2#if defined NONLINEAR && defined BIOLOGY 
    6************************************************************************
 
    8** the current design allows the user to have a lot of latitude for   **
 
    9** customizing or adding any particular ecosystem model.              **
 
   11** each ecosystem model is composed of seven files:                   **
 
   13**   (1) model source and sink discretized equations:                 **
 
   16**         fennel.h           bio_fennel                              **
 
   17**         hypoxia_srm.h      hypoxia_srm                             **
 
   19**         npzd_franks.h      npzd_franks                             **
 
   20**         npzd_iron.h        npzd_iron                               **
 
   21**         npzd_powell.h      npzd_powell                             **
 
   22**         red_tide.h         red_tide                                **
 
   24**   (2) internal model parameters declaration:                       **
 
   28**         hypoxia_srm_mod.h                                          **
 
   30**         npzd_franks_mod.h                                          **
 
   32**         npzd_powell_mod.h                                          **
 
   35**   (3) model parameters standard input script:                      **
 
   46**   (4) code to 
read input model parameters:                         **
 
   50**         hypoxia_srm_inp.h                                          **
 
   52**         npzd_franks_inp.h                                          **
 
   54**         npzd_powell_inp.h                                          **
 
   57**   (5) code to assign indices to model variables during the         **
 
   58**       reading of metadata information from 
"varinfo.yaml":         **
 
   62**         hypoxia_srm_var.h                                          **
 
   64**         npzd_franks_var.h                                          **
 
   66**         npzd_powell_var.h                                          **
 
   69**   (6) code to define input model parameters in all 
output          **
 
   74**         hypoxia_srm_def.h                                          **
 
   76**         npzd_franks_def.h                                          **
 
   78**         npzd_powell_def.h                                          **
 
   81**   (7) code to 
write out input model parameters in all 
output       **
 
   86**         hypoxia_srm_wrt.h                                          **
 
   88**         npzd_franks_wrt.h                                          **
 
   90**         npzd_powell_wrt.h                                          **
 
   94** note that all the *.h files are located in roms/nonlinear/biology  **
 
   95** and included within  <...>  to allow the user to customize any of  **
 
   96** them in the project directory  
while keeping the distributed code  **
 
   97** intact(check the build script for details).                       **
 
   99************************************************************************
 
  102# if defined BIO_FENNEL 
  106# elif defined HYPOXIA_SRM 
  107#  include <hypoxia_srm.h> 
  110# elif defined NPZD_FRANKS 
  111#  include <npzd_Franks.h> 
  112# elif defined NPZD_IRON 
  113#  include <npzd_iron.h> 
  114# elif defined NPZD_POWELL 
  115#  include <npzd_Powell.h> 
  116# elif defined RED_TIDE 
  117#  include <red_tide.h>