'ELISE', an interactive software for modelling complex aquatic ecosystems

As the need is growing more and more for realistic and reliable modelling of various processes in aquatic ecosystems (lakes, rivers, estuaries, coastal and oceanic zones), a larger accessibility to numerical tools is required. “ELISE” software has been developed during these last years at IFREMER according to the three following requirements. 1) It must be portable : made of C and FORTRAN 77 routines, “ELISE” is a self-contained package implemented under UNIX environment, using Xwindow interface. 2) It must be easy-to-use : the user interface is built thanks to OSF/Motif and is based on the familiar windows- and pop-up menu philosophy. Only the biological terms of the differential equations must be written in FORTRAN 77 by the user, according to a pre-established pattern with guidelines. Graphical outputs in time or phase space, in one or two dimensions are easily selected by the user, with automatic or imposed scaling. 3) It must be well-adapted to the modelling of spatially complex aquatic ecosystems. Great care has been taken in “ELISE” to easy interfacing numerical outputs of fine grid hydrodynamical models with box-models commonly used by ecologists. The topology of the box-model can be interactively drawn by the user on the map of the site. Advective fluxes between these boxes are then automatically computed using data files for currents. Automatic correction for box connectivity and conservativity of fluxes is provided by “ELISE”. Different applications are presented, related to phytoplankton ecology and nutrient biogeochemical cycles in coastal zones.