Acclimation and phenotypic plasticity of echinoderm larvae in a changing ocean

• Main Author: Suarez-Bosche, Nadia Elisa
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: Pacific; Ocean acidification
• Online Access: https://eprints.soton.ac.uk/336450/; https://eprints.soton.ac.uk/336450/1/Suarez-Bosche_PhD_2011.pdf

Echinoderms are keystone organisms that have representatives in virtually every marine ecosystem. They possess a number of features that makes them an excellent model system, namely 1) their susceptibility to changes in the chemistry of seawater and temperature 2) their ossified skeletons are major contributors to many carbonate formations 3) their variety of life history strategies that enable successful reproduction (e.g. asexual reproduction, fission, cloning and regeneration). In most parts of the ocean, CO2 and temperature co-vary, making it difficult to extrapolate isolated effects of any one variable to natural scenarios. Laboratory and field work was conducted to assess the physiological and biogeochemical response of sea urchin Psammechinus miliaris larvae to changes in water carbonate chemistry. This study used two approaches: 1) the incubation of the larvae with naturally CO2-enriched deep-seawater, and 2) the study of the effect of ocean acidification and ocean warming. It is reported that there was no effect of in situ naturally high CO2 seawater, or laboratory induced CO2 concentrations, on larval physiology or morphology. However, elevated CO2 was found to cause a decrease in fertilization and calcification. An increase in temperature appeared to counteract significantly the negative effect that high CO2 has on fertilization and biocalcification. Therefore, it is argued that the developmental stages of sea urchins may adapt to predicted ocean acidification and increasing temperature scenarios, which is advantageous to maintaining stability and survival of populations under environmental selection pressure. Furthermore, the regeneration capability of the Pacific seastar larvae Pisaster ochraceus and Orthasterias koehleri was investigated. The successful complete re-growth of the larvae can be considered a specific developmental strategy that facilitates the species’ survival. This research suggests that echinoderm larvae are resilient to conditions in a changing ocean, due to their high acclimation ...