Papers in Marine Biology and Oceanography, Suppl. to vol. 3 of Deep-Sea Research, pp. 7-11. 



A further example of the patchiness of plankton distribution 



By A. C. Hardy 

 Department of Zoology and Comparative Anatomy, Oxford 



Summary. — 32 consecutive plankton samples were taken by identical tow-nets in a straight line 

 covering a total distance of nearly 11 miles. A marked patchiness was demonstrated for all animals 

 occurring in sufficient numbers. The results are considered in relation to those of some other 

 such samplings already published. 



In JANUARY 1927, when the Royal Research Ships Discovery and William Scoreshv 

 were making a survey of the plankton of the sub-antarctic whaling grounds round 

 the island of South Georgia, two series of consecutive net hauls were taken to find 

 out how patchy in distribution were the main elements in the macroplankton. One 

 series consisted of 23 samples and the other of 48. The results, showing a marked 

 patchiness, particularly in the distribution of Euphausia superba and the amphipod 

 Parathemisto gaudichaudi, were published by Hardy and Gunther (1935, pp. 255- 

 263). A similar series of 32 consecutive samples were taken further to the south in the 

 Bransfield Strait off Graham Land by the Discovery in April of the same year. As 

 this series lay far outside the region of the South Georgia survey the results were 

 not included in the former report and have not hitherto been published. Knowing 

 that Professor Bigelow was much interested in the matter of uneven plankton 

 distribution I have thought that, small as it is, this additional evidence of patchiness 

 might not be an inappropriate contribution to this volume in his honour; I wish it 

 could have been a larger study, but it is the only piece of marine work that I have at 

 the moment ready for immediate publication. 



The series of samples now to be described was taken by the Discovery on April 7ih, 

 1927, at Station 207 which lay some fifteen miles south of Livingstone Island; the 

 exact positions at the beginning and end of the observations were respectively 62° 

 54' 00" S., 59° 50' 30" W. and 62° 49' 30" S., 60° 10' 30" W. The procedure adopted was 

 the same as that on the two earlier occasions except that the nets used were of 70 cm 

 diameter instead of the larger 100 cm diameter nets used formerly; a detailed descrip- 

 tion of these nets (N70H and NIOOH) will be found in Kemp and Hardy (1929. pp. 

 183-185). Two nets, exactly similar to each other in every particular, were used. The 

 first net was lowered away from the starboard quarter and towed just below the surface 

 for exactly 10 minutes at a speed of 2 knots and then hauled in; as this net was coming 

 in, the second net was lowered away from the port quarter and towed for a similar 

 period. Whilst this net was being towed the first net was washed down, the bucket 

 emptied and replaced and the net got ready for reshooting; then as the second net 

 came in at the end of its ten minutes the first net went out again. In this manner the 

 sampling was continued to give a series of 32 consecutive hauls each beginning just 

 as the one before it ended so that a continuous line of observation (except for one four- 

 minute gap) was made over a distance of nearly 11 miles. The sampling began at 

 0300 hrs and ended at 0824 hrs; there was a loss of 4 minutes between sample 30 and 

 31 due to one of the nets being torn and having to be replaced by a new one. At the 



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