Analyses 



Water samples for analyses of the chemical and biochemical 

 composition and enzyme activity in particulate matter were 

 filtered onto precombusted (350°C, 12-h) GF/F filters (either 

 2.5 or 4.7 cm diameter depending on analysis) with vacuum <200 

 mm. Filters for ATP and acetone-extracted chlorophyll were 

 extracted immediately. Samples for particulate C and N and 

 biologically available protein were frozen over dessicant at 

 -15°C and for total protein and ETS frozen in liquid N 2 . 



Acetone-extracted chlorophyll was measured f luorometrically 

 according to Yentsch and Menzel (1963). 



Particulate carbon and nitrogen were measured on a Carlo- 

 Erba 1106 CHN analyzer. 



Total protein was extracted with 10% trichloroacetic acid 

 and analyzed by a modified Lowry method (Dortch et al., 1984). 

 Biologically available protein is that part of particulate 

 protein which can be degraded by protease (Mayer et al., 1986). 



ATP was extracted by boiling filters in 0.125 M phosphate 

 buffer with 4 mM EDTA and 20 mM MgCl 2 at pH 7.75 for 5 min. The 

 samples were diluted back to their original volume, centrifuged, 

 decanted into small vials and frozen at -15°C. They were 

 analyzed using the firefly bioluminescence reaction (Karl, 1980). 



Enzymatic respiratory electron transport activity was 

 determined according to Packard (1986). 



Organism Counts 



Samples for bacterial counts were preserved with 4% buffered 

 formalin and stored in the refrigerator until they could be 

 counted. Cell numbers were determined on 10 ml samples from each 

 depth using a DAPI stain and epif luorescence (Porter and Feig, 

 1980) . 



Autotrophic and heterotrophic nanoplankton were counted on 

 the ship with an epif luorescence microscope and distinguished by 

 chlorophyll autof luorescence and primulin fluorescence according 

 to Caron (1983) . 



Microzooplankton and mesozooplankton were screened (35 um) 

 from 70 1 of water from the 3 30 1 Niskins and preserved in 4% 

 buffered formalin. 



Particle Volume and Size Distribution 



The particle volume and size distribution between 1.5 and 25 

 um were measured with a Coulter Electronics ZM particle analyzer. 



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