bluuebunny/crossref_metadata_2025 huggingface dataset:
Incidence and types of plastic in gannets' nests in the northwest Atlantic
Authors: Montevecchi W. A.
Published: January 2008

Plastics are widespread, persistent environmental pollutants. The incidence and types of plastic in the nests of northern gannets (Sula bassana) were quantified at two colonies in eastern Newfoundland. Overall, 97% of the nests sampled had plastic incorporated in them, and there was no significant difference in the incidence of nests with plastic in the two colonies. Most nests (78%) contained fishing gear (rope, line, netting); plastic package strapping (12%), bags or sheets (7%), and hard plastic (3%), including shotgun shell casings, and lobster pot tags, occurred in many nests. A diversity of other plastic items was also found. A small percentage of adult and chick mortality resulted from entanglement in synthetic materials incorporated in nests. Present levels of the occurrence of plastic in nests at other gannetries should be assessed, because the relative abundances of different types of debris in nests could be used as mega- and meso-scale indicators of synthetic materials in different oceanographic regions.
Seasonal changes in the ratio of serum urea to creatinine in feeding and fasting polar bears
Authors: Ramsay Malcolm A. , Nelson Ralph A. , Stirling Ian
Published: January 2008

When mammals fast, the ratio of serum urea to serum creatinine (U/C) typically rises. Blood samples from 668 free-ranging polar bears (Ursus maritimus) of differing nutritional status were collected for determination of serum concentrations of urea and creatinine. Adult female polar bears in spring that had just emerged with their cubs from dens and had been without food for more than 7 months had markedly low U/C values. This atypical pattern of U/C levels during a fast is similar to that of black bears (Ursus americanus) at the end of their overwinter fast. Whereas black bears only show reduced U/C values during their overwinter fast, however, some polar bears had low serum U/C values in all seasons, suggesting that those bears were in a nutritional state similar to that of a fasting and winter dormant bear. We suggest that when food is unavailable, regardless of the time of year, polar bears can rapidly adopt appropriate physiological and biochemical means to control urea recycling and, consequently, are one of the most proficient terrestrial mammals at undertaking extended fasts.
Mitochondrial DNA and isozyme electrophoretic analyses of the endangered Acadian whitefish, Coregonus huntsmani Scott, 1987
Authors: Bernatchez L. , Edge T. A. , Dodson J. J. , Qadri S. U.
Published: January 2008

Electrophoretic analysis of isozymes and mitochondrial DNA (mtDNA) restriction analysis were used to study the genetic divergence between the Acadian whitefish, Coregonus huntsmani, and members of the subgenera Coregonus (lake whitefish, C. clupeaformis) and Leucichthys (Arctic cisco, C. autumnalis, and lake cisco, C. artedii). Results obtained from both studies demonstrated that the Acadian whitefish is genetically highly distinct from the other coregonines examined. mtDNA restriction analysis revealed that the Acadian whitefish possesses a unique mitochondrial genotype which is divergent from that of the two cisco species or lake whitefish. Twelve of 13 restriction enzymes used were informative in distinguishing the Acadian whitefish from the other species, and species-specific fragment patterns were observed for 10 enzymes. In isozyme analysis of five loci, the Acadian whitefish was monomorphic at two loci for alleles not found in lake whitefish. Acadian whitefish also possessed an additional isozyme at another locus that was not found in lake whitefish and Arctic cisco specimens. This isozyme is unknown from the genetic model for lake whitefish at this locus. These results provided useful genetic markers to identify the Acadian whitefish. They emphasize that the extinction of the species would represent a major loss of both genetic diversity and potential information concerning the contentious phylogeny of coregonine fishes.
The incidence of Glugea stephani (Protozoa: Microsporida) in winter flounder, Pseudopleuronectes americanus, from the New York – New Jersey Lower Bay Complex and factors influencing it
Authors: Cali Ann , Takvorian Peter M.
Published: January 2008

