Dr. Hermann Lenhart is employed as a senior scientist in the team of the AquaEcology consulting company (www.aquaecology.de) with strong ties to the reseach group scientific computing of the Univesität Hamburg. At present his focus lies on coordination of model studies in the context of the OSPAR and WFD assessment framework. Since 2009 he is chair of the OSPAR Intersessional Correspondence Group on Eutrophication Modelling (ICG-EMO). In 2022 he coordinated a model study with 7 European marine ecosystem models to provide extimates for pre-eutrophic reference condition. In close dialogue with the OSPAR eutropication committee (ICG-EUT) these were used to derive eutrophication target values for key eutrophication parameter under the COMP4 assessment (see 2019 workshop). Within the nationally funded project ModOSPro he is coordinating a new ICG-EMO model study to estimate „maximum allowable nutrient input“ for OSPAR member states (see 2022 workshop).

Besides his basic studies in physical oceanography, Hermann Lenhart was always interested in the connection of hydrodynamics and marine ecology. He was part of the first European-based model development within the ERSEM team. With focus on the practical application of models, his PhD thesis dealt with the analysis of a scenario related to the river load reduction of dissolved inorganic phosphorus (DIP) and nitrogen (DIN) by 50%, as proposed by OSPAR. In the EU-funded project EUROCAT, he further developed these reduction scenarios by combining estimates of real measures of nutrient reduction from a catchment model with a North Sea ecosystem model.

In a number of nationally funded projects, he applied ecosystem modelling in the context of the Marine Strategy Framework Directive (MSFD) and the definition and implementation of its Descriptor 5 “Eutrophication”, as part of the contribution of the German Environment Agency (Umweltbundesamt; UBA) to OSPAR. He joined the OSPAR Intersessional Correspondence Group on Eutrophication Modelling (ICG-EMO) in 2005 and acts as its chair since 2009. The latest work included the first reduction scenario for the North Sea compliant with the Water Framework Directive (WFD) and including a Trans-Boundary Nutrient Transport (TBNT) analysis, which quantifies the changes in the individual national contributions to total nitrogen (TN) in the German Exclusive Economic Zone in relation to the OSPAR Common Procedure.

Hermann Lenhart further supervised the UBA-funded PhD project of Fabian Große, which focused on the oxygen dynamics of the North Sea . It included the analysis of regions susceptible to the occurrence of oxygen deficiency and the interpretation of oxygen time series measurements by means of mass balance calculations using an ecosystem model. This work resulted in the development of a software tool, which offers an extension of the classical TBNT approach towards the source-specific analysis of oxygen deficiency.

• Understanding the process of degradation of marine ecosystems by nutrient enrichment, its assessment and its “recreational potential” via ecosystem models.
• Scenario simulation to analyse the effect of proposed measures under WFD or MSFD to combat eutrophication.
• Support the interpretation of in-situ measurements by process analysis of ecosystem model results.
• Analyse the impact of the wake effect from OWFs on the hydrodynamic structure of the water column and the consequences for the marine environment.

