bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparaison de méthodes d'estimation des débits journaliers
Authors: Bennis Saad , Bruneau Pierre
Published: February 2008

The aim of the first part of our research, described in this paper, was to compare daily streamflow estimation techniques and models. A general application software named DebEst was developed for the purpose. The Saint-François River basin was used as a physical test area because of the availability of several hydrometric stations in this region. All techniques and models used gave good results. However, principal component analysis and multiple regression applied to deterministic models gave better results than ARIMA models. The least square recursive algorithm was more flexible than the other techniques, although discrepancies sometimes appeared because of incorrect weighting of measuring and modelling noise. Results improved significantly when seasonal models were used and when the variation of parameters was taken into account as a function of flow. All techniques described yielded autocorrelated residuals, at least for the first three time lags. The amplitude of the residual autocorrelation function was reduced by seasonal models although it still remained high. In the second part of our research, the Kalman filter technique will be used in conjunction with the methods described above to extract residual information and generate truly independent residuals. Key words: missing streamflow record, principal components, least squares, recursive parameter estimation, residual autocorrelation. [Journal translation]
Hibernia development project — development of the construction site
Authors: Woodhead H. Roger
Published: February 2008

The Hibernia oil field, 315 km southeast of St. John's, Newfoundland, was discovered in 1979. It is located on the Grand Banks in 80 m of water and is estimated to contain about 525 million barrels of recoverable oil. A concrete gravity base structure is being built to develop the reservoir. This paper discusses the method of constructing a gravity base structure and the development of the construction site at Bull Arm in Trinity Bay, Newfoundland. In particular, the organization of Site Development Engineering is outlined. Then the construction of the dry dock berm, the main marine quays, and the accommodation camp is discussed. Key words: construction site, oil development, megaproject, dry dock, camp, marine.
Fine structure of the retinal epithelium, Bruch's membrane, and choriocapillaris of the pigeon (Columba livia)
Authors: Braekevelt C. R.
Published: February 2008

As part of a comparative morphological study, the fine structure of the retinal pigment epithelium, the choriocapillaris, and Bruch's membrane (complexus basalis) has been studied by light and electron microscopy in the pigeon (Columba livia). In this species the retinal pigment epithelium consists of a single layer of cuboidal cells, which show numerous very deep basal (scleral) infoldings and extensive apical (vitreal) processes enclosing photoreceptor outer segments. These epithelial cells are joined laterally by prominent basally located tight junctions. Internally, smooth endoplasmic reticulum is the most abundant cell organelle with only small amounts of rough endoplasmic reticulum present. Polysomes are abundant as are mitochondria, which often display a ring-shaped structure. The cell nucleus is large and vesicular. Melanosomes are plentiful in both the apical region of the cell body and within the apical process in the light-adapted condition. Myeloid bodies are large and numerous and very often have ribosomes on their outer border. Bruch's membrane shows a pentalaminate structure but with only a poorly represented central elastic lamina. Profiles of the choriocapillaris are relatively small and not overly abundant. The endothelium of the choriocapillaris, while extremely thin facing the retinal epithelium, is but minimally fenestrated.
Two new species of Xiphinema (Nematoda: Longidoridae) from British Columbia vineyards
Authors: Ebsary B. A. , Vrain T. C. , Graham M. B.
Published: February 2008

Xiphinema bricolensis n.sp. and Xiphinema pacificum n.sp. are described and illustrated from British Columbia vineyards. Xiphinema bricolensis differs from X. occiduum by the longer odontostyle, longer tail, smaller a value, and larger c′ value. It differs from X. thornei by the smaller c value, larger c′ value, longer tail, and greater anal body width. Xiphinema pacificum is closely related to X. californicum but differs by the longer tail, larger c′ value, longer odontophore, more posterior vulva, and position of the caudal papillae.
Growth and sexual maturation in diploid and polyploid salamanders (genus Ambystoma)
Authors: Licht Lawrence E. , Bogart James P.
Published: February 2008

On Pelee Island, Ontario, mole salamanders, Ambystoma laterale and Ambystoma texanum, coexist with their diploid, triploid, and tetraploid hybrids. In an initial study, A. laterale and hybrid larvae were raised in groups, but from metamorphosis to 5 months postmetamorphosis, individuals were raised in isolation. In a second study, A. texanum and hybrids were raised as isolated individuals under uniform feeding and laboratory conditions from the egg stage to 22 months postmetamorphosis. The total length of larvae at 14 days posthatching was correlated with size of eggs. Tetraploids originated from larger eggs, were larger at 2 weeks posthatching, and maintained their larger size throughout larval development. Tetraploids metamorphosed later and were heavier than all other genotypes. The heavier mass at metamorphosis was maintained and relatively increased so that by 22 months postmetamorphosis, when compared with other groups, tetraploids were heavier in mass, but not larger in snout–vent length. Bodies of tetraploids were more robust and tails, although not longer, were thicker. In contrast to A. texanum and diploid and triploid hybrids, among which 50% of individuals developed fully pigmented, yolk-filled ova by 22 months, no tetraploids showed such signs of sexual maturity. The growth and reproductive patterns of diploids and polyploids are discussed.
Marquage collectif de rongeurs sauvages au moyen de fluoromarqueurs vitaux des tissus calcifiés
Authors: Fichet Élisabeth , Pascal Michel
Published: February 2008

