Dolphin was concerned with the Cromwell 

 Current or Equatorial Undercurrent (Knauss 

 and King, 1958) and Doldrums with the Equa- 

 torial Counter cur rent (Knauss and Pepin, 1959). 

 Currents were measured at intervals of 15- 

 20 m. between the surface and 300 m. The 

 usual technique was to nnake measurements 

 from a drifting ship and measure the apparent 

 velocity at different depths from the flow of 

 water past the meter, while at the same time 

 observing by radar the drift of the ship from 

 an anchored taut wire buoy. Ship drift was 

 subtracted vectorially from the nneter reading 

 to give the true velocity. 



The work was supported in part (about 50 

 percent) by the Office of Naval Research. 



Telerecording Bathythermograph 

 (J. W. Snodgrass) 



Support was given to the improvement of 

 the telerecording BT (Snodgrass and Cawley, 

 1957), which is not yet suitable for routine 

 oceanographic work. This work is now being 

 continued by a private manufacturer, who 

 has outlined plans to correct the undue in- 

 stability and hysteresis observed on field 

 trials. 



LIGHT, NUTFUENTS, AND BIOTA: 

 METHODS AND EXPERIMENTS 



It was shown under "Special Operations" 

 that the STOR cruise program included a wide 

 range of observations on submarine light and 

 biota, and this was also the case with chemical 

 nutrients as shown below. This part of the 

 paper gives some inforn-iation about what was 

 done to obtain these data and process them, 

 and it also gives particulars of the laboratory- 

 experimental part of the research program. 

 The next section, "Light, nutrients, and biota: 

 statistical ajialysis of ocean data," shows 

 more clearly the uses to which the data are 

 being put. 



light collecting surface of each detector con- 

 sists of translucent plexiglass which has been 

 abraded with carborundum powder (#180 grit). 

 This surface collects irradiance according 

 to the Lanibert or cosine law. 



The sensitivity of this unit is adequate for 

 photosynthetic studies, i.e., irradiance (down- 

 welling) can be nneasured in the blue-green 

 region of the spectrunn (480 nrip.) down to 

 depths of 100 m. on bright clear days in clear 

 ocean water. Increased sensitivity at low light 

 levels may be obtained by amplifying the 

 signal. 



The circuitry is straightforward and per- 

 mits the measurement of depth and submarine 

 detector signals simultaneously. Each detector 

 output IS measured separately. The selection 

 of the particular detector is made in the 

 vessel's laboratory, and output of detector 

 may be made at any depth in the 0-100, 

 0-120 m. range. Both the depth and detector 

 signals are transmitted simultaneously over 

 a two-wire system. A sea return is used in 

 the detector switching circuitry. 



A paper entitled "A multiple detector ir- 

 radiance nneter and electronic depth sensing 

 unit for use in biological oceanography" is in 

 press in Journal of Marine Research. 



Measurement of Nutrient Concentrations 



(W. H. Thomas) 



This work arose out of the program of 

 physiological experiments with oceanic phyto- 

 plankton (see below, Results v/ ith Gymnodinium), 

 and the general feeling among Pacific ocea- 

 nographers that inorganic phosphorus (phos- 

 phate) concentration is an imperfect measure 

 of availability of plant nutrients in general. 

 Phosphate concentration is routinely deter- 

 mined on STOR cruises, and it was decided 

 that attention should be paid also to nitrate, 

 nitrite, and silicate. 



Modified Submarine Photometer 



(R. W. Holmes and J. M. Snodgrass) 



The importance of submarine daylight in 

 governing photosynthetic rates below the sur- 

 face of the sea has led to the development of 

 a versatile irradiance meter and associated 

 depth sensing element. 



This meter can be used with up to five 

 detectors which may accomnnodate five dif- 

 ferent filters, or which nnay accommodate the 

 same filters and measure horizontal and/or 

 upwelling and downwelling irradiance. The 

 depth sensing component enables depth meas- 

 urements to be made at the same time as 

 irradiance n-ieasurements are being made. The 



Cruise TO-59-2 provided an opportunity for 

 testing measurement methods developed ashore 

 (mainly those of Strickland, 1958) under sea- 

 going conditions. It was found that nitrite and 

 silicate could be measured at sea as satis- 

 factorily as phosphate, although nitrate meas- 

 urement was much more difficult. Vertical 

 distributions of nitrate and silicate resembled 

 those of phosphate; but quantitatively, phos- 

 phate appeared to be a poor index of other 

 nutrients in and above the thernnocline, since 

 ratios of phosphate to nitrate and silicate 

 were very variable. 



The Inter-American Tropical Tuna Com- 

 mission's cruise to the Costa Rica Donne in 

 November 1959 provided 300 frozen water 



25 



