Showing papers in "Canadian Journal of Zoology in 1983"
TL;DR: The structure and function of the gills of freshwater fish are briefly summarized and the responses to low pH are reviewed, with particular reference to the salmonid fishes.
Abstract: The structure and function of the gills of freshwater fish are briefly summarized and the responses to low pH are reviewed, with particular reference to the salmonid fishes. Major influences are se...
276 citations
TL;DR: The most primitive known pterygote terga, wing articulation, wings, and upper leg segments with exites, occur in gigantic Upper Carboniferous Paleodictyoptera, Homoiopteridae, and brief comparisons with Paleozoic Diaphanopterodea, Permothemistida, Ephemeroptera
Abstract: The most primitive known pterygote terga, wing articulation, wings, and upper leg segments with exites, occur in gigantic Upper Carboniferous Paleodictyoptera, Homoiopteridae. Fossil features are u...
261 citations
TL;DR: There is currently only circumstantial evidence for neural or endocrine control of metamorphosis in barnacles, molluscs, hydroids, echinoids, and ascidians in the context of the neurological and behavioral model of stimulus and response.
Abstract: The induction of metamorphosis by environmentally derived cues is reviewed in barnacles, molluscs, hydroids, echinoids, and ascidians in the context of the neurological and behavioral model of stim...
196 citations
TL;DR: Overall, the survivorship of water-breathing fishes was significantly higher than that of bimodal species at 1....
Abstract: Six bimodal and six water-breathing species of fish were exposed to predation by a green heron (Butorides striatus) in a laboratory experiment to examine the hypothesis that aerial predation selects against the evolution and use of air breathing. Tests were performed at 1.6 and 0.5 mg O2∙L−1 ( and 9 Torr, respectively; 1 Torr = 133.322 Pa). Most water breathers avoided the surface at 1.6 mg∙L−1 but not at 0.5 mg∙L−1, where they performed aquatic surface respiration. Most bimodal species breathed air at both oxygen concentrations. The risk of capture increased with proximity to the surface. The prey species responded to the predator by increasing mean depth, decreasing the rate of air breathing or aquatic surface respiration, and avoiding the vicinity of the predator when surfacing. Despite these and other antipredator characteristics, all species were vulnerable to capture in the test situation. Overall, the survivorship of water-breathing fishes was significantly higher than that of bimodal species at 1....
184 citations
TL;DR: Multiple regression analyses of previously published data were performed to describe the effect of variations in body mass and temperature on the rate of oxyge...
Abstract: Multiple regression analyses of previously published data were performed to describe the effect of variations in body mass (M, in grams) and temperature (t, in degrees Celsius) on the rate of oxyge...
171 citations
TL;DR: Female zebrafish become attractive to male conspecifics by means of a specific sex attractant secreted by the ovaries, which motivates them to start a series of courtship actions, by olfaction.
Abstract: Female zebrafish become attractive to male conspecifics by means of a specific sex attractant secreted by the ovaries. This sex attractant consists of steroid glucuronides; most likely a mixture co...
151 citations
TL;DR: A theoretical model is developed to describe the mechanics and energetics of medusae which swim by jet propulsion and leads to four generalizations: the acceleration reaction, not drag, is the dominant fluid force experienced by swimmingmedusae.
Abstract: A theoretical model is developed to describe the mechanics and energetics of medusae which swim by jet propulsion. The model leads to four generalizations: (i) The acceleration reaction, not drag, ...
145 citations
TL;DR: This blind test is the first to demonstrate that fecal analysis can yield reasonable estimates of food eaten by insectivorous bats, but it also indicates the amount of "error" that one can expect in these kinds of analysis.
Abstract: To evaluate the reliability of fecal analysis in determining food habits of insectivorous bats, individual insects were identified to major taxa by the first author, weighed, enumerated, and fed to...
144 citations
TL;DR: Pregnancy rates were predictable from the female dressed weight at rut, but in areas where calves become pregnant, yearlings may have a lower pregnancy rate than expected from their weights.
Abstract: Pregnancy status and dressed weights were obtained from female reindeer killed during autumn and winter in five areas in southern Norway. Body weight, mandible length, and lactation status were obtained from females killed during the hunting season in the same areas. Pregnancy rates (P) were predictable from the female dressed weight at rut (W), from the equation P = 1–e[−0.169(W–21)]. In areas where calves become pregnant, yearlings may have a lower pregnancy rate than expected from their weights.
136 citations
TL;DR: Recruitment of lynx (Lynx canadensis) on Cape Breton Island declined from 1977–1978 through 1979–1980 concurrent with a decrease in snowshoe hare densities.
