Program

Marine coastal ecosystems provide food and livelihoods for millions of people. However, global stressors, such as Ocean Acidification (OA) constitute a rapidly emerging and significant problem for marine organisms, ecosystem functioning, and services. The coastal ecosystems of the Humboldt Current System (HCS) off Chile harbour a broad physical-chemical latitudinal and temporal gradient with considerable patchiness in local oceanographic conditions. This heterogeneity may, in turn, modulate the specific tolerances of organisms to climate stress in species with populations distributed along this environmental gradient. A meta-analysis of studies carried out along the HCS has revealed adaptive intraspecific variability in the response of individuals to pCO2 changes among local populations. In general, negative response ratios are observed in species models exposed to pCO2 changes far from the average and extreme pCO2 levels experienced in their native habitats. This response leads to inter-population variability that reveals the potential role of local adaptation and/or adaptive phenotypic plasticity in increasing resilience of species to environmental change. The growing use of standard OA scenarios and treatment levels in experimental protocols brings with it a danger that inter-population differences are confounded by the varying environmental conditions naturally experienced by different populations. Here, we propose the use of simple indexes taking into account the natural variability in environmental pCO2, for a more realistic interpretation of the potential consequences of OA on species inhabiting variable coastal ecosystems. Consequently, to ensure a more realistic evaluation of the potential consequences of OA on species inhabiting these particular coastal ecosystems, a step change in how the OA experiments are designed is required. Using scenarios taking into account the natural variability will allow understanding the limits to plasticity across traits, populations, and species.