Life Between Tide-Marks in North America: IIIB. Nova Scotia and Prince Edward Island: The Geographical Features of the Region

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Abstract
The population of the s. Atlantic coast of Nova Scotia and of the Bay of Fundy is a cold-temperate one, inhabiting waters in which the winter temp., while falling well below 10[degree]C, does not usually fall below zero in open water, though doing so locally (especially in inlets) with formation of ice. The s. Gulf of St. Lawrence is a special area affected by massive amounts of ice in winter, but with an almost warm-temperate summer; here the population is modified, though fundamentally of a cold-temperate type. The population of the whole region consists primarily of cold-water n. hemisphere spp., among which are widespread or cosmopolitan forms, including eurythermic southern spp. at the n. end of their range. At least half of the common spp. are circumpolar. About 80% of them also occur in Britain, though there are marked differences between the 2 sides of the Atlantic, exemplified by the absence from the American side of Pelvetia canaliculata, Himanthalia elongata, Littorina neritoides and Patella, and the presence there of spp. not found in Britain. The Nova Scotian (Acadian) region constitutes a distinct geographical province, n. of which lie subarctic and arctic provinces. S. of it lies the coast between Cape Cod and Cape Hatteras, regarded here as an overlap between the Acadian province and the warm-temperate Carolinian province south of Cape Hatteras. S. again of the latter lies the tropical West Indian province, including the Florida Keys. The effects of cold and ice on shore populations in the Acadian province are discussed, and it is shown that while some of them suffer little or no damage from ice, others show a marked reduction due primarily to this cause. Further subjects considered are the characteristics of zonation in the region; the occurrence of Fucaceae and Littorina on the 2 sides of the Atlantic; the local absences of common spp.; and seasonal variation.