THE SUCCESS OF REPRODUCTION IN SAGITTA ELEGANS 

 IN THE BAY OF FUNDY AND THE GULF OF ST. LAWRENCE 



By a. G. Huntsman and Margaret E. Reid, 

 University of Toronto. 



The plankton of the Bay of Fundy is very poor in larvae of fishes. 

 The tributary bays or basins, it is true, may contain rather large quanti- 

 ties of fish fry, particularly in the spring and early summer; but the bay 

 itself seems remarkably barren. The larvae that do occur are of those 

 fishes that have attached or demersal eggs. The larvae of fishes with 

 pelagic or floating eggs are noticeably absent. The floating eggs them- 

 selves are common enough, although rarely very abundant. It is 

 reasonable to conclude that the eggs fail to give rise to larvae. 



What are the peculiarities of this region that distinguish it from those 

 coastal waters in which development of these fishes is successful? The 

 Bay of Fundy is noted for its high tides, for its strong tidal currents, 

 and for the prevalence of fogs. We have here a chain of conditions. 

 The shape of the bay and the nature of its connections give full play to 

 tidal action. The resultant swift currents in flowing over shoals and 

 through passages mix the water rather thoroughly from surface to bot- 

 tom, particularly between the group of islands, known as the Western 

 Archipelago, placed at and near the entrance to Passamaquoddy bay. 

 The effect of the mixing is that the surface water is never able to attain 

 a high temperature during the summer. It, therefore, remains cool, 

 and chills the air above it, thus producing the fogs. The surface water 

 is not only kept cool, but is also kept very salt by being constantly mixed 

 with the colder, salter water below. We thus have a correlation between 

 these conditions and the failure in the development of certain fishes. 

 Whether the failure is the result of one of these conditions, or of some 

 factor associated with them, remains to be determined. 



Not only are many fishes affected in this way, but also a number of 

 invertebrates. The medusa, Aglantha, the amphipod, Parathemisto, 

 the schizopod, MeganycHphanes, and the pteropod, Clione, may be men- 

 tioned as species that are to be found in the bay as adults, but that 

 fail to reproduce successfully there, although doing so elsewhere along 

 our coast. It has been stated (Huntsman, 1919, p. 468) that the young 

 of the Chaetognath, Sagitta elegans, are to be found generally along our 

 coast in the summer, but are noticeably few or' lacking in the Bay of 

 Fundy, although the adults are usually to be found there in large numbers. 



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