• Deriving pre-eutrophic conditions from an ensemble model approach for the North-West European Seas (Sonja van Leeuwen, Hermann Lenhart, Theo Prins, Anouk Blauw, Xavier Desmit, Liam Fernand, René Friedland, Onur Kerimoglu, Geneviève Lacroix, Annelotte van der Linden, Alain Lefebre, Johan van der Molen, Martin Plus, Itzel Ruvalcaba Baroni, Tiago Silva, Christoph Stegert, Tineke Troost, Lauriane Vilmin), In Frontiers in Marine Science, Series: 10, pp. 519, (Editors: Christophe Rabouille), Frontiers (Avenue du Tribunal Fédéral 34, CH-1005 Lausanne, Switzerland), 2023
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• ICG-EMO report on model comparison for historical scenarios as basis to derive new threshold values. (Hermann Lenhart, Anouk Blauw, Xavier Desmit, Liam Fernand, René Friedland, Birgit Heyden, Onur Kerimoglu, Geneviève Lacroix, Annelotte van der Linden, Johan van der Molen, Martin Plus, Theo Prins, Itzel Ruvalcaba Baroni, Tiago Silva, Christoph Stegert, Daniel Thewes, Tineke Troost, Lauriane Vilmin, Sonja van Leeuwen), Reports of OSPAR ICG-EMO Working group (Publication 895/2022), OSPAR Commission (London, United Kingdom), 2022
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• Evaluating Uncertainties in Reconstructing the Pre-eutrophic State of the North Sea (Christoph Stegert, Hermann Lenhart, Anouk Blauw, René Friedland, Wera Leujak, Onur Kerimoglu), In Frontiers in Marine Science, Series: Vol 8, pp. 1–17, ISSN: 2296-7745, 2021
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• Wadden Sea Eutrophication: Long-Term Trends and Regional Differences (Justus E. E. van Beusekom, Jacob Carstensen, Tobias Dolch, Annika Grage, Richard Hofmeister, Hermann Lenhart, Onur Kerimoglu, Kerstin Kolbe, Johannes Pätsch, Johannes Rick, Lena Rönn, Hans Ruiter), In Frontiers in Marine Science, Series: 6, pp. 370, (Editors: Christophe Rabouille), Frontiers (Avenue du Tribunal Fédéral 34, CH-1005 Lausanne, Switzerland), 2019
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• A model-based projection of historical state of a coastal ecosystem: relevance of phytoplankton stoichiometry. (Onur Kerimoglu, Fabian Große, Markus Kreus, Hermann Lenhart, Justus van Beusekom), In Sci. Total Environ., Series: 639, pp. 1311–1323, 2018
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• A model–based projection of historical state of a coastal ecosystem: Relevance of phytoplankton stoichiometry (Onur Kerimoglu, Fabian Große, Markus Kreus, Hermann Lenhart, Justes E.E. van Beusekom), In Science of the Total Environment, Series: 639, pp. 1311–1323, Elsevier Science Publishers B. V. (Amsterdam, The Netherlands), ISSN: 0048-9697, 2018
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• Assessing the Effects of WFD Nutrient Reductions Within an OSPAR Frame Using Trans-boundary Nutrient Modeling (Hermann Lenhart, Fabian Große), In Frontiers in Marine Science, Series: 5, pp. 447, (Editors: Christophe Rabouille), Frontiers (Avenue du Tribunal Fédéral 34, CH-1005 Lausanne, Switzerland), 2018
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• Wissenschaftliches Rechnen - Scientific Computing - 2016 (Yevhen Alforov, Eugen Betke, Konstantinos Chasapis, Anna Fuchs, Fabian Große, Nabeeh Jumah, Michael Kuhn, Julian Kunkel, Hermann Lenhart, Jakob Lüttgau, Philipp Neumann, Anastasiia Novikova, Jannek Squar, Thomas Ludwig), Research Group: Scientific Computing, University of Hamburg (Deutsches Klimarechenzentrum GmbH, Bundesstraße 45a, D-20146 Hamburg), 2017-06-19
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• A Novel Modeling Approach to Quantify the Influence of Nitrogen Inputs on the Oxygen Dynamics of the North Sea (Fabian Große, Markus Kreus, Hermann Lenhart, Johannes Pätsch, Thomas Pohlmann), In Frontiers in Marine Science, Series: 4, pp. 383, (Editors: Christophe Rabouille), Frontiers (Avenue du Tribunal Fédéral 34, CH-1005 Lausanne, Switzerland), 2017
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• Looking beyond stratification: a model-based analysis of the biological drivers of oxygen deficiency in the North Sea (Fabian Große, Naomi Greenwood, Markus Kreus, Hermann Lenhart, Detlev Machoczek, Johannes Pätsch, Lesley A. Salt, Helmuth Thomas), In Biogeosciences, Series: 13, pp. 2511–2535, (Editors: Veronique Garçon), Copernicus Publications (Bahnhofsallee 1e, 37081 Göttingen, Germany), 2016
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• Speicherung großer Datenmengen und Energieeffizienz (Thomas Ludwig, Manuel Dolz, Michael Kuhn, Julian Kunkel, Hermann Lenhart), Max-Planck-Gesselschaft (München), 2015
