Biogeochemistry, macronutrient and carbon cycling in the benthic layer of coastal and shelf-seas

Gary Fones (Portsmouth), Gennadi Lessin (PML), Steve Widdicombe (PML), Martin Solan (Southampton) 

Coastal and shelf sediments constitute <9% of the global seafloor, but are responsible for the majority of global benthic biogeochemical cycling of organic matter. Despite their functional importance, however, it remains unclear whether extensive regions of coastal and shelf sea habitat act as a net source or a net sink for nutrients and carbon. Further, the processes that lead to changes in the internal pool of dissolved and particulate nutrients are not fully understood. 

 Understanding complex interactions which underpin chemical transformations and fluxes within sediments will require a far more integrated assessment of biological, chemical and physical fluxes. For example, the activities of sediment dwelling organisms (redistribution of particles and fluids, excretion and respiration) are known to alter the distribution of key elements, provide microhabitats for microbial communities (bacteria, archaea and microphytobenthos) involved with major nutrient transformation pathways and, ultimately modify rates of benthic-pelagic coupling (via nutrient transformations, carbon burial and elemental fluxes across the sediment-water interface). 

This session aims to bring together an interdisciplinary community of scientists investigating the processes controlling benthic biogeochemical cycling in coastal and shelf environments. We encourage submissions that advance theoretical understanding or that enhance the mechanistic understanding of benthic biogeochemical processes, including sediment-water exchange processes and fluxes, impact of sediment permeability, lability of benthic organic matter, bioturbation and bioirrigation, from field, laboratory, or modelling studies. We also encourage submissions that consider the importance of extreme and episodic events, particularly in relation to erodability, sediment resuspension and ecosystem recovery. The session also aims to provide a forum for newly developed data collection techniques and a networking opportunity to promote future collaborative initiatives.