bluuebunny/crossref_metadata_2025 huggingface dataset:
Diving activity in nursing bearded seal (Erignathus barbatus) pups
Authors: Lydersen Christian , Hammill Mike O. , Kovacs Kit M.
Published: July 2008

In this study we used time-depth recorders to quantify the diving activity of four nursing bearded seal (Erignathus barbatus) pups over a 10-day period. The pups were 4–7 days old at the start of the experiments. Their daily mass gain was 3.3 ± 0.4 kg (mean ± SD). A total of 530 h, which included 6248 dives, was recorded from the four pups. The pups spent an average of 53% of the recorded time in the water and 47% of the time hauled out. When the pups were in the water they were submerged 42% of the time, while 58% of the time was spent at the surface. Most dives were shallow and of short duration. Dive depth and duration were 10 ± 10 m and 62 ± 46 s and the maximum recorded values were 84 m and 5.5 min, respectively. The pups spent more time in the water and increased the number of long dives and the mean dive duration with age. The duration of haul-out intervals where nursing could take place was 1.93 ± 2.01 h, with a recorded maximum of 8.25 h. The time between these haul-out intervals was 2.18 ± 2.44 h, with a maximum of 9.73 h. A diurnal pattern in haul-out activity was documented; pups spent significantly more time hauled out from 07:00 to 10:00 and from 21:00 to 24:00 than during the rest of the day.
Biotype, genomotype, and genotype: variable effects of polyploidy and hybridity on ecological partitioning in a bisexual–unisexual community of salamanders
Authors: Lowcock Leslie A.
Published: July 2008

It is hypothesized that coexistence of bisexual and unisexual salamanders depends upon various forms of ecological partitioning, as in analogous complexes of fishes. The mixture of clonal and nonclonal, obligately sperm-dependent reproduction occurring in unisexual mole salamanders of the genus Ambystoma suggests that some of this partitioning may be manifest in the variable reproductive attributes of different biotypes and in community structure. Within biotypes, ecological differences related to genomic composition (genomotype) and specific origin (genotype) of individuals are also expected. Using data gathered over a 4-year period from a large population of the A. laterale–jeffersonianum complex from Haliburton, Ontario, I examined four areas of reproductive ecology that may contribute to ecological partitioning: (1) fluctuating sex, hybrid, and ploidy ratios; (2) differential migratory response by triploid and tetraploid genomotypes; (3) ontogenetic differences among triploid and tetraploid genomotypes; and (4) genotypic differences within unisexual genomotypes. For each case I was able to reject a null hypothesis ascribing ecological equivalency to those biotypes involved. The most germane ecological differences among unisexuals were imbedded in the broad syndrome of delays in larval development, metamorphosis, and sexual maturity displayed by tetraploids. These findings parallel those reported in a large body of literature generated from laboratory studies of polyploid salamanders. Using these corresponding data, I conducted a broad review of potential developmental, physiological, and biotypic causes and consequences of the observed delays. The results indicated that several effects of polyploidy and hybridity directly influence community ecology and contribute to stable coexistence of bisexuals and unisexuals. Based on these findings, a strategic model summarizing interaction in these communities was constructed, from which testable hypotheses may be derived for future research. The findings of this study confirmed the ontological status of the biotypic distinctions (genomotype versus genotype) advanced here.
Comportement sexuel et stratégie reproductrice chez le Chryseida bennetti Burks (Hymenoptera: Eurytomidae), parasitoïde de la bruche du haricot. I. Effet de l'âge des partenaires
Authors: Pérez-Lachaud Gabriela , Campan Mireille
Published: July 2008

This paper relates a female age effect to the mating behavior of Chryseida bennetti Burks, an ectoparasitoid of the bean weevil (Acanthoscelides obtectus (Say)). The sexual behavior includes rapid courtship and copulation followed by a postmating courtship behavior ("guarding"). Male guarding behavior varies according to the females' age, with males guarding females of 2–3 days old longer than younger and older females. A period of sexual maturation is necessary for most of the males. Females' attractiveness begins at the pupal stage, and their receptivity on emergence. Mated females are still attractive to males. Multiple matings (up to four copulations) with the same male have been observed. The females' age seems to control copulation frequency and the duration of the postmating courtship behavior. Two- and three-day-old females had more successive multiple matings with the same male than the other females did, and males spent much more time guarding them. The age of the males (except from newly emerged males) did not seem to influence copulation frequency. On the other hand, the complexity of the sequential courtship behavior increased with the age of the partners. The function of males' postmating courtship is discussed.
Individual and geographical variation in pigmentation patterns of the harbour porpoise, Phocoena phocoena (L.)
Authors: Koopman H. N. , Gaskin D. E.
Published: July 2008

Photographs of 393 harbour porpoises (Phocoena phocoena (L.)) from the waters of Denmark (n = 224), Japan (n = 19), and Canada (Bay of Fundy (n = 95), Gulf of St. Lawrence (n = 40), and coast of British Columbia (n = 15)) were analyzed for variation in pigmentation patterns. Animals were classified according to morphs of each of 12 pigmentation characters. Patterns were not unique to particular areas and cannot be used as a tool for absolute discrimination among geographically isolated groups of porpoises. However, statistical frequencies of certain morphs of seven characters varied significantly among the five geographical groups, matching some of the subpopulations proposed by Gaskin in 1984. Pigmentation patterns of harbour porpoises were unique to each animal and were not gender dependent. Variation in pigmentation patterns may have implications for intra-individual recognition. All porpoises showed bilaterally asymmetrical pigmentation, providing a new record of consistent asymmetry in an odontocete species.
Changes in female colour across the ovulatory cycle in the brook stickleback, Culaea inconstans (Kirtland)
Authors: McLennan Deborah A.
Published: July 2008