To evaluate the efficiency of collective marking of riparian populations of rodents in the field, baits coated with either fluorescein (0.5 g/kg) or xylenol orange (2 g/kg), two vital fluorochromes of bones, were distributed on a 1.5 km riverbank. A system of traps was monitored for 20 consecutive days after marking. A total of 98 Myocastor coypus, 26 Ondatra zibethicus, 13 Arvicola sapidus, 3 Rattus norvegicus, 5 Apodemus sylvaticus, and 2 Microtus arvalis were trapped. Examination of thin cross sections of the mandibula and the incisor (I1) of all trapped rodents showed that specimens of all species but one, M. arvalis, were labelled. The phalanx, easily taken without killing the animal, was rarely marked. However, analysis of marking topography on the incisor and knowledge of its growth seem to indicate that marking diagnosis without killing the animal is possible by simple removal of a fragment of the tooth. In M. coypus and O. zibethicus, the analysis of marking rate in relation to trapping schedule and animal age showed that the marking method is usable with these species and that young animals are more frequently and clearly labeled than older animals. Moreover, the two species proved to have an entirely different strategy with respect to the trapping schedule, which leads us to question the reliability of a trapping schedule in the study of dispersion phenomena in rodents. The possibility of using this collective marking method to address certain problems in population biology is discussed.
Involvement of the X chromosome in fertility of male and female hybrids of Glossina morsitans morsitans and Glossina morsitans centralis (Diptera: Glossinidae)
Authors: Gooding R. H.
Published: February 2008

In hybrid females of Glossina morsitans morsitans Westwood and Glossina morsitans centralis Machado that carried four well-separated marker genes, suppression of intrachromosomal recombination occurred between the loci for glucose-6-phosphate dehydrogenase (G6pd) and arginine phosphokinase (Apk) on the X chromosome. Fertility of backcross females was not influenced by whether they mated with G. m. morsitans or G. m. centralis, but it was higher in females that received both of their X chromosomes from G. m. morsitans than it was in females that received one X chromosome from G. m. morsitans and the other from G. m. centralis.
Diving patterns of California sea lions, Zalophus californianus
Authors: Feldkamp Steven D. , DeLong Robert L. , Antonelis George A.
Published: February 2008

The diving patterns of 10 adult female California sea lions (Zalophus californianus) were examined during the summer breeding season on San Miguel Island, California, in 1982 and 1983 using time–depth recorders. During 17 feeding trips, representing 40.6 days at sea, animals made over 8900 dives, the deepest of which was estimated at 274 m, while the longest was 9.9 min. The majority of dives, however, were less than 3 min in duration and 80 m in depth. From estimates of body oxygen stores, we predict that dives up to 5.8 min can be supported aerobically. Therefore, cost–benefit considerations based on prey availability and encounter rate may be more important than physiological limits in shaping the foraging patterns of Zalophus. Sea lions were active virtually throughout their time at sea, resting on the surface for only 3% of the average trip. Peak diving frequency occurred during the twilight hours near sunrise and sunset. Dives were frequent, however, during all hours of the day and were typically clustered into bouts that lasted a mean (±SD) of 3.3 ± 1.5 h. We suggest that these bouts represent active feeding on discrete prey patches. During short bouts (<3 h), dive depth was less variable than for dives occurring between bouts. During longer bouts, dive depth changed in a manner consistent with pursuit of vertically migrating prey. During the 1983 El Niño, sea lions compensated for a reduction in food availability by lengthening dive bouts. These seasonal and diel variations in diving patterns suggest that the rate of prey encounter strongly influences the depth and duration of individual dives.
Comparative population ecology of the dragonflies Libellula lydia and Libellula luctuosa (Odonata: Libellulidae)
Authors: Wissinger Scott A.
Published: February 2008

Temporal and spatial patterns of habitat use, population size structure, and survivorship were compared over three generations of Libellula lydia and Libellula luctuosa in a small pond in Indiana. The two species were univoltine, had similar phenologies, and converged on the same within-pond habitats. There was little evidence for any spatial and (or) temporal habitat partitioning that might be expected between such morphologically and ecologically similar species. Larval populations of each species were highly size structured because oviposition and hatching were extended over 3 months in summer. Intraspecific size differences were greater than those frequently reported to accommodate interspecific coexistence. Thus, intraspecific resource partitioning and cannibalism should have an important effect on population dynamics. Both similar and disparate interspecific size combinations frequently co-occurred in time and space so that competition and predation should simultaneously affect coexistence. Larval mortality was high in late summer and fall, negligible in winter, and high again in spring. Fewer than 10% of either species survived to emerge from the pond. Interodonate predation is a likely source of much of this larval mortality, given that other odonates are among the most abundant large predators in fishless ponds.
Seasonal changes in thyroid hormones and osmoregulation in mature male parr and 1- and 2-year-old immature parr of Baltic salmon (Salmo salar L.)
Authors: Rydevik M. , Bergström E. , Lundqvist H. , Eriksson L.-O.
Published: February 2008