Abstract: Recruitment of lynx (Lynx canadensis) on Cape Breton Island declined from 1977–1978 through 1979–1980 concurrent with a decrease in snowshoe hare (Lepus americanus) densities. Suppressed recruitmen...
128 citations
TL;DR: Bottlenose dolphins, Tursiops truncatus, can be separated into coastal and offshore ecotypes based upon hemoglobin levels, packed cell volumes and red blood cell counts, the offshore form having higher values for all three measures.
Abstract: Bottlenose dolphins, Tursiops truncatus, can be separated into coastal and offshore ecotypes based upon hemoglobin levels, packed cell volumes, and red blood cell counts, the offshore form having higher values for all three measures. Captive-bred crosses between coastal and offshore types produce animals with intermediate hematologic profiles suggesting a significant genetic basis for these differences.
TL;DR: The problem of unequal catchability among individuals in an open population is discussed in regard to estimates of population size and comparisons are made with minimum number alive techniques which attempt complete enumeration of the population.
Abstract: The problem of unequal catchability among individuals in an open population is discussed in regard to estimates of population size. Properties of the Jolly–Seber (J–S) estimate are clarified and co...
TL;DR: Juvenile steelhead trout and starry flounders were reared 64–76 days under various experimental feeding regimes to determine if feeding periodicity influen...
Abstract: Juvenile steelhead trout (Salmo gairdneri) and starry flounders (Platichthys stellatus) were reared 64–76 days under various experimental feeding regimes to determine if feeding periodicity influenced the production of daily growth increments on the otoliths. Both species produced daily increments when fed thrice daily, daily, or once every 3 days, as well as through 26–32 days of starvation. Daily growth increments were also deposited in vateritic ("crystalline") otoliths, which constituted 27% of the trout sagittae sampled. Feeding frequency affected increment appearance and the incidence of subdaily increments in trout, but not in flounders. The difference in effect was probably due to the higher metabolic rate of trout. Increment deposition in all flounders was far more variable than in trout, and some flounders apparently ceased increment formation altogether.
TL;DR: The seasonal movements of Eidolon helvum, Myonycteris torquata, and Nanonycters veldkampi were studied over a 2-year period in West Africa, indicating that both species migrate at least to the southern Sudanese savanna zone during the wet season.
Abstract: The seasonal movements of Eidolon helvum, Myonycteris torquata, and Nanonycteris veldkampi were studied over a 2-year period in West Africa. During the dry season, E. helvum roosts in at least one large colony (ca. 500 000 individuals) in the southern forest zone of Ivory Coast. Following the birth of young in February, males and females move into the savanna zones, and the progressive establishment and decline of colonies along a south–north axis indicates that E. helvum migrates at least to the Niger River basin by the middle of the wet season (July). During the dry season, both M. torquata and N. veldkampi are absent from savanna sites, but are common in the forest zone. With the onset of the rainy season in March, catch rates of both species increase first at a southern Guinea savanna site and subsequently at a savanna site 400 km to the north, indicating that both species migrate at least to the southern Sudanese savanna zone during the wet season. Both sexes of N. veldkampi migrate, but the migratio...
TL;DR: This study was conducted to determine the swimming velocities and breathing patterns of south-migrating gray whales (Eschrichtius robustus) and to estimate their minimum costs of transport during migration.
Abstract: This study was conducted to determine the swimming velocities and breathing patterns of south-migrating gray whales (Eschrichtius robustus) and to estimate their minimum costs of transport during m...
TL;DR: A negative correlation between colony size and chick fledging weights suggests that colony size may be an important determinant of intercolony differences.
Abstract: Comparison of growth rates and fledging weights recorded for Thick-billed Murre chicks (Uria lomvia) by previous investigators shows that these parameters vary widely between studies. We measured growth rates and fledging weights at four colonies in the Hudson Strait area to examine the magnitude of variation both within and among colonies. Significant variations among years and among different areas of a single colony were detected but found to be less important than colony-specific factors in determining overall variation. A negative correlation between colony size and chick fledging weights suggests that colony size may be an important determinant of intercolony differences.
TL;DR: From an analysis of the trophic dynamics of production, seston energetics, and rates of consumption, it is concluded that the zooplankton released from the reservoir greatly enriches the seston in a narrow size range (105–864 μm) that corresponds to the size of theZooplankington releasedfrom the reservoir and the capture net mesh size ofThe hydropsychids.
Abstract: Production was estimated (size frequency method) for five species of Hydropsychidae and two species of Philopotamidae at two sites on the impounded North Anna River and two sites on the free-flowin...
TL;DR: Humpback whales off Newfoundland in summer formed groupings containing from 1 to over 10 animals, and the size of feeding groups was closely related to the horizontal size of the prey school, whereas nonfeeding humpbacks were generally found in pairs.