The colour signal of the female brook stickleback (Culaea inconstans) is a mosaic of five components: intensity (1) and distribution (2) of black colouration on the body, presence or absence of gold colouration on the body (3), degree of development of the black eye bar (4), and colour intensity of the black dorsal spines (5). These components interact to produce three mosaics corresponding to the stage reached by a female in her ovulatory cycle. Nonbreeding individuals display a silver ventral surface, grey–green dorsal and lateral surfaces bearing dark grey, reticulate variegations, no eye bars, and noncoloured fins and spines. Interspawning-interval females develop a silvery gold ventral surface, light grey, spotted dorsal and lateral surfaces, narrow eye bars, noncoloured fins, and dark spines. The intensity of a female's body and spine colour is positively correlated with her aggressive response to an intruding male. Spine colour intensity is also positively correlated with her aggressive response to an intruding female. Courting females project a distinct signal comprising a pink–gold body, medium grey dorsal and lateral swirls, no eye bars, and noncoloured fins and spines. The golden courting female contrasts with the velvety black courting male, enhancing the exchange of information about species, sex, and sexual motivation via the two nuptial signals.
Larval development of the parasitic copepod Salmincola edwardsii on brook trout (Salvelinus fontinalis)
Authors: Conley David C. , Curtis Mark A.
Published: July 2008

We conducted laboratory experiments to determine the developmental time from larva to adult of the parasitic copepod Salmincola edwardsii on brook trout (Salvelinus fontinalis) at 13 °C. Healthy fingerlings were exposed to large doses of recently hatched copepodids for 12 h. Three infected fingerlings were sacrificed at 12-h intervals until day 6 and then at 24-h intervals until day 20 postexposure. The gills, opercula, and pectoral fins were the major sites of attachment. Adult males were detected as early as day 3 and as late as day 8 postexposure, with the greatest number occurring about day 5. Adult males may live for up to 3 days at 13 °C. Adult females were detected as early as day 11 postexposure but not consistently until day 13, indicating that permanent bulla attachment took place between 11 and 16 days postexposure. Infection intensity declined rapidly until day 9 postexposure then less quickly for the rest of the experiment.
Costs of bot fly infection in white-footed mice: energy and mass flow
Authors: Munger James C. , Karasov William H.
Published: July 2008

We quantified the impact of bot fly larvae (Cuterebra fontinella) on the energy budget of their small-mammal hosts (white-footed mice, Peromyscus leucopus). We estimated the fluxes of water from the host to the parasite and from the parasite to the host by injecting infected hosts (or bot fly larvae) with tritiated water and measuring the uptake by the parasite (or the host). Using these fluxes, we then constructed a fluid flux budget for the host–parasite system, and estimated that a bot fly larva receives ca. 1% of the host's nutrient budget. We also found a 5% increase in the metabolic rate of infected hosts in the laboratory, but no such effect in the field. No effect of bot fly larvae on digestive efficiency or food consumption was detected; however, infected mice lost body mass during a field trial. We conclude that bot fly larvae have a relatively modest effect, although energetically stressed individuals, such as lactating females, could suffer substantially.
Organochlorine residues in harp seals, Phoca groenlandica, from the Gulf of St. Lawrence and Hudson Strait: an evaluation of contaminant concentrations and burdens
Authors: Beck Gregor Gilpin , Smith Thomas G. , Addison Richard F.
Published: July 2008

We evaluated organochlorine contaminant concentrations and burdens in blubber samples from 50 harp seals (Phoca groenlandica) obtained from the estuary and northern Gulf of St. Lawrence and Hudson Strait, Canada, between December 1988 and December 1989. The concentration and burden of PCBs increased significantly during the winter months for males occupying the St. Lawrence estuary. The potential for rapid accumulation of contaminants in the estuary was also observed among females: nine postpartum females (1 month after weaning) had higher organochlorine levels than prepartum females from the same location. The lowest observed contaminant concentrations and burdens were in seals from Hudson Strait in autumn. In winter specimens, males had DDT and PCB concentrations about 4 and 2 times as great, respectively, as females of similar age distribution and collection date. Congeners with IUPAC Nos. 138 and 153 accounted for more than 50% of total identifiable PCBs, which is consistent with their prevalence in other marine biota. The concentration of PCBs has declined and the percent p,p′-DDE of total DDT has increased between 1982 and the present study. Unlike the beluga whale (Delphinapterus leucas), harp seals occupy the more polluted waters of the estuary only seasonally, and this may account for their lower residue concentrations.
Keratin polypeptides in the epidermis of the larval (ammocoete) sea lamprey, Petromyzon marinus L., show a cell type-specific immunolocalization
Authors: Alarcón V. B. , Filosa M. F. , Youson J. H.
Published: July 2008

