Koji Tominaga

• Pilla, Rachel M.; Mette, Elizabeth M.; Williamson, Craig E.; Adamovich, Boris V.; Adrian, Rita & Anneville, Orlane [Show all 86 contributors for this article] (2021). Global data set of long-term summertime vertical temperature profiles in 153 lakes. Scientific Data. ISSN 2052-4463. 8, p. 1–12. doi: 10.1038/s41597-021-00983-y. Full text in Research Archive
• Hessen, Dag Olav; Andersen, Tom; Tominaga, Koji & Finstad, Anders Gravbrøt (2017). When soft waters becomes softer; drivers of critically low levels of Ca in Norwegian lakes. Limnology and Oceanography. ISSN 0024-3590. 62(1), p. 289–298. doi: 10.1002/lno.10394. Full text in Research Archive
• Barton, David N; Andersen, Tom; Bergland, Olvar; Engebretsen, Alexander; Moe, S. Jannicke & Orderud, Geir I [Show all 9 contributors for this article] (2016). Eutropia: Integrated Valuation of Lake Eutrophication Abatement Decisions Using a Bayesian Belief Network. In Neal, Zachary P. (Eds.), The Routledge Handbook of Applied System Science. Routledge. ISSN 978-0415843324. p. 297–320. Full text in Research Archive Show summary

  The term “integrated valuation” is defined and its relevance is discussed in terms of bridging the gap between cost-effectiveness analysis and economic valuation in the implementation of the European Union Water Framework Directive. We demonstrate how to integrate benefit valuation with the ecosystem services cascade framework using an Object-Oriented Bayesian Network (OOBN). The OOBN is then used to assess the benefits of nutrient abatement measures across a cascade of submodels of the driver-pressure-state-impact-response (DPSIR) chain for the Vanemfjord lake in Morsa catchment in south-eastern Norway. The lake is part of a complex lake system in a semi-urbanized catchment dominated by forest and agriculture. The catchment has highly variable seasonal climatic conditions affecting nutrient run-off and algal blooms. It has been one of the most eutrophic lakes in Norway with periodic cyanobacteria blooms, but continues to attract a large recreational user population, despite the large variations in water quality. The “DPSIR-OOBN” model is used as a case study of “integrated valuation” and evaluated for its applicability for decision support in nutrient abatement. We find that the DPSIR-OOBN model meets seven of the nine criteria we propose for “integrated valuation”. The model struggles to meet the criteria that ecological, social and economic values should be defined consistently in relation to impacts on lake quality. While the DPSIR-OOBN integrates from valuation methods across an ecosystem cascade to management alternatives, it is neither a full benefit-cost analysis, nor a multi-criteria analysis. However, we demonstrate how the DPSIR-OOBN can be used to explore issues of consistency in scaling and weighting of different ecological, social and economic values in the catchment system. Bayesian belief networks offer a consistent approach to analysing how management implementation probability may determine economic valuation. We discuss the implication of our integrated valuation not being able to account for farmer responses, in particular the incentive effects of the model not being able to predict abatement effectiveness and value. The resolution of the nutrient monitoring data and modeling technologies that were at our disposal are probably better in the Morsa catchment than for any other catchment of this size in Norway. We therefore conclude that using our integrated valuation model for assessing benefits of eutrophication abatement measures as part of the EU Water Framework Directive still lies in the realm of utopia – euphemistically speaking a “eutropia”.

• Finstad, Anders Gravbrøt; Andersen, Tom; Larsen, Søren; Tominaga, Koji; Blumentrath, Stefan & de Wit, Heleen A. [Show all 8 contributors for this article] (2016). From greening to browning: Catchment vegetation development and reduced S-deposition promote organic carbon load on decadal time scales in Nordic lakes. Scientific Reports. ISSN 2045-2322. 6. doi: 10.1038/srep31944. Full text in Research Archive Show summary

  Increased concentrations of dissolved organic carbon (DOC), often labelled “browning”, is a current trend in northern, particularly boreal, freshwaters. The browning has been attributed to the recent reduction in sulphate (S) deposition during the last 2 to 3 decades. Over the last century, climate and land use change have also caused an increasing trend in vegetation cover (“greening”), and this terrestrially fixed carbon represents another potential source for export of organic carbon to lakes and rivers. The impact of this greening on the observed browning of lakes and rivers on decadal time scales remains poorly investigated, however. Here, we explore time-series both on water chemistry and catchment vegetation cover (using NDVI as proxy) from 70 Norwegian lakes and catchments over a 30-year period. We show that the increase in terrestrial vegetation as well as temperature and runoff significantly adds to the reduced SO4-deposition as a driver of freshwater DOC concentration. Over extended periods (centuries), climate mediated changes in vegetation cover may cause major browning of northern surface waters, with severe impact on ecosystem productivity and functioning.