Abstract: Humpback whales off Newfoundland in summer formed groupings containing from 1 to over 10 animals. The size of feeding groups was closely related to the horizontal size of the prey school, whereas n...
TL;DR: It is concluded that fish swimming in the gymnotiform mode may be subject to significantly less viscous drag than fish of equivalent size swimming at the same speed in the subcarangiform mode.
Abstract: The kinematics of steady forward swimming in six species of Gymnotidae and three species of Notopteridae are described. All the gymnotids and one notopterid (Xenomystis nigri) are propelled by the action of an undulatory anal fin (gymnotiform mode). Notopterus notopterus and Notopterus chilata employ the body and anal fin as a single propulsive unit and generate a body wave. Rapid bouts of burst swimming activity (e.g., escape responses) are generated by large amplitude motions of the entire body in all species studied. Experimentally determined drag coefficients exceed the theoretical rigid body predicted minimum values for the case of a laminar boundary layer and reasons for this are suggested. Values of the drag coefficient inferred from hydromechanical theory are within 20% of the experimental values. It is concluded that fish swimming in the gymnotiform mode may be subject to significantly less viscous drag than fish of equivalent size swimming at the same speed in the subcarangiform mode. Hydromecha...
TL;DR: In this paper, the scaling of red muscle with body weight and red muscle distribution within the body were compared in seven scombrid fish species to determine relationships between red muscle function and body weight.
Abstract: The scaling of red muscle with body weight and the distribution of red muscle within the body were compared in seven scombrid fish species to determine relationships between red muscle function and...
TL;DR: A trailing study of fisher (Martes pennanti) and marten in the boreal forest of Manitoba showed that both species preferred coniferous ridges and had temporal differences in their habitat use that could be partially explained by their different responses to soft snow cover.
Abstract: A trailing study of fisher (Martes pennanti) and marten (Martes americana) in the boreal forest of Manitoba, conducted over two winters, showed that both species preferred coniferous ridges. They a...
TL;DR: Parameters were fitted to a bioenergetics model to determine the energy budgets of pike from Lac Ste Anne, Alberta and a poor fit was obtained when comparing the predicted ration and growth (from the model) to the estimated ration andgrowth (in the field), indicating that estimates for some budget components were in error.
Abstract: Allocation of energy by northern pike (Esox lucius) to maintenance, growth, and reproduction was estimated by a combination of laboratory and field techniques. Parameters were fitted to a bioenergetics model to determine the energy budgets of pike from Lac Ste Anne, Alberta. A poor fit was obtained when comparing the predicted ration and growth (from the model) to the estimated ration and growth (in the field), indicating that estimates for some budget components were in error. Further examination indicated that field ration data were probably inaccurate, and budgets were then calculated avoiding these data. The relative cost of maintenance was very low for age 0 fish (~60%) and increased with age. Relative allocations to reproduction and growth were similar from ages 1 to 3, although the relative energy allocated to growth declined from age 0 to 1. There were differences between energy budgets of males and females; females ingested 1.1- to 1.3-fold more energy annually than did males, and this extra ener...
TL;DR: During the 1960s Double-crested Cormorants breeding on Lake Huron experienced a decline in numbers and an elevation in body and egg contaminant burdens, and colony size continued to decline in 1973.
Abstract: During the 1960s Double-crested Cormorants breeding on Lake Huron experienced a decline in numbers and an elevation in body and egg contaminant burdens. In 1972 and 1973 the Canadian Wildlife Service visited their colonies to collect demographic data and eggs for residue analysis. In 1972, colonies were small. They suffered high egg breakage and loss (95%) and nearly total reproductive failure (0.06–0.11 young per nest). Eggshells were 23.9% thinner than normal. Clutch size (2.0 ± 1.2 eggs) was low but egg production (4.1 ± 1.9 eggs) appeared normal. Subsequent clutches appeared in 45% of the nests. Levels of DDE (14.5 ± 5.6 ppm, wet weight) and PCBs (23.8 ± 9.6 ppm) in the eggs were higher than in other cormorant populations in Canada. Levels of DDT, DDD, dieldrin, heptachlor epoxide, hexachlorobenzene, and mercury were less than 1 ppm. Organochlorine levels in eggs from Georgian Bay were similar to those from the North Channel, but mercury levels were higher. Colony size continued to decline in 1973, al...
TL;DR: The results show that food-niche breadth is not a species property but is determined by the food resources locally available; neither does it become narrower in larger assemblages nor is it correlated with raptor size.
Abstract: Food-niche relationships of diurnal raptors have been claimed to be shaped by either competitive interactions or opportunistic feeding. We confront these alternatives by analyzing the patterns of p...
TL;DR: Number of days of stream connection in the spring was not significantly correlated with fish species richness in the pools, and a significant correlation was found between species richness and the logarithm of pool area.
