Effects of global warming and ocean acidification on fertilisation, larvae development and settlement of the sea urchins in the canary islands

Resumen

This thesis is set within the framework of the Spanish scientific funding programme `Plan Nacional de I+D+I¿, specifically within the project entitled `Influence of phitocenosis at littoral rocky habitats on pH variability and its implications for calcifying invertebrate populations in a climate change scenario (ACIDROCK- CTM 2010-21724)¿. This project aims to evaluate the impact of several phitocenosis at coastal habitats on the natural variability of seawater pH, assessing the implications of these pH regimes and the ones foreseeable due climate change for the larval development, settlement, survival and growth of key calcifying invertebrates. Facing this scenario, this study tries to assess the impact of climate change processes on early development of key calcifying sea urchin species on the Canary Islands coastal ecosystems. To reach this general aim, this thesis has been structured in seven chapters. Five of them correspond to original research manuscripts according to the specific objetives that we stablished: 1) Evaluate how fertilization success, cleavage rate and early pluteus survival and development, in the main species of sea urchins from the Canary Islands, are affected by climate change processes (ocean warming and acidification). 2) Assess the combined effects of global warming and food availability on survival, growth and development of the larvae of the sea urchin Paracentrotus lividus. 3) Test the impact of ocean acidification on larval survival, growth, development and postlarval settlement of Paracentrotus lividus. 4) Evaluate whether the interaction of climate change related environmental factors (temperature and pH) has the potencial to change the responses of Paracentrotus lividus larvae and postlarvae performance. 5) Compare larval development and settlement of Paracentrotus lividus between constant pH conditions and daily natural fluctuations to a better understanding and forecast of its performance in more realistic future scenarios.