28 



RECORDS OF OBSERVATIONS, SCRIPPS INSTITUTION OF OCEMOGRAPHY 



forms, the smaller copepods and nauplii also 

 escape, and the first of these may at times bulk 

 rather large. Also, the relative numbers of 

 nauplii are important indications of the pro- 

 ductive periods in the area (fig. 11). 



In the remainder of the cruises diatoms oc- 

 curred only in moderation and enter seriously 

 into the bulk only where volumes are over 15 

 milliliters as measured by displacement. 



The phytoplankton population will be more 

 fully discussed in separate reports, but a few 

 remarks should be made in passing. In general, 

 the net catches support the findings on distri- 

 bution and abundance as indicated by special 

 study of diatoms. Three factors are brought out 

 rather clearly, (l) The main diatom outbursts 

 are indicated in April and June. During the re- 

 mainder of the cruises only moderate numbers were 

 taken in the net. (2) During the maximum "flow- 

 ering" of diatoms, the phenomenon is not local- 

 ized but occurs over nearly the whole area (ex- 

 cept as indicated below) , as shown by the June 

 cruise. It would appear that the impulse had 

 moved from south in April to the more northerly 

 sections in the later cruises. (3) Only the 

 stations situated inside the main southerly flow 

 of water are productive, that is, the stations 

 characterized by more or less mixed waters. 



Composition of zooplankton. - The zoaplankton 

 is qualitatively very heterogeneous, with euph- 

 ausiids, radiolaria, chaetognaths, Appendicularia, 

 and various invertebrate larvae as important con- 

 stituents. The animal plankton is, however, 

 dominated by the copepods and the present report 

 will be limited mainly to this group, of which 

 at least 91 species in 45 genera were taken. Spe- 

 cies not yet determined are counted as one, though 

 in several instances the genus concerned is known 

 to be made up of several local species, namely the 

 genera Corycaeus, Oithona , and Oncea, together with 

 a few microcalanids. Many, but not all, of the 

 copepods have previously been recorded from this 

 area by Esterly, but the following list, com- 

 piled only in the course of general plankton an- 

 alysis, gives twenty-six species not previously 

 found in this area (starred). At least seven of 

 these are in genera not previously found off this 

 coast. 



fclausi 

 Acartia-idanae* 



STXriONS 4 5 8 



LJj iLhir" ■nsisl. JLuu. 



u 



en lUEs 31 



sn. r s 4 



:i eo IB lu IB IT le a e9 it u vazt so si 



zo 



I CRUISE I? 



JuiLiUlJlL^illJliimalmM 



STA T ■ 9 4 3 t I • ■ U 10 r04 II a 13 E3 Ef El EO II lU IT II a E4 13 ET EMES CMC* 30 SI 



bIUhI^ aU JIi IIbIiI .Bill 



Jr . > . 1 . 



B • »A II a 13 



II 11*11 IT IS 19 E3 ET Eatt EUEI 30 31 



20 g 



Sn. 7 « _8 S_ 



CRUISE 21 



• I M 10 



1, hhB m aiBan 



u » i» !•* !• 16 18 e4 a tr z» mi 



Fig. 11. Numbers of Copepod nauplii, 200- 

 to 0-meter hauls. "E. W. Scripps" Cruises II-VI. 

 Only the stations at which plankton samples were 

 taken are shown. 



aethiopica 

 bipinnata 

 bispinosa * 

 curta 



Candacia 



simplex* 

 tenuimana* 

 '■ varicans* 



p , ,., r lucidus 



Centraugaptilus • nr 



2_E Iporcill 



llus* 



Centropages \ . ^ » 

 ^—^ — l violaceus * 



Chirundina streetsi 



Clausocalanus arcuicornis 



Clytemnestra rostrata 



Ctenocalanus vanus * 



Copilia mirabilis * 



Copilia sp. 



n ffurcifer* 



Corycaeus \ — 



—^ Ispp. 



Euaugaptilus sp.* 



tonsa 



Aegisthus mucronatus * 



Aetideus giesbrechti * 



Arietellus setosus 



r, T r finmarchicus 

 Calanus i -r ■■ ■■ — 



l tenuicornis 



Calocalanus I T • * 



I tenuis* 



Eucalanus 



Euchaeta 



attenuatus 



bungii calif ornicus 



crassus 



elongatus 



sub tenuis 



acuta 



elongata 



media 



prop in qua 



spinifera 



spinosa 