The microsporidium Glugea stephani is endemic in winter flounder from the New york – New Jersey area. The prevalence of infection fluctuates with water temperature on a seasonal basis, increasing in summer and decreasing in winter. From March 1981 through December 1983, 32 monthly collections were conducted. During this period 4002 winter flounder were caught and examined, 301 (7.5%) of which were infected. Data collected during the study indicated that although several factors may influence the host–parasite interaction, only water temperature changes could be statistically correlated with G. stephani infection in this winter flounder population. In an effort to determine what factors other than temperature affect prevalence of infection, fish length, sex, diet, and spawning behaviour were examined. Although these factors do not, at first, appear to influence infectivity, stress imposed on the host by physiological and environmental changes may be significant. Our results are compared with those from G. stephani in its type host, the European flounder Platichthys flesus.
Morphology of the hemipenes of some Amphisbaenia (Reptilia: Squamata)
Authors: Rosenberg Herbert I. , Cavey Michael J. , Gans Carl
Published: January 2008

Preserved amphisbaenids with fully everted hemipenes are rare and few studies have described these intromittent organs in detail. Some previous descriptions are misleading as they are based on partially everted hemipenes. In this paper the hemipenes of several species of amphisbaenids are described on the basis of gross anatomical, histological, and scanning electron microscopy observations. Study of a series of specimens of Amphisbaena caeca and of A. innocens indicates that many hemipenes were not fully everted during fixation. The typical amphisbaenian hemipenis consists of a main truncus that bifurcates to form two lobes. The distal tips of the lobes may bear fields of lamellae that surround the termination of the sulcus spermaticus. Various regions of the outer surface of the lobes may also bear microornamentation. Some possible roles of lamellae and papillae during copulation are discussed.
Patterns of survivorship in turtles (order Testudines)
Authors: Iverson John B.
Published: January 2008

Survivorship data by general age-class are reviewed for 30 species of turtles representing nine families. Survivorship varies significantly across age-classes, with mortality generally inversely related to age (type III survivorship). Survivorship also varies significantly across habitat types, with marine and terrestrial turtles exhibiting higher survivorship early in life than freshwater turtles. Marine turtles also tend to have the lowest survivorship as adults. The implications of these findings for the evolution of marine and terrestrial turtles form ancestral freshwater forms are discussed.
Demography and ecological impacts of the invading mollusc Dreissena polymorpha
Authors: Hebert Paul D. N. , Wilson Christopher C. , Murdoch Mary H. , Lazar R.
Published: January 2008

The bivalve mollusc Dreissena polymorpha colonized Lake St. Clair in 1986 as a result of ballast water discharge. The present study shows that since initiating reproduction in 1988, its population density at all of the sites originally colonized has increased more than a 1000-fold. The species has, as well, expanded its range in Lake St. Clair dramatically. The density and range increase is not yet complete, as populations at most sites remain dominated by juveniles. Densities in excess of 5000 individuals/m2 seem likely to be achieved at most sites in Lake St. Clair within 5 years. It appears likely that D. polymorpha will have a significant impact on composition of the benthos. Shells of individual unionids carry in excess of 10 000 D. polymorpha, and lipid reserves of such unionids are only half those of unaffected individuals. Aside from direct interactions with benthic organisms, the filtering activity of D. polymorpha populations may be sufficient to result in a significant impact on the turbidity of water exiting Lake St. Clair.
Blood protozoans of fish from the Davis Strait in the northwestern Atlantic Ocean
Authors: Khan R. A. , Lee E. M. , Whitty W. S.
Published: January 2008

A study was carried out to determine the occurrence and prevalence of blood protozoans in benthic marine fish from the Davis Strait, an area between Baffin Island and Greenland (61–70°N, 53–63°W) in the northwestern Atlantic Ocean. Parasites were seen in all 17 species offish examined; piroplasms were most prevalent (78% of 413), infecting all fish species. Prevalences of infection were substantially lower for trypanosomes (23%) and haemogregarines (4%), both of which infected only 10 and 6 of the fish species, respectively. Prevalences were greater in 5 of the fish species examined, Reinhardtius hippoglossoides, Hippoglossoides platessoides, Lycodes lavalaei, Macrourus berglax, and Raja radiata, than in the other 12 species. Though the prevalence of trypanosomes decreased considerably in the most northerly of three areas, no differences were apparent for piroplasms. Prevalences noted in this paper are comparable to those observed in fish taken off the coast of Labrador but considerably greater than those of the Grand Banks or in areas south of latitude 50°N. Based on occurrence and prevalence, it is likely that fish haematozoans and their leech vectors originated in the northern latitudes and radiated southwards.
Larval identification of the ruffe, Gymnocephalus cernuus (Linnaeus) (Percidae: Percini), in the St. Louis River Estuary, Lake Superior drainage basin, Minnesota
Authors: Simon Thomas P. , Vondruska Joe T.
Published: January 2008

