bluuebunny/crossref_metadata_2025 huggingface dataset:
Metabolic substrate change during daily torpor in deer mice
Authors: Nestler James R.
Published: January 2008

Various metabolic substrates were measured in plasma (glucose, free fatty acids (FFA), ketones, lactate), heart, liver, and skeletal muscle (glycogen, ketones, lactate) of deer mice (Peromyscus maniculatus) in association with their daily torpor cycle. Immediately after feeding, substrate levels were similar to those observed in other mammals. However, within 8–10 h carbohydrate indices (glucose, glycogen) decreased significantly in plasma, liver, and skeletal muscle, with prominent increases in FAA and ketones. Thus the metabolic condition of normothermic deer mice (body temperature 35–38 °C) resembled that seen during acute starvation. Conditions during the actual torpor bout (body temperature 19–24 °C) were similar to those immediately prior to torpor entrance. Glycogen levels in heart were actually highest during daily torpor, possibly as an 'anticipatory' response prior to arousal. Following arousal no repletion of glucose or glycogen was noted, while ketone levels exceeded 5 mM (plasma) and 5 μmol/g (tissues). Adjustments in FFA and ketone utilization may be important in sparing carbohydrate and protein during daily torpor, enabling foraging activity necessary for restoration of endogenous fuel following arousal.
Lesser Scaup diets during migration and winter in the Mississippi flyway
Authors: Afton Alan D. , Hier Ross H. , Paulus Stuart L.
Published: January 2008

We examined diets of Lesser Scaup (Aythya affinis) during midwinter (N = 41) in southwestern Louisiana (1986), and during spring (N = 57) and fall (N = 48) in northwestern Minnesota (1984–1988). Diets of males and females generally were similar during migration and winter. Diets of adults and immatures differed during fall migration but were similar during winter. In fall, immature scaup fed heavily on amphipods and did not consume certain foods, such as fish and fingernail clams, that were important in adult diets. Aggregate percent dry weight of animal foods was higher during fall (adults 91%, immatures 93%) and spring (92%) than during midwinter (61%). Important foods during all periods were crustaceans, insects, and mollusks.
The fine structure of uniporous and nonporous pegs on the distal antennal segment of the diving beetle Graphoderus occidentalis Horn (Coleoptera: Dytiscidae)
Authors: Jensen J. C. , Zacharuk R. Y.
Published: January 2008

The terminal segment of the antenna of the predaceous diving beetle Graphoderus occidentalis Horn bears approximately 50 sensilla of nine different types. There are six types of uniporous chemosensilla, one type of nonporous mechanosensitive peg, and two types of multiporous pegs. Two types of uniporous pegs, which occur only at the antennal tip, have features of both contact chemosensilla and thermo- and hygro-sensilla. Three other types that occur only on the terminal segment below the apex also exhibit some features of chemosensilla and thermo- and hygro-sensilla. The sensilla are innervated by one to four neurons and most are ensheathed by two accessory cells. Four types of sensilla exhibit elaborate sheath cell configurations and secretions associated with their sinus that may reflect an adaptation to an aquatic or a dual aquatic–terrestrial habitat. All are atypical of generalized insect sensilla in having portions of the proximal dendrites and axons as well as the entire neuronal perikarya unsheathed and exposed to the hemocoel. The neuronal perikarya of two sensillar types contain virus-like particles.
Spectral sensitivity of the horse fly Tabanus nigrovittatus (Diptera: Tabanidae)
Authors: Allan S. A. , Stoffolano Jr. J. G. , Bennett R. R.
Published: January 2008

Spectral sensitivity functions were calculated from electroretinograms recorded from dark-adapted compound eyes of male and female horse flies (Tabanus nigrovittatus Macquart). Females had a broad sensitivity in the violet to green area of the spectrum; their spectral sensitivity was fitted by a theoretical mixture containing 20% of 440-nm and 80% 520-nm rhodopsins. Older females (8–18 days) were 93 times more sensitive than 1-day-old females. Males showed a narrower sensitivity function with more blue and less green sensitivity. Older males (8–18 days) were the most blue-sensitive of all groups; their spectral sensitivity was best fitted by a mixture containing 10% 440-nm, 70% 480-nm, and 20% 520-nm rhodopsins. Older males that were light-adapted to red light showed an apparent decline in the contribution of the 520-nm rhodopsin to overall sensitivity, as expected if this pigment is present in a separate system. The sensitivity function of 1-day-old males was best fitted by a mixture of 55% 480-nm and 45% 520-nm rhodopsins. The absolute sensitivity of both groups of males was close to that of the older females. All flies had substantial ultraviolet sensitivity, averaging 67% of the sensitivity at the longer wavelength maximum. The role of the differing sensitivities in males and females, and in young and old females, is discussed in relation to the visual behavior and sexual dimorphism of horse flies.
Coronary artery reactivity in the mako shark, Isurus oxyrinchus
Authors: Farrell Anthony P. , Davie Peter S.
Published: January 2008

