Modelling the effects of benthic fauna on carbon, nitrogen and phosphorus dynamics in the Baltic Sea
<p>Even though the effects of benthic fauna on aquatic biogeochemistry have been long recognized, few studies have addressed the combined effects of animal bioturbation and metabolism on ecosystem–level carbon and nutrient dynamics. Here we merge a model of benthic fauna (BMM) into a physical–...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-07-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/19/3337/2022/bg-19-3337-2022.pdf |
| Summary: | <p>Even though the effects of benthic fauna on aquatic
biogeochemistry have been long recognized, few studies have addressed the
combined effects of animal bioturbation and metabolism on ecosystem–level
carbon and nutrient dynamics. Here we merge a model of benthic fauna (BMM)
into a physical–biogeochemical ecosystem model (BALTSEM) to study the
long-term and large-scale effects of benthic fauna on nutrient and carbon
cycling in the Baltic Sea. We include both the direct effects of faunal
growth and metabolism and the indirect effects of its bioturbating
activities on biogeochemical fluxes of and transformations between organic
and inorganic forms of carbon (C), nitrogen (N), phosphorus (P) and oxygen
(O). Analyses of simulation results from the Baltic Proper and Gulf of Riga
indicate that benthic fauna makes up a small portion of seafloor active
organic stocks (on average 1 %–4 % in 2000–2020) but contributes
considerably to benthic–pelagic fluxes of inorganic C (23 %–31 %), N
(42 %–51 %) and P (25 %–34 %) through its metabolism. Results also
suggest that the relative contribution of fauna to the mineralization of
sediment organic matter increases with increasing nutrient loads. Further,
through enhanced sediment oxygenation, bioturbation decreases benthic
denitrification and increases P retention, the latter having far-reaching
consequences throughout the ecosystem. Reduced benthic–pelagic P fluxes
lead to a reduction in N fixation and primary production, lower organic
matter sedimentation fluxes, and thereby generally lower benthic stocks and
fluxes of C, N and P. This chain of effects through the ecosystem overrides
the local effects of faunal respiration, excretion and bioturbation. Due to
large uncertainties related to the parameterization of benthic processes, we
consider this modelling study a first step towards disentangling the complex
ecosystem-scale effects of benthic fauna on biogeochemical cycling.</p> |
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| ISSN: | 1726-4170 1726-4189 |