BG-PART project: how do interactions between plankton and suspended particulate matter affect the habitability of Belgian coastal waters? | Marine@Ugent

BG-PART project: how do interactions between plankton and suspended particulate matter affect the habitability of Belgian coastal waters?

Suspended Particulate Matter (SPM) is a key determinant of biological processes, ecosystem functioning and biogeochemical fluxes in coastal ecosystems. While SPM dynamics is strongly controlled by hydrodynamic processes (currents, tides, weather) and the physical and chemical properties of the particles, it is becoming increasingly clear that biological activity as well affects the size and settling of particle aggregates. The release of exopolymeric substances (EPS) by phytoplankton and the formation of sticky marine gels can stimulate the formation of flocs, while bacterial mineralisation and zooplankton grazing can break down the flocs. To date, however, the impact of biological processes on SPM dynamics in coastal ecosystems is insufficiently understood: while biology is affected by the variation in SPM concentration and composition, biological processes themselves can in turn impact SPM dynamics. This would result in complex feedback loops affecting the functioning, services and habitability of the whole coastal ecosystem.

In the BG-PART project, we aim to address major unresolved questions related to such interactions between biology and SPM dynamics in the Belgian coastal waters.

We will investigate (1) how the cohesiveness of the mineral fraction and the composition (refractory vs fresh) of the organic matter fraction of the SPM affect seasonal flocculation dynamics and SPM settlement; (2) which phytoplankton species produce sticky marine gels and under which conditions; (3) how feedback loops between phytoplankton and suspended particles drive the seasonal dynamics of both SPM and the phytoplankton bloom. It is hypothesized that marine gels will enhance flocculation and settlement of suspended particles, which will lower turbidity and pave the way for phytoplankton species with higher light requirements; (4) how bacterial mineralisation and zooplankton grazing affect floc and particle degradation and their dynamics.

The above questions will be addressed in both on- and offshore environments, as we expect that differences in light, nutrients and SPM composition between these environments will result in marked differences in primary production, marine gel production and flocculation, and how these processes interact.

Both sampling campaigns and experimental approaches will be used to elucidate the interactions between SPM and biology. The data will then feed into a suite of increasingly integrated numerical models, starting from a marine gel production model and a flocculation model, and ending with a biogeochemical box model to describe and predict marine gel, phytoplankton and SPM dynamics in a simulated environment reproducing the conditions of the Belgian coastal/offshore waters.

Like other shallow coastal systems worldwide, Belgian coastal waters are increasingly exposed to the multiple effects of human activities, ranging from climate change, (de)eutrophication, and acidification, to changes in marine food webs (e.g. through fisheries or the introduction of invasive species). Our project will yield a more thorough understanding of how plankton and SPM dynamics interact, which will be essential to predict the future habitability of our coastal waters and to implement future mitigation and adaptation measures.


BG-PART is coordinated by the Royal Belgian Institute of Natural Sciences (RBINS), Operational Directorate ‘Natural Environment’ (OD Nature), with Ghent University (UGent, Protistology & Aquatic Ecology Lab) and the Flanders Marine Institute (VLIZ) as partners.

Contact persons: Xavier Desmit (RBINS,, UGent contact person and author of the article: Koen Sabbe (