bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of feeding ecology on mercury accumulation in walleye (Stizostedion vitreum) and pike (Esox lucius) in Lake Simcoe
Authors: Mathers R. Alastair , Johansen Peter H.
Published: March 2009

In Lake Simcoe, mercury was accumulated by walleye to a greater maximum concentration (2700 ng g−1) and at a faster rate (119 ng g−1 year−1) than pike (maximum concentration, 850 ng g−1; rate, 78 ng g−1 year−1). Field studies showed that relative to pike, the total diet of walleye was more highly mercury contaminated primarily because it contained a higher proportion of smelt, the most highly contaminated prey for either predator. Additionally, as walleye and pike became older, their prey became larger and the species composition changed. Consequently, as they grew older, the diet of these predators contained more mercury. Bioenergetic equations predicted that on an age-specific basis, walleye had a higher food consumption rate (grams of food per gram of fish per year) that pike and thus are predicted to consume more mercury with their diet than pike. This study supports the hypothesis that the diet of feral fish has a strong influence on the accumulation of mercury.
Intrinsic regulation of flow in an isolated tail preparation of the ocean pout (Macrozoarces americanus)
Authors: Canty A. A. , Farrell A. P.
Published: March 2009

Autoregulatory responses to changes in vascular transmural pressure (myogenic autoregulation) and to changes in pH and [Formula: see text] (metabolic autoregulation) were examined in an isolated tail preparation of the ocean pout (Macrozoarces americanus). Reducing perfusate [Formula: see text] had no effect on inflow. Inflow was, however, dependent on perfusate pH, vasoconstriction occurring with alkalosis, and vasodilation with acidosis. The finding that metabolic autoregulation occurred in response to pH and not [Formula: see text] may be related to the highly anaerobic nature of the white muscle mass found in the tail of the ocean pout. An increase in the external hydrostatic pressure which would produce vascular compression did not elicit compensatory myogenic autoregulation.
Sibling species and sex chromosomes in Eusimulium vernum (Diptera: Simuliidae)
Authors: Brockhouse C.
Published: March 2009

The polytene chromosomes of larvae from samples of Eusimulium vernum, E. bicorne, and an undescribed species (designated here as Eusimulium "Yukon") were examined. Twelve cytotypes within E. vernum were distinguished, of which at least eight appear to be good biological species. These cytotypes, together with the two allied morphospecies, were related in a cytophylogeny. An ecological segregation between some of the siblings was observed. One cytotype apparently utilizes two (possibly three) separate chromosome (arms) in sex determination. Five of the total of six chromosome arms are involved in sex determination in the various members of this complex. The genetics of sex determination and the mechanisms of sex-locus shift are discussed in the context of these findings.
Giant nerve axons and escape swimming in Amphogona apicata with notes on other hydromedusae
Authors: Mills C. E. , Mackie G. O. , Singla C. L.
Published: March 2009

The trachyline medusa Amphogona apicata (family Rhopalonematidae) possesses giant axons and other special features previously described in Aglantha digitale and shows similar escape-swimming and slow-swimming responses. A review of the literature and new observations on several species suggest that, with the possible exception of members of the Ptychogastriidae, these locomotory adaptations are peculiar to certain rhopalonematid hydromedusae.
Metazoan parasites and commensals of five crab (Brachyura) species from eastern Canada
Authors: Brattey John , Elner Robert W. , Uhazy Leslie S. , Bagnall Anne E.
Published: March 2009

Seven hundred and twenty-one brachyuran crabs (Cancer borealis, Cancer irroratus, Carcinus maenas, Chionoecetes opilio, Geryon quinquedens) were collected in waters off eastern Canada during 1980–1982 and the prevalences of metazoan parasites and commensals determined. The survey revealed larval stages of three species of parasite, Microphallus sp. (Platyhelminthes: Digenea), Polymorphus sp. (Acanthocephala: Palaeacanthocephala), Nectonema sp. (Nematomorpha: Nectonematoidea), and five species of ectocommensal, Eteonopsis geryonicola (Annelida: Polychaeta), Johanssonia arctica (Annelida: Hirudinea), Ectocotyla paguri and Ectocotyla multitesticulata (Platyhelminthes: Turbellaria), and Carcinonemertes sp. (Nemertea: Monostilifera). New host records are reported for E. geryonicola in the branchial chambers of C. opilio and for Carcinonemertes sp. on egg masses of ovigerous G. quinquedens. All of the larval parasites, except Nectonema sp., and all of the ectocommensals, except J. arctica and Ectocotyla spp., are previously unreported from crabs off eastern Canada. Our findings suggest that the crab species studied do not support a diverse community of metazoan parasites or commensals.
Characterization and distribution of arginine kinase in the tissues of the scorpion, Palamneus phipsoni
Authors: Arjunwadkar A. V. , Reddy S. Raghupathi Rami
Published: March 2009

Arginine kinase in claw muscle extracts of the scorpion, Palamneus phipsoni, was characterized. The enzyme, with a pH optimum of 8.5 in the direction of phosphoarginine synthesis, showed activation by Mg2+, high specificity towards L-arginine as the guanidino substrate, slight inhibition by high concentrations of L-arginine and ATP, and a molecular weight of 33 500. On polyacrylamide gel electrophoresis at pH 8.3 the enzyme migrated to the anode as a single molecular species. In addition to the claw muscle, the enzyme activity was also found to be present in the heart, alimentary canal, hepatopancreas, and nervous system. In general, scorpion muscle arginine kinase appears to be similar in its properties to the enzyme from other arthropods.
Direct and indirect effects of low pH on the transformation of detrital energy by the shredding caddisfly, Clistoronia magnifica (Banks) (Limnephilidae)
Authors: Frankenhuyzen K. van , Geen G. H. , Koivisto C.
Published: March 2009

