The deep-sea is increasingly recognised as an important area for the extraction of mineral resources, including manganese nodules from nodule fields on the abyssal plains. Deep-sea mining activities will indisputably affect the status of the environment both directly by substrate (i.e. nodule) removal and seafloor disturbance and indirectly by re-settling of re-suspended particles away from the mining site that will smother the sediment and benthic fauna.
It is however extremely challenging to quantify, let alone predict, the impacts of these disturbances on the abyssal benthic food web. With this proposal, we plan to take part in cruise SO242-II to revisit the DISCOL area; a Pacific nodule field that has been subjected to a severe, experimental mining-related disturbance 25 years ago. During this cruise, we will perform state-of-the-art in situ experiments to provide data for advanced food-web modeling which, for the first time, will allow quantifying differences in food web structure and functioning of abyssal plain food webs following a large-scale disturbance. In situ pulse-chase experiments using 13C/15N labeled algae will be conducted to quantify the C and N fluxes in the benthic food web at various levels of seafloor disturbance. These experimental data will feed linear inverse food-web models that will allow quantifying mining impacts on the benthic food web. The results will form an important contribution to the output of the JPIO Pilot Action ?Ecological aspects of deep-sea mining? and will be used to provide urgently needed prognostic analyses of mining impacts on the deep sea.