• Couture, Raoul-Marie; de Wit, Heleen; Tominaga, Koji; Kiuru, Petri & Markelov, Igor (2015). Oxygen dynamics in a boreal lake responds to long-term changes in climate, ice phenology, and DOC inputs. Journal of Geophysical Research (JGR): Biogeosciences. ISSN 2169-8953. 120(11), p. 2441–2456. doi: 10.1002/2015JG003065. Full text in Research Archive
• Yang, Hong; Andersen, Tom; Dörsch, Peter; Tominaga, Koji; Thrane, Jan-Erik & Hessen, Dag Olav (2015). Greenhouse gas metabolism in Nordic boreal lakes. Biogeochemistry. ISSN 0168-2563. 126(1-2), p. 211–225. doi: 10.1007/s10533-015-0154-8. Full text in Research Archive Show summary

  Boreal lakes are important net sources of greenhouse gases (GHGs). In this study we analyzed concentrations of CO2, CH4, N2O as well as O2, N2 and argon (Ar) from the epilimnion of 75 boreal lakes covering gradients in total organic carbon (TOC), phosphorus (P) and nitrogen (N) deposition. The Ar-corrected gas saturation deficit was used as a proxy of net metabolic changes from spring overturn to mid-summer sampling (all lakes were dimictic). Emission fluxes were calculated for CO2, CH4 and N2O based on partial pressure, water temperature and wind speed. Gas concentrations, actual and Ar-corrected, were related to lake specific properties. TOC was the main predictor of CO2 concentrations and fluxes, followed by total P, while total P and chlorophyll a governed CH4 concentrations and fluxes. Nitrogen (NO3 - or total N) were key predictors of N2O concentrations and fluxes, followed by total P. Altitude, area and depth were not strong predictors of CO2, CH4 and N2O concentrations and fluxes, likely because only lakes with an area of [1 km2 were included. CO2 molar concentrations were negatively correlated with O2 concentrations, while the slope of CO2 concentration to Ar corrected O2 deficit was 1.039. Together with the poor correlation between area-specific primary production and CO2 as well as O2, this suggests that these gases are mostly affected by catabolic processes and probably photo-oxidation in these nutrient-poor, boreal lakes investigated in this study. Increasing inputs of TOC (i.e. lake ‘‘browning’’) is likely to promote the net heterotrophy and hence emissions of all GHGs, while elevated N deposition in particular may cause elevated emissions of N2O.

• Romarheim, Aleksandra Tmic; Tominaga, Koji; Riise, Gunnhild & Andersen, Tom (2015). The importance of year-to-year variation in meteorological and runoff forcing for water quality of a temperate, dimictic lake. Hydrology and Earth System Sciences (HESS). ISSN 1027-5606. 19(6), p. 2649–2662. doi: 10.5194/hess-19-2649-2015. Full text in Research Archive
• Romarheim, Aleksandra Tmic; Tominaga, Koji; Riise, Gunnhild & Andersen, Tom (2014). Natural stochasticity vs. management effort: use of year-to year variance for disentangling significance of two mutually confounding factors affecting water quality of a Norwegian cold dimictic lake. Hydrology and Earth System Sciences Discussions (HESSD). ISSN 1812-2116. 11, p. 12489–12518. doi: 10.5194/hessd-11-12489-2014. Full text in Research Archive
• Couture, Raoul-Marie; Tominaga, Koji; Starrfelt, Jostein; Moe, S. Jannicke; Kaste, Øyvind & Wright, Richard Frederic (2014). Modelling phosphorus loading and algal blooms in a Nordic agricultural catchment-lake system under changing land-use and climate. Environmental Science: Processes & Impacts. ISSN 2050-7887. 16(7), p. 1588–1599. doi: 10.1039/c3em00630a. Full text in Research Archive Show summary

  A model network comprising climate models, a hydrological model, a catchment-scale model for phosphorus biogeochemistry, and a lake thermodynamics and plankton dynamics model was used to simulate phosphorus loadings, total phosphorus and chlorophyll concentrations in Lake Vansjø, Southern Norway. The model network was automatically calibrated against time series of hydrological, chemical and biological observations in the inflowing river and in the lake itself using a Markov Chain Monte-Carlo (MCMC) algorithm. Climate projections from three global climate models (GCM: HadRM3, ECHAM5r3 and BCM) were used. The GCM model HadRM3 predicted the highest increase in temperature and precipitation and yielded the highest increase in total phosphorus and chlorophyll concentrations in the lake basin over the scenario period of 2031–2060. Despite the significant impact of climate change on these aspects of water quality, it is minimal when compared to the much larger effect of changes in land-use. The results suggest that implementing realistic abatement measures will remain a viable approach to improving water quality in the context of climate change.

• Trolle, Dennis; Hamilton, David P.; Hipsey, Matthew R.; Bolding, Karsten; Bruggeman, Jorn & Mooij, Wolf M. [Show all 24 contributors for this article] (2012). A community-based framework for aquatic ecosystem models. Hydrobiologia. ISSN 0018-8158. 683(1), p. 25–34. doi: 10.1007/s10750-011-0957-0.
• Mooij, Wolf M.; Trolle, Dennis; Jeppesen, Erik; Arhonditsis, George; Belolipetsky, Pavel V. & Chitamwebwa, Deonatus B. R. [Show all 31 contributors for this article] (2010). Challenges and opportunities for integrating lake ecosystem modelling approaches. Aquatic Ecology. ISSN 1386-2588. 44(3), p. 633–667. doi: 10.1007/s10452-010-9339-3.