Using immunofluorescent staining, the localization of keratin polypeptides in the epidermis of the larval (ammocoete) sea lamprey, Petromyzon marinus L., is described. Immunostaining with monoclonal antibodies against human keratin polypeptides showed that immunoreactivity was distributed in a cell type-specific pattern among the epidermal cells of ammocoete skin: immunoreactivity for keratin polypeptides Nos. 7 and 18 was prominent in skein and granular cells, respectively, while that for keratin polypeptide No. 19 was in cytoplasmic regions near the plasma membrane of both specialized (skein, granular, and mucous) and germinal cells. Positive immunostaining with a polyclonal antibody against bovine keratins suggests that there are other, as yet unidentified, keratin polypeptides in the epidermis. The significance of keratins as molecular markers of epidermal development is discussed.
Spawning patterns and interspecific matings of sympatric white (Catostomus commersoni) and longnose (C. catostomus) suckers from the Gouin reservoir system, Quebec
Authors: Dion R. , Richardson M. , Roy L. , Whoriskey F. G.
Published: July 2008

White (Catostomus commersoni) and longnose (C. catostomus) suckers from the Gouin reservoir, Quebec, and a small upstream lake (Lac des Cinq Miles) spawned in the same stream. White suckers numerically dominated the runs in all years; however, abundances of both species decreased eightfold during a year when the reservoir level was lowered for maintenance. Return rates of individuals of both species tagged during the spawning run were poor in the following year, and only a few fish (<0.6%) skipped a year to spawn 2 years later. Although some individuals of both species occurred at all monitored spawning areas, white suckers concentrated their spawning activity over sites with boulders, whereas longnose suckers were most abundant over gravel. Differences in the courtship behaviour of the two species initially discouraged interspecific matings. However, white sucker males ultimately participated in 32% of the female longnose sucker matings, though spawning of male longnose suckers with female white suckers was not observed. White suckers spawned in groups or in pairs, whereas in all instances longnose suckers spawned with two or more males.
Climate, trophic factors, and breeding patterns of the Nile grass rat (Arvicanthis niloticus solatus): a 5-year study in the Sahelian region of Burkina Faso (formerly Upper Volta)
Authors: Sicard Bruno , Maurel Daniel , Fuminier Frédéric , Boissin Jean
Published: July 2008

From 1984 to 1989, five populations of the Nile grass rat, Arvicanthis niloticus solatus, living in five different habitats of the Sahelian region were studied in northern Burkina Faso (Oursi, 14°N). The following were investigated: (i) seasonal variations in the percentages of sexually active males and females and the percentage of the population less than 6 weeks old, and (ii) seasonal variations in testis and seminal vesicle masses and plasma testosterone levels in adults. Both the large form of A. niloticus occupying habitats with stable trophic resources and the small form of the species occupying habitats with fluctuating resources showed seasonal breeding, mainly in the dry season, in contrast with what we have observed elsewhere in other species in this region. In dry years with normal rainfall (rains between June and September), breeding occurred from mid-October to mid-July in habitats with constant trophic resources and from mid-October to mid-April in habitats with fluctuating resources. In 1986, a year with exceptional rainfall (additional rains in January), breeding was continuous in habitats where this climatic disturbance caused a reappearance of primary production and there was a population outbreak of A. n. solatus. Relationships between (i) breeding cycles, (ii) long-day periods, which have a gonadoinhibitory effect, (iii) seasonal variations in relative humidity and temperature, and (iv) dietary characteristics of A. n. solatus suggest that this subspecies is capable of breeding throughout the year. This is due to its adaptable dietary habits, which allow it to take advantage of resources that are either constant (insects, harvest wastes, and the water-rich bark of certain woody plants) or seasonal (rain-dependent herbaceous plants and farm vegetables). The end of breeding appears to be related to the relative timing of the stimulatory effect of certain foods and the inhibitory effects of photoperiod, temperature, and humidity. Under this hypothesis, the gonadoinhibitory effect of long days was masked in 1986 by an earlier stimulatory effect related to the reappearance of vegetation following the exceptionally heavy rainfall in January.
Field metabolic rate of blue grouse during winter
Authors: Pekins Peter J. , Gessaman James A. , Lindzey Frederick G.
Published: July 2008

We measured the field metabolic rate (FMR) of seven free-ranging and two captive blue grouse (Dendragapus obscurus) with doubly labeled water. Average carbon dioxide production (1.016 ± 0.088 L CO2∙kg−0.734∙h−1) of free-ranging grouse was 8% higher but not significantly different (P < 0.05) from captive grouse (0.944 ± 0.058 L CO2∙kg−0.734∙h−1). Ambient temperature was not correlated with FMR (P = 0.268). The mean fat content of free-ranging blue grouse was 39 g (3.4%), which was equal to the energy equivalent of about 3× daily standard metabolie rate (SMR). The FMR of free-ranging grouse averaged 657 ± 62 kJ/d or 1.6 × SMR. The FMRs of free-ranging blue grouse averaged about 25% below FMRs predicted from allometric equations; most were 35–40% below those predicted. We suggest that there is little energetic constraint on blue grouse during winter because they are able to maintain a positive energy balance by minimizing energy costs through effective thermoregulation, microhabitat selection, and reduced activity.
Long-term effects of malnutrition on reproduction: a laboratory study with meadow voles, Microtus pennsylvanicus, and red-backed voles, Clethrionomys gapperi
Authors: Bondrup-Nielsen Søren , Foley Peter M.
Published: July 2008

