Biogeochemistry, macronutrient and carbon cycling in the benthic layer

Using three dedicated research cruises and multiple supplemental research cruises in the Celtic, Irish and North seas, we will directly quantify the pools and exchanges of macronutrients and carbon across a range of sediment habitats using an extensive range of physical, biological, chemical, acoustic and optical techniques in order to generate a holistic understanding of the biogeochemistry of shelf sea systems. We will combine these observations with an extensive series of manipulative laboratory and field experiments aimed at linking multiple aspects of change (temperature, ocean acidification, tidal and storm induced resuspension, trawling intensity) with changes in naturally assembled communities associated with altered habitat condition (cohesive to non-cohesive sediments) and water column stratification (stratified vs mixed) and establish how these interact to affect the stocks and flows of carbon and macronutrients (N, P, Fe Si), in a representative natural shelf sea system. Our specific objectives are to:

1. quantify the short term stocks and flows of N, P, Si and C in both cohesive and non-cohesive sediments,
2. assess the potential role of shelf sea sediments in long term carbon storage,
3. evaluate the role of macrofaunal invertebrates in mediating sediment biogeochemistry,
4. determine the influence of natural & anthropogenic sediment disturbance on process rates, including the role of diffusive and pumped sediment water exchange and resuspension,

In so doing, we will develop model frameworks to predict carbon and macronutrient stocks and flows at regional scales and use these to generate new visualization tools for predicting biogeochemical condition across a range of environmental contexts. Collectively, these objectives will allow us to establish the generalities of how abiotic and biotic interactions, including feedbacks and linkages, will affect macronutrient and carbon exchange in shelf sea systems, including responses to anthropogenic drivers and climate change.