Ecological perspectives from an end-to-end representation of the Baltic Sea using Ecopath with Ecosim in Fortran (EwE-F) coupled to the Baltic Sea Long-Term Large Scale Eutrophication Model

Akoğlu E., Müller Karulis B., Tomczak M., Gustaffson B.

Ecopath 35 years – Making Ecosystem-Based Management Operational, Florida, United States Of America, 4 - 11 December 2019, pp.27

  • Publication Type: Conference Paper / Summary Text
  • City: Florida
  • Country: United States Of America
  • Page Numbers: pp.27
  • Middle East Technical University Affiliated: Yes


Ecosystem-based marine management can be considered to be most effective through establishing
end-to-end representations of marine ecosystems from physical processes to fish using ecosystem
models. Yet no single model includes sophisticated delineations of physical, biogeochemical and food
web processes altogether to form a realistic picture of marine environment. Therefore, coupling models of
different realms, i.e., physical, biogeochemical and trophodynamic, is required to set up holistic
ecosystem representations. When first released in 2015, the Fortran version of the widely-adopted food
web model Ecopath with Ecosim (EwE-F) opened up new possibilities to form such representations by
integrating oceanographic models of physics and biogeochemistry with the sophistication of EwE’s
trophodynamic modelling framework. In this work we form such a representation of the Baltic Sea
ecosystem using the Baltic Sea Long-Term Large Scale Eutrophication Model (BALTSEM) with an EwE-F
model of the Baltic Sea food web to delineate the interactions between food web dynamics and
biogeochemical processes to quantify the impacts of; i) higher-trophic-level (HTL) dynamics on the
biogeochemical processes, and ii) bottom-up propagation of the effects of biogeochemical processes in
the HTL food web. This is the first study that attempts to build a validated end-to-end representation of a
large marine ecosystem, i.e., Baltic Sea, by integrating EwE-F and a sophisticated biogeochemical model
in a two-way and online coupled framework. Results of the simulations showed that HTL processes
modified the production of primary producers through changes in nutrient cyclings that, in turn, impacted
planktivorous species in the food web model. This cascaded up to the planktivorous fish through
zooplankton and then to top predators in the food web. Consequently, in the coupled model monthly
average zooplankton standing stock was simulated to be lower than the standalone BALTSEM model
simulation. These results indicated that a more realistic representation of the ecosystem is possible by
integrating trophodynamic and biogeochemical models of the Baltic Sea.