Vasoactivity was examined in isolated vascular rings from the coronary arteries of the mako shark, Isurus oxyrinchus, a representative of the athletic elite among elasmobranch fishes. Adenosine relaxed vascular rings. ADP contracted vascular rings at concentrations less than 0.1 mM and relaxed them at higher concentrations. Theophylline inhibited both the ADP-mediated contraction and adenosine-mediated relaxation. Prostaglandin F2α produced strong constrictions. Serotonin had no vasoactive effect. Adrenaline and noradrenaline produced relaxations, indicating a population of β-adrenoceptors. ACh produced weak relaxations at concentrations greater than 10 μM. With the notable exception of the response to adenosine, these vasoactive responses were similar to those previously observed for the coronary arteries in another elasmobranch, the rough skate (Raja nasuta).
Activité alimentaire nocturne des Bécasseaux semipalmés (Calidris pusilla) lors d'une halte migratoire dans la baie de Fundy
Authors: Manseau Micheline , Ferron Jean
Published: January 2008

During their migratory stopover at Mary's Point, Semipalmated Sandpipers fed during both daytime and nightime low tides. However, at night, the sandpipers tended to be less numerous, did not feed as intensively, and were encountered only for part of the mudflat exposure period. Moreover, their feeding activity was comparable between diurnal periods, but varied greatly from one night to another independently of moonlight.
Separation of enzymatically distinct populations of trout hepatocytes
Authors: Mommsen Thomas P. , Danulat Eva , Gavioli M. Emilia , Foster Glen D. , Moon Thomas W.
Published: January 2008

Two different approaches were chosen to investigate the heterogeneity of rainbow trout (Oncorhynchus mykiss) hepatocytes. (i) Hepatocytes were isolated following selective liver infusion with a short pulse of digitonin from either the portal or the hepatic vein. Cell isolates, presumably enriched in cells from either "periportal" or "perivenous" liver regions, were then compared with cells obtained from the nondigitonized part of the same liver (control). No significant differences between hepatocytes were found in the activities of six key metabolic enzymes or in the rate of pyruvate oxidation. All cell isolates were responsive to glucagon, glucagon-like peptide, and insulin (all at 10 nM). If the liver was digitonized through the hepatic vein, resulting cell isolates revealed higher rates of gluconeogenesis from pyruvate, and gluconeogenic flux was more responsive to glucagon (at 10 nM) than controls. The experimental evidence for metabolic zonation in trout liver is weak. (ii) Enzymatically different subpopulations of hepatocytes were successfully separated by Percoll gradient centrifugation after isolation of cells by the conventional collagenase perfusion technique. Two prominent subpopulations of hepatocytes differed in the activities of glycogen phosphorylase, pyruvate kinase, lactate dehydrogenase, citrate synthase, glutamate dehydrogenase, phosphoenolpyruvate carboxykinase, and alanine and aspartate aminotransferases, but not in their content of glycogen. However, the relative distribution of enzymes did not follow the mammalian pattern of perivenous or periportal hepatocytes. These data support cellular heterogeneity in the trout liver, with gluconeogenesis and oxidative metabolism dominating in some hepatocytes, whereas others display a relatively larger scope for glycogen breakdown, glycolysis, and amino acid metabolism.
The Sphaeroceridae (Diptera) of the Queen Charlotte Islands, British Columbia
Authors: Marshall S. A. , Wheeler Terry A.
Published: January 2008

Sphaeroceridae were collected in the Queen Charlotte Islands, British Columbia, in July 1988, and their distributional patterns were examined to test the hypothesis that the archipelago was the site of a Wisconsinan glacial refugium. A total of 27 species of Sphaeroceridae was identified. Ten of these species show widespread Holarctic distributions, four species are widespread across North America, seven species are restricted to North America west of the Rocky Mountains, three species are restricted to the coastal forest west of the Coast Range, and three species are supralittoral along the coast. There is no indication of endemism or relict distributions on the islands; the sphaerocerid fauna is similar to that found on the adjacent mainland. The most parsimonious explanation for the origin of the present sphaerocerid fauna of the archipelago is postglacial colonization from mainland North America. The sphaerocerid distribution pattern was compared with patterns for other Diptera and Coleoptera from the region. In general, the Sphaeroceridae corroborate the pattern seen in most other insect taxa, with postglacial dispersal from mainland source areas accounting for the present sphaerocerid fauna of the Queen Charlotte Islands.
Adaptations for hibernation in the depot fats of a ground squirrel (Spermophilus beldingi)
Authors: Frank Craig L.
Published: January 2008

Ground squirrels are small herbivores that hibernate during winter. The ecological–nutritional limitations on hibernation are virtually unknown, but one constraint may be the melting point of stored fat. Lipids must be fluid to be metabolizable, and body temperatures maintained during hibernation are usually 30 °C below the melting point of typical mammalian fats. Fats containing greater amounts of unsaturated fatty acids, however, have correspondingly lower melting points. White adipose tissue was sampled from free-ranging Belding's ground squirrels, Spermophilus beldingi, during both the summer and fall. The lipids were twice as unsaturated as those of other rodent species, most of the increased unsaturation being due to the accumulation of plant-produced polyunsaturated fatty acids derived from the animals' diet. The melting points of S. beldingi fats were consequently 25 °C lower than those of other mammals. These results suggest that ground squirrels may depend upon their plant diet for the polyunsaturates necessary to produce the lipids with low melting points that are needed for hibernation.
Larval development of Canadian Atlantic oregoniid crabs (Brachyura: Majidae), with emphasis on Hyas coarctatus alutaceus Brandt, 1851, and a comparison with Atlantic and Pacific conspecifics
Authors: Pohle Gerhard W.
Published: January 2008