Infant malnutrition has long-term behavioural effects. We determined the long-term effects of infant malnutrition on reproduction in meadow voles (Microtus pennsylvanicus) and red-backed voles (Clethrionomys gapperi). Experimental animals received standard diets diluted with cornstarch (2:1) during a combination of the following periods: gestation, lactation, and for 3 weeks postweaning. Growth and reproduction of these animals were compared with those of control individuals. During the administration of starch-diluted diets growth was retarded but subjects experienced "catch-up" once they were put on normal diets. Effects on reproduction of individuals that had experienced malnutrition as infants were minimal. Litter size was greater (both species), the proportion of females reproducing was greater (meadow voles), and birth mass was greater (meadow voles), but the growth rate of offspring was slightly lower (both species), for females malnourished as infants. The ecological implications of infant malnutrition are discussed.
Influence of crude oil and pulp and paper mill effluent on mixed infections of Trichodina cottidarium and T. saintjohnsi (Ciliophora) parasitizing Myoxocephalus octodecemspinosus and M. scorpius
Authors: Khan R. A. , Barker D. E. , Williams-Ryan K. , Hooper R. G.
Published: July 2008

Samples of longhorn sculpin (Myoxocephalus octodecemspinosus) were exposed to sediment contaminated with crude oil or pulp and paper mill effluent for periods up to 13 months in the laboratory. Other samples were collected at sites where crude oil or effluent from a pulp and paper mill are discharged. The intensity of gill infections of Trichodina spp. on exposed fish was significantly higher than on controls 5, 9, and 13 months after exposure. The intensity of the ciliates was also greater on sculpins collected near an oil-receiving terminal than on those sampled 5 km from the polluted site. Field collections of longhorn and shorthorn (Myoxocephalus scorpius) sculpins at and distant from a pulp and paper mill had high and low intensities of the ciliates, respectively. Similarly, the intensity of trichodinid ciliates was also significantly greater in longhorn sculpins exposed to effluent-contaminated sediment than in controls 5 months after exposure. The results suggest that the intensity of gill-inhibiting species such as trichodinids in susceptible fish hosts increases after chronic exposure to crude oil and to pulp and paper mill effluent, and the parasites may serve as indicators of pollution.
The hemocytes of the mealybugs Phenacoccus manihoti and Planococcus citri (Insecta: Homoptera) and their role in capsule formation
Authors: Russo Jacqueline , Allo Marie-Rose , Nenon Jean-Pierre , Brehélin Michel
Published: July 2008

Hemocytes of Phenacoccus manihoti and Planococcus citri were studied to determine general ultrastructure, phenoloxidase activity, and the presence or absence of a glycocalyx. Prohemocytes, oenocytoids, and granular hemocytes of types 1 (GH1), 2 (GH2), and 3 (GH3) were observed in P. manihoti. In P. citri we observed only GH2 and GH3 (macrophage-like cells). In addition to these hemocyte types, other cells that we believe to be fat-body cells were also observed free in the hemolymph. There was evidence of phenoloxidase activity in GH2 and GH3. The intensity of this reaction increased after parasitization of P. manihoti by the wasp Epidinocarsis lopezi. In most hemocyte types the glycocalyx was very little developed. In P. manihoti, lysis of hemocytes was observed in the vicinity of the parasitoid larva, leading to the formation of a capsule.
Données préliminaires sur la taille, la croissance et la longévité du varan du Nil (Varanus niloticus) dans la région du lac Tchad
Authors: Buffrénil Vivian de , Chabanet Claire , Castanet Jaques
Published: July 2008

A sample of 288 Nile varanids, including only adults and subadults (153 males and 135 females), was collected in the Tchadian part of Lake Tchad where the species is regularly exploited. Each animal was measured (L, total length; MC, snout–vent length) and weighed, and its age was determined by the skeletochronological technique. No information of this sort, collected on a wide sample, was hitherto available. For the age-classes studied, the most representative sizes in the population (the medians being considered) were close to 155 cm for males and 134 cm for females, with respective masses of about 5 and 3 kg. The difference between sexes was highly significant. Conversely, age structure in the samples were not significantly different among sexes (except for one age-class: 4 years). The longevity of these lizards is about 8 years in the Lake Tchad region. The relationship between tail length and snout–vent length shows similar tendencies in both sexes (Q = 1.06MC + 21.48). The tail becomes proportionally shorter with growth. Both sexes also display similar tendencies for the relationship between total length and mass (M = 8.131E − 9L3.992 − 8.131E − 9(213..992) + 0.034). Body growth in the Nile varanids corresponds to a model derived from Von Bertalanffy's general model: L = K(1 − e−b(age)) + a. Growth of males is faster and steadier than that of females. Males reach their asymptotic size (207 cm) at a later age (9 years) than the females (154.8 cm reached at age 6 years). Though comparative data are very scarce, the growth rate in the animals examined seems high compared with that of other large species of varanids, especially Varanus komodoensis.
Observations on a motile prelarva in Chaussieria venustissima (Berlese, 1882) (Acari: Anystidae), with a description of the larva
Authors: Otto J. C. , Olomski R.
Published: July 2008