A shredding caddisfly, Clistoronia magnifica (Banks), was used to test the hypotheses that increased acidity would reduce the transformation of detrital energy into shredder biomass by (i) reducing survival, (ii) increasing maintenance costs at the expense of growth, and (iii) reducing food quality as a result of inhibition of microbial activity on the leaf litter. Low pH reduced larval survival immediately after hatching and during the moult from third to fourth instar. However, surviving larvae developed faster at pH 4.2–5.2 than at pH 5.8–6.4 and produced larger pupae and adults. Low pH did not alter metabolic costs or ingestion rates of fourth- and fifth-instar larvae. Accelerated growth resulted from indirect effects of low pH on the food resource, which suggested improved nutritional quality of leaf litter conditioned at low pH. However, enhanced growth of late instar larvae did not compensate for reduced survival of early instar larvae, possibly resulting in lower shredder production under acidic conditions.
Arctocyclopina pagonasta, a new genus and species of the family Cyclopinidae (Cyclopoida, Copepoda) from the annual sea ice in the Canadian Arctic
Authors: Mohammed A. A. , Neuhof Vidar
Published: March 2009

A new genus and species of Cyclopoida is described; Arctocyclopina pagonasta is found inhabiting the arctic sea ice. Comparison is made with Cyclopina gracilis Claus, with which it may be confused.
Long- versus short-range foraging strategies of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats and the consequences for prey selection
Authors: Barclay Robert M. R.
Published: March 2009

Habitat use, temporal activity, foraging behaviour, and prey selection of hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans) were studied at Delta Marsh, Manitoba. Bat activity was assessed by monitoring echolocation calls with ultrasonic detectors. Prey availability was determined using sticky and Malaise traps and dietary information was obtained from fecal analysis. Both species were active all night and foraged primarily in the lee of a narrow forested ridge. Lasionycteris noctivagans foraged in a manner that indicates that it detects and pursues prey over short distances. These bats fly slowly, are highly manoeuverable, and were commonly observed feeding on swarms of insects in small clearings. They use echolocation calls that support the notion of a short-range foraging strategy and feed opportunistically on whatever insects are available. Lasiurus cinereus, on the other hand, uses a long-range prey detection and pursuit foraging strategy. They fly rapidly along straight line paths in open areas and use echolocation calls designed to detect insects at a distance. The diet consists primarily of large insects (moths, beetles, and dragonflies), but the bats nonetheless feed opportunistically. The foraging strategy likely restricts the availability and profitability of small insects as prey.
Song matching in western meadowlarks
Authors: Falls J. Bruce
Published: March 2009

Song playback to western meadowlarks (Sturnella neglecta) at Delta, Manitoba, using recordings of song types that the subjects had in their repertoires, showed that the tendency of males to respond with the same song type (match) depended on the source of the recording. Song-type matching decreased from own to stranger to neighbor recordings (not significantly above the chance level in the latter case). An explanation for these results is offered that combines elements of facilitation and neighbor recognition. Correspondence between response latency and intersong intervals of the responding bird suggested that matching song was entrained by the playback but nonmatching responses were not. This indicates that matching and nonmatching are qualitatively different responses. However, matching and nonmatching responses did not differ with respect to conventional measures of response strength. Matching directs a response to a particular singer and may facilitate one-to-one exchange of information, for example, concerning location of the singers. Comparisons are drawn with parallel studies of great tits (Parus major).
Basal metabolic rates and thermoregulatory abilities in four small mammals
Authors: Tomasi Thomas E.
Published: March 2009

Metabolic measurements are reported for Sorex vagrans, Microtus montanus, Peromyscus maniculatus, and Reithrodontomys megalotis. Basal metabolism, resting metabolism, thermal neutral zone, and conductance were assessed and compared with values predicted by body size. Most values were in close agreement with the predictions and with previous studies. While these measurements have not previously been made for S. vagrans, this species appears to be metabolically similar to other members of the genus and to shrews in general. A model for evaluating relative thermoregulatory ability via the calculation of a "thermoregulatory index" is also discussed. It is concluded that S. vagrans is as good a thermoregulator as are the rodent species studied.
Respiration of a low oxygen tolerant galatheid crab, Munida quadrispina (Benedict, 1902)
Authors: Burd Brenda J.
Published: March 2009

A recent study on Munida quadrispina in the cliff community of Saanich Inlet, an intermittently anoxic fjord, showed that these crabs have a size distribution corresponding to the vertical oxygen gradient. This study tested the hypothesis that the size gradient was caused by a size-dependent respiratory tolerance. The factor used for comparison was Pc (critical oxygen concentration below which the rate of oxygen consumption declines). Size specific Pc was compared with habitat oxygen levels at which different sized animals were captured in Saanich Inlet. Regulated oxygen consumption and Pc decreased significantly (p < 0.01) with increasing wet weight of crabs. Pc decreased significantly (p < 0.01) as carapace length increased. The slope and elevation of the latter relationship were not significantly different (p < 0.01, ANCOVA) from the slope and elevation of the relationship of carapace length versus habitat oxygen. This observation is consistent with the hypothesis that the vertical size gradient in Saanich Inlet is related to a size-specific Pc. The minimum Pc observed (0.14 mL oxygen/L) corresponded with the lowest oxygen levels at which crabs were found in Saanich Inlet (0.1–0.15 mL oxygen/L).
Sex determination in northern painted turtles: effect of incubation at constant and fluctuating temperatures
Authors: Schwarzkopf Lin , Brooks Ronald J.
Published: March 2009

