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Imposex, the manifestation of male morphological sex characters in females of functionally dioecious neogastropod taxa, is an abnormal response to tri-n-butyltin (TBT) contamination introduced to the marine environment in antifouling paints. Since the phenomenon has been thoroughly described only in Atlantic species, a comparative survey of field populations from British Columbia was undertaken, and field studies were carried out to assess the relative value as bioindicators of species in the genus Nucella from the Pacific coast. The majority of neogastropods studied to date have demonstrable signs of imposex, although this leads to sterilization of females in only a few species, depending on differences in the development in females of a palliai vas deferens. Within the Nucella species complex, N. lamellosa, N. canaliculata, and N. emarginata show promise as TBT bioindicators. Only the response of N. emarginata, however, was related to TBT bioaccumulation, based on measurements of a limited number of samples. This is attributed to the apparent irreversibility of imposex, the temporal variability of both environmental levels and tissue burdens of TBT, and the considerably shorter life-span of N. emarginata relative to that of N. lamellosa and N. canaliculata. The geographic distribution of imposex in Nucella spp. suggests that water-borne concentrations of TBT sufficiently high to induce imposex occur over large areas within British Columbia where exchange with oceanic water is limited.

Twenty-one species of marine enchytraeid oligochaetes within the genera Enchytraeus, Grania, Marionina, and Lumbricillus are confirmed as occurring on the Pacific Coast of Canada. Taxonomic reviews with redescriptions where necessary are provided for 48 species, bringing 13 into synonymy. A further three species were left as taxa inquirenda. Marionina is the least homogeneous of the genera, and further species revisions may change the present concept of the genus. Species habitat preference is largely intertidal, often with decomposing algae, but some subtidal species have been found. There appears to be a Pacific regional fauna.

T HE first trained biologist to examine the shores of Baffin Island was Ludwig Kumlien who was a member of the Howgate Polar expedition 1877-8 which wintered in Cumberland Sound (Kumlien, 1879). Previous to his report at least one collection was known, for Hancock (1846) describes a series of shells brought back from Cumberland Sound by "Messrs. Warham and Harrison, masters of whaling vessels belonging to the port of Newcastle". The German polar expedition of 1882-3 also visited Cumberland Sound and the expedition's doctor, W. Schliephake, collected a few shelled animals (Pfeffer, 1886). Most of the specimens from these last two collections were not from the shore but from shallow water and frequently the exact site was not recorded. So far this century there are reports from six expeditions. Occasional marine biological collections were made by the Neptune expedition of 1903-5 to the eastern Arctic (Dall, 1924). T h e reports of the Fifth Thule expedition, 1921-4 also contain scattered records and the Godthaab expedition in 1928 took shore and offshore animals from Totnes Road, Exeter Sound (Riis-Carstensen, 1931). In 1948 E. Grainger brought back some intertidal animals from Frobisher Bay. However, the two most recent collections were those made in 1951 and 1952 by the Calmaw expeditions, organized by the Fisheries Research Board of Canada. From the published reports and a preliminary examination of the Calanus shore collections, it seemed pro'bable that the intertidal fauna north of Cumberland Sound differed from that within the sound. T h e intertidal fauna of the nearby coasts of Greenland is fairly well known, Madsen having described a transition in the intertidal fauna north of Angmagssalik in east Greenland (1936, p. 49) and a similar transition on the west Greenland coast near Upernavik (1940, pp. 7-8). Knowledge of the shore fauna of Cumberland Sound and Totnes Road indicated that the intertidal transition in Baffin Island might be similar to that in Greenland. From June to September 1953, V. C. Wynne-Edwards and the writer visited Frobisher Bay, Pangnirtung, and several other settlements on the east coast of Baffin Island, collecting shore animals and studying the intertidal environment. The shore or intertidal zone was regarded as the region between high and low tidal levels, and animals collected on the shore by hand or hand net are counted as intertidal animals. The terms "littoral", "infralittoral", etc.