EG was funded by the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). MASTS was funded by the Scottish Funding Council (Grant reference HR09011) and contributing institutions. EG is currently funded by the Hellenic Foundation for Research and Innovation (HFRI) (grant number 1874) and the General Secretariat for Research and Technology (GSRT). This study was funded by the MASTS Marine Biogeochemistry Forum small grants scheme and their support is gratefully acknowledged.