Temperature-dependent sex determination was studied in a northern population of painted turtles (Chrysemys picta) in both laboratory and field. Eggs incubated at constant temperatures of 30 and 32 °C produced females only, whereas those kept at 22, 24, and 26 °C produced males only. Both sexes occurred at 20 and 28 °C. The threshold temperatures (temperatures producing 50% males) were estimated to be 27.5 and 20.0 °C, and were similar to those reported for more southerly populations of C. picta. In both 1983 (a relatively warm summer) and 1984 (an average summer), temperatures in natural nests regularly fluctuated above and below both threshold temperatures. Mean nest temperatures were warmer in 1983 than in 1984, but were not useful to predict nest sex ratios. Mean nest temperatures were not similar to constant temperatures in their effect on sex ratio. Sex ratios in nests could be described best by the total number of hours for which the temperature at each nest was intermediate to the two threshold temperatures. Sex ratios (proportion male) of hatchlings in 1983 and 1984 were similar and female biased (0.12 and 0.13, respectively).
Reproduction and egg guarding by Atlantic wolffish (Anarhichas lupus: Anarhichidae) and ocean pout (Macrozoarces americanus: Zoarcidae) in Newfoundland waters
Authors: Keats D. W. , South G. R. , Steele D. H.
Published: March 2009

The reproductive season, the sex that provides parental care, and the relationship of feeding with reproduction are reported for Atlantic wolffish and ocean pout in eastern Newfoundland. Both species move into shallow water in the spring, pair during the summer, and spawn in holes under and between boulders during the autumn. Apparently, male Atlantic wolffish provide solitary parental care of the eggs, while in ocean pout females provide this function. Feeding is reduced for females and probably males of both species as the gonads approach maximum size. After pair formation, male ocean pout reduce feeding; male Atlantic wolffish do so to a lesser degree. Male Atlantic wolffish and female ocean pout feed little or not at all while guarding egg masses.
Chronology, distribution, and sizes of larval fish sampled by light traps in macrophytic Chemung Lake
Authors: Gregory Robert S. , Powles Perce M.
Published: March 2009

Light traps were used to assess larval abundance and chronology of appearance in Chemung Lake in 1982. Eleven of 21 resident species were captured, totalling 7234 individuals. The most abundant were yellow perch (2809), Iowa darter (2571), pumpkinseed sunfish (1288), bluntnose minnow (200), and carp (123). Iowa darter and pumpkinseed were taken only as prolarvae (yolk-sac larvae) and postlarvae, but yellow perch, from 5 to 33 mm total length, were attracted. Common carp and bluntnose minnow entered traps almost exclusively as prolarvae (6–13 mm and 6–12 mm total length, respectively). Perch had the shortest emergence period, May 6–12 (15–17 °C), followed by darters. May 9–31 (15–21 °C). Pumpkinseed and carp emerged over a 6-week period from June 3 to July 23 (16–25 °C). Perch prolarvae preferred shallow, high-density macrophyte areas; their postlarvae preferred deep, low-density macrophyte zones. All stages of larval darter selected shallow, macrophyte-dense regions, as did the young of pumpkinseed.
Courtship, copulation, and sperm trading in the sea slug, Navanax inermis (Opisthobranchia: Cephalaspidea)
Authors: Leonard Janet L. , Lukowiak Ken
Published: March 2009

Navanax inermis are internally fertilizing, simultaneous hermaphrodites that normally mate in pairs. Copulations usually occur in bouts with active alternation of sexual roles and function. Over the study, individuals copulated equally often and for equal periods of time as each sex. The sequence of behaviors involved in courtship, copulation, and role switching is described. While the sequence of behaviors associated with each sexual role is quite stereotyped, the temporal relationship between the behaviors of the two partners is variable. A mating bout is initiated when one individual assumes the male role, finding and following a conspecific mucous trail, and then courts and copulates as a male. Each individual initiated approximately one-half of the copulatory bouts in which it was involved; size played no role in determining which individual initiated the bout. Our observations suggest that in N. inermis, individuals are always willing to be female, while willingness to be male varies over time. The mating system of N. inermis is based on sperm trading. Individuals apparently act as males, donating sperm, to obtain sperm, and are more willing to be fertilized than to fertilize, in violation of Bateman's principle. In N. inermis, females control fertilization and therefore copulation involves greater risks for males than females. The sperm-trading system is "enforced" by the maintenance of intromission until the partner shows courtship behaviour.
Aggregative mechanisms and behavior in ring-billed gulls departing from a colony
Authors: Evans Roger M. , Welham Clive V. J.
Published: March 2009