A reproducing population of the Eurasian percid Gymnocephalus cernuus was discovered in the St. Louis River, Lake Superior basin, near Duluth, Minnesota. This study is the first documented evidence of the species occurrence and reproduction in North America. Larvae resemble typical percids and are described with emphasis on meristic, morphometric, and pigmentary characters. Ruffe are distinguished from all native North American percids by the presence of a slightly concave head becoming attenuated at larger length intervals, a pointed snout with teeth on the maxillary and premaxillary by the time a length of 11 mm is reached, a large dorsally pigmented swim bladder, a serrated preopercle, and few postanal myomeres (usually 18–22). In particular, ruffe superficially resemble johnny darters as yolk-sac larvae, and walleye, yellow perch, and logperch at lengths greater than 10 mm, but can be distinguished by the previously mentioned characteristics and a deep shoulder depth and a narrow caudal peduncle.
The feeding mechanism of the basket star Gorgonocephalus arcticus
Authors: Emson Roland H. , Mladenov Philip V. , Barrow Karen
Published: January 2008

The feeding mechanism of the euryaline basket star Gorgonocephalus arcticus (Leach) from the Bay of Fundy is described from in situ and laboratory observations of feeding behaviour, analysis of gut contents, and examination of the anatomy and microanatomy of the arms. Gorgonocephalus arcticus, which is abundant in areas of moderate to strong current flow, is a fortuitous predatory suspension feeder, coiling and bending its arms to capture prey. The predominant food item in the gut was the euphausiacean Meganyctiphanes norvegica. Food capture by arm bending and coiling is assisted by the adherence of food to rings of sharp hooks on the arm. The role of the tube feet in food capture appears to be minor. Owing to the form of the feeding fan, the animal is adapted for life in strong currents. There is morphological evidence for the presence of mutable collagenous tissues which may be important in maintaining the feeding fan.
Neuromuscular properties of the quintuply innervated flexor muscle in lobster limbs
Authors: Wiens T. J. , Pearce Joanne , Govind C. K.
Published: January 2008

The flexor muscle of the lobster's walking leg was shown by enzyme histochemistry and electrophysiology to display a regional segregation of fibre types: medial fibres have a higher ATPase activity, lower oxidative capacity, and shorter membrane time constant than peripheral fibres lying near the cuticle. The muscle was confirmed to receive one inhibitory and four excitatory motor axons. As judged by the properties of their output excitatory junctional potentials (ejp's), the four excitors lie along the fast-to-slow gradient defined by the two specialized excitors of dually excited muscles. The Fα axon produces initially large ejp's which facilitate weakly or antifacilitate; they are similar to those of fast axons in other muscles. The Fρ axon at the other end of the spectrum produces strongly facilitating ejp's which are initially small, resembling those of known slow axons. The Fβ and Fγ axons show intermediate properties. The inhibitor, which is the common inhibitor of all leg muscles, innervates preferentially the more tonic muscle fibres, as does Fρ. Muscle fibres were observed to receive anywhere from one to five efferents, most receiving two to four. Serial electron microscopic observations in several regions revealed a rich supply of synaptic terminals, usually comprising a single inhibitory terminal and two or three excitatory ones. The inhibitory terminal typically has a few large synapses, each with more than one active site. Excitatory terminals, on the other hand, have many more smaller synapses, each with at least one active site. Although excitatory and inhibitory terminals were often closely juxtaposed, no synaptic interactions were observed between them.
Description of the life-history stages of Amphiascus undosus Lang (Copepoda, Harpacticoida)
Authors: McMillan Graham J.
Published: January 2008

The six naupliar and six copepodite stages of the harpacticoid copepod Amphiascus undosus Lang are described in detail. Thoracic leg segmentation and armature are presented in tabular form for the copepodite stages. The species becomes sexually dimorphic at the fourth copepodite stage. Average egg-to-adult development time is approximately 31.5 days at 22 ± 1 °C. Up to four successive pairs of egg sacs from a single female are produced in the laboratory, yielding a maximum of 76 progeny. Some discrepancies exist between the original description of the California type specimens and the present British Columbia material, particularly in the adult male maxillule, maxilliped, and first, fifth, and sixth legs, and the caudal setae of the adult female. A brief comparison is made with the developmental similarities and differences of six other diosaccid harpacticoid copepods.
Absence of temperature-dependent sex determination in northern populations of two cyprinodontid fishes
Authors: Conover D. O. , DeMond S. B.
Published: January 2008