Larval development of Hyas coarctatus alutaceus Brandt, 1851, consisting of two zoeal stages followed by a megalopa, is described for the first time from larvae of known parentage. Mean duration of the first and second zoeal stages was 41 and 30 days at ambient temperature (3–12 °C) and 30 and 36 days at 9 °C, respectively. First megalopae appeared after 69 and 62 days post-hatching at ambient temperature and 9 °C, respectively. For comparison, all larval stages of Hyas araneus, Hyas coarctatus coarctatus, and Chionoecetes opilio were also cultured from local populations. Zoeae of all these species were found to be very similar. Larvae of H. c. alutaceus were significantly larger than those of H. c. coarctatus, surpassing even those of H. araneus. Laboratory-reared and wild-caught larvae from different geographic areas were also compared. Characters potentially useful in the interspecific and subspecific differentiation of zoeae are presented. These include (i) relative dimensions of the carapace, spinules on carapace spines, setae on antennal exopodites, lateral abdominal spines relative to abdominal somites, spines on the telson furca, and dorsolateral spines on abdominal somite 3; (ii) presence or absence of spinules on lateral abdominal spines and knobs on eyestalks; (iii) setation of appendages; and (iv) pigmentation. Megalopae are also compared morphometrically and meristically. Larvae vary more than appeared previously. A key for the identification of larval stages of C. opilio and Hyas spp. is provided.
Life-cycle variation of Musculium partumeium (Bivalvia: Sphaeriidae) from a temporary and a permanent pond in Minnesota
Authors: Hornbach Daniel J. , Deneka Tony , Dado Robert
Published: January 2008

Variations in the life cycle of the fingernail clam Musculium partumeium were noted both within and between two ponds in Minnesota over a 34-month period. One of the ponds was permanent, and M. partumeium displayed a spring and a fall generation. There was little or no growth of the spring-born generation over the summer. The other population inhabited a pond that was normally ephemeral. In the years when the pond dried in the fall, only a spring generation was produced. In the odd year that the pond remained wet in the fall, a second generation was produced and the ephemeral-pond population switched to a "permanent-pond" life cycle. A transfer experiment between the two ponds was carried out and indicated that the differences in life cycle were phenotypic in nature. Clams transferred between the ponds displayed the life cycle of the pond to which they were transferred rather than of the pond from which they were removed. There were differences in population density between the ponds. The permanent-pond population apparently died out during the study period. Comparisons of the life-cycle traits with other published reports for M. partumeium indicate that there was more within-population than between-populations variation in life cycle, even when examined over a latitudinal gradient. The populations of M. partumeium from Minnesota, however, did appear to be more dense than more southerly populations of this species.
Observations morphologiques sur deux nyctothères (ciliés hétérotriches) commensaux de batraciens anoures du Québec
Authors: Affa'a Félix-Marie
Published: January 2008

Using pyridinated ammoniacal silver nitrate and Protargol impregnation, the author characterized the infraciliature of two nyctotheran ciliates from the gut of anuran Amphibia from Quebec. On this basis, he proposes a morphological redescription and taxonomic revision of Nyctotheroides parvus (Walker, 1909) n.comb. and the creation of a new species, Nyctotheroides deslierresae.
Seasonal thermogenesis and body-mass dynamics of Clethrionomys gapperi
Authors: Merritt Joseph F. , Zegers David A.
Published: January 2008

The role of seasonal changes in resting metabolic rate (RMR), nonshivering thermogenesis (NST), and body mass of livetrapped southern red-backed voles (Clethrionomys gapperi) as adaptations that enhance over-winter survivorship were examined in this study. Average RMR for voles was highest in September and April and lowest in July. No significant changes in RMR occurred on a seasonal basis. Mean NST was lowest in summer, increased throughout autumn, peaked in winter, and declined through spring. Maximum NST capacity occurred in mid-March, following a period in which ambient, ground, and subsurface temperatures reached an annual low. NST values showed an inverse relationship to minimum environmental temperature at the capture site. Mean body mass exhibited significant monthly variation. Average mass dropped significantly between September and November and increased from a low in January to the peak mass in May concomitant with reproductive activity. Analysis of mass changes of individuals conformed to the above trends. The favorable over-winter survival of C. gapperi is due in part to the ability of this species to increase thermogenic capacity by means of nonshivering thermogenesis coupled with energy conservation in the form of growth retardation during winter. Red-backed voles may opt to channel energy into growth or thermoregulation on a priority basis as dictated by food availability and temperatures encountered during their foraging.
Sprint-training effects on trout (Oncorhynchus mykiss) white muscle structure
Authors: Gamperl A. Kurt , Stevens E. Don
Published: January 2008

In mammals, sprint-type exercise protocols induce muscular adaptation different from that caused by endurance training. Although there are many published studies on endurance training in fish, few have examined sprint (anaerobic) training. This study is an examination of whether sprint-training changes white muscle morphology in addition to its previously shown ability to improve trout fast-start acceleration performance. Rainbow trout (Oncorhynchus mykiss) white muscle was sampled following 4, 8, and 12 weeks of sprint training (30 s duration, every 2nd day). White muscle fiber cross-sectional area and perimeter were unchanged by the sprint-training regimen. The volume density of terminal cisternae, T-tubules, mitochondria, and lipid droplets were also not significantly different following training. A formula relating muscle fiber perimeter and area, derived from trout white muscle, appears to describe accurately the perimeter–area relationship for muscle fibers, regardless of species or fiber type.
The elevation of cAMP levels by a putative diuretic hormone in the osmoregulatory organs of the freshwater snail Helisoma duryi
Authors: Abraham Isaac , Khan Hamid R. , Saleuddin A. S. M.
Published: January 2008

