Effect of freshets on Passamaquoddy plankton 



327 



daily at high water at four difTerent points: (I) near the mouth of the Digdcguash 

 estuary (James Carson's shore); (2) Indian Point at St. Andrews; (3) Mascabin 

 Point in the outer part of Letite Passage; and (4) Wilson's Beach in the outer part 

 of Head Harbour Passage. The results (Fig. 4) showed that the greatest effect at St. 

 Andrews was on August 14, and that there was a clear effect at Wilson's Beach only 

 on August 18. On that same day, the most marked efTect appeared at Mascabm 

 Point. But there was a complexity, which seems to have been owing to the facts that 

 there is on the whole more inward than outward movement through Letite Passage, 

 and that the outflow is largely through the main Head Harbour Passage. Along such 



25 



JAMES CARSON S 



_L 



_L 



_L 



15 



DAYS 



20 



A 



/ 



25 



Fig. 4. Shore salinity at high water at four different points in Passamaquoddy Bay and in the related 

 Passages on successive days in August, 1951, following freshets on August 10 and 19. 



course, Letite Passage and St. Andrews are on opposite shores of the half-way point. 

 When the fresher water was most noticeable at St. Andrews four days after the hea\ icst 

 discharge, there was very slight freshening at Mascabin Point in Letite Passage. But. 

 another four days later, when the freshening was definite at Wilson's Beach, there 

 was a more marked freshening at Mascabin Point. This is evidence that the outflow 

 through Head Harbour Passage, which would be with the ebbing tide, was being 

 carried with flooding tide north to the entrance into Letite Passage. At high tide, 

 therefore, the latter showed a greater efTect from this than did Head Harbour Passage 

 itself. The slighter drop at Mascabin Point on August 17 indicates that the fresher 

 water was issuing from Head Harbour Passage on that day. Entrance of fresher 

 water into the Bay through Letite Passage on August 17 and 18 serves to explain the 



