Plastic responses of the larval slipper limpet Crepidula onyx to future climate conditions

• Main Author: Maboloc, Elizaldy Acebu
• Other Authors: Chow, King Lau, Chan, Kit Yu Karen
• Format: Thesis
• Language: English
• Published: 2020
• Subjects: Phenotypic plasticity; Limpets; Genetics; Larvae; Climatic factors; Ocean acidification
• Online Access: http://repository.ust.hk/ir/Record/1783.1-111109; https://doi.org/10.14711/thesis-991012936268803412; http://repository.ust.hk/ir/bitstream/1783.1-111109/1/th_redirect.html

Anthropogenic emission of carbon dioxide (CO 2 ) leads to ocean warming (OW) ocean acidification (OA). Despite the growing number of studies of their impacts, whether organisms can respond quickly to such changing conditions remains unclear. Phenotypic plasticity is one major mechanism through which organisms cope with environmental variations. Such plasticity can be passed on to subsequent generation through maternal provision and/or epigenetics. To test the overall hypothesis that pre-exposure to environmental stressors confers greater resilience to future climate conditions, three major studies were performed. Focusing on the non-indigenous slipper limpet Crepidula onyx, I investigated if stress response differed between populations. The introduced population in Hong Kong have larger eggs and shorter pelagic larval duration than the natives from California. Larvae from native population suffered increased mortality when starved but not the invasive ones, suggesting the possibility of local selection and/or genetic drift. When native adults are conditioned to warmer Hong Kong water temperature, their offspring had slower growth rates, highlighting tradeoff between maintenance and reproduction under stress. I then focus on behavioral plasticity of C. onyx to direct and indirect, trophic mediated effects of OA. While the nutritional quality of their algal food decreased in OA, the exposed larvae were able to cope with these stresses by increasing clearance rates and settling earlier to escape the stressful conditions in the water column. Such plasticity in behaviors was also observed in larval sand dollars, Dendraster excentricus, which swim to avoid low pH water strata. Finally, I tested if long-term exposure within and across generations enhances resilience. Individuals reared under OA from hatching through sexual maturity had higher mortality and reduced fecundity, but the size of their larvae were comparable to those in control condition. Transgenerational effect was observed with larvae from the pre-exposed adults experiencing reduced mortality and respiration rate when exposed to the same stress level. Overall, C. onyx is resilient and demonstrated high plasticity to cope with climate change stress. Such resilience could alter competition outcome with other species and reshape the coastal community structure.