MALONE: RELATIVE IMPORTANCE OF NANNOPLANKTON AND NETPLANKTON 



when southerly winds prevail. Since both pe- 

 riods are characterized by a downward flux of 

 water (subsidence and downwelling) and low 

 nutrient concentrations in the upper half of the 

 photic zone, they will be consolidated and re- 

 ferred to as the "Oceanic Period." 



The purpose of this study is to document tem- 

 poral and spatial variations in nannoplankton 

 and netplankton productivity and standing crop 

 and to evaluate these variations with respect to 

 dissolved inorganic nitrogen concentrations, 

 vertical water movements, and grazing pres- 

 sure. 



METHODS AND MATERIALS 



Measurements of netplankton and nanno- 

 plankton primary productivity and standing 

 crop were made at 17 stations in the California 

 Current system between lat 35° and 50° N dur- 

 ing July, August, and November 1970, and at 

 California Cooperative Oceanic Fisheries Inves- 

 tigations (CalCOFI) station 3 in Monterey Bay 

 from October 1969 to February 1971 (Figure 1). 

 The latter station is located over the Monterey 

 Submarine Canyon in about 1000 m of water 

 (lat 36°46.8' N, long 122°01' W) . All data were 

 collected during cruises of the RV Proteus (Stan- 

 ford University). 



Netplankton and nannoplankton photosyn- 

 thetic capacities (rate I of carbon fixation as 

 measured by the carboi>14 technique at light 

 saturation), chlorophyll-a concentrations, and 

 cell numbers were estimated from duplicate 

 water samples collected from 2 m below the 

 surface with two Van Dorn bottles. The dupli- 

 cate Van Dorn bottle samples were taken 3 hr 

 before local apparent noon and again 3 hr after 

 local noon. Four light and two dark bottles 

 (a total of 12 125-ml Pyrex bottles) were 

 drawn from each sample, inoculated with hfic 

 of Na2"C03, and incubated under fluorescent 

 light (about 0.06 langley/min) for 2 to 3 hr at 

 sea-surface temperatures (Doty and Oguri, 

 1958). Following incubation, half of the light 

 and dark bottles from each Van Dorn sample 

 were fractionated by passing the water first 

 through Nyte.x-net discs with 22-/n apertures 

 (netplankton) and then through HA Milli- 



FlGURE 1. — stations occupied along transects (1-A, B, 

 2, and 3) of the California Current during July and 

 August (G) and during November (□), 1970; the 

 shaded area represents the transition zone between off- 

 shore and inshore regions. 



pore' filters (nannoplankton). The remaining 

 four light and two dark bottles were HA Milli- 

 pore filtered directly as controls. The filter discs 

 were washed with about 30 ml of filtered sea- 

 water, dried in a CO2 free atmosphere, and their 

 activity measured with a Nuclear Chicago scalar 

 (model 161 A) equipped with a model D47 gas 

 flow chamber with a micromil window. Each 

 filter was counted for at least 5 min, and rates 

 of carbon fixation were calculated as described 

 by Doty and Oguri (1958) after averaging du- 

 plicate light bottle values. Mean coeflicients of 

 variation between duplicate light bottles were 

 6 ± I'^f for the nannoplankton and 26 ± 5% 

 (95';f confidence limits) for the netplankton. 

 The mean coefficient of variation between phy- 

 toplankton productivity values calculated from 

 the sum of the nannoplankton and netplankton 

 fractions and the unfractioned controls was 10 



± 29r. 



' The use of trade names is merely to facilitate de- 

 scriptions; no endorsement is implied. 



801 