The mite Chaussieria venustissima (Berlese) was reared from the egg to the larva. The prelarva is motile for a period of 1–5 h. It does not feed and shows negative phototaxis. It is the third known elattostasic prelarva. On the basis of existing phylogenies the presence of a motile prelarva can be explained either by convergent evolution that has occurred at least twice or by numerous convergent reductions. The prelarva may use motility to escape desiccation in its dry habitat. It may be led to moist habitats (cracks, vegetation) by its negative phototaxis. The prelarva possesses eyes, five pairs of dorsal setae, sickle-shaped tarsal claws, and a prominent Claparède's organ.
Life cycle of Crenosoma petrowi (Nematoda: Metastrongyloidea) from black bears (Ursus americanus)
Authors: Addison Edward M. , Fraser Grant A.
Published: July 2008

First-stage larvae of Crenosoma petrowi Morozov, 1939 from feces of black bears (Ursus americanus) developed to the third stage in the gastropod Mesodon thyroidus. In snails held at 23.5 °C, the first and second moults occurred on days 6–7 and 9–11, respectively, after infection. The prepatent period of C. petrowi was 19–25 days in five experimentally infected black bears. Both times of first and second moults and the prepatent periods are similar among species of Crenosoma. Crenosoma petrowi did not produce patent infections in, and no nematodes were recovered from, experimentally infected striped skunks (Mephitis mephitis), raccoons (Procyon lotor), or red foxes (Vulpes vulpes).
Summer foraging ecology of wapiti (Cervus elaphus roosevelti) in the Mount St. Helens blast zone
Authors: Merrill Evelyn H.
Published: July 2008

Summer–fall foraging behavior of wapiti was studied relative to seasonal changes in forage resources in early successional forests of the Mount St. Helens "blast zone." Seasonal changes in diet, plant community selection, and foraging behavior of wapiti were generally consistent with hypothesized ingestive and processing constraints on a large-bodied ruminant. When high-quality forage was abundant early in the growing season, forbs dominated in wapiti diets probably because of their high digestibility and cell-wall breakdown rates. As forb biomass declined, wapiti initially maintained a high intake of forbs by increasing search rates (m/min). Eventually wapiti switched to grasses, with consequent decreases in feeding time and increases in rumination time. Selection of plant communities by wapiti was related to the standing crop (kg/ha) of forage only in the fall, when grasses were the preferred forage type. Cover and spacing needs during calving and the influence of forage structure on intake rates and plant community selection are discussed.
Genetics and biological fitness of a beige elytral mutant of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)
Authors: Boiteau G. , Tai G. C. C. , Drew M. E.
Published: July 2008

A beige elytral mutant of the Colorado potato beetle, Leptinotarsa decemlineata (Say), has been isolated for the first time. The inheritance of the beige mutation is controlled by two dominant genes, both of which are required for the expression of the color. The mutation could be maintained at a low rate in the wild population by the presence of one of the two genes. The lower biological fitness of the beige mutant, characterized by a longer mean total development time and lower fertility, is demonstrated. The data suggest that the melanization of markings on different areas of the body of the Colorado potato beetle are under the control of different genes. This study suggests that the previous presumption that other elytral anomalies were nongenetic in origin may be in question.
Predation by the naticid gastropod Polinices lewisii (Gould) on littleneck clams Protothaca staminea (Conrad) in British Columbia
Authors: Peitso Eija , Hui Elizabeth , Hartwick Brian , Bourne Neil
Published: July 2008

Feeding rates and prey-size selection of the predatory naticid snail Polinices lewisii (Gould) on the littleneck clam Protothaca staminea (Conrad) were studied on the west coast of British Columbia. Caging experiments indicated that few clams of the smallest size class (10–35 mm shell length) were drilled by Polinices lewisii; predation was heaviest on clams in the size range 35–50 mm. Feeding rates of P. lewisii did not vary significantly over the range of densities provided in field experiments, nor were they influenced by the close proximity of other moon snails. Feeding rates were relatively low. Summer feeding rates of P. lewisii indicated a correlation with respect to snail size, and results from the annual study indicated a seasonal trend towards reduced consumption during the winter months. Polinices lewisii, feeding on P. staminea, was estimated to eat 0.1% of its own dry mass per day. Information from recovered shells of drilled clams showed that the diameter of boreholes was correlated with snail length but only poorly correlated with shell thickness. Boreholes on valves of P. staminea were found mainly in the umbo region. No strong preference for either left or right valve was observed. Random sampling of field populations indicated that prédation by P. lewisii was a minor source of mortality in P. staminea populations at Ladysmith Harbour, British Columbia, Canada.
Mass change in fasting immature male northern fur seals
Authors: Baker Jason D. , Fowler Charles W. , Antonelis George A.
Published: July 2008

Immature male northern fur seals (Callorhinus ursinus) lost an estimated 20–30% of their body mass while fasting during the breeding season on St. Paul Island, Alaska. This is somewhat less than the mass loss reported for territorial adult male pinnipeds. During fasting, absolute rates of mass change (averaging −0.68 kg∙day−1) were positively correlated with initial mass. Mass-specific rate of change (averaging 2%∙day−1) did not vary with age or initial mass. Although they lose large amounts of mass while fasting, immature male fur seals achieve a net increase in mass during the breeding season by making feeding trips to sea. We postulate that the capability for prolonged fasting in immature males facilitates the development of social and sexual skills that are likely to increase future reproductive success.
Size, condition, and territory ownership in male tree swallows (Tachycineta bicolor)
Authors: Lozano George A.
Published: July 2008

