Publications

2021

• D. P. Tittensor, C. Novaglio, C. S. Harrison, R. F. Heneghan, N. Barrier, D. Bianchi, L. Bopp, A. Bryndum-Buchholz, G. L. Britten, M. Büchner, W. W. L. Cheung, V. Christensen, M. Coll, J. P. Dunne, T. D. Eddy, J. D. Everett, J. A. Fernandes-Salvador, E. A. Fulton, E. D. Galbraith, D. Gascuel, J. Guiet, J. G. John, J. S. Link, H. K. Lotze, O. Maury, K. Ortega-Cisneros, J. Palacios-Abrantes, C. M. Petrik, H. du Pontavice, J. Rault, A. J. Richardson, L. Shannon, Y. Shin, J. Steenbeek, C. A. Stock, and J. L. Blanchard, “Next-generation ensemble projections reveal higher climate risks for marine ecosystems,” Nature climate change, 2021.
  [Bibtex]

  @article{Tittensor2021,
  author= {Tittensor, Derek P. and Novaglio, Camilla and Harrison, Cheryl S. and Heneghan, Ryan F. and Barrier, Nicolas and Bianchi, Daniele and Bopp, Laurent and Bryndum-Buchholz, Andrea and Britten, Gregory L. and Büchner, Matthias and Cheung, William W. L. and Christensen, Villy and Coll, Marta and Dunne, John P. and Eddy, Tyler D. and Everett, Jason D. and Fernandes-Salvador, Jose A. and Fulton, Elizabeth A. and Galbraith, Eric D. and Gascuel, Didier and Guiet, Jerome and John, Jasmin G. and Link, Jason S. and Lotze, Heike K. and Maury, Olivier and Ortega-Cisneros, Kelly and Palacios-Abrantes, Juliano and Petrik, Colleen M. and du Pontavice, Hubert and Rault, Jonathan and Richardson, Anthony J. and Shannon, Lynne and Shin, Yunne-Jai and Steenbeek, Jeroen and Stock, Charles A. and Blanchard, Julia L.},
  year={2021},
  month={10},
  title={Next-generation ensemble projections reveal higher climate risks for marine ecosystems},
  journal={Nature Climate Change},
  abstract={Projections of climate change impacts on marine ecosystems have revealed long-term declines in global marine animal biomass and unevenly distributed impacts on fisheries. Here we apply an enhanced suite of global marine ecosystem models from the Fisheries and Marine Ecosystem Model Intercomparison Project (Fish-MIP), forced by new-generation Earth system model outputs from Phase 6 of the Coupled Model Intercomparison Project (CMIP6), to provide insights into how projected climate change will affect future ocean ecosystems. Compared with the previous generation CMIP5-forced Fish-MIP ensemble, the new ensemble ecosystem simulations show a greater decline in mean global ocean animal biomass under both strong-mitigation and high-emissions scenarios due to elevated warming, despite greater uncertainty in net primary production in the high-emissions scenario. Regional shifts in the direction of biomass changes highlight the continued and urgent need to reduce uncertainty in the projected responses of marine ecosystems to climate change to help support adaptation planning.}
  issn={1758-6798},
  url={https://doi.org/10.1038/s41558-021-01173-9},
  doi={10.1038/s41558-021-01173-9}
  }

• R. F. Heneghan, E. Galbraith, J. L. Blanchard, C. Harrison, N. Barrier, C. Bulman, W. Cheung, M. Coll, T. D. Eddy, M. Erauskin-Extramiana, J. D. Everett, J. A. Fernandes-Salvador, D. Gascuel, J. Guiet, O. Maury, J. Palacios-Abrantes, C. M. Petrik, H. du Pontavice, A. J. Richardson, J. Steenbeek, T. C. Tai, J. Volkholz, P. A. Woodworth-Jefcoats, and D. P. Tittensor, “Disentangling diverse responses to climate change among global marine ecosystem models,” Progress in oceanography, p. 102659, 2021.
  [Bibtex]