One-year-old Atlantic salmon improved their seawater adaptability in late spring, at a time when 2-year-old fish smoltify, though not to the same degree as the latter. One-year-old males that matured precociously were less able to adapt to seawater than immature fish. Both 1- and 2-year-old immature salmon increased their plasma levels of thyroxine when entering the smolt stage; however, both the increase and the levels were much lower in the 1-year-old fish. The seasonal patterns of plasma triiodothyronine and thyroxine were studied in immature parr and precocious males held in fresh and brackish water. The most consistent difference was that the levels of triiodothyronine and thyroxine were higher in mature males than in immature fish during winter.
Descriptions and ecological notes on seven new species of Cladotanytarsus (Chironomidae: Diptera) collected from an experimentally acidified lake
Authors: Bilyj Bohdan , Davies Ian J.
Published: February 2008

Descriptions of male and female imagines and pupal exuviae are given for Cladotanytarsus tribelus sp.n., Cladotanytarsus fusiformis sp.n., Cladotanytarsus pinnaticornis sp.n., Cladotanytarsus muricatus sp.n., Cladotanytarsus elaensis sp.n., and Cladotanytarsus daviesi sp.n. Included also is the description of the parthenogenetic female of Cladotanytarsus aeiparthenus sp.n. and its pupal exuviae. Diagnostic characters are selected to separate males, females, and pupae of similar species. In addition, the pupal diagnosis to Cladotanytarsus has been revised to accommodate the 21 Holarctic species included in a pupal key. All type specimens were collected primarily from lake 223, an experimentally acidified system at the Experimental Lakes Area, northwestern Ontario. Information is also provided on the phenologies, depth distributions, and effects of pH changes on the tolerance ranges of the seven new species.
Tissue solubilizer as an agent for isolating dense animal structures for scanning electron microscope examination
Authors: Bleakney J. Sherman , DeVenney R. L.
Published: February 2008

A standard, commercially available animal tissue solubilizer was tested as an agent for the separation of dense, nonaqueous structures from their surrounding tissues. The method proved effective for sponges, annelids, molluscs, echinoderms, and mammals, but not tunicates. It could be applicable to many other animal groups. Three major advantages are the following: (i) the soft tissues quickly become cleared, well before dissolving, and thus the dense structures can be studied in situ, (ii) total time of exposure to the solubilizers is not critical for the dense structures, and (iii) the results are equivalent whether the original sample is fresh, alcohol preserved, or formalin hardened.
Control of length of the courtship season in the red-sided garter snake, Thamnophis sirtalis parietalis: the role of temperature
Authors: Krohmer Randolph W. , Crews David
Published: February 2008

The influence of temperature on the length and intensity of the courtship season was examined in both field and laboratory populations of red-sided garter snakes (Thamnophis sirtalis parietalis) over a 2-year period. Snakes were exposed to fluctuations in temperature following emergence from hibernation and activation of courtship behavior. In the field, males were exposed to four temperature regimens: extended hibernation (0L:24D, 4 ± 1.5 °C), cool (14L:10D, 12 ± 2.3° C), warm (14L:10D, 28 °C:ambient), or control (ambient temperatures and light). Control animals exhibited courtship behavior fluctuating in intensity with daily ambient temperatures. Animals exhibited high intensity courtship behavior when exposed to warm conditions following emergence from either natural hibernation or a secondary period of laboratory hibernation. Animals placed in the cool regimen were active but exhibited very little courtship behavior. Animals maintained under the cool regimen for 14 days did not initiate courtship behavior when placed in the warm regimen. Studies conducted in the laboratory support the field results. However, whereas animals maintained under the cool regimen for 14 days and then placed in the warm regimen exhibited dramatically reduced courtship behavior, animals placed in the warm regimen after 21 days under the cool regimen initiated courtship of normal intensity and duration. Following the end of all courtship behavior, males exposed to conditions of hibernation for a brief period reinitiated courtship behavior. These data suggest that the areas of the central nervous system critical for the perception of temperature fluctuations and initiation of courtship behavior remained sensitive in late spring. Following the end of the courtship season, females exposed to a brief period of hibernation also reinstated courtship behavior in noncourting males. These data suggest that the length of the courtship season ultimately may be controlled by the presence of attractive females.
A world review of the tiliarum species group in the genus Typhlodromus Scheuten (Acari: Phytoseiidae)
Authors: Chant D. A. , Yoshida-Shaul E.
Published: February 2008

