FROM 



THE 



ARCHIVES 



Of THE 



WOODS HOLE OCEANOGRAPHIC INST1TUTI6JJ 



WOODS HOLE. MASSACHUSETTS 



PLANKTON OF THE OFFSHORE WATERS OF THE GULF OF MAINE 



By HENRY B. BIGELOW 

 Museum of Comparative Zoology, Harvard University 

 With tables of copepods by C. B. Wilson, and tables of diatoms by Albert Mann 



CONTENTS 



Page 



Introduction 5 



The plankton 15 



Section 1. — General survey of the animal 



plankton (zooplankton) 16 



Vertical distribution 24 



Neritic and oceanic plankton 31 



Seasonal fluctuations in the planktonic 



communities 37 



Immigrant planktonic communities 51 



Tropical visitors 53 



Arctic visitors 59 



Other immigrants 62 



Migrations of pelagic fish eggs and 



larva? 69 



Quantitative distribution 78 



Density of association 90 



Annual variations in abundance 96 



Plankton as food for whales and fishes. 97 



Food of the plankton 106 



The more important groups of plank- 

 tonic animals 112 



MoUusks 112 



Cephalopods 112 



Pteropods 116 



Limacina retroversa 116 



Limacina helicina 125 



Clione limacina 125 



Other pelagic mollusks 129 



Crustaceans 130 



Adult decapods 130 



Pasiphsa 131 



Euphausiids 133 



Thysanoessa inermis 135 



Thysanoessa longicaudata 139 



Thysanoessa gregaria 142 



Thysanoessa raschii 143 



Nematoscelis megalops 146 



Page 

 Section 1. — General survey of the animal 



plankton (zooplankton) — Continued. 

 The more important groups of plank- 

 tonic animals — Continued. 

 Crustaceans — Continued. 

 Euphausiids — Continued. 



Euphausia krohnii 146 



Meganyctiphanes norvegica 147 



Thysanopoda acutifrons 155 



Other euphausiids 155 



Hyperiid amphipods 156 



Euthemisto 156 



Other hyperiids 165 



Hyperia 165 



Hyperoche 165 



Parathemisto oblivia 166 



Oceanic hyperiids 166 



Copepods 167 



Acartia clausi 171 



Acartia longiremis 177 



Acartia tonsa 181 



^Etidius armatus 182 



Anomalocera pattersoni 182 



Asterocheres beecki 187 



Calanus finmarchicus 188 



Calanus gracilis 211 



Calanus hyperboreus 212 



Candacia armata 218 



Centropages bradyi 219 



Centropages hamatus 220 



Centropages typicus 221 



Dacty lopusia thisboides 226 



Dwightia gracilis 226 



Ectinosoma neglectum 227 



Eucalanus attenuatus 228 



Eucalanus elongatus 228 



Euchceta media 230 



1 