  @article{HENEGHAN2021102659,
  title = {Disentangling diverse responses to climate change among global marine ecosystem models},
  journal = {Progress in Oceanography},
  pages = {102659},
  year = {2021},
  issn = {0079-6611},
  doi = {https://doi.org/10.1016/j.pocean.2021.102659},
  url = {https://www.sciencedirect.com/science/article/pii/S0079661121001440},
  author = {Ryan F. Heneghan and Eric Galbraith and Julia L. Blanchard and Cheryl Harrison and Nicolas Barrier and Catherine Bulman and William Cheung and Marta Coll and Tyler D. Eddy and Maite Erauskin-Extramiana and Jason D. Everett and Jose A. Fernandes-Salvador and Didier Gascuel and Jerome Guiet and Olivier Maury and Juliano Palacios-Abrantes and Colleen M. Petrik and Hubert {du Pontavice} and Anthony J. Richardson and Jeroen Steenbeek and Travis C. Tai and Jan Volkholz and Phoebe A. Woodworth-Jefcoats and Derek P. Tittensor},
  keywords = {Climatic change, Modelling, Fishery oceanography, Marine ecology, FishMIP, Structural uncertainty},
  abstract = {Climate change is warming the ocean and impacting lower trophic level (LTL) organisms. Marine ecosystem models can provide estimates of how these changes will propagate to larger animals and impact societal services such as fisheries, but at present these estimates vary widely. A better understanding of what drives this inter-model variation will improve our ability to project fisheries and other ecosystem services into the future, while also helping to identify uncertainties in process understanding. Here, we explore the mechanisms that underlie the diversity of responses to changes in temperature and LTLs in eight global marine ecosystem models from the Fisheries and Marine Ecosystem Model Intercomparison Project (FishMIP). Temperature and LTL impacts on total consumer biomass and ecosystem structure (defined as the relative change of small and large organism biomass) were isolated using a comparative experimental protocol. Total model biomass varied between -35% to +3% in response to warming, and -17% to +15% in response to LTL changes. There was little consensus about the spatial redistribution of biomass or changes in the balance between small and large organisms (ecosystem structure) in response to warming, and LTL impacts on total consumer biomass varied depending on the choice of LTL forcing terms. Overall, climate change impacts on consumer biomass and ecosystem structure are well approximated by the sum of temperature and LTL impacts, indicating an absence of nonlinear interaction between the models’ drivers. Our results highlight a lack of theoretical clarity about how to represent fundamental ecological mechanisms, most importantly how temperature impacts scale from individual to ecosystem level, and the need to better understand the two-way coupling between LTL organisms and consumers. We finish by identifying future research needs to strengthen global marine ecosystem modelling and improve projections of climate change impacts.}
  }

2020

• A. Tagliabue, N. Barrier, H. Du Pontavice, L. Kwiatkowski, O. Aumont, L. Bopp, W. W. L. Cheung, D. Gascuel, and O. Maury, “An iron cycle cascade governs the response of equatorial pacific ecosystems to climate change,” Global change biology, vol. 26, iss. 11, pp. 6168-6179, 2020.
  [Bibtex]

  @article{https://doi.org/10.1111/gcb.15316,
  author = {Tagliabue, Alessandro and Barrier, Nicolas and Du Pontavice, Hubert and Kwiatkowski, Lester and Aumont, Olivier and Bopp, Laurent and Cheung, William W. L. and Gascuel, Didier and Maury, Olivier},
  title = {An iron cycle cascade governs the response of equatorial Pacific ecosystems to climate change},
  journal = {Global Change Biology},
  volume = {26},
  number = {11},
  pages = {6168-6179},
  keywords = {climate change, iron, marine ecosystems, net primary production, ocean},
  doi = {https://doi.org/10.1111/gcb.15316},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15316},
  eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15316},
  abstract = {Abstract Earth System Models project that global climate change will reduce ocean net primary production (NPP), upper trophic level biota biomass and potential fisheries catches in the future, especially in the eastern equatorial Pacific. However, projections from Earth System Models are undermined by poorly constrained assumptions regarding the biological cycling of iron, which is the main limiting resource for NPP over large parts of the ocean. In this study, we show that the climate change trends in NPP and the biomass of upper trophic levels are strongly affected by modifying assumptions associated with phytoplankton iron uptake. Using a suite of model experiments, we find 21st century climate change impacts on regional NPP range from −12.3\% to +2.4\% under a high emissions climate change scenario. This wide range arises from variations in the efficiency of iron retention in the upper ocean in the eastern equatorial Pacific across different scenarios of biological iron uptake, which affect the strength of regional iron limitation. Those scenarios where nitrogen limitation replaced iron limitation showed the largest projected NPP declines, while those where iron limitation was more resilient displayed little future change. All model scenarios have similar skill in reproducing past inter-annual variations in regional ocean NPP, largely due to limited change in the historical period. Ultimately, projections of end of century upper trophic level biomass change are altered by 50\%–80\% across all plausible scenarios. Overall, we find that uncertainties in the biological iron cycle cascade through open ocean pelagic ecosystems, from plankton to fish, affecting their evolution under climate change. This highlights additional challenges to developing effective conservation and fisheries management policies under climate change.},
  year = {2020}
  }

