Modelling the effects of benthic fauna on carbon, nitrogen and phosphorus dynamics in the Baltic Sea

Abstract. Even though the effects of benthic fauna on aquatic biogeochemistry have been long recognized, few studies addressed combined animal bioturbation and metabolism ecosystem–level carbon nutrient dynamics. Here we merge a model (BMM) into physical–biogeochemical ecosystem (BALTSEM) to study long-term large-scale cycling in Baltic Sea. We include both direct faunal growth indirect its bioturbating activities biogeochemical fluxes transformations between organic inorganic forms (C), nitrogen (N), phosphorus (P) oxygen (O). Analyses simulation results from Proper Gulf Riga indicate that makes up small portion seafloor active stocks (on average 1 %–4 % 2000–2020) but contributes considerably benthic–pelagic C (23 %–31 %), N (42 %–51 %) P (25 %–34 through metabolism. Results also suggest relative contribution mineralization sediment matter increases with increasing loads. Further, enhanced oxygenation, decreases denitrification retention, latter having far-reaching consequences throughout ecosystem. Reduced lead reduction fixation primary production, lower sedimentation fluxes, thereby generally C, P. This chain overrides local respiration, excretion bioturbation. Due large uncertainties related parameterization processes, consider this modelling first step towards disentangling complex ecosystem-scale cycling.