The SONaR-CO2 project

The Marie Skłodowska-Curie funded project Southern Ocean Nanoplankton Response to CO₂ (SONaR-CO2) aims to shed light on the ongoing debate whether or not ocean acidification will lead to a replacement of heavily-calcified coccolithophores by lightly-calcified ones in subpolar ecosystems. SONaR-CO2 aims to answer the call by the European Project on OCean Acidification (EPOCA) and Southern Ocean Observing System (SOOS) for urgent and increased effort in research initiatives that address the impacts of ocean acidification on marine and coastal ecosystems and resources.

Project Description

Australian and New Zealand sediment trap programs were launched in the late ‘90s along two latitudinal transects (140°E and 178°E meridians). These collections represent the longest deep Southern Ocean time-series and provide an exceptional opportunity to examine the response of marine calcifying organisms to ocean acidification. Indeed, a previous comparison of the planktonic foraminifera communities captured by the Australian subantarctic traps with those from the underlying Holocene-aged sediments have revealed a shell weight reduction of 30-35%, consistent with reduced calcification today induced by ocean acidification.

In this project, cutting-edge and traditional microscopy techniques combined with biogeochemical analyses will be applied to the longest existing subantarctic time-series records and sediment samples from two sectors of the Southern Ocean in order to achieve the following objectives:

1. Detect changes in the calcification response of the dominant coccolithophore species Emiliania huxleyi in relation to changes in the CO2 concentration in the surface waters of the SAZ at different time scales.

2. Determine the diversity, abundance and temporal community changes of coccolithophores.

3. Estimate, for the first time, the partial contribution of coccolithophores to total carbonate export at different depths of the water column and in sediments of the Subantarctic Zone.

4. Explore the potential impacts of environmental stressors on the biomarker signature of coccolithophores.