PHYSICAL SUBSYSTEM 



SYSTEM FORCING FUNCTION 



BIOLOGICAL SUBSYSTEM 



SYSTEM SINKS 



SYSTEM INPUTS 



Meteorology 



Photosynthesis 



Upper Ocean 

 Dynamics 



Mesoscale 

 Circulation 



Vertical 

 Velocities 



Bottom 

 Typography 



Water 

 Conditioning 



Nutrient Uptake 



1 



Grazing 



Zooplankton 



Phytoplankton 



Grazing 



Nekton 



.j'^^y\j 



Benthos 



Fecal Pellets 



Excretion 



SYSTEM FEEDBACKS 



Figure 24 Conceptual model of the upwelling ecosystem, suggesting thie relationstiip 

 between the biological and physical parts of the system. 



refine the field study design and generate 

 increasingly accurate predictions about the 

 behavior of the upwelling system. 



The biological goals of the program are 

 parallel to those of the physical oceanographic 

 program components — i.e., to understand the 

 production processes and their temporal and 

 spatial scales. The approach is the same as 

 that of the program in general. First, the im- 

 portant biological variables in time and space 

 must be defined — especially those of the 

 nutrients and phytoplankton. Naturally, there 

 is interest in the fields of organisms at higher 

 trophic levels, but the prediction of fish popu- 

 lations, for example, is not an initial project 

 goal. The prediction of the fields of phyto- 

 plankton is, however, a fundamental aspect 

 of the biological system and is an early goal 

 of the project. Second, experiments must be 

 carried out to determine the nature of the 

 dominant processes and their rates. Third, the 

 first two aspects must be combined in a bio- 

 logical systems model. Finally, the physical 

 and biological models must be combined in a 

 total ecological systems model. 



Procedures and Equipment 



The general field work design begins with 

 locating the strongest upwelling areas. Auto- 

 mated shipboard equipment makes it possible 

 to collect water continuously at 3 m and 

 throughout the upper levels of the water col- 

 umn to 100 m. While the ship follows a 

 zig-zag course in the upwelling area, the sur- 

 face water can be sampled, and the variables 

 of interest determined. This surface mapping 

 can be done at night, and regular oceano- 

 graphic or productivity stations can be occu- 

 pied during the day to provide water for the 

 biological processes experiments. During sur- 

 face mapping, water enters a sea chest where 

 in situ determinations of temperature and 

 salinity are made. The water then flows to 

 the ship's lab where nutrient and fluorescent 

 determinations are done. The measurements 

 are recorded by a shipboard computer, and 

 surface maps of the variables can be produced 

 as graphic output. 



Intensive onboard experimentation and im- 

 plantment of the oceanographic buoy arrays 



41 