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• The North Sea – A shelf sea in the Anthropocene (Kay-Christian Emeis, Justus van Beusekom, Ulrich Callies, Ralf Ebinghaus, Andreas Kannen, Gerd Kraus, Ingrid Kröncke, Hermann Lenhart, Ina Lorkowski, Volker Matthias, Christian Möllmann, Johannes Pätsch, Mirco Scharfe, Helmuth Thomas, Ralf Weisse, Eduardo Zorita), In Journal of Marine Systems, Series: 141, pp. 18–33, Elsevier Science Publishers B. V. (Amsterdam, The Netherlands), 2015
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• Looking beyond stratification: a model-based analysis of the biological drivers of oxygen depletion in the North Sea (Fabian Große, Naomi Greenwood, Markus Kreus, Hermann Lenhart, Detlev Machoczek, Johannes Pätsch, Lesley A. Salt, Helmuth Thomas), In Biogeosciences Discussions, Series: 12, pp. 12543–12610, Copernicus Publications (Bahnhofsallee 1e, 37081 Göttingen, Germany), 2015
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• Influence of large offshore wind farms on North German climate (Marita Boettcher, Peter Hoffmann, Hermann Lenhart, Heinke Schlünzen, Robert Schoetter), In Meteorologische Zeitschrift, Series: 24, pp. 465–480, Borntraeger Science Publishers (Stuttgart), ISSN: 0941-2948, 2014
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• Report on “Distance to Target” Modelling Assessment by ICG-EMO (Hermann Lenhart, Xavier Desmit, Fabian Große, David Mills, Geneviève Lacroix, Hans Los, Alain Ménesguen, Johannes Pätsch, Tineke Troost, Johan van der Molen, Sonja van Leeuwen, Sarah Wakelin), Reports of OSPAR ICG-EMO Working group, OSPAR Commission (London, United Kingdom), 2012
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• Wake Effects (Petra Nerge, Hermann Lenhart), In Analyzing Coastal and Marine Changes: Offshore Wind Farming as a Case Study. Zukunft Küste - Coastal Futures Synthesis Report. (Marcus Lange, Benjamin Burkhard, Stefan Garthe, Kira Gee, Andreas Kannen, Hermann Lenhart, Wilhelm Windhorst), Series: No. 36, Chapters: 5.3, pp. 68–73, LOICZ Research and Studies (GKSS Research Center, Geesthacht, Germany), 2010
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• Modellbasierte Bewertung der Auswirkungen von Offshore-Windkraftanlagen auf die ökologische Integrität der Nordsee (Benjamin Burkhard, Silvia Opitz, Hermann Lenhart, Kai Ahrendt, Stefan Garthe, Bettina Mendel, Petra Nerge, Wilhelm Windhorst), In Forschung für ein integriertes Küstenzonenmanagement: Fallbeispiele Odermündungsregion und Offshore-Windkraft in der Nordsee (A. Kannen, G. Schernewski, I. Krämer, M. Lange, H. Janßen, N. Stybel), Series: 15 (2010), pp. 15–29, Coastline Reports (EUCC - Die Küsten Union Deutschland e. V., c/o Leibniz-Institut für Ostseeforschung Warnemünde, Seestr. 15, 18119 Rostock, Germany), ISBN: 978-3-9811839-7-9, 2010
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• Predicting the consequences of nutrient reduction on the eutrophication status of the North Sea (Hermann Lenhart, David K. Mills, Hanneke Baretta-Bekker, Sonja M. van Leeuwen, Johan van der Molen, Job W. Barettad, Meinte Blaase, Xavier Desmite, Wilfried Kühna, Geneviève Lacroixf, Hans J. Lose, Alain Ménesgueng, Ramiro Nevesh, Roger Proctori, Piet Ruardijj, Morten D. Skogenk, Alice Vanhoutte-Brunierg, Monique T. Villarse, Sarah L. Wakelini), In Journal of Marine Systems, Series: 81 (1-2), pp. 148–170, Elsevier B.V (Amsterdam, Netherlands), ISSN: 0924-7963, 2010
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• Ecosystem based modeling and indication of ecological integrity in the German North Sea - Case study offshore wind parks (Benjamin Burkhard, Silvia Opitz, Hermann Lenhart, Kai Ahrendt, Stefan Garthe, Bettina Mendel, Wilhelm Windhorst), In Ecological Indicators, Series: 11-1, pp. 168–174, Elsevier B.V (Amsterdam, Netherlands), ISSN: 1470-160X, 2009
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• Ecological risk as a tool for evaluating the effects of offshore wind farm construction in the North Sea (Corinna Nunneri, Hermann Lenhart, Benjamin Burkhard, Wilhelm Windhorst), In Regional Environmental Change, Series: 8-1, pp. 31–43, Springer (Berlin / Heidelberg, Germany), ISSN: 1436-3798, 2008-03
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• The use of 'ecological risk' for assessing effects of human activities: an example including eutrophication and offshore wind farm construction in the North Sea (Corinna Nunneri, Hermann Lenhart, Benjamin Burkhard, Franciscus Colijn, Felix Müller, Wilhelm Windhorst), In Landscape online, Series: 5, ISSN: 1865-1542, 2008