In the freshwater snail Helisoma duryi, the kidney and mantle are major organs for osmoregulation and the visceral ganglion is the putative source of diuretic hormone. The role of cAMP as a second messenger in hormonal regulation of these organs has been studied. Hypo-osmotic treatment of snails raised the levels of intracellular cAMP in their kidney and mantle tissues. Forskolin, isobutylmethylxanthine, and theophylline also increased the levels of intracellular cAMP in these tissues. In addition, when these tissues from snails that were acclimated in isosmotic medium were treated in vitro with extracts of visceral ganglion of snails that were acclimated in hypo-osmotic medium, elevated levels of cAMP were observed, 12-fold for the kidney tissue and 4-fold for the mantle tissue. The stimulatory substance from the visceral ganglion was heat stable but labile to proteolytic digestion. In similar in vitro experimental conditions, hemolymph taken from hypo-osmotically treated snails also raised levels of cAMP. It is suggested that in H. duryi cAMP is involved as a second messenger for hormonal osmoregulation by kidney and mantle, and that the putative diuretic hormone is a neuropeptide.
Chemotaxis and lunge-feeding behaviour of Dendronotus iris (Mollusca: Opisthobranchia)
Authors: Shaw G. D.
Published: January 2008

This study provides evidence that Dendronotus iris Cooper can detect odours of Pachycerianthus fimbriatus at a distance. When searching for food, D. iris crawls forward, waving its head and large rhinophore stalks. It exhibits chemotaxis and can select the scented arm of a Y-maze, crawling against current flow when the water contains food extracts. In the natural environment, D. iris is able to locate P. fimbriatus in both the presence and absence of currents. Feeding behaviour is described under three phases from observations made in situ and in aquaria: (i) In the detection of food and during the food-seeking phase, D. iris advances towards its prey while waving its head. (ii) After contact has been made, the opisthobranch centres its oral region by alternatively touching left and right frontal processes to the tentacles of the prey. Head waving continues with upward movement and anterior protraction (i.e., lunge) of the oral region. (iii) Finally, the bite-strike response is exhibited, followed by further bite strikes and intermittent closings of the masticatory margins. Retraction of the radula brings anemone tentacles through the opened masticatory margins. The masticatory margins function to cut food into pieces, which are then thrust into the esophagus by the radula.
Pellucidhaptor eriensis n.sp. and Pellucidhaptor thelostea n.sp. (Monogenea: Dactylogyridae) from catostomids (Cypriniformes) found in Lake Erie, Ontario, Canada
Authors: Beverley-Burton Mary , Chisholm Leslie A. , Dechtiar A. O.
Published: January 2008

A collection of dactylogyrid Monogenea from catostomid fishes taken in Lake Erie, Ontario, Canada, included Pellucidhaptor eriensis n. sp. from Carpiodes cyprinus and Moxostoma macrolepidotum; P. thelostea n.sp. from Moxostoma macrolepidotum and M. anisurum; P. angularis Kritsky and Hathaway, 1969 from Carpiodes cyprinus; P. micracanthus Kritsky, Leiby, and Shelton, 1972 from Carpiodes cyprinus; P. moxostomi Mergo and White, 1982 from Moxostoma anisurum (new Canadian record) and P. nasalis Dechtiar, 1969 from Catostomus commersoni. Pellucidhaptor eriensis is differentiated from other Pellucidhaptor species by the shape of the superficial root of the dorsal hamuli, the shape of the dorsal bar, and the configuration of the male copulatory apparatus. Pellucidhaptor thelostea is readily distinguished from other members of the genus by the sclerotized "wishbone"-shaped support of the male copulatory organ. Supplementary data are provided for the previously described species and an updated list of parasite–host records is included.
The eggs of Forficula auricularia L. (Dermaptera, Forficulidae): ultrastructure and resistance to low and high temperatures
Authors: Chauvin Georges , Hamon Claude , Vancassel Michel , Vannier Guy
Published: January 2008

The morphology, ultrastructure, and resistance to low and high temperatures of the fertilized egg of Forficula auricularia were studied both before and after water absorption. The increase in volume resulting from water absorption did not modify the ultrastructure of the envelopes. The chorion was found to be made of five distinct layers and of a vitelline envelope under which a serosal cuticle was secreted by the embryo. Before hydration, the supercooling point of the egg was −27 °C; after hydration, it was −22 °C. Hydration did not alter the resistance of the egg to heat. It withstood a thermal rise to 36 °C without apparent damage. Morphological and physiological changes due to water absorption did not result in a modification of the viability of the eggs when they were exposed to temperature differences.
Effects of body size, body fat, and change in pressure with depth on buoyancy and costs of diving in ducks (Aythya spp.)
Authors: Lovvorn James R. , Jones David R.
Published: January 2008

