NECCTON Report on integrated model developments for Suspended Particulate Matter (SPM) and habitat suitability (D6.2).

The NECCTON D6.2 report describes the additions and improvements made to the suite of marine biogeochemical models used in NECCTON, in connexion to the modelling of the benthic system and, in particular, suspended particulate matter (SPM), benthic flora, and benthic fauna habitat suitability. This deliverable documents the codes that have been developed in WP6 and are available on Github.

The current biogeochemical models, and particularly those used in the Copernicus marine service, oversimplify modelling of the benthic compartment. In particular, they mostly ignore the effect of benthic life variability on benthic pelagic coupling, while SPM modelling mainly focuses on the organic component of SPM and usually oversimplifies the deposition/erosion processes.

Here, we describe new formulations and parameterizations of SPM. These additions include refined parameterisations of sinking, flocculation, deposition and resuspension. Specifically, these new formulations include the effect of waves derived from wave products provided by CMS.

Current ocean numerical models also oversimplify or completely ignore the variability of seafloor life  and its impact on biogeochemical cycles and ecosystem functioning. Providing regional maps of the ecological processes delivered by the benthos (e.g. biomixing, biodeposition), may  the variability of the functions of macrobenthos may constrain diagenetic models. Moreover, we have developed correlative models based on machine learning algorithms (i.e. Species Distribution Models, SDMs) to reconstruct the ecological niche and the distribution of a total of 339 benthic fauna species and 2 seagrass species (Posidonia oceanica and Cymodocea nodosa).