2019

• H. K. Lotze, D. P. Tittensor, A. Bryndum-Buchholz, T. D. Eddy, W. W. L. Cheung, E. D. Galbraith, M. Barange, N. Barrier, D. Bianchi, J. L. Blanchard, L. Bopp, M. Büchner, C. M. Bulman, D. A. Carozza, V. Christensen, M. Coll, J. P. Dunne, E. A. Fulton, S. Jennings, M. C. Jones, S. Mackinson, O. Maury, S. Niiranen, R. Oliveros-Ramos, T. Roy, J. A. Fernandes, J. Schewe, Y. Shin, T. A. M. Silva, J. Steenbeek, C. A. Stock, P. Verley, J. Volkholz, N. D. Walker, and B. Worm, “Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change,” Proceedings of the national academy of sciences, vol. 116, p. 12907{–}12912, 2019.
  [Bibtex]

  @article {24,
  title = {Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change},
  journal = {Proceedings of the National Academy of Sciences},
  volume = {116},
  year = {2019},
  pages = {12907{\textendash}12912},
  abstract = {
  Climate change can affect the distribution and abundance of marine life, with consequences for goods and services provided to people. Because different models can lead to divergent conclusions about marine futures, we present an integrated global ocean assessment of climate change impacts using an ensemble of multiple climate and ecosystem models. It reveals that global marine animal biomass will decline under all emission scenarios, driven by increasing temperature and decreasing primary production. Notably, climate change impacts are amplified at higher food web levels compared with phytoplankton. Our ensemble projections provide the most comprehensive outlook on potential climate-driven ecological changes in the global ocean to date and can inform adaptive management and conservation of marine resources under climate change.While the physical dimensions of climate change are now routinely assessed through multimodel intercomparisons, projected impacts on the global ocean ecosystem generally rely on individual models with a specific set of assumptions. To address these single-model limitations, we present standardized ensemble projections from six global marine ecosystem models forced with two Earth system models and four emission scenarios with and without fishing. We derive average biomass trends and associated uncertainties across the marine food web. Without fishing, mean global animal biomass decreased by 5\% (\±4\% SD) under low emissions and 17\% (\±11\% SD) under high emissions by 2100, with an average 5\% decline for every 1 \°C of warming. Projected biomass declines were primarily driven by increasing temperature and decreasing primary production, and were more pronounced at higher trophic levels, a process known as trophic amplification. Fishing did not substantially alter the effects of climate change. Considerable regional variation featured strong biomass increases at high latitudes and decreases at middle to low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to variations in marine ecosystem and Earth system models were similar. Ensemble projections performed well compared with empirical data, emphasizing the benefits of multimodel inference to project future outcomes. Our results indicate that global ocean animal biomass consistently declines with climate change, and that these impacts are amplified at higher trophic levels. Next steps for model development include dynamic scenarios of fishing, cumulative human impacts, and the effects of management measures on future ocean biomass trends.
  },
  issn = {0027-8424},
  doi = {10.1073/pnas.1900194116},
  url = {https://www.pnas.org/content/116/26/12907},
  author = {Lotze, Heike K. and Tittensor, Derek P. and Bryndum-Buchholz, Andrea and Eddy, Tyler D. and Cheung, William W. L. and Galbraith, Eric D. and Barange, Manuel and Barrier, Nicolas and Bianchi, Daniele and Blanchard, Julia L. and Bopp, Laurent and B{\"u}chner, Matthias and Bulman, Catherine M. and Carozza, David A. and Christensen, Villy and Coll, Marta and Dunne, John P. and Fulton, Elizabeth A. and Jennings, Simon and Jones, Miranda C. and Mackinson, Steve and Maury, Olivier and Niiranen, Susa and Oliveros-Ramos, Ricardo and Roy, Tilla and Fernandes, Jos{\'e} A. and Schewe, Jacob and Shin, Yunne-Jai and Silva, Tiago A. M. and Steenbeek, Jeroen and Stock, Charles A. and Verley, Philippe and Volkholz, Jan and Walker, Nicola D. and Worm, Boris}
  }