Recent studies of diving ducks (Aythya spp.) have shown that buoyancy is far more important to locomotor costs of shallow diving than is hydrodynamic drag. Working with Canvasbacks (A. valisineria), Redheads (A. americana), and Lesser Scaup (A. afftnis), we investigated factors affecting buoyancy in models of locomotor energetics. Body volume can be accurately estimated from body mass (r2 = 0.82–0.95), but equations sometimes differ among species, and body volume relative to mass is higher in winter than in summer. Wing molt does not influence body volume or buoyancy. In scaup, an increase in body lipid from 35 to 190 g (from 5.4 to 22.3% of body mass) increases the energy costs of descent more through the inertial effects of higher mass and added mass of entrained water (82.8% of change) than through greater work against drag (12.0%) or buoyancy (5.2%). Costs of foraging at the bottom are 20% lower in the fatter birds because increased inertial resistance to the buoyant force is greater than the increase in buoyancy. Maximal changes in body lipid and associated hypertrophied muscle raise overall costs of diving to a depth of 2 m by only 2%. Such effects can be offset by altering respiratory and plumage air volumes (+ 15 mL for a 155-g lipid increase) or the relative amount of time spent at the bottom. Hence, diving energetics contrast with the energetics of flight, which are strongly affected by body mass changes. Reduced buoyancy from compression of air spaces with depth lowers costs of bottom foraging in scaup by 24% at 1.2 m and 36% at 2 m. Mass-specific plumage air volume decreases with increasing body mass (slope = 0.12), and body tissues are incompressible relative to air. Thus, buoyancy decreases faster with increasing pressure in smaller birds and they become negatively buoyant at shallower depths (about 43 m for Oldsquaws, Clangula hyemalis). Ducks such as eiders (Somateria spp.) weighing over 1200 g and diving to less than 60 m probably never become negatively buoyant.
Predation of zebra mussels by crayfish
Authors: Martin Gordon W. , Corkum Lynda D.
Published: January 2008

The introduction of zebra mussels, Dreissena polymorpha (Pallas), to the Great Lakes has redirected a large amount of energy from the planktonic community to the benthic community. The direct transfer of energy from zebra mussels to other large organisms depends on the resistance of the mussels to predation. This study investigated the ability of the crayfish Orconectes propinquus (Girard) to use zebra mussels as a food source. Laboratory experiments were designed in which predator and prey sizes, as well as densities, were manipulated. When presented with zebra mussels of a range of sizes (5–20 mm), crayfish of all sizes (carapace length 1.5–2.9 cm) ate mussels ≤ 8 mm in length almost exclusively, but mussels up to 17 mm were also consumed. No significant difference in utilization of zebra mussels was found between male and female crayfish. Our findings suggest that crayfish have the potential to alter the size structure of zebra mussel populations, but that per capita mussel consumption decreased at densities > 4 crayfish/m2. Mutual interference among predators or a lack of habitat complexity may explain the reduction of mussel consumption at high densities of crayfish.
The functional morphology of the retractor lentis muscle of a teleost fish, Astronotus ocellatus
Authors: Andison M. E. , Sivak J. G.
Published: January 2008

Visual teleost species such as the oscar, Astronotus ocellatus, accommodate by moving the lens within the eye. This movement is controlled by a smooth muscle, the retractor lentis. We observed two components in the accommodative lens movement: a nasotemporal and a mediolateral component. In the present study, the anatomical basis of these two components was investigated. Photographs of freshly dissected specimens were used to determine the position and relative size of the retractor lentis muscle in situ. Light microscopy sections reveal two fibre orientations within the muscle. Scanning electron micrographs illustrate that the muscle ligament fans out in two primary directions where it inserts into the lens capsule. The observation that two independent lens movements occur during accommodation is supported anatomically by the orientation of the fibres within the muscle and by the nature of the insertion of the ligament into the lens capsule.
Effects of adult salinity acclimation on larval survival and early development of Strongylocentrotus droebachiensis and Strongylocentrotus pallidus (Echinodermata: Echinoidea)
Authors: Roller Richard A. , Stickle William B.
Published: January 2008

Larval survival and development rates of Strongylocentrotus droebachiensis and Strongylocentrotus pallidus were determined as a function of salinity in two experiments by (i) directly transferring fertilized eggs obtained from adults acclimated to sea water at a salinity of 30‰ to cultures containing seawater at salinities of 30, 27.5, 25, 22.5, 20, 17.5, 15, 12.5, and 10‰ at 10 °C; and (ii) acclimation of adult sea urchins to the salinity–temperature conditions described above for 2, 3, and 4 weeks prior to spawning. Subsequent development occurred under these acclimation conditions. Development rates and percent survival of larvae prior to metamorphosis varied directly with salinity. Survival of S. pallidus plutei to metamorphosis decreased at salinities below 30‰. Strongylocentrotus droebachiensis plutei survived to metamorphosis at 20‰ and above. Lactic acid concentrations in the coelomic cavity fluid of adult S. droebachiensis and S. pallidus acclimated to low salinity were significantly higher than initial controls at 30‰. Cell volumes of fertilized eggs of both species exhibited osmotic swelling when exposed to lowered salinity. LC50 values (‰), development rates, and percent survival to metamorphosis indicate that acclimation of adult urchins to lower salinity prior to spawning and fertilization does not enhance development or survival of embryos of these two species exposed to low salinity. Furthermore, our results show that S. pallidus larvae are stenohaline when compared with larvae of other echinoderm species.
Doubly labelled water measurements of field metabolic rate in White-tailed Ptarmigan: variation in background isotope abundances and effect on CO2 production estimates
Authors: Thomas Donald W. , Martin Kathy , Lapierre Hélène
Published: January 2008