The revised tiliarum species group in the genus Typhlodromus Scheuten is defined by the presence of setae Z1, S2, S4, and S5 as well as J2, J5, Z4, and Z5 on the opisthoscutum, excluding sublateral seta R1 which may or may not be inserted on the opisthoscutum. The chaetotaxy on the opisthoscutum of the revised tiliarum group is identical with that of the australicus (in part) and simplex groups. However, the tiliarum group is distinguished from the former by the absence of seta z6 on the podoscutum and from the latter by differences in the nature of the peritreme and of the setae on the dorsal shield and by the shape of the ventrianal shield. The original tiliarum group included only 3 species whereas the revised group comprises 26 species, including one new species: T. comptus Corpuz, Typhlodromus crassipilis (Athias-Henriot and Fauvel) comb, nov., T. aceri Collyer, T. tuberculatus Wainstein, Typhlodromus runiacus (Kolodochka) comb, nov., T. transitans Gupta, T. tiliarum Oudemans, T. perforatus Athias-Henriot, Typhlodromus carmeli (Rivnay and Swirski) comb, nov., Typhlodromus montforti (Rivnay and Swirski) comb. nov., T. elisae Schicha and McMurtry, T. spaini Collyer, T. cassiniae Collyer, T. steveni Schicha, T. myopori Collyer, T. steeli Schicha and McMurtry, T. cottieri Collyer, T. dachanti Collyer, T. novaezealandiae Collyer, T. manukae Collyer, T. glenfieldensis Schicha, T. oleariae Collyer, T. corrugatus Schicha, Typhlodromus ashleyae sp.nov., T. armidalensis Schicha and Elshafie, and T. nesbitti Womersley. Heteroseiulus aceris Lehman is synonymized with T. aceri, Typhloctonus prunus Denmark and Rather with T. transitans, and Seiulus sexapori Karg and Edland with T. tuberculatus. Shiehia multispinosa Tseng and Typhloctonus vollsella Chaudhri are proposed provisionally as junior synonyms of T. comptus and T. transitans, respectively. Four genera, Neoseiulella Muma, Typhloctonus Muma, Pegodromus Athias-Henriot and Fauvel, and Heteroseiulus Lehman are designated as new junior synonyms of the genus Typhlodromus and one genus, Shiehia Tseng, as a provisional junior synonym. Most species in this group are recorded from temperate climates; 16 of the 26 recorded species are limited to the Australian faunal region. Various generic concepts relating to the species in the tiliarum group are reviewed and the general characters of the group are described. A key, descriptions, and illustrations for adult females of each species are provided.
Comparative urogenital morphology and external sex determination in muskellunge, Esox masquinongy Mitchill
Authors: Lebeau Bernard , Pageau Gérard
Published: February 2008

Primary and secondary sexual characteristics in northern pike, Esox lucius Linneaus, and muskellunge, Esox masquinongy Mitchill, differ markedly. Differences in the internal urogenital anatomy include the structure of the genital ducts and the angle they form with the ventral surface. Externally, the genital and urinary ducts open directly to the environment in northern pike, whereas in muskellunge they open into a muscular papilla and then through a urogenital pore. Differences in sexual dimorphism between the two closely related esocids constitute a structural basis to explain the known differences in spawning behaviour and reproductive success. Differences in secondary sexual characteristics explain why the methods developed by Demchenko or Casselman to externally sex pike are inapplicable to muskellunge. To develop and test two external sexing techniques for muskellunge, specimens were collected from two regions in Canada from 1980 to 1987. Examination of reproductive products obtained from stripping provided an accurate indicator of sex and sexual maturity, but demonstrated serious limitations. A simple method to sex muskellunge by examination of the external urogenital morphology is described for juveniles and adults. Dissection of fish revealed that with the urogenital examination technique we sexed juveniles with a success rate of 92–98%, and adults with 100% accuracy.
Skewed sex ratio in a northern wintering population of mallards
Authors: Pattenden R. K. , Boag D. A.
Published: February 2008

The object of this study was to document the chronology of female disappearance in an isolated population of mallards (Anas platyrhynchos) relative to changes in the winter environment. A sex ratio biased towards males was formed at the onset of winter during both years of study, but during one environmentally harsh winter the proportion of females in the population, as well as the size of the population, continued to decline. Differential emigration at the onset of winter is probably the major factor creating biased sex ratios in most northern wintering duck populations, a bias that apparently can be exacerbated by adverse environmental conditions.
Reproduction, croissance et morphologie comparées des Grands Corégones (Coregonus clupeaformis) nains et normaux du réservoir Outardes-2 (Québec)
Authors: Fortin Réjean , Gendron Marc
Published: February 2008

Fall experimental fishing for spawners and drift net samples of eggs revealed the presence of sympatric populations of dwarf and normal lake whitefish in Outardes-2 Reservoir. Dwarfs mature at a younger age (1 + vs. 4 + ) than normal spawners. They also show a much slower growth rate, a lower absolute fecundity (1009 vs. 9787 eggs), a higher relative fecundity (32.2 vs. 11.8 eggs/g), and a smaller ovarian egg diameter (1.60 vs. 2.63 mm). Four morphometric variables out of the 13 measured differed significantly between the two forms, including the length and depth of the caudal peduncle and the diameter of the orbit; six out of the seven meristic variables that were enumerated also differed between the two forms, including the number of gillrakers on the first gill arch (dwarfs, 24.7; normal whitefish, 25.9). Reproductive isolation is virtually nonexistent, the two forms using the same spawning site, with a minimal time lag between their mean dates of egg deposition (1983: normal whitefish, November 15 and dwarfs, November 22; 1984: normals, November 9 and dwarfs, November 12). The characteristics associated with dwarfism in the various sympatric populations of Coregonus clupeaformis are discussed.
Teneur azotée des ressources et choix trophiques du Mulot sylvestre (Apodemus sylvaticus) dans un système oligotrophe
Authors: Butet Alain
Published: February 2008