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• Nutrient emission reduction scenarios in the North Sea: An abatement cost and ecosystem integrity analysis (Corinna Nunneri, Wilhelm Windhorst, R. Kerry Turner, Hermann Lenhart), In Ecological Indicators, Series: 7-4, pp. 776–792, Elsevier B.V (Amsterdam, Netherlands), ISSN: 1470-160X, 2007
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• Catchment-coastal zone interaction based upon scenario and model analysis: Elbe and the German Bight case study (J. Hofmann, H. Behrendt, A. Gilbert, R. Jannssen, A. Kannen, Hermann Lenhart, W. Lise, Corinna Nunneri, Wilhelm Windhorst), In Regional Environmental Change, Series: 5 (2-3), Springer (Berlin / Heidelberg, Germany), ISSN: 1436-378X, 2005
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• Defining a good ecological status of coastal waters - a case study for the Elbe plume (Wilhelm Windhorst, Franciscus Colijn, Saa Kabuta, Remi Laane, Hermann Lenhart), In Managing European Coasts (Jan Vermaat, Wim Salomons, Laurens Bouwer, Kerry Turner), pp. 59–74, Springer (Berlin / Heidelberg, Germany), ISBN: 978-3-540-23454-8, 2005
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• North Sea Hydrodynamic Modelling: A Review (Hermann Lenhart, Thomas Pohlmann), In Senckenbergiana maritima, Series: 34-(1/2), pp. 53–88, (Editors: Ingrid Kröncke, Michael Türkay, Jürgen Sündermann), 2004
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• Nährstoffe und Eutrophierung (Uwe Brockmann, Hermann Lenhart, Heinke Schlünzen, Dilek Topcu), In Warnsignale aus Nordsee und Wattenmeer - Eine aktuelle Umweltbilanz (Jose L. Lozan, Eike Rachor, Karsten Reise, Jürgen Sündermann, Hein Westernhagen), pp. 61–76, ISBN: 978-3000101663, 2002
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• Effects of river nutrient load reduction on the eutrophication of the North Sea, simulated with the ecosystem model ERSEM (Hermann Lenhart), In Senckenbergiana maritima, Series: 31-2, pp. 299–311, (Editors: Ingrid Kröncke, Michael Türkay, Jürgen Sündermann), 2000
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• The ICES-boxes approach in relation to results of a North Sea circulation model (Hermann Lenhart, Thomas Pohlmann), In Tellus, Series: 49 A, pp. 139–160, Blackwell (Oxford, United Kingdom), ISSN: 0280-6495, 1997
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• The effects of river input on the ecosystem dynamics in the continental coastal zone of the North Sea using ERSEM (Hermann Lenhart, Günther Radach, Piet Ruardij), In Journal of Sea Research, Series: 38 (3-4), pp. 249–274, Elsevier B.V (Amsterdam, Netherlands), ISSN: 1385-1101, 1997
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• Influence of variability in water transport on phytoplankton biomass and composition in the southern North Sea: a modelling approach (FYFY) (A. J. Van Den Berg, H. Ridderinkhof, R. Riegman, P. Ruardij, Hermann Lenhart), In Continental Shelf Research, Series: 16-7, pp. 907–917, Elsevier B.V (Amsterdam, Netherlands), ISSN: 0278-4343, 1996
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• Nutrient dynamics in the North Sea: Fluxes and budgets in the water column derived from ERSEM (Günther Radach, Hermann Lenhart), In Netherlands Journal of Sea Research, Series: 33 (3-4), Elsevier B.V (Amsterdam, Netherlands), ISSN: 0077-7579, 1995
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• Simulations of the North Sea circulation, its variability, and its implementation as hydrodynamical forcing in ERSEM (Hermann Lenhart, Günther Radach, Jan O. Backhaus, Thomas Pohlmann), In Netherlands Journal of Sea Research, Series: 33 (3-4), pp. 271–299, Elsevier B.V (Amsterdam, Netherlands), ISSN: 0077-7579, 1995
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• Nährstoffe in der Nordsee - Eutrophierung, Hypertrophierung und deren Auswirkungen (G. Radach, W. Schönfeld, Hermann Lenhart), In Warnsignale aus der Nordsee (José .L. Lozan, Walter Lenz, Eike Rachor, Burkard Watermann, Heinz v. Westernhagen), pp. 48–65, Paul Parey Verlagsbuchhandlung (Hamburg / Berlin), 1990
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• Assessing trans-boundary nutrient modelling results including WFD reduction scenario within an OSPAR frame (Hermann Lenhart, Fabian Große), 4th International Symposium on Research and Management of Eutrophication in Coastal Ecosystems (EUTRO2018), Nyborg, Denmark, 2018-06-18