Departures of ring-billed gulls (Larus delawarensis) from a breeding colony were significantly clumped in time and space. Mean departure directions did not correlate among successive days, but were highly correlated with wind direction. Most gulls circling about the colony did not depart. Gulls that did depart typically flew directly away from the colony and approximately half emitted distinctive "contact" calls. Significantly more gulls departed when others were soaring on nearby thermals than at other comparable times. Playback experiments showed that contact calls and calls from thermal flocks attracted other gulls. A causal model of flock formation, derived from the assumption that temporal clumping arises from social facilitation superimposed upon random departure times, was supported by (i) random fly-up times by nondeparting gulls, (ii) demonstrated attractiveness of contact calls, (iii) characteristically direct flight paths of departing gulls, and (iv) by simulations of departing gulls. Social attraction, temporal and spatial grouping, wind, and visual contact between successively departing birds all appear to facilitate aggregation within localized regions of the habitat.
Birth to weaning in 4 days: remarkable growth in the hooded seal, Cystophora cristata
Authors: Bowen W. D. , Oftedal O. T. , Boness D. J.
Published: March 2009

A brief lactation period with rapid neonatal weight gain may be adaptive for seals breeding on unstable pack ice. We studied the duration of lactation and growth of known-age pups of the hooded seal, Cystophora cristata, on the pack ice off Labrador. Mean body weight of pups increased from 22.0 kg at birth (n = 21) to a maximum of 42.6 kg on day 4 (n = 11) and then declined. On the basis of maternal absence, weight change, gastric contents, and clarity of blood serum, we conclude that pups are weaned 4 days after birth (range, 3–5 days). This is the shortest lactation period known for any mammal. Tagged pups captured on sequential days gained on average 7.1 kg per 24 h from the day after birth to weaning. Maternal effort supported a relative rate of weight gain (145 g∙kg maternal weight−0.75∙day−1) that is 2.5–6 times that of other phocids. By combining a large birth weight with rapid neonatal weight gain, hooded seals achieve a weaning weight comparable to other phocids in one-third to one-tenth the amount of time after birth.
Fish cell culture: two newly developed cell lines from Atlantic sturgeon (Acipenser oxyrhynchus) and guppy (Poecilia reticulata)
Authors: Li M. F. , Marrayatt Vivian , Annand C. , Odense P.
Published: March 2009

Two new cell cultures from fish, SH cells from cardiac tissue of a mature Atlantic sturgeon (Acipenser oxyrhynchus) and GFT cells from fully formed unborn embryos of a female guppy (Poecilia reticulata), were established through a series of subcultivations. The SH cells (sturgeon heart) are fibroblastlike and the GFT cells (guppy fetal tissue) are epithelioid in morphology. The SH cell line was started in 1977 and the GFT line in 1979, and both are past their 30th passage. Maximum growth, after 15 days, was observed at 18 °C for both cell lines. They require 3–5% extra salt for optimum growth. Generally, GFT cells have higher relative plating efficiency and a shorter generation time than SH cells. Sensitivity of both SH and GFT cells to viral infection was tested using an amphibian virus (LT-1V) and a fish virus (IPNV). Cytopathic changes, of the cells experimentally infected by these viruses were evaluated. A low sensitivity of SH cells and GFT cells was found in response to IPNV and LT-1V, respectively. Electron microscopy revealed that both viruses appeared to have different sites of replication in the infected cell lines. Metaphase plates of GFT cells indicated prominent metacentric and submetacentric chromosomes. The chromosomes of SH cells consisted of both micro- and macro-chromosomes. At least three isozymes (lactic acid dehydrogenase, malate dehydrogenase, and phosphohexose isomerase) were found to be suitable for distinguishing among GFT, SH, and lumpfish cell lines.
Cestodes of reindeer (Rangifer tarandus platyrhynchus Vrolik) on the Arctic islands of Svalbard
Authors: Bye Karstein
Published: March 2009

Moniezia benedini and cysticerci of Taenia ovis krabbei were found during examination of 108 reindeer on Svalbard. Moniezia benedini occurred in calves and only in October. Cysticerci of Taenia ovis krabbei were found only in adult animals (>1 year). In females, the prevalence of T. o. krabbei was highest during summer (100% in August 1981). The overall prevalence in females differed significantly between 1981 and 1982 with mean values of 61% and 29%, respectively.
Sphaerospora araii n. sp. (Myxosporea: Sphaerosporidae) from the kidney of a longnose skate (Raja rhina Jordan and Gilbert) from the Pacific Ocean off Canada
Authors: Arthur J. R. , Lom J.
Published: March 2009

Sphaerospora araii n. sp., from the lumen of the kidney tubules of Raja rhina collected from the Pacific Ocean off British Columbia, Canada, is described and illustrated. It is distinguished from all previously described members of the genus by the large dimensions of the mature spore (length of 14.3–18.4 μm), the high number of coils of the polar filament (7–9), and the pattern of valvular ornamentation. A list of named species of Sphaerospora is appended and the following new combinations are proposed: Sphaerospora brevis (Polyansky. 1955) for Myxoproteus brevis; S. hypophthalmichthydis (Chen and Hsieh, 1984) for Podospora hypophthalmichthydis: Mitraspora donecae (Gazimagomedov, 1970) for Sphaerospora donecae; Mitraspora dubinini (Shulman, 1962) for Sphaerospora dubinini; Ortholinea irregularis (Kabata, 1962) for Sphaerospora irregularis; Ortholinea percotti (Dogiel and Akhmerov in Akhmerov, I960) for Sphaerospora percotti; and Ortholinea undulans (Meglitsch, 1970) for Sphaerospora undulans.
Structure of enteric helminth communities in two populations of Eptesicus fuscus (Chiroptera)
Authors: Lotz Jeffrey M. , Font William F.
Published: March 2009

