Potential for adaptation to ocean acidification along an upwelling system: Lessons of the southernmost South American sea urchin Loxechinus albus

Chair: Peter Thor

Juan Diego Gaitan-Espitia(1), Leonardo Bacigalupe(2)

1 Oceans & Atmosphere, CSIRO, Hobart, TAS, 7000, Australia
2 Univesidad Austral de Chile, Valdivia, 5090000, Chile

Background
Over the next century, global fisheries will face the combined threats of harvest pressure and climate change. All of these factors will affect the abundance, reproduction and growth rate of many commercially important taxa. In mid-latitude ecosystems, coastal habitats exhibit both daily and seasonal variation in temperature and pH, due to the effects of wind-driven upwellings and daily cycles of biological processes. Spatial and temporal variations of these physico-chemical factors are important in the context of global change because: i) these variations may exceed the thresholds for tolerance of some species in some populations; and ii) their historical trends may have influenced local adaptation to low pH and high thermal variability in some populations. This means that we cannot generalize results from a single population, but also that some populations might warrant a higher priority for conservation, as a source of individuals with greater tolerance of future conditions

Methods
In this work we explored the adaptive capacity to OA of one of the most economically important species of the southeast Pacific of South America, the sea urchin Loxechinus albus. Using a common garden experiment and a quantitative genetic approach we assessed the additive and maternal/non-additive genetic variation in a suite of morpho-physiological traits in populations from its latitudinal range (18-55°S), characterized by regional variation in the strength of upwellings.

Findings
Our results evidenced greater tolerances to OA in low latitude populations. However, these populations exhibited the lowest values of genetic variability of morpho-physiological traits probably as a result of directional selection towards greater tolerances in areas with stronger upwellings.

Conclusions
Geographic variation on G-matrices suggests different paths in the evolution of trade-offs to OA along the natural distribution of L. albus with potential implications in local extinction events under future OA scenarios.