• Riverine nitrogen and oxygen deficiency in the North Sea: Extending trans-boundary nutrient transports for the ecological management of low oxygen conditions (Fabian Große, Markus Kreus, Hermann Lenhart, Johannes Pätsch), Advances in Marine Ecosystem Modelling Research (AMEMR), Plymouth, UK, 2017-07-04
• WFD-compliant nitrogen reductions within the OSPAR framework: A source-oriented approach for the North Sea (Fabian Große, Hermann Lenhart), Innovative modelling in support of MSFD implementation, Brussels, Belgium, 2017-03-22

• The influence of riverine nitrogen on the North Sea oxygen minimum zone (Fabian Große, Markus Kreus, Hermann Lenhart, Johannes Pätsch), EGU General Assembly 2016, Vienna, Austria, 2016-04-20

• Looking beyond stratification: A model-based analysis of the biological drivers of oxygen depletion in the North Sea (Fabian Große, Hermann Lenhart, Uwe Brockmann), 46th International Liège Colloquium, Liègei, Belgium, 2014-05-06

• Auswirkungen von Windfeldänderungen durch Offshore-Windparks auf das marine Umfeld (Hermann Lenhart, Petra Nerge), Abschlusssymposium Zukunft Küste - Coastal Futures, Hamburg, Deutschland, 2010-03-04 Presentation

• Energy usage analysis of HPC applications (Tim Jammer), Bachelor's Thesis, Advisors: Hermann Lenhart, Michael Kuhn, 2016-12-06, Publication details
• Performanceanalyse der Ein-/Ausgabe des Ökologiemodells ECOHAM5 (Simon Kostede), Master's Thesis, Advisors: Michael Kuhn, Fabian Große, Hermann Lenhart, 2016-08-22, Thesis – Publication details