Male tree swallow (Tachycineta bicolor) territory owners and floaters were compared in terms of size and nutritional condition to test the resource holding potential hypothesis. Owners were larger than floaters when compared using six morphological measurements. There were no differences in dry mass, ash, or fat content, but territory owners were heavier and had larger protein reserves than floaters. Territory owners may be those individuals who win intrasexual conflicts for the possession of nest boxes, or those who, because of their better nutritional condition, can arrive at the breeding grounds earlier to secure a territory.
Egg production in Arctic charr (Salvelinus alpinus L.) broodstock: effects of photoperiod on the timing of ovulation and egg quality
Authors: Gillet C.
Published: July 2008

Arctic charr were subjected to different photoperiod manipulations applied at several stages of the reproductive cycle to advance or delay ovulation. Spawning was delayed by 6 weeks when the fish were subjected to long days (17 h light: 7 h dark) from midsummer. Ovulations were spread over a period of 2.5 months if fish were maintained under a long-day regime until spawning. When the long-day treatment was stopped in December, ovulations were synchronized to within 1 month. Long days early in the year followed by short days at the beginning of summer advanced spawning by 3 months. Immature, 20-monfh-old fish maintained in constant long days from 1 October started to spawn at the beginning of the following summer, i.e., 6 months before fish kept in a natural light period. The eggs produced in January by females with delayed ovulation were of better quality than those of fish kept in a natural day length in December. This improvement was probably due to a decrease in water temperature from 8 to 6 °C between December and January, since overripening of the ova was reduced when the temperature was decreased. It seems possible that by manipulating the photoperiod, viable eggs can be obtained from Arctic charr broodstock all year round provided the cold-water requirement of spawners is taken into account.
Taxonomy, distribution, and ecology of the freshwater bryozoans (Ectoprocta) of eastern Canada
Authors: Ricciardi Anthony , Reiswig Henry M.
Published: July 2008

The freshwater Bryozoa (Ectoprocta) are one of the most poorly known faunal groups in Canada. A recent survey of 80 freshwater habitats in eastern Canada (from Ontario to Newfoundland) revealed 14 species of bryozoans, representing 56% of described species in North America. The greatest numbers of species and specimens were found in alkaline waters (pH 7.0–9.8) near lake outflows, wherever hard substrates were present. Paludicella articulata, Cristatella mucedo, Fredericella indica, and Plumatella fungosa are among the most frequently encountered, widely distributed, and eurytopic species. Pottsiella erecta and Plumatella fruticosa are rare, and new to eastern Canada. Lophopodella carteri, an exotic Asian species discovered in Lake Erie in the early 1930s, has become firmly established in the lower Ottawa and upper St. Lawrence rivers. Detailed notes on taxonomy, morphology, distribution, and ecology are given for each bryozoan. New limits of tolerance to water temperature, pH, and calcium and magnesium hardness are established for several species. A taxonomic key to the freshwater bryozoans of eastern Canada, including a key to statoblast types, is presented for the first time.
Population trend of the Yellowstone grizzly bear as estimated from reproductive and survival rates
Authors: Eberhardt L. L. , Blanchard B. M. , Knight R. R.
Published: July 2008

The trend of the Yellowstone grizzly bear (Ursus arctos horribilis) population was estimated using reproductive rates calculated from 22 individual females and survival rates from 400 female bear-years. The point estimate of the rate of increase was 4.6%, with 95% confidence limits of 0 and 9%. Caution in interpreting this result is advised because of possible biases in the population parameter estimates. The main prospects for improving present knowledge of the population trend appear to be further study of possible biases in the parameter estimates, and the continued use of radiotelemetry to increase the number of samples on which the estimates are based.
Chromosome polymorphism of Atlantic salmon (Salmo salar) from the River Dzwina, Baltic Sea Basin: arm length and NOR location variation of the eighth chromosome
Authors: Woznicki Pawel , Jankun Malgorzata
Published: July 2008

A population of Atlantic salmon from the River Dzwina was karyotyped using conventional staining and banding techniques. The chromosome number was 2n = 58, and the chromosome arm number (NF) was 74. Variation in the size of the long arm of the eighth chromosome pair was observed. The presence of constitutive heterochromatin on this arm was confirmed by C-banding. Silver banding revealed variability in the location of nucleolus organizer regions (NORs) on this arm. Four cytotypes and three phenotypes of the NOR-bearing chromosome were found. The polymorphism of the eighth metacentric pair of chromosomes observed in Atlantic salmon was probably due to deletion and paracentric inversion of the arm involved.
A proposed technique for quantifying muscle progesterone content in minke whales (Balaenoptera acutorostrata)
Authors: Yoshioka Motoi , Okumura Takuji , Aida Katsumi , Fujise Yoshihiro
Published: July 2008