We measured background 2H and 18O abundances and field metabolic rate (FMR) for White-tailed Ptarmigan (Lagopus leucurus) above 3600 m elevation in the Colorado Rocky Mountains between May and July. 18O abundances ranged from 1982.4 to 2018.6 ppm [Formula: see text], while 2H abundance ranged from 142.8 to 154.0 ppm [Formula: see text]. Mean 2H abundance followed closely (−0.3 ppm deviation) the level predicted by Tatner's empirical model relating 2H and ambient temperature. However, 18O was more enriched than predicted (+3.4 ppm), which may reflect 18O fractionation in the plant diet. FMR, measured by means of the doubly labelled water method, ranged from 206.4 to 442.7 kJ/d and was not related to body mass. However, for males, FMR was significantly and positively related to age. Because of high variation in background isotope levels, the use of mean 2H and 18O background abundances instead of individual backgrounds would introduce a mean error of 7.1% (range −8.9 to +11.4%) in calculations of CO2 production and FMR.
Ultrastructure of the aporous sensilla on the galea of larval Mamestra configurata (Walker) (Lepidoptera: Noctuidae)
Authors: Shields Vonnie D. C.
Published: January 2008

The galea of fifth-instar Bertha armyworms, Mamestra configurata, has three types of aporous sensilla: one spire-shaped basiconic peg, two short basiconic pegs, and one campaniform sensillum. The spire-shaped peg is set in an inflexible socket, innervated by three bipolar neurons, and enveloped by three sheath cells. One microtubule-laden dendrite completely fills the distal portion of the dendritic sheath and ends within the peg. It is joined by a lamellate and a scolopidium-like dendrite that end near and below the base of the peg, respectively. The ciliary sinus is large and the membrane of the enveloping inner sheath cell is highly elaborate. This sensillum exhibits features characteristic of thermo-hygrosensilla. The short basiconic pegs and campaniform sensillum are each innervated by a single bipolar neuron and each is associated with three sheath cells. In both sensilla, the dendrite ends in a tubular body, typical of mechanosensilla.
Use of ice-scoured depressions by marsh-foraging snow geese (Chen caerulescens atlantica)
Authors: Bélanger L. , Bédard J.
Published: January 2008

We describe the foraging behaviour of staging greater snow geese (Chen caerulescens atlantica) as they feed in depressions caused by ice scouring in tidal marshes along the St. Lawrence River. We compared feeding success during the fall and spring staging season as the birds extracted rhizomes of Scirpus americanus. In these marshes, every growth cycle (summer) is followed by two distinct episodes of intensive exploitation by geese (fall and the following spring). Two kinds of foraging bouts were considered: (1) successful (i.e, with one or more ingestions) and (2) unsuccessful (i.e, without any ingestion). Geese sampled fewer depressions in the fall than in the spring because the proportion of depressions sampled with success was greatest in this season. Geese spent less time per depression in the spring, whether they were successful or not, but sampled more depressions instead. There was a decrease in the number of depressions sampled over the spring period. It is concluded that geese adjust their use of ice-scoured depressions to both inter- and intra-seasonal food availability (depletion). Behavioural mechanisms they might use to do so are discussed.
mtDNA gene sequence, allozyme, and morphological uniformity among red diamond rattlesnakes,Crotalus ruberandCrotalus exsul
Authors: Murphy Robert W. , Kovac Viera , Allen G. Scott , Fishbein Alex , Mandrak Nicholas E. , Haddrath Oliver
Published: January 2008

Genetic and morphological diversity were investigated in two species of red diamond rattlesnakes. Crotalus exsul Garman, 1884 occurs on Isla de Cedros, and Crotalus ruber Cope, 1892 is found on the peninsula of Baja California, in southern California, and on many islands in the Gulf of California. A partial sequence consisting of 297 nucleotide base pairs from cytochrome b of the mitochondrial DNA genome revealed a single difference only, a level of variation common between rattlesnake subspecies. A phylogenetic analysis showed C. exsul to possess the derived state. The products of 29 gene loci were resolved using horizontal starch gel electrophoresis. No fixed differences were observed to occur, although gene frequencies at one locus, catalase-A, were significantly different (P < 0.00004). Among the 16 morphological characters gathered, none served to unequivocally identify the two taxa. The results of a principal components analysis, using eight morphological characters, revealed that the characters of the Isla de Cedros specimens represented a small subset found in the peninsular Baja California specimens. A multivariate discriminate function analysis could correctly identify 94% of C. ruber and 83% of C. exsul. Because of the close similarity among these two taxa, we believe the red diamond rattlesnakes are best considered a single species, C. exsul, and the peninsular population retained as C. e. ruber; one Gulf of California population is recognized as C. e. lorenzoensis.
Locomotion and antipredator behaviour in three species of semi-aquatic snakes
Authors: Scribner Stephen J. , Weatherhead Patrick J.
Published: January 2008