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• Barton, David Nicholas; Andersen, Tom; Bergland, Olvar; Engebretsen, Alexander Melvold; Moe, S. Jannicke & Orderud, Geir [Show all 9 contributors for this article] (2016). Eutropia: Integrated Valuation of Lake Eutrophication Abatement Decisions Using a Bayesian Belief Network. In Neal, Zachary P. (Eds.), Handbook of Applied System Science. Routledge. ISSN 978-0-415-84332-4. doi: 10.4324/9781315748771.ch14.
• Su, Ming; Tominaga, Koji & Andersen, Tom (2015). Yuqiao modelling.
• Couture, Raoul-Marie; de Wit, Heleen; Tominaga, Koji; Kiuru, Petri & Markelov, Igor (2015). Modelling the impact of increasing dissolved organic carbon load on seasonal anoxia in a boreal humic lake. Show summary

  Boreal lakes are impacted by climate change, reduced acid deposition and changing loads of dissolved organic carbon (DOC) from the catchment. We set to explore how these changes, in particular the increasing DOC load, modulate ice phenology and dissolved oxygen (DO) of a boreal humic lake located in southeastern Norway. Observed trends in daily air temperature (+0.045 oC yr-1) and weekly DOC concentration (0.1 mg C yr-1, +1% annually) measured over the past 40 years at the study site were used as forcings for the lake model MyLake. The model was parametrized against year-round time-series of water temperature and DO from a high-frequency lake buoy. A backcast of ice freezing and break-up dates to 1974 reveals that ice break-up occurs on average 8 days earlier in 2014 than in 1974. An earlier ice break-up enhances water column ventilation, resulting in higher DO in the spring. Later in the season, warmer water in late summer lead to longer anoxic periods, as microbial DOC turnover increases. Long-term increase in DOC concentrations causes decline in lake DO, leading to 15% more hypoxic days (< 3 mg L-1) and 10% more anoxic days (< 15 ug L-1) in 2014 than in 1974. We conclude that climate warming and increasing DOC loads are antagonistic with respect to their effect on DO availability. The model suggests that DOC is a stronger driver of DO consumption than temperature. DOC increase thus has the potential to reduce the oxythermal habitat of fish and aquatic biota in boreal lakes.

• Vogt, Rolf David; An, Wei; Andersen, Tom; Bin, Zhou; Deng, Xiaowen & Jiahua, Pan [Show all 21 contributors for this article] (2015). SinoTropia - Watershed Eutropication management in China through system oriented process modelling of pressures, impacts and abatement measures.
• Tominaga, Koji (2013). Warming and eutrophication: Similarities and discrepancies in their impact on lake ecosystems.
• Tominaga, Koji (2013). Lake modelling - an interdisciplinary context.
• Tominaga, Koji (2013). How to make friends with environmental models: three points of views.
• Engebretsen, Alexander Melvold; Tominaga, Koji & Barton, David Nicholas (2012). Modellering av næringsstofftransport i Morsa vassdraget - Kobling av modellers usikkerhet og bruk av Bayesianske nettverk.
• Tominaga, Koji; Finstad, Anders Gravbrøt; Kaste, Øyvind & Andersen, Tom (2012). From changes in climate to changes in lake thermal status.
• Tominaga, Koji; Finstad, Anders Gravbrøt; Kaste, Øyvind & Andersen, Tom (2012). Future climate impact on lakes in Fennoscandia: A dynamic mechanistic modelling approach.
• Tominaga, Koji (2012). MyLake Storefjorden and Vestre Vansjø.
• Tominaga, Koji (2012). Simulating limnological responces to various runoff scenarios using MyLake.
• Tominaga, Koji (2011). Why you should care about MyLake (or ecological models in general).
• Tominaga, Koji (2010). Ensemble model framework for lake ecosystem modelling - case study from acidification modelling. Show summary

  While the structural details may vary, there are many environmental models with the same functionality. The lake ecosystem modelling community is no exception; for example, many models are able to simulate policy relevant variables such as lake nutrient concentrations. Despite this parallel situation, only one model is often chosen and applied to a given modelling problem. This may pose serious policy or management implications, if lake ecosystem models aspire to change their role as a ‘research tool’ to a ‘policy tool’. In this presentation, experiences in incorporating multiple acidification ecosystem models for a single catchment are illustrated. Benefits and challenges for such a study are discussed, with an emphasis of relevance to lake ecosystem modelling.

• Tominaga, Koji (2009). EUTROPIA – Modelling eutrophication in Lake Vansjø.
• Tominaga, Koji (2009). EUTROPIA – modelling eutrophication in Lake Vansjø.
• Tominaga, Koji; Andersen, Tom; Vogt, Rolf David & Saloranta, Tuomo (2013). Lake modelling - an interdisciplinary context. Faculty of Mathematics and Natural Sciences, University of Oslo. ISSN 1501-7710.

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