Ecopath and Ecosim as tools in foodweb understanding - the Gulf of Gdansk example.
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1
National Marine Fisheries Research Institute, Poland
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2
Baltic Sea Centre, Stockholm University, Sweden
The understanding foodweb dynamics in coastal areas and their response to various anthropogenic pressures, including climate change and different economic scenarios, allows us to foresee their future state and their ecosystem goods and services. Therefore, Ecopath and Ecosim models for the Gulf of Gdansk (Southern Baltic Sea) have been prepared and tested as a case study for coastal areas.
The Gulf of Gdansk is subjected to strong anthropogenic pressures. The Vistula River, the second largest river in the Baltic catchment, discharges more than 30 km3 year-1 of nutrient loaded freshwater into the gulf, contributing to its eutrophication. During the past decades, changes in the Polish economy and the implementation of various mitigation measures resulted in declining nutrient loads to the gulf, but despite these efforts the response of its coastal ecosystems seems to be relatively weak.
The Gulf of Gdansk fish assemblages are under constant, strong fishing pressure. Commercial fishing is diversified, targeting mainly sprat, herring and cod. In the coastal waters a small-boat fishery is focused on herring, flatfish, salmonids and freshwater species.
Based on biomass data of individual ecosystem components, knowledge of their trophic relationships, and group specific fishing pressure, a trophic ecosystem model of the Gulf of Gdansk was constructed for the period 2004-2006 using Ecopath software. It consists of 17 groups, including detritus. The pelagic part of the model consists of fish (cod, flounder, herring, sprat, other predatory fish, other non-predatory fish, and round goby), zoo- and phytoplankton. Benthos is represented by four groups (deposit feeders, predators, filtrators and meiofauna). The model was also completed by piscivorous and benthivorous birds. A "Fisheries" module, with fishing mortality specified for different gear types, describes fishing pressure.
Based on the Ecopath model, a dynamic Ecosim model was created that describes the time-development of all model groups for the period 2006-2016. Biomass time series extracted from monitoring data and environmental studies, as well as time-dependent fishing pressure derived from fisheries statistics, were used to calibrate and force the model. In addition, the model was forced by a set of environmental factors (e.g. temperature, nutrients, salinity, oxygen). Thus, apart from trophic dependencies and changes in fishing pressure, the variability of environmental factors shape the biomass development of the different groups in the model. Among the set of environmental factors represented in the model by forcing functions, the best model fit was when primary producers were forced with river nutrient loads, and selected consumer groups by water temperature and hypoxic bottom.
Environmental forcing time-series were generated by the BALTSEM model, a biogeochemical model of the Baltic Sea. BALTSEM can simulate changes in nutrient state, primary production, and oxygen conditions for different Baltic Sea nutrient load and climate scenario. Forcing the Ecosim model with the biogeochemical model output will allow us to predict ecosystem change in response to climate projections and nutrient load scenarios.
Acknowledgements
This work resulted from the BONUS BLUEWEBS project which has received funding from BONUS (Art 185), funded jointly by the EU, the Academy of Finland, Projektträger Jülich (PtJ), Germany, the State Education Development Agency of Latvia, the National Centre for Research and Development, Poland, and the Swedish Research Council Formas.
Keywords:
food web,
modelling,
Gulf of Gdansk,
Ecopath,
Ecosim,
Climate Change
Conference:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.
Presentation Type:
Poster Presentation
Topic:
Oceanography, Modelling and Dynamics of Ecosystems
Citation:
Calkiewicz
J,
Drgas
A,
Smolinski
S,
Tomczak
MT,
Margonski
P,
Muller-Karulis
B and
Szymanek
L
(2019). Ecopath and Ecosim as tools in foodweb understanding - the Gulf of Gdansk example..
Front. Mar. Sci.
Conference Abstract:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) .
doi: 10.3389/conf.fmars.2019.08.00014
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Received:
29 Jul 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Dr. Joanna Calkiewicz, National Marine Fisheries Research Institute, Gdynia, Poland, jcalkiewicz@mir.gdynia.pl