BIGELOW: COAST WATER EXPLORATION OF 1913. 337 



that no great change, i. e., no great ingress of water of either northern 

 or Gulf Stream origin had taken place. In both years the plankton 

 of the Gulf was typically boreal. But species which we can safely 

 say are contributed to the fauna of the Gulf by the surface water of 

 the Gulf Stream, i. e., Salpae, and the warm water siphonophores, 

 were distinctly less abundant, and less widespread in the Gulf, in 

 1913 than in 1912. On the other hand, several boreal and Arctic- 

 boreal species, i. e., Limacina balea, Calanus hyperhoreus, Metridia 

 longa, Eucheata norvegica, Eukrohnia hamata, and Aglantha digitale, 

 were more prominent faunally in 1913 than in the preceding summer. 

 And there is good reason to include Euthemisto bispinosa in the Arc- 

 tic-boreal category, judging from its occurrence on the other side of 

 the Atlantic and in the Arctic Ocean (Tesch, 1911). This suggests, of 

 course, that St. Lawrence water was proportionally greater, Gulf 

 Stream water less in amount in the summer of 1913; the plankton 

 thus corroborating the evidence of salinity and temperature (p. 250). 



The general quantitative distribution of the macroplankton was 

 much the same for the two years; but the local differences were far 

 greater in 1912 than in 1913; and nowhere, in the latter year, was the 

 water as barren as the coastal zone east of Penobscot Bay in 1912. 

 Whether or not the very rich plankton which was noted in Ipswich Bay 

 in 1912, was reproduced there in 1913, is not known, because that exact 

 locality was not revisited. 



A question of importance is whether the Gulf as a whole was 

 richer or poorer in macroplankton, i. e. in food for pelagic fish, in 

 1913 than in 1912, and here copepods play the chief role. The 

 actual volumes, and relative number of copepods (p. 329) at corre- 

 sponding stations for the two years are given in the table : — 



Station Station Volume Volume Copepods Copepods 



Averages 5.5 10.3 6S 111 