2018

• O. Aumont, O. Maury, S. Lefort, and L. Bopp, “Evaluating the potential impacts of the diurnal vertical migration by marine organisms on marine biogeochemistry,” Global biogeochemical cycles, vol. 32, pp. 1622-1643, 2018.
  [Bibtex]

  @article {25,
  title = {Evaluating the Potential Impacts of the Diurnal Vertical Migration by Marine Organisms on Marine Biogeochemistry},
  journal = {Global Biogeochemical Cycles},
  volume = {32},
  year = {2018},
  pages = {1622-1643},
  abstract = {
  Diurnal vertical migration (DVM) of marine organisms is an ubiquitous phenomenon in the ocean that generates an active vertical transport of organic matter. However, the magnitude and consequences of this flux are largely unknown and are currently overlooked in ocean biogeochemical models. Here we present a global model of pelagic ecosystems based on the ocean biogeochemical model NEMO-PISCES that is fully coupled to the upper trophic levels model Apex Predators ECOSystem Model, which includes an explicit description of migrating organisms. Evaluation of the model behavior proved to be challenging due to the scarcity of suitable observations. Nevertheless, the model appears to be able to simulate approximately both the migration depth and the relative biomass of migrating organisms. About one third of the epipelagic biomass is predicted to perform DVM. The flux of carbon driven by DVM is estimated to be 1.05\ \±\ 0.15\ PgC/year, about 18\% of the passive flux of carbon due to sinking particles at 150\ m. Comparison with local studies suggests that the model captures the correct magnitude of this flux. Oxygen is decreased in the mesopelagic domain by about 5\ mmol\ m\−3 relative to simulations of an ocean without DVM. Our study concludes that DVM drives a significant and very efficient flux of carbon to the mesopelagic domain, similar in magnitude to the transport of DOC. Relative to a model run without DVM, the consequences of this flux seem to be quite modest on oxygen, due to compensating effects between DVM and passive fluxes.
  },
  keywords = {biogeochemistry, carbon cycle, diurnal vertical migration, ecosystem, export, ocean},
  doi = {10.1029/2018GB005886},
  url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GB005886},
  author = {Aumont, Olivier and Maury, Olivier and Lefort, Stelly and Bopp, Laurent}
  }

2016

• J. Guiet, O. Aumont, J. Poggiale, and O. Maury, “Effects of lower trophic level biomass and water temperature on fish communities: a modelling study,” Progress in oceanography, vol. 146, pp. 22-37, 2016.
  [Bibtex]

  @article {27,
  title = {Effects of lower trophic level biomass and water temperature on fish communities: A modelling study},
  journal = {Progress in Oceanography},
  volume = {146},
  year = {2016},
  pages = {22 - 37},
  abstract = {
  Physical and biogeochemical changes of the oceans have complex influences on fish communities. Variations of resource and temperature affect metabolic rates at the individual level, biomass fluxes at the species level, and trophic structure as well as diversity at the community level. We use a Dynamic Energy Budget-, trait-based model of the consumers\’ community size-spectrum to assess the effects of lower trophic level biomass and water temperature on communities at steady state. First, we look at the stressors separately in idealized simulations, varying one while the second remains constant. A multi-domain response is observed. Linked to the number of trophic levels sustained in the consumers\’ community, the regimes highlighted present similar properties when lower trophic level biomass is increased or temperature decreased. These trophic-length domains correspond to different efficiencies of the transfer of biomass from small to large individuals. They are characterized by different sensitivities of fish communities to environmental changes. Moreover, differences in the scaling of individuals\’ metabolism and prey assimilation with temperature lead to a shrinking of fish communities with warming. In a second step, we look at the impact of simultaneous variations of stressors along a mean latitudinal gradient of lower trophic level biomass and temperature. The model explains known observed features of global marine ecosystems such as the fact that larger species compose fish communities when latitude increases. The structure, diversity and metabolic properties of fish communities obtained with the model at different latitudes are interpreted in light of the different trophic-length domains characterized in the idealized experiments. From the equator to the poles, the structure of consumers\’ communities is predicted to be heterogeneous, with variable sensitivities to environmental changes.
  },
  issn = {0079-6611},
  doi = {https://doi.org/10.1016/j.pocean.2016.04.003},
  url = {http://www.sciencedirect.com/science/article/pii/S0079661115300367},
  author = {J{\'e}r{\^o}me Guiet and Olivier Aumont and Jean-Christophe Poggiale and Olivier Maury}
  }