Twenty-one species of helminths were recovered from Eptesicus fuscus in Eau Claire, Wisconsin, and thirteen species were collected from E. fuscus in St. Peter, Minnesota. Contingency table analyses of all species pairs from each locality detected no interactions in the St. Peter group. In the Eau Claire group the trematode pairs Paralecithodendrium naviculum – Acanthatrium oligacanthum and Allassogonoporus marginalis – Ochoterenatrema diminutum exhibited positive associations, whereas P. naviculum was negatively associated with the cestode Hymenolepis roudabushi. When the intestinal distribution of each species was summed over all hosts from each locality, the intestinal overlap of each species pair averaged 31% in bats from Eau Claire and 24% in bats from St. Peter. The overlaps dropped to 2% in bats from Eau Claire and 1% in those from St. Peter when intestinal distributions were not summed across hosts. A randomization analysis of intestinal distributions for all pairs of species from the two localities revealed that H. roudabushi overlapped less than expected with P. naviculum in Eau Claire and with the trematode Plagiorchis vespertilionis in St. Peter. The intestinal distributions of four pairs of species from St. Peter and eight pairs from Eau Claire overlapped more than expected. We conclude that contemporary interactions are of minor importance in structuring infracommunities for the two localities and that positive interactions are more common than negative interactions.
The influence of parasitism on the life history of a high arctic insect, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae)
Authors: Kukal Olga , Kevan Peter G.
Published: March 2009

The life history of Gynaephora groenlandica was studied in the high arctic at Alexandra Fiord, Ellesmere Island. Life history events (larval development, pupation, adult emergence, mating, oviposition, hatching, and moulting to the second larval instar) occurred only in the 3–4 weeks before mid-July. Larvae fed mainly on Salix arctica. They stopped feeding by the end of June, hid, and spun hibernacula. Nineteen percent of third- and fourth-instar larvae were parasitized by the wasp Hyposoter pectinatus (Ichenumonidae); 52% of fifth- and sixth-instar larvae and pupae were parasitized by the fly Exorista sp. (Tachinidae). We estimated that G. groenlandica has a life cycle lasting 14 years. Parasitism caused 56% of overall mortality, whereas cumulative winter mortality was calculated as 13% of a cohort passing through a 14-year life cycle. Peak of activity of adult parasitoids coincided with inactivity of Gynaephora larvae during July. Selective pressure of parasitism may restrict development of G. groenlandica to a short period before adult parasitoids are most active. The importance of parasitoids in the life history of G. groenlandica suggests that parasitism is as significant as climate in population regulation of insects living in the high arctic.
Nondestructive sampling of mitochondrial DNA from voles (Microtus)
Authors: Plante Yves , Boag Peter T. , White Bradley N.
Published: March 2009

We present two techniques for sampling mitochondrial DNA (mtDNA) without killing individual voles. Total cellular DNA was extracted from small blood samples (100–250 μL) and tail segments (2 cm long) collected from meadow voles (Microtus pennsylvanicus). Restriction fragment patterns produced by the restriction endonucleases HindIII, BamH1, and EcoR1 after hybridization with a probe of nick-translated mtDNA compared well with standard mtDNA assays. Both techniques can be used in the field, and should prove useful in biochemical taxonomy as well as in investigations of population structure, dispersal, and social interactions on both micro- and macro-geographic scales. The Southern blots produced by these procedures have the added advantage of being reuseable, so that nuclear DNA polymorphisms can be examined with appropriate probes.
Descriptions of Neolebouria tinkerbellae n.sp. (Trematoda: Digenea: Opecoelidae) from experimental fish hosts, and of metacercariae of N. tinkerbellae and an unidentified digenean from Pandalus jordani (Decapoda: Penaeidae) from the Pacific coast of Canada
Authors: Thompson A. B. , Margolis L.
Published: March 2009

Neolebouria tinkerbellae n.sp. (Trematoda: Opecoelidae) is described from specimens obtained from experimental infections in Platichthys stellatus (Pallas), Gasterosteus aculeatus Linnaeus, and Leptocottus armatus Girard. The metacercarial stage occurs in the heart muscle of Pandalus jordani Rathbun (smooth pink shrimp) from the Pacific coast of Canada and forms a translucent white cyst. A second, unidentified species of metacercaria found in P. jordani forms a cyst surrounded by a brown pigmented layer in the somatic musculature. Both metacercariae are described.
The porpoising of penguins: an energy-conserving behavior for respiratory ventilation?
Authors: Hui Clifford A.
Published: March 2009

The leaps of porpoising captive Humboldt (Spheniscus humboldti) and blackfoot (Spheniscus demersus) and free-ranging Adelie (Pygoscelis adeliae) penguins were analyzed from film. Captive and free-ranging penguins leap with a mean (±SD) emergence angle of 32°(±5°), significantly different from the 45° angle assumed by some hydromechanical models. Captive bird leaps occurred over a maximum of 22% of the total distance travelled, making energy savings marginal. Although physically able to leap at 2.3 m s−1, captive birds showed a minimum swimming speed of 3 m s−1 for the onset of leaping behavior, providing minimum in-air time comparable to the measured respiratory inhalation time. Porpoising may minimize energy expended for ventilation.
Nesting of northern pintails in Alberta: laying date, clutch size, and renesting
Authors: Duncan David C.
Published: March 2009