The nitrogen content of plant tissue is an essential factor for the growth and survival of many wild phytophagous vertebrates. We tried to analyse the trophic choices of the wood mouse (Apodemus sylvaticus) in relation to the nitrogen content of various plant organs in a heathland, a common ecosystem in Brittany. Patterns of plant resources utilisation observed in this ecosystem show that this rodent species always selects concentrated resources, namely energy- or nitrogen-rich plant tissues. In other respects, the ingestion of animal prey in quantities varying according to the availability of highly nutritious plant resources is another adaptive response to this selection pressure. This strategy of nitrogen allocation based on seed and insect eating is compared with those observed in various other small rodents and correlations with their demographic and space utilization patterns are discussed.
Ultrastructure of Xenopus laevis forelimbs: effects of denervation and delayed amputation
Authors: Liversage Richard A. , Khan Paul A.
Published: February 2008

Ultrastructural studies were carried out on left forelimbs of postmetamorphic Xenopus laevis froglets which had been denervated 1 week prior to limb amputation. Limbs were fixed at intervals of 3, 9, and 15 days postamputation. In control and sham-denervated series limbs in which peripheral (brachiospinal) nerves remained intact, tissue regeneration of the amputated forelimb ensued. Extracellular matrix deposition was observed to be minimal among the cells that accumulate subjacent to the wound epithelium of the control and sham cases, not unlike that observed in intact limbs. However, regeneration was not observed in denervated limbs. In denervated forelimbs 9 and 15 days postamputation, deposition of extracellular matrix surrounding the limited fibroblast or fibroblast-like cellular accumulation in the amputated limb stumps was considerably greater than was observed in normally innervated cases. Presumably, extracellular matrix binds fibroblasts together to form scar tissue (cicatrix) which leads to stumping of a denervated, amputated limb. The fibroblasts become narrower, fusiform, and more elongate in denervated nonregenerating forelimbs by 15 days postamputation compared with controls. In all cases fixed 3 days postamputation, epithelial wound healing appeared to proceed normally in the absence of peripheral innervation; also, no ultrastructural difference was observed among amputated control and sham-control limbs that had intact nerves. This investigation is the first to provide a fine-structure analysis of the effects of denervation and delayed amputation on the earlier stages of tissue regeneration in X. laevis froglets.
Evolution and zoogeography of the invertebrate cave faunas of the Driftless Area of the Upper Mississippi River Valley of Iowa, Minnesota, Wisconsin, and Illinois, U.S.A.
Authors: Peck Stewart B. , Christiansen Kenneth
Published: February 2008

This paper reports the results of a long-term survey of the invertebrates living in caves and other subterranean habitats in the Upper Mississippi River Valley, particularly in the region frequently but erroneously called the Driftless Area. Sixteen troglobitic species are known: two flatworms, two amphipods, one isopod, four spiders, one mite, and six collembolans. The terrestrial troglobite fauna probably represents cave invasion and isolation following Early Pleistocene glaciation, and demonstrates that the caves were habitable while the region was at the margin of Late Pleistocene glaciations. The groundwater troglobite fauna may have survived in situ while the region was covered by glacial ice in the Early Pleistocene. The troglophile fauna consists of at least 78 species, and these species may or may not have come into the region since the Wisconsinan glaciation recession. The presence of troglophile species in a particular cave is highly sporadic.
Plasticity in foraging behaviour of a lotic minnow (Rhinichthys cataractae) in response to different light intensities
Authors: Beers Chris E. , Culp Joseph M.
Published: February 2008

Unlike most cyprinids, the longnose dace (Rhinichthys cataractae) forages primarily at night in streams in southern Alberta. This nocturnal strategy may result from intrinsic capabilities, like dark-adapted vision, or extrinsic constraints due to biotic interactions during the day. Our objectives were to determine, in the absence of biotic interactions such as predation and competition, (i) whether this foraging habit maximized the foraging ability of the dace in terms of search time, reaction distance, and attack efficiency; and (ii) if dace foraging behaviour was sufficiently plastic to adjust to changes in light intensity. All measures of foraging ability were superior under twilight conditions. Although search times in starlight were double those in twilight, this increase was much smaller than was predicted using a hemispherical search volume model. The daces' ability to offset small nocturnal search volumes was accomplished by changing their pattern of search behaviour. In particular, use of a benthic rooting behaviour increased, and we hypothesize that this behaviour is associated with location of prey by olfaction. Although the nocturnal foraging strategy of dace does not appear to maximize net energy gain, this strategy may be a response to other constraints, such as high predation risk during diel periods with increased illumination.
Dynamics of filter feeding in Corbicula fluminea (Bivalvia: Corbiculidae)
Authors: Way Carl M. , Hornbach Daniel J. , Miller-Way Christine A. , Payne Barry S. , Miller Andrew C.
Published: February 2008