For temperate-zone ectotherms, a potential cost of an aquatic lifestyle may be impaired locomotor performance, due to rapid cooling of the body when in cold water. Contrary to the hypothesis that more-aquatic species should be better adapted for locomotion at low temperatures, the decline in swimming performance with temperature was similar for three species of snakes (the northern water snake (Nerodia sipedon), eastern ribbon snake (Thamnophis sauritus) and common garter snake (Thamnophis sirtalis)) that varied in their association with aquatic habitats. The effect of temperature on antipredator behaviour was also similar for the three species; at lower body temperatures, snakes relied more on alternative defensive behaviours. However, antipredator behaviour was used less by water snakes than by garter and ribbon snakes. Except for the smallest individuals, all snakes crawled more slowly than they swam, and the difference in performance was greatest for the largest snakes. When crawling, all three species relied more on alternative defensive behaviours than when swimming. In the field, water snakes fled at greater distances from human "predators" than did garter and ribbon snakes, which tended to rely on crypsis. The greater dependence on flight as the primary antipredator behaviour by water snakes, and on other tactics such as crypsis by garter and ribbon snakes, does not conform to the generalization that a species' antipredator behaviour is related to its characteristic dorsal pigmentation pattern. Species differences in antipredator behaviour appear to be more strongly related to habitat use.
Spatial and temporal isolating mechanisms: the formation of discrete breeding aggregations of sockeye salmon (Oncorhynchus nerka)
Authors: Hendry Andrew P. , Leonetti Frank E. , Quinn Thomas P.
Published: January 2008

This study examined the spatial and temporal isolation of breeding aggregations of sockeye salmon (Oncorhynchus nerka) along a single island beach in Iliamna Lake, Alaska. The density and spatial extent of these aggregations varied among years, but one of the sites (Fuel Dump Point) was consistently separated from another major spawning area (Fuel Dump Bay) by at least 15 m of unused but generally similar habitat. Females settled first at the Point and this site supported higher spawner densities than the adjacent Bay. Male breeding opportunity, estimated from operational sex ratios, was higher in the Bay soon after spawning commenced. However, few males moved from the Point into the Bay and all movement that occurred was late in the season, when breeding opportunities for males were very limited. The reproductive success of males that moved from the Bay to the Point was estimated to be 0.003% of the total reproductive success of all males at the Point. The reproductive success of males that moved from the Point to the Bay was estimated to be 3% of the total reproductive success of all males at the Bay. Thus, spatial and temporal variation in settling largely isolated the two spawning aggregations within a breeding season. We suggest that variation in habitat quality may interact with the heritability of spawning date, contributing to the formation of distinct breeding groups.
A simplified method for determining the gross chemical composition of pinniped milk samples
Authors: Arnould J. P. Y. , Boyd I. L. , Clarke A.
Published: January 2008

Recent studies of lactation in wild mammals have emphasised the need for accurate information on milk composition, requiring the analysis of large numbers of samples. A simplified method for determining milk composition in pinnipeds was assessed using samples collected from Antarctic fur seals (Arctocephalus gazella). The stoichiometric relationships between elemental C, H, and N in the ash-free dry mass were used to determine the organic composition and energy content of samples. The results were compared with those obtained by conventional biochemical analyses. Stoichiometric estimates of lipid content were positively correlated with those obtained by methanol–chloroform extraction (r2 = 0.62, P < 0.0001) but consistently lower (P < 0.0005). The mean difference between the results of the two methods was 3.56 ± 0.89% of total milk volume (range −16.98 to +7.47%). Variation between replicates was significantly lower when the stoichiometric method was used (P < 0.05). Gross energy content, calculated from stoichiometric estimates of milk composition, was closely correlated with, though consistently higher than (P < 0.0005), that determined by bomb calorimetry (r2 = 0.96, P < 0.0001). The difference between the two methods, however, was negligible (1.8 ± 0.08%, range −5.0 to +5.6%). The sum of the milk components measured by the stoichiometric method accounted, on average, for 96.5% of the wet mass and varied inversely with lipid content (r2 = 0.29, P < 0.001). This small error is most likely due to retained water in the oven-dried milk. The stoichiometric method for determining organic composition allows the processing of samples at a much faster rate, requiring much smaller volumes, than conventional techniques and should prove useful in ecological studies of lactation.
Larval black fly feeding (Diptera: Simuliidae): use of endogenous glycoconjugates
Authors: Fry Kenneth M. , Craig Douglas A.
Published: January 2008

Histochemical techniques were used to determine the origin and possible function of glycoconjugates in the head region of larval black flies. Late-instar larvae of Simulium vittatum Zetterstedt and Gymnopais dichopticoides Wood were stained with Alcian blue at pH 0.5, 2.5, and 3.2, aldehyde fuchsin, and periodic acid – Schiff's reagent to determine the chemical affinities of the glycoconjugates. Additionally, larvae were fed inert Dayglo®particles and then sectioned and stained as above to determine the origin of glycoconjugates observed in the gut contents and on the labral fan rays. Examination showed that carboxylated and weakly sulphated glycoconjugates are secreted from what are redescribed here as dorsal and ventral cephalic glands. These glands are associated with the labral, mandibular, hypostomal, and maxillary epidermis. The secretion product is not used to enhance food capture or handling. Instead, it is hypothesized that these glycoconjugates aid in formation of mouthpart structures during the pharate stages, or facilitate ecdysis. Glycoconjugates, previously observed in the gut and on the surface of the mouthparts, must be of exogenous origin.
Potential, realized, and actual fecundity in the crayfish Orconectes immunis from southwestern Ontario
Authors: Stechey Daniel P. M. , Somers Keith M.
Published: January 2008