Nesting of northern pintails was studied in southern Alberta where breeding densities are high. Adults nested earlier and laid larger clutches than did yearlings in the wild. Captive pintails nested earlier, laid larger clutches, and appeared to renest more readily than did wild birds. Food may limit each of these parameters in the wild. The reproductive output of female pintails nesting in high densities in southern Alberta appears to be lower than that of birds breeding at Delta, Manitoba, because of reduced clutch size and lower renesting rate. Clutch size was strongly correlated with laying date but the laying of larger clutches by adults in the wild (and by captive birds relative to wild birds) was not simply a consequence of earlier nesting. A number of proximate causes suggested to explain the seasonal decline in clutch size (hen age, renesting, declining food resources, and decreased body reserves) were rejected. Whatever the mechanism through which laying date influences clutch size, the ultimate reason for this phenomenon may be a seasonally declining survival rate of young which has selected for reduced reproductive effort later in the breeding season. Captive pintails fed a 14% or 29% protein diet after laying their first clutches did not differ in frequency of renesting, clutch size, or renest interval.
Fat distribution and indices of carcass composition in Coats Island caribou (Rangifer tarandus groenlandicus)
Authors: Adamczewski J. Z. , Gates C. C. , Hudson R. J.
Published: March 2009

Twenty-seven barren-ground caribou (Rangifer tarandus groenlandicus) carcass sides were dissected on Coats Island, Northwest Territories, Canada, to calibrate indices of dissectible fat, muscle, and bone. Carcass muscle weight was accurately predicted from weight of the gastrocnemius muscle (In (carcass muscle, kg) = −2.791 + 1.071 In (gastrocnemius, g); r2 = 0.98), and carcass bone weight was accurately predicted from weight of the femur (In (carcass bone, kg) = −4.878 + 1.137 In (femur, g); r2 = 0.98). These allometric relationships held for calves and adults and for animals gaining and losing fat. The subcutaneous, intermuscular, pelvic, and internal omental and perirenal fat depots were weighed for each of 23 animals. The intermuscular and subcutaneous depots were largest and subcutaneous fat increasingly predominated at advanced fatness. Total dissectible fat in the five depots was most accurately predicted from depth of back fat and weight of kidney fat (dissectible fat (kg) = −0.178 + 1.058 depth of back fat (cm) + 24.147 kidney fat (kg); r2 = 0.98) and the regression was unaffected by age or condition. Comparison with similar studies suggests that such within-tissue relationships may be valid for all subspecies of Rangifer.
Comparison of parasite fauna of juvenile sockeye salmon (Oncorhynchus nerka) from southern British Columbian and Washington State lakes
Authors: Bailey R. E. , Margolis L.
Published: March 2009

Sixteen species and juveniles of four taxa of parasites (Myxosporea, 4; Monogenea, 1; Trematoda, 5; Cestoda, 4; Nematoda, 2; Acanthocephala, 2; Copepoda, 2) were encountered in 1550 sockeye salmon (Oncorhynchus nerka) smolts and presmolts examined from 15 Fraser River lakes, Nimpkish Lake on Vancouver Island, and Lake Washington, Washington State, U.S.A. The most common taxa were Diphyllobothrium sp. (spp.?) plerocercoids, Philonema agubernaculum, Eubothrium sp., and Proteocephalus sp. Various statistical techniques (K - nearest neighbour and cluster analyses based on Jaccard and percent dissimilarity matrices) were used to compare the parasite fauna in sockeye from the different lakes. K - nearest neighbour analysis demonstrated that considerable overlap existed among many of the studied lakes, whereas little overlap occurred among other lakes. Cluster analyses revealed similar faunas among some lakes within biogeoclimatic zones and lakes of similar trophic status. Cluster analyses also revealed parasites that tended to co-occur. Parasites with similar modes of transmission or geographic range tended to cluster together.
Composante biominérale du ciment du tube chez Sabellaria alveolata (L.), Annélide Polychète
Authors: Gruet Yves , Vovelle Jean , Grasset Michèle
Published: March 2009

Different methods of microanalysis (energy of wavelength dispersive X-ray spectrometry microprobes, ion microanalyser) combined with histochemistry, allowed us to analyse the cement of the tube and the main glands connected to the building organ of Sabellaria alveolata (L.). These methods clearly showed a mineral component of which the main elements are phosphorus, probably linked to the organic component, calcium, and magnesium, with some manganese and iron. The biomineral is produced by glandular cells having "heterogeneous spherulae." The quick hardening of this cement probably takes place independent of and before the quinonic tanning of the inner organic lining of the wall of the tube.
Growth of American and European eel leptocephali as revealed by otolith microstructure
Authors: Castonguay Martin
Published: March 2009

Results of a microstructural study of sagittae of 21 Anguilla spp. leptocephali using a scanning electron microscope are presented. Assuming that one growth increment was formed every day, a growth rate of 0.38 mm total length/day was calculated. Hatching dates of a subsample of larvae were between 4 May and 26 June. These late dates may account for the small size of the larvae and their atypical geographic location. This sample of larvae apparently grew faster than those in previous studies, for which rates were based on regressions of length on date of capture.
Hypercapnic acidosis in the rainbow trout (Salmo gairdneri). I. Branchial ionic fluxes and blood acid–base status
Authors: Perry S. F. , Malone S. , Ewing D.
Published: March 2009

