92. Ocean Acidification and Increased Temperature have both Positive and Negative Effects on Early Ontogeny Traits of a Rocky Shore Keystone Predator Species

Manriquez PH (1)*, Torres R (2), Jara ME (1), Seguel ME (1), Alarcon E (2), Lee MR (3)

1 Laboratorio de Ecología y Conducta de la Ontogenia Temprana (LECOT), Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Avenida Ossandón 877, Coquimbo, Chile
2 Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique, Chile
3 Centro i~mar, Universidad de Los Lagos, Camino a Chinquihue km. 6, Puerto Montt, Chile.

Background
Juveniles of marine invertebrates with complex life histories are the most vulnerable stage in the benthic phase. The gastropod Concholepas concholepas is a rocky shore keystone predator characteristic of the south-eastern Pacific coast of South America and an important natural resource exploited by small-scale artisanal fishermen along the coast of Chile and Peru. In this study, we used small juveniles of C. concholepas collected from the rocky intertidal of southern Chile (39°S) to evaluate under laboratory conditions the potential consequences of projected near-future levels of ocean acidification and warming for important early ontogenetic traits.

Methods
The individuals were exposed long-term (5.8 months) to contrasting pCO2 (500 and 1400 μatm) and temperature (15, 19 °C) levels. After this period we compared body growth traits, dislodgement resistance, self-righting and metabolic rates.

Findings
None of these traits were significantly affected by the interaction between pCO2 and temperature. Shell growth was negatively affected by high pCO2 levels only at 15 °C. High pCO2 levels also had a negative effect on the predator-escape response. However, dislodgement resistance and self-righting were positively affected by high pCO2 levels at both temperatures. High tenacity and fast self-righting would reduce predation risk in nature and might compensate for the negative effects of high pCO2 levels on other important defensive traits such as shell size and escape behaviour.

Conclusions
We conclude that the implications of climate change projections for C. concholepas in the Chile-Peru Humboldt current system might be less severe than expected.