We have developed a new technique for the quantitative extraction of progesterone from very small pieces of muscle tissue of minke whales (Balaenoptera acutorostrata) post mortem. Ethanol extracts of approximately 0.5 g of tissue contained, on average, 15.3 ng/g progesterone in the case of pregnant females (SD = 12.7, n = 9) and 0.32 ng/g progesterone in the case of immature females (SD = 0.03, n = 9). Differences in muscle progesterone levels between females in the two reproductive states were significant, as has been previously reported also for serum levels. Our technique is expected to be applicable in the near future to the determination of the presence or absence of the corpus luteum in the ovaries and the reproductive status of free-ranging female whales, provided that sampling techniques for muscle biopsies are developed.
The stress response and the plasma disappearance of corticosteroid and glucose in a marine teleost, the sea raven
Authors: Vijayan M. M. , Moon T. W.
Published: July 2008

The objective of the study was to examine the physiological response to stress in a marine species with a sluggish life-style. The sea raven (Hemitripterus americanus), a marine benthic predator, did not produce elevated catecholamine levels when handled for blood removal, which facilitated repeated blood sampling from the same fish without cannulation. However, this species did release catecholamines in response to an acute stress (1 min of air exposure followed by 1 min of chasing), suggesting a high threshold (degree of external stimulation) for catecholamine release in this species. Plasma cortisol concentration increased significantly only after 1 h and remained elevated 4 h post-stress, showing a delayed response compared with salmonids. Plasma glucose concentration increased significantly at 0.5 h post-stress and remained elevated even at 24 h, while lactate levels dropped between 4 and 24 h post-stress. The delayed cortisol increase may not be due to altered plasma clearance, as no change in the plasma disappearance or tissue uptake of cortisol-derived radioactivity occurred with confinement stress in this species. Also, confinement stress did not alter the plasma disappearance or tissue uptake of radioactivity derived from glucose, indicating a higher production of glucose during stress. Food deprivation significantly increased the plasma disappearance and tissue uptake of both cortisol- and glucose-derived radioactivity in the sea raven. These results indicate that the hormonal response to stress in the sea raven is different from that of salmonids. This altered response may be an adaptation to prevent excess energy mobilization in a species with an inactive life-style and low metabolic activity.
Annual reproductive cycle of the Japanese holothurian Eupentacta chronhjelmi
Authors: Catalan Maria Antonina B. , Yamamoto Masamichi
Published: July 2008

The reproductive cycle of the small temperate dendrochirote holothurian Eupentacta chronhjelmi was studied in the intertidal zone of Aoshima Island, in the Seto Inland Sea of Japan, from July 1989 to January 1991. Reproductive status was assessed by the gonadal index method and histological analysis of the largest (tertiary) gonadal tubules. The primary and secondary tubules are cryptic and difficult to find, so no reference to the animal's annual cycle in terms of gametogenesis is made. The gonad wall was thickest in September for females and October for males, when the gonadal index was at its peak the rapid final stages of vitellogenesis in females (and completion of spermatogenesis in males) depleted reserves in the gonad wall, producing gametes that were spawned in October to December. When gametes were spawned in December the gonadal index and gonad wall thickness decreased. We suggest that the gonadal index reflects gonadal growth by oocyte production and an increase in gonad wall thickness. In the laboratory, spawning occurred from midnight to 04:00, at ambient seawater temperature (12 °C). Individuals elevated their anterior, oral end, waved their tentacles, and released gametes for about an hour. Based on its large egg size (300 ± 5 μm (mean ± SE) diameter) and low fecundity (1500 ± 10 ripe oocytes per individual), we infer lecithotropic development with an abbreviated larval stage.
On the developmental pathway to nonanadromy in sockeye salmon, Oncorhynchus nerka
Authors: Foote Chris J. , Mayer Ian , Wood Chris C. , Clarke W. Craig , Blackburn J.
Published: July 2008

The evolution of nonanadromous forms of salmonids has been linked to adaptive similarities between migration to the sea and migration to lakes, and to inhibition of smoltification by rapid development rates and early maturation. We examined the seasonal cycle of seawater adaptability in a landlocked (10 000 years) population of kokanee, Oncorhynchus nerka, to determine if the typical anadromous cycle persists in the absence of recent gene flow from sockeye salmon, as would be expected if components of smoltification are beneficial to a lacustrine existence. We also monitored the effects of maturation on seawater adaptability, to determine if they had an inhibitory effect on smoltification, as would be expected if a developmental conflict was responsible for the evolution of nonanadromous forms. Maturation was measured through the growth of gonadal tissue and the increase in circulating testosterone and 11-ketotestosterone. Landlocked kokanee showed the seawater adaptability cycle typical of sockeye salmon, and maturation had no inhibitory effect on seawater adaptability until near, or at, full maturity. We conclude that at least some components of smoltification must be beneficial to a life in lakes to account for the continued maintenance of the cycle. Further, rapid development and maturation on their own do not appear to account for the evolution of nonanadromous populations of O. nerka.
The biology and adaptations of the hippopotamus leech Placobdelloides jaegerskioeldi (Glossiphoniidae) to its host
Authors: Oosthuizen J. H. , Davies Ronald W.
Published: July 2008