Filtration rates of Corbicula fluminea were measured using 2-μm microspheres from three riverine habitats which differed in ambient suspended particle concentration; rates were measured at particle concentrations spanning the range for the three habitats. Filtration rates were significantly different across the three habitats, and were inversely correlated with the mean ambient suspended particle concentrations: 66.4 mL/h for 11 mg/L, 100.2 mL/h for 7 mg/L, and 144.9 mL/h for 4 mg/L for the Tombigbee, Ouachita and Tangipahoa rivers, respectively. However, the weight of particles filtered by clams from the three rivers was not significantly different. These results indicate that C. fluminea can make physiological adjustments to its filtration rate to achieve some "optimal" rate of particle removal. Within each habitat, particle concentration had a significant effect on filtration rates for the Tombigbee River and Tangipahoa River populations; maximal filtration rates were observed in the range of ambient particle concentrations for each habitat. The effects of particle size and type on filtration rates were examined for clams from the Tombigbee River. Filtration rates were measured with microspheres of various sizes, natural suspended particles, and Chlorella. Filtration rates were highest with natural suspended particles; these particles were also the smallest in size (3 × 5 μm). Rates were also highest when measured with particles representative of the size range encountered in the field. There was no significant difference in filtration rates measured with similar-sized microspheres and Chlorella. Pseudofeces were produced by all sizes of clams from each population at particle concentrations greater than 12 mg/L. For the Tombigbee River population, pseudofeces were produced by all sizes of clams at particle sizes greater than or equal to 16 μm. These data indicate that there are potential morphological constraints on the clam gill that limit the range of particle concentrations and sizes that can be processed. Laboratory observations also demonstrated the capacity for deposit feeding in C. fluminea. Our data indicate that filter feeding in C. fluminea is a complex phenomenon, requiring an understanding of how the physiological process of feeding is influenced by morphological constraints imposed upon gill functioning and by the temporal effects of environmental variables. In addition, the plasticity in the filter-feeding response and the capacity for alternative feeding modes contribute to the success of C. fluminea as an invasive species.
Long-term survival, length of breeding season, and operational sex ratio in a boreal population of common frogs, Rana temporaria L.
Authors: Elmberg Johan
Published: February 2008

A population of individually marked adult Rana temporaria was studied during the breeding season in 1979–1988 in east-central Sweden. Annual return rate averaged 31% (range 16–51%) in males and 16% (range 5–33%) in females. Return rate was not size dependent but increased with every successful previous hibernation, indicating an increased survival rate with age. Return rate was not correlated with winter harshness. Once adult, males had on average 1.5 (maximum 6) seasons with the possibility of reproducing. Corresponding values for females were 1.4 and 4. Mean length of the breeding season was 20 (SD = 2) days. Calling generally started at water temperatures below 3 °C. The lowest spawning temperature was 1 °C. Average temperatures at spawning onset and peak spawning were 5 and 6 °C, respectively. Large males tended to arrive earlier at the pond than small males. Males arrived earlier and stayed longer than did females. The overall population sex ratio was close to unity. The operational sex ratio (OSR) varied during the breeding season, averaging 0.54 (one female to two males). No male was observed to mate more than once per season. I argue that survival selection is more important to male lifetime mating success than is competition in the breeding pond (sexual selection as affected by OSR and length of the breeding season).
Lack of association between allozymic variation and social dominance in free-living White-throated Sparrows
Authors: Westneat David F. , Piper Walter H. , Wiley R. Haven
Published: February 2008

This study examined possible associations between allozymic variation in metabolic enzymes and social dominance or survival in a large free-living population of wintering White-throated Sparrows (Zonotrichia albicollis). Electrophoresis of 15 enzymes resolved from muscle biopsies from 173 sparrows revealed nine enzymes with some variation. Two of these (PGM and 6-PGD) showed substantial variation, with the frequency of the common allele below 0.9. During two seasons dominance interactions among the biopsied birds were observed at three feeding stations. There was no association between social dominance (percentage of opponents dominated) and genotype at the two most variable loci or overall proportion of heterozygotes at either the two most variable loci or the seven most consistently scored loci. Older birds were more likely than expected to be heterozygous at both the PGM and 6-PGD loci, but heterozygotes did not return more frequently than homozygotes in subsequent years. Although we cannot exclude a weak association of dominance and isozyme variability, we can conclude that social dominance during winter lacks any strong relationship with variation at loci for metabolic enzymes.
Evaluating preference in laboratory studies of diet selection
Authors: Rodgers Arthur R.
Published: February 2008

The food habits of animals may be studied in the laboratory or in the field. Field studies describe diet selection of populations but do not permit analysis of the factors causing individual variation in the foraging behaviour of animals. Although numerous indices have been developed to compare use and availability of foods in field diets of animals, little attention has been given to laboratory approaches for comparing food choices. Tests of food choice must account for the order, consumption rate, and total amount of each food type eaten. Current measures fail to account for one or more of these parameters. This often results in highly ambiguous preference rankings, making comparisons among individuals or species difficult. To solve this problem, I propose using the area under the curve of the cumulative proportion eaten versus time for each food type. This index may be used to assess individual variation and determine the relative importance of each major component of the diet selection process in animals.
Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae)
Authors: Conlan Kathleen E.
Published: February 2008