2013

• O. Maury and J. Poggiale, “From individuals to populations to communities: a dynamic energy budget model of marine ecosystem size-spectrum including life history diversity,” Journal of theoretical biology, vol. 324, pp. 52-71, 2013.
  [Bibtex]

  @article {26,
  title = {From individuals to populations to communities: A dynamic energy budget model of marine ecosystem size-spectrum including life history diversity},
  journal = {Journal of Theoretical Biology},
  volume = {324},
  year = {2013},
  pages = {52 - 71},
  abstract = {
  Individual metabolism, predator\–prey relationships, and the role of biodiversity are major factors underlying the dynamics of food webs and their response to environmental variability. Despite their crucial, complementary and interacting influences, they are usually not considered simultaneously in current marine ecosystem models. In an attempt to fill this gap and determine if these factors and their interaction are sufficient to allow realistic community structure and dynamics to emerge, we formulate a mathematical model of the size-structured dynamics of marine communities which integrates mechanistically individual, population and community levels. The model represents the transfer of energy generated in both time and size by an infinite number of interacting fish species spanning from very small to very large species. It is based on standard individual level assumptions of the Dynamic Energy Budget theory (DEB) as well as important ecological processes such as opportunistic size-based predation and competition for food. Resting on the inter-specific body-size scaling relationships of the DEB theory, the diversity of life-history traits (i.e. biodiversity) is explicitly integrated. The stationary solutions of the model as well as the transient solutions arising when environmental signals (e.g. variability of primary production and temperature) propagate through the ecosystem are studied using numerical simulations. It is shown that in the absence of density-dependent feedback processes, the model exhibits unstable oscillations. Density-dependent schooling probability and schooling-dependent predatory and disease mortalities are proposed to be important stabilizing factors allowing stationary solutions to be reached. At the community level, the shape and slope of the obtained quasi-linear stationary spectrum matches well with empirical studies. When oscillations of primary production are simulated, the model predicts that the variability propagates along the spectrum in a given frequency-dependent size range before decreasing for larger sizes. At the species level, the simulations show that small and large species dominate the community successively (small species being more abundant at small sizes and large species being more abundant at large sizes) and that the total biomass of a species decreases with its maximal size which again corroborates empirical studies. Our results indicate that the simultaneous consideration of individual growth and reproduction, size-structured trophic interactions, the diversity of life-history traits and a density-dependent stabilizing process allow realistic community structure and dynamics to emerge without any arbitrary prescription. As a logical consequence of our model construction and a basis for future studies, we define the function \Φ as the relative contribution of each species to the total biomass of the ecosystem, for any given size. We argue that this function is a measure of the functional role of biodiversity characterizing the impact of the structure of the community (its species composition) on its function (the relative proportions of losses, dissipation and biological work).
  },
  keywords = {Biodiversity, Dynamic Energy Budget theory, Predation, Schooling, Size spectrum},
  issn = {0022-5193},
  doi = {https://doi.org/10.1016/j.jtbi.2013.01.018},
  url = {http://www.sciencedirect.com/science/article/pii/S002251931300043X},
  author = {Olivier Maury and Jean-Christophe Poggiale}
  }

2010

• O. Maury, “An overview of apecosm, a spatialized mass balanced “apex predators ecosystem model” to study physiologically structured tuna population dynamics in their ecosystem,” Progress in oceanography, vol. 84, pp. 113-117, 2010.
  [Bibtex]