Branchial solute fluxes as well as blood respiratory, ionic, and acid–base variables were monitored before, during, and after 72 h of exposure to external hypercapnia (1% CO2; [Formula: see text]). Hypercapnia induced an immediate extracellular respiratory acidosis that was gradually regulated over the 72-h period by an elevation of the plasma bicarbonate [Formula: see text] level. Red blood cell pH changed in a manner similar to whole blood pH but the reduction of red blood cell pH during hypercapnia was significantly less than that predicted from in vitro experiments. We argue that elevated plasma levels of epinephrine in the first 12 h of hypercapnia may serve to stabilize red blood cell pH during the severe reduction of whole blood pH, thereby preventing excessive depressions of arterial oxygen content. Elevated external CO2 tension caused changes in the branchial net flux (JnetCl−) such that the arithmetic difference between sodium net flux (JnetNa+) and JnetCl− (JnetNa+ – JnetCl−) increased during hypercapnia and then decreased post-hypercapnia. These results are consistent with enhanced branchial acid excretion and are discussed with reference to the involvement of the gill in the regulation of hypercapnic acidosis.
Evolution and the fossil record: patterns, rates, and processes
Authors: Gingerich Philip D.
Published: March 2009

Mammals have an unusually good Cenozoic fossil record providing evidence of their evolutionary diversification. We view this record in hindsight, which biases our perception in many ways. Overall worldwide diversity appears to increase exponentially through time, while intensive sampling in local areas indicates that modern levels of diversity were achieved early in the Cenozoic. The evident significance of Pleistocene extinctions depends critically on how extinction rates are quantified. Our taxonomic hierarchy probably reflects the number of major faunal turnovers a group has survived rather than declining intensity of successive turnovers. Morphological innovation and taxonomic diversification appear following intervals of climatic cooling, suggesting that major features of evolution are extrinsically controlled. Favorable stratigraphic settings yield detailed records of gradual anagenesis and cladogenesis in mammals, with intermediates present as evidence of transition. The apparent dichotomy between high evolutionary rates measured by neontologists over short intervals of time and low evolutionary rates measured by paleontologists over long intervals of time disappears when rates are measured on intermediate scales of time. Microevolution and macroevolution are manifestations of common underlying processes expressed on different time scales.
On speciation in Ice Age mammals, with special reference to cervids and caprids
Authors: Geist Valerius
Published: March 2009

Five types of species can be identified in large mammals. The evolution of three types, Ice Age giants, island dwarfs, and hybrids, can be explained, but not that of tropical food specialists and continental paedomorphs. Ice Age giants, which arose while colonizing latitudes (altitudes) with increasingly seasonal climates and productivity pulses, are characterized by ornate social organs, large bodies, and ecological plasticity. Colonizing landscapes with decreasing seasonality appears to conserve (or re-evolve) primitiveness, producing paedomorphs. Island dwarfs appear to be shaped by efficiency selection in the absence of predators. The explanation of mammalian Ice Age evolution hinges on the sensitivity of mammals to environmental factors, in particular nutrition. Extremes in food abundance generate extremes in phenotypes and selection regimes. Abundance is linked to colonization and selection for new social and ecological adaptations; scarcity is typical of settled areas and maintenance regimes. These select for efficiency in the procurement, processing, and use of food. Rapid speciation is predicted during colonization, followed by a gradual, continuous fine tuning of the ecology of the new form. Neither the punctuated nor the gradualistic model of speciation adequately explains evolution in large mammals. Early predictions of the "dispersal hypothesis" of mammalian evolution have now been tested for caprids. Results from cytogenetic, electrophorectic, and immunodiffusion studies support the dispersal hypotheses.
Asymmetric species specificity in reponses to female sexual pheromone by males of two species of Trichogaster (Pisces: Belontiidae)
Authors: McKinnon Jeff S. , Liley N. Robin
Published: March 2009

We examined the species specificity of the responses to female pheromones by males of Trichogaster trichopterus, the blue gourami, and Trichogaster pectoralis, the snakeskin gourami, sympatric belontiids from Southeast Asia. Using only chemical signals, males of both species discriminated between ripe females and nonripe females, suggesting that the female chemical signal functions in reproduction. Trichogaster trichopterus males also discriminated between and nonripe females and plain water. Two different experimental procedures showed that male T. pectoralis discriminated between chemical cues from conspecific and heterospecific females while male T. trichopterus did not. This asymmetric specificity of male response is consistent with the ecological histories of the experimental stocks. Trichogaster trichopterus used in these experiments came from a population historically isolated from congeneric species, while T. pectoralis came from a population originally sympatic with three congeners.
Assimilation and metabolism of exogenous glucose by yolk-sac embryos after intraovarian preincubation and in vitro in Zoarces viviparus
Authors: Korsgaard Bodil
Published: March 2009

