NO. 3583 COPEPODS — GRICE AND HULSEMANlSr 5 



1965). Species considered contaminants in samples collected with 

 Nansen vertical net below 1000 m (in addition to those species 

 listed by Grice and Hulsemann, 1965) are as follows: 



Calamis tcnuicornis Paracalanus denudaius? Scolecithrix nicobarica 



Canthocalanus paiiper Paracalanus nanus Temora discaudata 



Nannocalanus minor Clausocalanus farrani Undinella simplex 



Neocalanus gracilis Euaetideus acutus Lucicutia gaussae 



Undinula darwini Scolecithricella maritima, Candacia catula 



Acrocalanus longicornis new species Paracandacia hispinosa 



Acrocalamis monachxis Scolecithricella species Paracandacia iruncata 



Calocalanus pavo Scolecithrix bradyi Labidocera detruncata 



Calocalanus plumulosus Scolecithrix danae Acartia danae 



In addition to the contaminant species recognized in the NV 

 collections from the Indian Ocean, shallow-hving species were also 

 observed among the copepods in the six Be net samples. To illustrate, 

 14 female Metridia effusa (a new species described below), a relatively 

 large species (1.58-1.79 mm), were foimd in three Be net samples that 

 presumably sampled the 2000-1000 m depth interval; yet this species 

 (18 females) also occured in five NV samples, all of which were 

 collected in depth intervals between 1000 and 200 m. In none of 

 the 12 NV collections obtained between 2000-1000 m was M. effusa 

 observed. It was hkewise absent from the 12 other NV collections 

 obtained below 2000 m. These occurrence records for this species 

 suggest that the depth data for species collected in the 2000-1000 m 

 depth interval by the Be net may not be rehable. For tliis reason 

 we have included in the following discussion of vertical distribution 

 only those species collected by the NV net as we are more famihar 

 with the operation of this particular type of closing net. 



Zooplankton and Copepod Abundance 



The discussion in the following two sections is based on the analy- 

 ses of the NV samples as only these collections were obtained quan- 

 titatively from several depth intervals in the water column and in 

 the same manner as those collections previously analyzed by us 

 from the northeastern Atlantic (Grice and Hulsemann, 1965). 



Displacement volumes. — The displacement volumes of the 

 samples collected by the NV net are shown in figure 2(A). The 

 decrease in zooplankton concentration with increasing depth is clearly 

 evident at all stations but one (station 355). In the depth intervals 

 shown there appeared to be no region along the north-south transect 

 of stations where there were significantly larger or smaller concen- 

 trations of zooplankton. On the contrary, omitting one station 

 (station 347), there was no greater than a four-fold difference between 

 the maximum and minimum concentration within the three depth 

 intervals sampled. This is in contrast to our data (unpublished) on 