Abstract: Fish species richness in floodplain pools results from species addition by spring invasion from the stream and species subtraction by local extinction throughout the summer. Local extinction is the...
TL;DR: Comparative studies have revealed a correlation between mechanisms of yolk synthesis and the breeding patterns of polychaetes with the rate and type of vitellogenesis being related to the frequency of breeding.
Abstract: Two types of oogenesis have evolved in polychaetes: one (extraovarian) in which germ cells are ovulated into the coelomic cavity where they undergo vitellogenesis, and another (intraovarian) in which the germ cells are released from the ovary after or near the completion of vitellogenesis. There are many mechanisms of yolk synthesis and significant variation as to the sources of yolk precursors, their route of entry into developing oocytes, and the oocytic organelles involved in yolk synthesis. The evolution of the coelom and its role in nutrient storage and transfer, as well as the origin of germ cells, are intimately related to the evolution of vitellogenic mechanisms in polychaetes. Comparative studies have revealed a correlation between mechanisms of yolk synthesis and the breeding patterns of polychaetes with the rate and type of vitellogenesis being related to the frequency of breeding. Vitellogenic mechanisms in polychaetes are compared with those of other metazoans in an effort to better understan...
TL;DR: The behaviour, echolocation calls, and distribution of bats in Kootenay, Glacier, and Mount Revelstoke national parks in British Columbia, Canada are studied.
Abstract: We studied the behaviour, echolocation calls, and distribution of bats in Kootenay, Glacier, and Mount Revelstoke national parks in British Columbia, Canada. Presented here are keys for identification of nine species of bats by their echolocation calls as rendered by two different bat-detecting systems. The species involved include Myotis lucifugus, M. evotis, M. volans, M. septentrionalis, M. californicus, Lasionycteris noctivagans, Eptesicus fuscus, Lasiurus cinereus, and L. borealis. The distribution of these species within the three parks was assessed by capturing bats in traps and mist nets and by monitoring of their echolocation calls. Most of the species exploited concentrations of insects around spotlights, providing convenient foci of activity for assessing distribution. Although most species of Myotis were commonly encountered away from the lights, Lasiurus cinereus in Kootenay National Park was only regularly encountered feeding on insects at lights. This species was not detected in Glacier Nat...
TL;DR: Modifications of posterior midgut cells of Rhodnius prolixus following a meal of rabbit blood are described and changes in the rough endoplasmic reticulum and lysosomes and modifications to the apical cell surface appear to coincide with previously described proteinase activity.
Abstract: Modifications of posterior midgut cells of Rhodnius prolixus following a meal of rabbit blood are described. Prominent stacks and whorls of rough endoplasmic reticulum become redistributed following a blood meal but later reform during the postfeeding period. Lysosomes undergo internal structural changes and apparent fluctuations in their number per cell as a result of blood meal ingestion. Before blood feeding, the apical surface of the midgut cells show a typical arrangement of a plasma membrane covered on the lumenal surface by a glycocalyx. After a blood meal, a more complex organisation appears, consisting of two plasma membranes separated by an electron-dense matrix. The lumenal apical membrane proliferates during the digestion period to form loosely organised extracellular membrane layers which may function as a peritrophic membrane. Changes in the rough endoplasmic reticulum and lysosomes and modifications to the apical cell surface appear to coincide with previously described proteinase activity ...
TL;DR: It is found that pairs consisting of TS males and WS females showed biparental care in which the partners made approximately equal investment in feeding nestlings, and explanations for differences in contribution to nestlings between the sexes and between morphs are suggested.
Abstract: We compared relative contributions to nestlings between male and female parents among different pair types in the White-throated Sparrow (Zonotrichia albicollis). The amount of parental contribution between the two main pair types, white-striped (WS) male × tan-striped (TS) female and TS male × WS female, did not differ. However, we found that (a) pairs consisting of TS males and WS females showed biparental care in which the partners made approximately equal investment in feeding nestlings; (b) males of WS male × TS female pair types contributed far less than the female, and far less than a TS male; (c) in WS pairs, males and females contributed about the same as did WS birds in mixed pairings; and (d) secondary TS females nested in territories of already paired WS males, and these females raised young unassisted by a male. We suggest explanations for these differences in contribution to nestlings between the sexes and between morphs, and we discuss optimal reproductive strategies for each sex and morph.
TL;DR: It is suggested that the body form of many pelagic and nektonic fishes reflects a compromise appropriate for good burst-and-coast swimming performance.
Abstract: A simple hydromechanical model is employed to determine the influence of overall body form on intermittent (burst-and-coast) swimming in fish. The optimum fineness ratio with respect to maximizing ...