The crustacean amphipod genus Jassa is revised to encompass the type species J. falcata (Montagu, 1808), the previously recognized species J. ingens (Pfeffer, 1888), J. herdmani (Walker, 1893), J. pusilla (G. O. Sars, 1894), and J. marmorata Holmes, 1903, and the new species J. alonsoae, J. borowskyae, J. carltoni, J. fenwicki, J. gruneri, J. hartmannae, J. justi, J. morinoi, J. myersi, J. oclairi, J. shawi, J. slatteryi, J. staudei, and J. thurstoni. Jassa odontonyx (G. O. Sars, 1894) is synonymized with J. pusilla, and J. pulchella Leach, 1814 is confirmed as synonymous with J. falcata. Jassa wandeli Chevreux, 1906, J. multidentata Schellenberg, 1931, J. goniamera Walker, 1903, J. barnardi Stephensen, 1949, J. lilipuna J. L. Barnard, 1970, and J. ocia (Bate, 1862) will be assigned to other genera. The nomenclatural disposition of other species that were at one time assigned to the genus Jassa is also given. The genus Jassa can be distinguished from its closest relatives by the following key characters: the outer rami of the third uropods are tipped by a pair of cusps and a basally immersed, dorsally recurved spine; the palms of the first and second gnathopods are defined by a cluster of three spines; at the last molt the male produces a thumb-like protuberance on the propodus of the second gnathopods by incision of the palm anterior to the palm-defining spines; and thumbed males have dimorphic second gnathopods.
White noise and pure tone masking of pure tone thresholds of a harbour seal listening in air and underwater
Authors: Turnbull S. D. , Terhune J. M.
Published: February 2008

Background noises mask the detection of sound throughout a limited frequency range termed the critical bandwidth. Critical bandwidths of a harbour seal (Phoca vitulina) were measured, using behavioural psychophysical techniques, by indirect (critical ratios) and direct (two-tone masking) methods underwater and in air. Underwater critical ratios were determined at 4, 8, 16, and 32 kHz, using white noise spectrum levels of 50, 56, 60, and (or) 70 dB re 1 μPa. The critical ratios (pooled data, threshold ±SD) were 19 ± 9, 22 ± 7, 25 ± 7, and 27 ± 5 dB for the respective frequencies. In-air critical ratios were determined at 2, 4, 8, and 16 kHz, using white noise spectrum levels ranging from 23 to 50 dB re 20 μPa. The critical ratios (pooled data) were 25 ± 8, 23 ± 10, 21 ± 15, and 23 ± 16 dB for the respective frequencies. The arithmetic mean of the critical ratios in both media was 23 dB. This suggests that the seal is equally sensitive to pure tone signals in the presence of broad band noise in both air and water. Direct measurements of the critical bandwidth underwater were determined at 4, 8, 16, and 32 kHz, using a pure tone masker ranging from 96 to 120 dB re 1 μPa. In-air direct measurements of the critical bandwidth were measured at 2, 4, and 8 kHz, using a pure tone masker set at 80 dB re 20 μPa. The bandwidths, estimated at 23 dB below the masking level, were all under 2.25 kHz and become proportionately narrow at higher frequencies. These results show a narrow critical bandwidth for the harbour seal, thus indicating high frequency resolution in both media. The directly measured critical bandwidths from the two-tone masking study were not 2.5 times the critical bandwidth estimated from the critical ratios, as previously reported in some other mammals.
Body weight and lipid reserves of American Black Ducks and Mallards during autumn
Authors: Hanson Alan R. , Ankney C. Davison , Dennis Darrell G.
Published: February 2008

A comparison of body weight and lipid reserves (weights of mesenteric and abdominal fat) of American Black Ducks (Anas rubripes) and Mallards (Anas platyrhynchos) during autumn was done to provide insight regarding the recent contemporaneous decline in Black Duck and increase in Mallard populations of eastern North America. Data were collected on 350 Black Ducks and 1477 Mallards shot by hunters in southwestern Ontario from September 24 to December 20, 1986. Date shot and fresh body weight were recorded, and the head, a wing, a foot, and the viscera were removed and frozen. Body weight and lipid deposits (weight of mesenteric and abdominal fat) were compared between the two species. The first principal component from an analysis of nine morphometric measurements was used as a covariate in subsequent analysis to remove variation in body weight and lipid deposits caused by differences in structural size. Although all age-sex classes of Mallards and Black Ducks stored lipids during the autumn, adult male and juvenile female Black Ducks stored less lipids than did their Mallard counterparts (P ≤ 0.01). Differences in lipid reserves during fall migration may be a proximal reason for the lower survival of adult male and juvenile Black Ducks compared with Mallards and may also influence the timing of intraspecific, and the rate of interspecifc, pair formation.
Endocrine correlates of territoriality, breeding stage, and body molt in free-living willow ptarmigan of both sexes
Authors: Hannon Susan J. , Wingfield John C.
Published: February 2008

Concentrations of plasma testosterone, estradiol, corticosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured by radioimmunoassay in wild willow ptarmigan (Lagopus lagopus) of both sexes over the breeding season. In males, plasma concentrations of testosterone and LH increased once they became territorial, and this was paralleled by increases in comb size and initiation of molt into courtship plumage. A decline of testosterone and circulating LH levels during late territoriality and egg laying coincided with molt into summer plumage. FSH titers did not vary significantly through the season, but there was a trend for higher levels during the territorial period. Plasma concentrations of corticosterone were highest during pre- and late territoriality and brood rearing. In females, testosterone levels were about 13 times lower than in males and did not vary significantly, whereas LH was high from pre- to mid-territoriality and again in the brood season. Elevated LH levels may be correlated with aggressive behaviour in females. FSH and estradiol concentrations were highest during the period of egg formation. Corticosterone was correlated with chase time in both sexes.
Two new species of Carabodes (Acari: Oribatida: Carabodidae) from North America
Authors: Reeves R. Marcel
Published: February 2008

