild stock and satisfy international trade, but hatchery rearing poses a critical production bottleneck due partially to environmental stressors such as ocean acidification. Given that stress conditions exacerbated by anthropogenic activity are projected to intensify in the near-future, long-lived molluscs, such as Pacific geoduck Panopea generosa (known lifespan up to 168 years), may rely on intragenerational acclimation to buffer against rapid environmental change. While acute stressors can be detrimental, environmental stress conditioning can improve performance. For example, moderate oxidative stress (i.e. temperature, irradiance, and dietary restriction) shows evidence of dose-dependent benefits for many taxa, however stress acclimation remains understudied in marine invertebrates, despite being threatened by climate change stressors. To test the hypothesis that physiological status is altered by stress conditioning, we first subjected juvenile geoduck clams to repeated exposures of elevated pCO2 in a commercial hatchery setting followed by a period in ambient common garden. Our initial experiment found early exposure to low pH elicits compensatory carryover effects suggesting bioenergetic re-allocation facilitates growth compensation and metabolic recovery. Further, to test for life-stage and stress-intensity dependence in eliciting enhanced tolerance under subsequent stress encounters, we acclimatized post-larval geoduck for >100 days before re-exposure under two reciprocal periods of moderate and severe elevated pCO2. Stress acclimation followed by secondary and tertiary exposure to severe and moderate elevated pCO2 increased respiration rate, organic biomass, and shell size suggesting a stress-intensity-dependent effect on energetics. Moreover, stress-acclimated clams had lower antioxidant capacity compared to clams under initial ambient conditions, supporting the hypothesis that stress over ...