The specificity of the association between the freshwater leech Placobdelloides jaegerskioeldi and the hippopotamus was confirmed both by collections from the Kruger National Park and by laboratory experiments. Placobdelloides jaegerskioeldi is established as the only leech showing species specificity for a mammal. Forty sexually mature leeches were collected free-living and 2260 mature and immature leeches were collected from 40 of 53 culled hippopotami. In the field P. jaegerskioeldi was never found on any of the alternative hosts, and none fed in the laboratory when offered a range of potential hosts. A combination of unique attributes, including mode of locomotion, anatomical features, and feeding behaviour, makes it possible for this leech to utilize the hippopotamus as a host. Evidence suggests that mating in P. jaegerskioeldi is restricted to the rectum of the hippopotamus.
Development of temperature regulation in young birds: evidence for a vocal regulatory mechanism in two species of gulls (Laridae)
Authors: Wiebe Myra O. , Evans Roger M.
Published: July 2008

Endothermic thermoregulation is absent in birds until after hatching, and usually requires several hours or days to become fully functional in the young. Cold-induced vocalizations that elicit brooding by a cooperative parent or surrogate constitute an additional thermoregulatory mechanism potentially available to neonates of some avian and probably some mammalian species. We show that newly hatched ring-billed gulls (Larus delawarensis) and herring gulls (Larus argentatus) exposed in the laboratory to moderate chilling (20 °C) had a significantly improved ability to regulate body temperature when rewarmed (34 °C) for brief, 4-min periods in response to cold-induced vocalizations. Spontaneous calling by unchilled yoked controls was ineffective in maintaining body temperature. When chicks reached 3 days of age, vocally regulated temperaturee did not differ from that attained by thermogenesis, but vocally induced periods of rewarming reduced the duration of temperature challenge. The ability to regulate body temperature through vocalizations precedes the development of endothermy in gulls and other species so far examined, and in some species extends functional thermoregulation back to the late embryonic (pipped egg) stage of development.
Seasonal adaptation of crucian carp (Carassius carassius L.) heart: glycogen stores and lactate dehydrogenase activity
Authors: Vornanen Matti
Published: July 2008

The glycogen content of the crucian carp heart followed a clear annual cycle, while the size of the heart remained constant throughout the year. Glycogen stores were very abundant at the beginning of the winter (8% of heart mass) and were consumed during the winter and spring, so the stores were at their minimum in early summer (1.4% in May). New glycogen depositions accumulated in the heart during summer and autumn, the maximum glycogen content being attained at the end of October. Glycogen occurred in two distinct granular forms: small β particles about 25 nm in diameter and large α particles about 100 nm in diameter. In late autumn glycogen was mainly in the form of small β particles, which were gathered in vast "glycogen seas" up to 45 μm in length and 10 μm in width. In spring and especially in summer the larger α particles were more numerous than β particles. Lactate dehydrogenase (LDH) activity of the crucian carp heart was relatively high and constant throughout the year. The kinetic properties of cardiac LDH were intermediate between pure cardiac and pure muscle type LDH with a low Km value (0.1 mM) for pyruvate, but only moderately (30%) inhibited by high pyruvate concentrations. The isoenzyme composition and kinetics of LDH did not change seasonally. Crucian carp showed an immediate and strong reduction in heart rate when exposed to hypoxic water. These findings suggest that the crucian carp heart tolerates a long hypoxic winter period by suppressing energy consumption with strong bradycardic reflex and utilizing the massive glycogen stores of the tissues through anaerobic metabolism.
Intestinal helminths as indicators of segregation and social structure of pods of long-finned pilot whales (Globicephala melas) off the Faeroe Islands
Authors: Balbuena J. A. , Raga J. A.
Published: July 2008

The value of intestinal helminths as indicators of segregation and social structure of seven pods of long-finned pilot whales (Globicephala melas) caught in the Faeroe Islands was examined. A comparison of helminth abundances revealed significant overall differences across the pods. Although seasonal factors may partly account for such differences, the agreement of the results with previous pollutant and genetic studies suggests a certain degree of geographical, seasonal, or behavioural segregation of pods of Faeroese pilot whales. The evidence brought forward here, however, does not seem conclusive enough to confirm the presence of different stocks or populations in Faeroese waters. The exclusion of sexually mature males in the analyses had little effect on the patterns observed. However, adult males were more difficult to allocate to pods than the remainder, and the omission of these animals significantly improved the classification results in a canonical analysis. This evidence agrees with previous genetic studies suggesting that adult males avoid inbreeding by moving between pods. It is concluded that helminth parasites have potential value as biological indicators in population and behavioural studies of marine mammals.
Extracellular matrix components in the heart of the white bass, Morone chrysops (Rafinesque)
Authors: Raso Dominic S. , Terracio Louis , Borg Thomas K.
Published: July 2008

The distribution of laminin, collagen type IV, collagen bundles, proteoglycans, elastin, and periodic acid–Schiff's moieties (glycoproteins) within the heart of the adult white bass, Morone chrysops (Rafinesque), was investigated by means of immunohistochemical and histological techniques. Laminin and collagen type IV were heavily expressed within the epimysium and the basal lamina of the lining epicardial epithelium and valvular endothelium, moderately expressed within the myocardium, and slightly expressed within the subendocardium. This co-localized distribution of laminin and collagen type IV corresponds to the biochemically unidentified basal and external lamina observed in the hearts of other fish by previous ultrastructural investigations and is similar to the distribution observed in the hearts of birds and mammals. Also demonstrated was an interesting division of connective tissue components along the longitudinal axis of the atrioventricular valve, which is most likely intimately involved with the effective functioning and durability of the valve.