  @article {23,
  title = {An overview of APECOSM, a spatialized mass balanced "Apex Predators ECOSystem Model" to study physiologically structured tuna population dynamics in their ecosystem},
  journal = {Progress in Oceanography},
  volume = {84},
  year = {2010},
  pages = {113 - 117},
  abstract = {
  This paper gives an overview of the ecosystem model APECOSM (Apex Predators ECOSystem Model) which is developed in the framework of the GLOBEC-CLIOTOP Programme. APECOSM represents the flow of energy through the ecosystem with a size-resolved structure in both space and time. The uptake and use of energy for growth, maintenance and reproduction by the organisms are modelled according to the DEB (dynamic energy budget) theory (Kooijmann, 2000) and the size-structured nature of predation is explicit. The pelagic community is divided into epipelagic and mesopelagic groups, the latter being subdivided into vertically migrant and non-migrant species. The model is mass-conservative. Energy is provided as the basis of the model through primary production and transferred through 3D spatially explicit size-spectra. Focus species (tunas at present, but any predator species can be considered) are \“extracted\” from the global size-spectra without losing mass balance and represented with more physiological and behavioural details. The forcing effects of temperature, currents, light, oxygen, primary production and fishing are explicitly taken into account.
  },
  issn = {0079-6611},
  doi = {https://doi.org/10.1016/j.pocean.2009.09.013},
  url = {http://www.sciencedirect.com/science/article/pii/S0079661109001463},
  author = {Olivier Maury}
  }

2007

• O. Maury, B. Faugeras, Y. Shin, J. Poggiale, T. B. Ari, and F. Marsac, “Modeling environmental effects on the size-structured energy flow through marine ecosystems. part 1: the model,” Progress in oceanography, vol. 74, pp. 479-499, 2007.
  [Bibtex]

  @article {21,
  title = {Modeling environmental effects on the size-structured energy flow through marine ecosystems. Part 1: The model},
  journal = {Progress in Oceanography},
  volume = {74},
  year = {2007},
  pages = {479 - 499},
  abstract = {
  This paper presents an original size-structured mathematical model of the energy flow through marine ecosystems, based on established ecological and physiological processes and mass conservation principles. The model is based on a nonlocal partial differential equation which represents the transfer of energy in both time and body weight (size) in marine ecosystems. The processes taken into account include size-based opportunistic trophic interactions, competition for food, allocation of energy between growth and reproduction, somatic and maturity maintenance, predatory and starvation mortality. All the physiological rates are temperature-dependent. The physiological bases of the model are derived from the dynamic energy budget theory. The model outputs the dynamic size-spectrum of marine ecosystems in term of energy content per weight class as well as many other size-dependent diagnostic variables such as growth rate, egg production or predation mortality. In stable environmental conditions and using a reference set of parameters derived from empirical studies, the model converges toward a stationary linear log\–log size-spectrum with a slope equal to \−1.06, which is consistent with the values reported in empirical studies. In some cases, the distribution of the largest sizes departs from the stationary linear solution and is slightly curved downward. A sensitivity analysis to the parameters is conducted systematically. It shows that the stationary size-spectrum is not very sensitive to the parameters of the model. Numerical simulations of the effects of temperature and primary production variability on marine ecosystems size-spectra are provided in a companion paper [Maury, O., Shin, Y.-J., Faugeras, B., Ben Ari, T., Marsac, F., 2007. Modeling environmental effects on the size-structured energy flow through marine ecosystems. Part 2: simulations. Progress in Oceanography, doi:10.1016/j.pocean.2007.05.001].
  },
  keywords = {Bioenergetics, Dynamic energy budget (DEB) theory, Energy flow, Mathematical model, Predation, Size spectrum},
  issn = {0079-6611},
  doi = {https://doi.org/10.1016/j.pocean.2007.05.002},
  url = {http://www.sciencedirect.com/science/article/pii/S0079661107000985},
  author = {Olivier Maury and Blaise Faugeras and Yunne-Jai Shin and Jean-Christophe Poggiale and Tamara Ben Ari and Francis Marsac}
  }

• O. Maury, Y. Shin, B. Faugeras, T. B. Ari, and F. Marsac, “Modeling environmental effects on the size-structured energy flow through marine ecosystems. part 2: simulations,” Progress in oceanography, vol. 74, pp. 500-514, 2007.
  [Bibtex]

