. The Canadian field-naturalist. Natural history. 1997 Notes 663. 1Q0km, Figure 1. The Nueltin Lake collection (site 2) in relation to the downstream collection in Northwest Territories (site 3) and the previous collection in Manitoba (site 1). Nueltin Lake, in a quiet, sandy-bottomed backwater, approximately one-half metre in depth, with some aquatic vegetation. Gasterosteus aculeatus probably spread into the Tyrrell Sea from the Atlantic Ocean shortly after the ice retreated along the Labrador coast about 8000 years BP (McPhail and Lindsey 1970; Crossman and McAllister 1986). Hagen and Moodi
. The Canadian field-naturalist. Natural history. 1997 Notes 663. 1Q0km, Figure 1. The Nueltin Lake collection (site 2) in relation to the downstream collection in Northwest Territories (site 3) and the previous collection in Manitoba (site 1). Nueltin Lake, in a quiet, sandy-bottomed backwater, approximately one-half metre in depth, with some aquatic vegetation. Gasterosteus aculeatus probably spread into the Tyrrell Sea from the Atlantic Ocean shortly after the ice retreated along the Labrador coast about 8000 years BP (McPhail and Lindsey 1970; Crossman and McAllister 1986). Hagen and Moodie (1982) report- ed the species taken up to 410 km from the sea on the east coast, much farther inland than the specimen reported here. Certainly the Nueltin Lake population is not anadromous due to the great distance and physical barriers along the Thlewiaza River. Recent coloniza- tion from the Hudson Bay coast by human transport is unlikely. It is more probable that the species migrated up the Thlewiaza River during the late Holocene, shortly after deglaciation (about 7000 years BP). At that time the Tyrrell Sea extended approximately 120 km farther inland in the Thlewiaza River valley than the present location of the Hudson Bay shoreline, and was less than 140 km from Nueltin Lake (Dyke and Prest 1986). It was also approximately 183 m above the present level of Hudson Bay. Today, Nueltin Lake is 277 m above modern sea level, or 94 m higher than the elevation of the Tyrrell shoreline. Because little isostatic rebound had occurred by 7000 years BP, there prob- ably was even less elevation difference, possibly as little as a few tens of metres (E. Nielsen, personal communication 1996). This would suggest that the species, while rarely collected, is distributed more broadly and much far- ther inland than previously thought. It should be noted that few collections of any type have been made in this area, and those that have been made used methods that do not effectively sample s
Size: 1471px × 1699px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectnaturalhistory, booky