The ability of yolk-sac embryos of the blenny Zoarces viviparus (L.) to assimilate and metabolize exogenous glucose was investigated by in vivo and in vitro experiments. The investigations in vivo (experiment I) were performed by simultaneously injecting 14C-labelled glucose (30 μL (5 μCi)/100 g body weight) and unlabelled carrier glucose (100 mg/100 g body weight) into the ovary (loaded group). Controls received only 14C-labelled glucose (nonloaded group). The shape of the disappearance curve for the tracer glucose in the glucose-loaded group was similar to that for carrier glucose, with a gradual decrease during the first 9 h postinjection. Half-lives were calculated to be 5.17 h for tracer glucose and 5.41 h for carrier glucose in the loaded group. Both tracer and carrier glucose levels returned to control levels after 24 h in the loaded group. Accumulation of tracer glucose was significantly higher in yolk-sac embryos from the nonloaded control group compared with embryos from the loaded group. Tracer accumulation in maternal liver and kidney was low and showed an opposite pattern to accumulation in the embryos, with more tracer accumulated in the maternal liver and kidney from the loaded group compared with controls. After intraovarian preincubation with [14C]glucose, release of 14CO2 and DO14C (dissolved organic carbon) from assimilated tracers in the embryos in vitro was low. In another experiment (experiment II) the embryos were dissected out of the ovary of untreated females and incubated in vitro with [14C]glucose. The embryos assimilated the labelled glucose, and uptake rates were correlated with the ambient concentration of carrier glucose. Release from embryos into the medium of 14CO2 and DO14C from assimilated tracer glucose was at the same low level as after intraovarian preincubation with [14C]glucose in experiment I. In combination, the results show that as early as their yolk-sac period, embryos from Zoarces viviparus have the capacity for assimilating and metabolizing glucose from naturally occurring concentrations in the ovarian fluid in vivo or from media in vitro.
Scatterhoarding by territorial red squirrels: a test of the optimal density model
Authors: Hurly T. Andrew , Robertson Raleigh J.
Published: March 2009

We observed a high degree of scatterhoarding in a population of red squirrels and tested two predictions of the Optimal Density Model (ODM): (1) large food items will be cached at a greater distance from their source than small items; and (2) caches will be uniformly distributed about their source. Caching experiments supported prediction 1. Red squirrels carried large food items farther than small items before caching them. Prediction 2 was not supported; caches were distributed nonuniformly about their source both within and among caching bouts. We present a simple null model for scatterhoarding, which demonstrates that prediction 1 is not exclusive to the Optimal Density Model. Analyses of our cone-caching data and published data suggested that "optimal densities" were not the primary goal of the caching animal, but rather the result of a positive relationship between food value and investment in caching (carrying distance).
Descriptions of eggs, larvae, and early juveniles of the Iowa darter, Etheostoma exile (Girard), from Lac Heney, Quebec
Authors: Simon Thomas P. , Faber Daniel J.
Published: March 2009

Descriptive morphology of egg, larval, and early juvenile stages of the Iowa darter, Etheostoma exile (Girard), from Lac Heney, Quebec, were examined using morphological, meristic, morphometric, and pigment characteristics. The Iowa darter is a phyto-lithophil spawning on aquatic macrophytes and exposed tree roots. Ova are weakly indented and range in diameter from 0.9 to 1.3 mm, with larvae presumably hatching at ca. 3.6 mmTL. The Iowa darter has 16–18 preanal myomeres (typically 17), and from 20–23 postanal myomeres. Pigmentation is superficially most similar to the yellow perch. A synopsis of the known aspects of the early life history is presented and distinctive morphological characteristics of syntopic percids are compared.
Reighardia sternae (Diesing, 1864) (Pentastomida) from seabirds in Antarctica
Authors: Hoberg Eric P.
Published: March 2009

Specimens of the pentastome Reighardia sternae (Diesing, 1864) are reported for the first time in avian hosts from Antarctica. Mature female specimens were found in a southern black-backed gull (Larus dominicanus Lichtenstein) (1 of 21 examined) while an immature female was found in a south polar skua (Catharacta maccormicki (Saunders)) (1 of 20). Species of Reighardia have not previously been reported among any of the Stercorariinae. The degree of development of individuals of R. sternae provided evidence that the life cycle of this pentastome could be completed on the breeding grounds of its hosts in the region of the Antarctic Peninsula.
The prevalence of Paradistomum geckonum, Mesocoelium sociale, and Postorchigenes ovatus (Digenea) in lizards (Sauria) from Indonesia
Authors: Kennedy Murray J. , Killick L. M. , Beverley-Burton M.
Published: March 2009

Three species of Digenea were found in collections of seven species of lizards from Indonesia from May 1978 to February 1979: Paradistomum geckonum Bhalerao, 1929 (Dicrocoeliidae) was found in the gallbladder and bile duct of Hemidactylus frenatus, Cosymbotus platyurus, Gehyra mutilata, Gekko gecko, Calotes versicolor, and Takydromus sexlineatus; Mesocoelium sociale Lühe, 1901 (Mesocoeliidae) in the small intestine and stomach of H. frenatus, C. platyurus, G. gecko, C. versicolor, and Mabuya multifasciata; and Postorchigenes ovatus Tubangui, 1928 (Lecithodendriidae) in the small intestine of H. frenatus, C. platyurus, G. mutilata, and G. gecko. Data on prevalence, intensity, and location within the host are given for each digenean species. No variations were observed between wet and dry seasons. Prevalence and intensity of P. geckonum and P. ovatus were similar in males and females of each host species examined except for the gecko Gehyra mutilata, in which females had a significantly higher prevalence of infection of both parasites than males. This difference is possibly due to differential food preference.