  @article {22,
  title = {Modeling environmental effects on the size-structured energy flow through marine ecosystems. Part 2: Simulations},
  journal = {Progress in Oceanography},
  volume = {74},
  year = {2007},
  pages = {500 - 514},
  abstract = {
  Numerical simulations using a physiologically-based model of marine ecosystem size spectrum are conducted to study the influence of primary production and temperature on energy flux through marine ecosystems. In stable environmental conditions, the model converges toward a stationary linear log\–log size-spectrum. In very productive ecosystems, the model predicts that small size classes are depleted by predation, leading to a curved size-spectrum. It is shown that the absolute level of primary production does not affect the slope of the stationary size-spectrum but has a nonlinear effect on its intercept and hence on the total biomass of consumer organisms (the carrying capacity). Three domains are distinguished: at low primary production, total biomass is independent from production changes because loss processes dominate dissipative processes (biological work); at high production, ecosystem biomass is proportional to primary production because dissipation dominates losses; an intermediate transition domain characterizes mid-production ecosystems. Our results enlighten the paradox of the very high ecosystem biomass/primary production ratios which are observed in poor oceanic regions. Thus, maximal dissipation (least action and low ecosystem biomass/primary production ratios) is reached at high primary production levels when the ecosystem is efficient in transferring energy from small sizes to large sizes. Conversely, least dissipation (most action and high ecosystem biomass/primary production ratios) characterizes the simulated ecosystem at low primary production levels when it is not efficient in dissipating energy. Increasing temperature causes enhanced predation mortality and decreases the intercept of the stationary size spectrum, i.e., the total ecosystem biomass. Total biomass varies as the inverse of the Arrhenius coefficient in the loss domain. This approximation is no longer true in the dissipation domain where nonlinear dissipation processes dominate over linear loss processes. Our results suggest that in a global warming context, at constant primary production, a 2\–4\°C warming would lead to a 20\–43\% decrease of ecosystem biomass in oligotrophic regions and to a 15\–32\% decrease of biomass in eutrophic regions. Oscillations of primary production or temperature induce waves which propagate along the size-spectrum and which amplify until a \“resonant range\” which depends on the period of the environmental oscillations. Small organisms oscillate in phase with producers and are bottom-up controlled by primary production oscillations. In the \“resonant range\”, prey and predators oscillate out of phase with alternating periods of top-down and bottom-up controls. Large organisms are not influenced by bottom-up effects of high frequency phytoplankton variability or by oscillations of temperature.
  },
  keywords = {Bioenergetics, Carrying capacity, Energy flow, Environmental effects, Numerical simulations, Size spectrum},
  issn = {0079-6611},
  doi = {https://doi.org/10.1016/j.pocean.2007.05.001},
  url = {http://www.sciencedirect.com/science/article/pii/S0079661107000997},
  author = {Olivier Maury and Yunne-Jai Shin and Blaise Faugeras and Tamara Ben Ari and Francis Marsac}
  }

• B. Faugeras and O. Maury, “Modeling fish population movements: from an individual-based representation to an advection–diffusion equation,” Journal of theoretical biology, vol. 247, pp. 837-848, 2007.
  [Bibtex]

  @article {19,
  title = {Modeling fish population movements: From an individual-based representation to an advection{\textendash}diffusion equation},
  journal = {Journal of Theoretical Biology},
  volume = {247},
  year = {2007},
  pages = {837 - 848},
  abstract = {
  In this paper, we address the problem of modeling fish population movements. We first consider a description of movements at the level of individuals. An individual-based model is formulated as a biased random walk model in which the velocity of each fish has both a deterministic and a stochastic component. These components are function of a habitat suitability index, h, and its spatial gradient \∇h. We derive an advection\–diffusion partial differential equation (PDE) which approximates this individual-based model (IBM). The approximation process enables us to obtain a mechanistic representation of the advection and diffusion coefficients which improves the heuristic approaches of former studies. Advection and diffusion are linked and exhibit antagonistic behaviors: strong advection goes with weak diffusion leading to a directed movement of fish. On the contrary weak advection goes with strong diffusion corresponding to a searching behavior. Simulations are conducted for both models which are compared by computing spatial statistics. It is shown that the PDE model is a good approximation to the IBM.
  },
  keywords = {Biased random walk, Individual-based model, Partial differential equation, Population dynamics},
  issn = {0022-5193},
  doi = {https://doi.org/10.1016/j.jtbi.2007.04.012},
  url = {http://www.sciencedirect.com/science/article/pii/S0022519307001944},
  author = {Blaise Faugeras and Olivier Maury}
  }