Synthesis of the NEMURO model studies and future directions of marine ecosystem modeling

NEMURO, the North Pacific Ecosystem Model for Understanding Regional Oceanography, simulates the temporal evolution and dynamics of the North Pacific's nutrient-phytoplankton-zooplankton food web. The approach of developing a single model formulation allowed quantitative comparisons across various locations and time periods. Building on a common foundation enabled the linkages between lower trophic levels to the higher trophic (fish) components to proceed systematically. NEMURO was extended to NEMURO.FISH by using the lower trophic level output of NEMURO as input to a bioenergetic-based model of fish growth and population dynamics. This paper summarizes the contributions of individual papers that comprise this issue of Ecological Modelling and that all used the NEMURO family of models. Contributions represent a rich set of case-studies and in-depth modeling studies focused on the North Pacific that addressed: oceanic biogeochemistry, regional and seasonal variability of phytoplankton and zooplankton, reconstruction of 40-50 years of plankton dynamics, effects of climate on herring and saury growth and population dynamics, the feasibility of automatic calibration methods, the sensitivity of the model to parameter values, and projections of future states of the ecosystem under global warming. Next steps in the evolution of NEMURO are suggested and include increased resolution of the physical model underlying NEMURO, the addition of new biological state variables at the lower trophic levels to better represent the diversity of oceanic species and their potential for different responses under changing environmental conditions, and the addition of more higher trophic level species to allow for inter-specific (competition and predation) interactions. The NEMURO effort involved a diverse group of researchers working jointly on a common problem for several years. Consequently, the resulting contributions, even at the level of the individual papers, provide a broader perspective and integration of the results than would have occurred by working in isolation. The benefits of a large-scale collaborative effort to develop a common model formulation are clearly illustrated by the papers in this issue.