Data on crayfish life history are limited to a few populations of only a few species. Herein we examine the size-specific fecundity of a population of Orconectes immunis from southwestern Ontario. We compare log–log regressions of ovarian egg counts, abdominal egg counts, and the number of independent stage IV juveniles with the size of females to estimate reproductive losses associated with egg extrusion and hatching. We contrast these results with data from a Michigan population. Slopes of the three allometric regressions for the Ontario population were significantly greater than zero (P < 0.05); however, the slope for the ovarian egg counts was significantly less than the hypothesized value of 3.0 (P < 0.05), suggesting that ovarian egg counts did not scale volumetrically with size of females. An analysis of covariance indicated that the slope for the ovarian egg counts differed significantly from the slopes for abdominal egg counts and the number of juveniles (P < 0.05), but the latter two regressions were parallel. The proportional decline in fecundity between ovarian and abdominal egg counts could not be estimated unequivocally because the slopes differed. By contrast, the Michigan population exhibited a 35% decline between these stages. A comparison of size-adjusted abdominal egg counts and the number of juveniles revealed a decline of 58% for the Ontario population. The observed differences in size-specific fecundity at each reproductive stage support the hypothesis that each of these parameters summarizes distinct life-history features. The roles of biotic and abiotic factors on crayfish life history warrant further study.
Ecology of the lizard Kentropyx pelviceps (Sauria: Teiidae) in lowland rain forest of Ecuador
Authors: Vitt Laurie J. , Zani Peter A. , Caldwell Janalee P. , Carrillo Edwin O.
Published: January 2008

Kentropyx pelviceps was studied in lowland tropical forest of eastern Ecuador. Most individuals were first observed in leaf litter of treefall gaps or forest, approximately 30% being first observed above ground on trunks or branches of fallen trees. Activity occurred from 10:00 to 16:00 in microhabitats receiving maximum insolation. Body temperatures of active lizards averaged 34.1 ± 0.4 °C. Lizards active when sun was available had higher body temperatures than lizards active when sun was not available. When sun was available, lizards spent more time moving and moved farther than when sun was not available. When sun was hidden behind clouds, lizards typically ceased foraging, pressed their bodies against the substrate, and basked, receiving direct exposure. Most time active was allocated to basking, presumably as a result of limited availability of sunlight. Prey consisted primarily of roaches, orthopterans, and spiders, and prey size was determined to a large extent (69.6% of variation) by lizard body size. Males and females reached sexual maturity at 80 mm snout–vent length. Males reached a larger maximum size than females, and sexual dimorphism was apparent in nearly all morphological characteristics of adults when the effect of size was removed. Clutch size averaged 6.5 ± 0.3 eggs, and there was no relationship between clutch size and female size. Evidence suggests that the breeding season is extended. Comparisons with other studied species of Kentropyx suggest that many aspects of the ecology of K. pelviceps in eastern Ecuador are affected by the reduced time available for activity resulting from reduced sun availability.
The diet of grizzly bears in the Flathead River drainage of southeastern British Columbia
Authors: McLellan Bruce N. , Hovey Fred W.
Published: January 2008

Based on the analysis of 1100 feces or scats, the seasonal diet of grizzly bears (Ursus arctos) in the Flathead drainage between 1979 and 1991 was estimated. In the early spring, major foods included ungulates and hedysarum roots (Hedysarum sulphurescens). Later in the spring and early summer, green vegetation that mainly included horsetails (Equisetum arvense), graminoids, and cow parsnip (Heracleum lanatum) dominated the diet. Later in the summer, berries, particularly huckleberries (Vaccinium spp.) and soopolallie (Shepherdia canadensis), were most common. In the autumn, berries, ungulates, and hedysarum roots were major foods. Seasonal changes in nutrients were measured for major foods. The volume of a food consumed within a season was inversely related to food quality, suggesting that food availability and handling time may have been more important factors influencing diet selection. The proportions of food items in the scats, and species of fruit in particular, varied among years. The Flathead and contiguous Waterton Lakes National Park are so far the only study areas in North America that contain all major bear foods found across the interior of the continent, and in particular, both major berry species, huckleberries and soopolallie. This observation supports the hypothesis that a favourable food base in the Flathead is partially responsible for the high density of bears found there. It is important for managers to realize the possible uniqueness of the Flathead area and not extrapolate information without due caution.
Abundance and seasonal residence of sperm whales at Kaikoura, New Zealand
Authors: Childerhouse Simon J. , Dawson Stephen M. , Slooten Elisabeth
Published: January 2008

Photographic identification was used to document patterns of occurrence of individual sperm whales in the deep nearshore waters off Kaikoura, New Zealand. Between 1988 and 1993, 86 individuals were identified from nicks and marks in the trailing edge of their flukes. All individuals photographed were uniquely identifiable and no substantial changes in mark occurred over the study period. Resightings show that some whales spend several weeks or months in the area. Half have been seen in more than one field season. One individual has been seen every year from winter 1989 to winter 1992, and like several others appears to return to the area regularly. Others (35%) have been photographed on 1 day only and may be transients. Almost all (88%) of our sightings were of single whales. We used "open" capture–recapture models to estimate the size of the population that visits Kaikoura. These models suggest an average population of between 60 and 108 individuals present in any one season.