CAXADIW ri>iIIFTni:^ EXPEDITIOX, WH-Io 



179 



Table F. — Percentage of Copepod content in surface and vertical hauls at Acadia 



station 80, July 27, 4 p.m. 



The next important station is Acadia 83, 20 miles south of St. Pierre island. This 

 station, in its depth (172 metres) and proximity to the south coast of Newfoundland 

 resembles Princess station 41, which was similarly situated with reference to the north 

 shore of the gulf of St. Lawrence (see table VI). The plankton sample in the vertical 

 haul (Acadia 83) consisted of about 85 c.c. of material, but tliis was highly gelatinous 

 and there were only some 1,500 copepods altogether. In the surface haul (15 minutes) 

 the net was weighted so as to sink it to 5 to 10 fathoms; the amount taken was about 

 350 c.c, with excessive numbers of Obelia medusae and young schizopods, and a 

 moderate infiltration of copepods. The plurality of C. finm^rchicus in this tow (65 per 

 cent) corresponds to its normal midnight plurimvun at the same depth, according to 

 Esterly's computations. The agreement is not always so close. At station 86, July 

 28, 11.10 a.m., the subsurface haul yielded 100 per cent of C. finmarchicus, of 

 which 72 per cent belonged to stege V; at this station the temperature fell rapidly 

 from 13"S° C. at the surface to 2'6° at 50 metres, and still further to -0*4° at 75 metres. 

 Perhaps this minimum temperature, in conjunction with the currents, acted tempora- 

 rily as a false bottom, obstructing the normal daylight descent to the deeper strata. 

 The effect of currents upon the vertical migrations of Calanus have been little invest- 

 igated. The area within which Esterly's collections were made was expressly chosen 

 on account of its freedom from tidal currents and storms. 



Table G.— Acadia 83, July 2S, midnight (12.50 a.m.) 



Species. 



Surface. 



C. finmarchicus III . . . 



IV ... 



V . . . 



9 ... 

 Pseudocalanus elongatus. 

 Centropage.'* hamatus ... 



Temora longicorKis 



Anomalocera patersoni . . 



2 

 27 

 35 



1 



10 



100 



Vertical : 160 metres. 



16 



34 



20 



3 



X 



20 

 6 

 1 



100 



Stations 85 to 87 cross the Laurentian Channel and may be compared with Princess 

 stations 45 to 47 (table VII) and AcaMa stations 25 and 26 and 34 and 35 (table X). 