Carabodes wonalancetanus n.sp. and C. cochleaformis n.sp. are described. Adults of both species are large and black, with no notogastral setal dimorphism and with setae c2 positioned anterolaterally on the notogaster. Genital plate neotrichy, with up to six pairs of setae, is present in C. cochleaformis. The distributions of these species overlap in New Brunswick and New England, with C. wonalancetanus extending farther north and west into Canada, where it is transcontinental, and C. cochleaformis extending southwest along the Appalachian Mountains to North Carolina and Kentucky. In New Hampshire, both species were more frequently encountered and more abundant in old-growth or relatively undisturbed forests. Carabodes wonalancetanus prefers leaf litter and rotten logs of conifers, whereas C. cochleaformis is most abundant in fungi, leaf litter, and rotten logs of both conifers and hardwoods.
Seawater adaptability in Baltic salmon, Salmo salar, immature smolt and mature male parr: lack of effect of springtime castration
Authors: Lundqvist Hans , Berglund Ingemar , Mayer Ian , Borg Bertil
Published: February 2008

Seawater adaptability was tested in different categories of 2-year-old Baltic salmon from the Ume River stock over the smoltification period in late spring – early summer by means of seawater challenge tests. Previously mature male parr and immature fish adapted equally well in early to mid May, whereas in later May and June the previously mature males displayed much higher plasma sodium levels after challenge than the immature fish. Neither castration nor sham operation of previously mature males in March led to decreases in plasma sodium levels following seawater challenges in June. In addition, sham-operated immature females were not affected. The results indicate that sexual maturation exerts an effect on osmoregulation that prevails long after the androgen source has disappeared.
Age distribution of breeding female Antarctic fur seals in relation to changes in population growth rate
Authors: Boyd I. L. , Lunn N. J. , Rothery P. , Croxall J. P.
Published: February 2008

The age distribution of breeding female Antarctic fur seals at Bird Island, South Georgia, in 1988 was compared with the age distribution of a sample obtained in 1971–1973. The mean age in 1971–1973 was 7.41 (SE = 0.26) years and in 1988 it was 6.93 (SE = 0.20) years. After correction for age-dependent arrival time at the pupping beach in 1988, the mean age was 6.22 (SE = 0.14 years), which was significantly lower than in 1971–1973. Indicators of population size suggested that population growth at Bird Island had declined to below 3% annually by 1988 compared with rapid growth (17%) in 1958–1972. Exponential models fitted to the frequency distribution of age-classes greater than age 5 years and corrected for the rate of increase of the population gave adult survival rates of 0.66 (SE = 0.03) and 0.88 (SE = 0.02) for the 1988 and 1971–1973 samples, respectively. The reduced apparent adult survival rate in the 1988 sample was probably caused by emigration brought about by high densities of females on the pupping beaches. There are few signs from this analysis that the fur seal population at South Georgia is close to carrying capacity.
Distribution of blubber in the northwest Atlantic harp seal, Phoca groenlandica
Authors: Beck Gregor Gilpin , Smith Thomas G.
Published: February 2008

We examined blubber distribution in 50 mature harp seals (Phoca groenlandica) from the St. Lawrence River estuary, Canada, between December 1988 and April 1989. Blubber was thickest and most variable dorsally, becoming gradually thinner through the neck region and around the foreflippers. Blubber thickness relative to body radius was greatest dorsally at positions from 40 to 70% of standard length (measured back from the snout) and in the posterior region; it varied less topographically than blubber thickness alone, thereby increasing the insulating effectiveness of blubber stores. The largest sexual and seasonal differences in blubber were at the sites with the greatest relative blubber thicknesses. Pregnant females (winter) had thicker blubber than males (winter) or postpartum females (April) at corresponding body sites. Pregnant females had significantly thinner blubber ventrally in the abdominal region than at corresponding lateral positions, whereas males and postpartum females had a more uniform distribution. Blubber mass was highly correlated with estimated blubber volume (R2 = 0.9967, p < 0.0001), and can be approximated from maximum girth alone (R2 = 0.7847, p < 0.0001). Measured blubber density was 0.92 ± 0.01 g∙cm−3. We discuss the pattern of blubber distribution in harp seals with respect to the multiple functions of energy demands, thermal insulation, streamlining, and mobility.
Ecological plasticity of morphological design: an experimental analysis with tit species
Authors: Carrascal Luis M. , Moreno Eulalia , Mozetich Ingrid M.
Published: February 2008

To determine whether behavioural plasticity in foraging modes is contingent upon the morphology of the species, we analyzed the variability in frequency of use of foraging postures (standing versus hanging) under the selection pressure of predation risk. We studied the leg morphology of two contrasting tit species (Blue Tit, Parus caeruleus, and Crested Tit, P. cristatus). Results demonstrated that the leg morphology of the Blue Tit provides it with greater ecological plasticity in terms of foraging posture than that of the Crested Tit. Observed interspecific differences in ecological plasticity are not attributable to interspecific differences in morphological variability (between individuals within species). The morphofunctional bases of ecological plasticity in foraging posture are discussed. Morphological design may be considered an important factor in explaining niche width and potential for niche shifts, as morphology might determine the range of ecological "space" within which a species is allowed to move. The same niche shift in different species could represent different costs when morphological constraints are considered in relation to behavioural performance.