328 ^- G. Huntsman 



otherwise anomalous slight drop in salinity at St. Andrews on those days. This would 

 mean that the fresher water was in part making a circuit around Deer Island in its 

 position between the two Passages. 



It will be noted in Fig. 4 that the crest of the fresh water flood was sharp and lasted 

 about a day only, at St. Andrews, while at Wilson's Beach it lasted for two days and 

 was little pronounced. The definite return of Salter water to Head Harbour Passage 

 was on August 20, that is, 1 1 days after the rainfall of August 9. This is in agreement 

 with the data for the rainfall of September 17-18, 1933, which gave no increase in 

 deep salinity at the inner end of Head Harbour Passage until 1 1 days or more later. 



At the time of the freshet in 1951, August 9-10, Calanus finmarchicus was abundant 

 in the passages leading out of Passamaquoddy Bay. There was also a most unusual 

 plankton in the Bay, namely large numbers of Salps, mainly Salpa fusiformis and a few 

 S. zonaria. Salpa seemed to be largely concentrated in the Bay, as Calanus certainly 

 was in Head Harbour Passage. Such differential distribution was shown in tows 

 made at 15 metres depth with a net of No. 5 mesh on August 8 at four stations, which 

 were in the centre of the Bay (CJ, in the middle of Letite Passage (C g), at the inner end 

 (C24) and at the outer end (Qs) of Head Harbour Passage. At these stations in the 

 order given, the numbers of large Calanus and of Salpa respectively were as follows : 

 C4, and 5; Cg, 28 and 0; C24, and 1 ; Qg, 347 and 1. The Salps must have come 

 from the " Gulf Stream " water of the open Atlantic outside the continental slope, 

 but they were, as near-surface forms, concentrated in the Bay, as was the locally 

 produced Aurelia, which is quite in evidence in calm, clear weather. In contrast, 

 Calanus was, as a deep-living form, concentrated in the Passages, as was also Sagitta 

 elegans, another immigrant from the depths of the Gulf of Maine. 



Surface tows were taken daily at Wilson's Beach in the outer part of Head Harbour 

 Passage with net of No. mesh from August 1 1 to 23. The numbers of Calanus in 

 hundreds on successive days were: 347; 312; 712; 125; 372; 108; 34; 23; 6; 

 21; 104; 78; and 525. It will be noted that the number was definitely down by 

 August 17 and lowest on August 19, with marked recovery by August 21. The numbers 

 of 5'flg^///a, although small, show a similar course : 9; 3; 18; 10; 14; 1; 2; 1; 0; 

 2; 2; 5; 17. The freshet seemed to exert an effect in removing Cfl/a«w5 and Sa^/rra 

 from the Passage, beginning perhaps on August 16, reaching a peak on August 19, 

 and passing away by August 23 with full return of these planktonts. The freshet would 

 thus have worked out of the Bay through Head Harbour Passage during a period of 

 six days, centred on the 10th day after the rainfall, or the 9th day after the peak of the 

 discharge into the head of the Bay. 



Euphausiid Crustaceans, of the genera Meganyctiphanes and Thysanoessa, are also 

 indicative of deep indraught from the Gulf of Maine. Like Calanus and Sagitta, 

 they were to be found in Head Harbour Passage at the time of the freshet. They occur 

 in schools and more or less avoid the net, which made their numbers in the plankton 

 hauls less representative of their distribution. The numbers of individuals of those 

 two genera respectively in the hauls of successive days from August 11 to 23 were : 

 1 and 0; and 0; 10 and 4; 1 and 1 ; 14 and 0; 4 and 0; 5 and 1 ; and 0; 451 

 and 3; 29 and 110; 85 and 22; 15 and 4; and 24 and 0. There was thus a marked 

 increase in their numbers on August 19, at the very beginning of the strong resurgence 

 of Salter water as shown at St. Andrews and at Mascabin Point, rather than at Wilson's 

 Beach. It may be inferred that they had been in much greater abundance in deep 