We tested for an effect of temperature during embryonic and larval development on the sex ratio of offspring in two cyprinodontid fishes (Fundulus heteroclitus and Cyprinodon variegatus) having life histories in which temperature-dependent sex determination might be expected to occur. In both species, field collections showed that as young of the year recruited to the population, the sex ratio did not vary over time, nor did it deviate from 1:1. In laboratory experiments, there was no influence of incubation temperature on sex ratio in either species and sex ratios were near unity in all treatments. Although there was no evidence of temperature-dependent sex determination in the populations we studied, this result should be confirmed on other populations before it is generalized to the species level.
Catecholaminergic neurons supplying the hindgut of the crayfish Procambarus clarkii
Authors: Mercier A. Joffre , Orchard Ian , Schmoeckel Arthur
Published: January 2008

The crayfish hindgut is surrounded by a dense plexus of nerve terminals which are known to contain catecholamines. This plexus is positively stained using a monoclonal antibody to tyrosine hydroxylase, the enzyme that catalyzes the rate-limiting step in catecholamine biosynthesis. Two immunoreactive neurons, whose cell bodies are located in the third and fourth abdominal ganglia, contribute to the nerve plexus. Each of these neurons sends a single axon posteriorly through the ventral nerve cord and into the intestinal nerve, where the axon bifurcates to supply the anterior and posterior hindgut regions. High-performance liquid chromatography, coupled to electrochemical detection, demonstrates the presence of dopamine in the intestinal nerve of Procambarus clarkii. Dopamine increases the motility of the isolated hindgut in a dose-dependent manner. The results suggest that two dopaminergic neurons are involved in the neurogenic coordination of hindgut movements.
Cytogenetic studies in North American minnows (Cyprinidae). XXII. Chromosomal nucleolar organizer regions in the genus Pimephales
Authors: Li Yucheng , Gold John R.
Published: January 2008

Chromosomal nucleolar organizer region (NOR) phenotypes are documented for all four extant species in the North American cyprinid fish genus Pimephales. All four species (P. notatus, P. promelas, P. tenellus, and P. vigilax) possess 2n = 50 chromosomes and a pair of NOR-bearing chromosomes with the NOR situated terminally on the short arm of a medium-sized to large submetacentric chromosome (NOR phenotype C). Trypsin G-banding demonstrated that the C NOR chromosome in all four species is homologous. Two of the species (P. tenellus and P. promelas) also possess a C′ NOR chromosome, which is defined as an NOR situated terminally on the short arm of a large submetacentric chromosome that is also the largest chromosome in the complement. The C′ NOR chromosome occurs infrequently in P. promelas, being found in only 8% or so of all metaphases examined. Trypsin G-banding demonstrated that the C′ NOR chromosomes in the two Pimephales species are homologous to one another and to the C′ NOR chromosomes found in the cyprinid genus Cyprinella. A presumed derivative of the C′ NOR chromosome occurs in the monotypic cyprinid genus Opsopoeodus. The NOR chromosomal data support monophyly of the four extant species of Pimephales, and further suggest that the genus Pimephales belongs in a monophyletic assemblage with, among others, the cyprinid genera Cyprinella and Opsopoeodus. The data do not support the previous hypothesis that Pimephales is a basal clade outside of a larger assemblage of "Notropis"-like, shiners.
A new North American species of Simulium (Hellichiella) (Diptera: Simuliidae)
Authors: Adler Peter H. , Wood D. M.
Published: January 2008

All life stages and the polytene chromosomes of Simulium (Hellichiella)curriei, a new species from western North America, are described and illustrated. This species is the only Nearctic member of the subgenus with an eight-filamented pupal gill. It is the sister-species of S. rivuli.
Diacyclops albus n.sp. and Parastenocaris palmerae n.sp. (Crustacea: Copepoda) from the meiofauna of a stream bed in Virginia, U.S.A.
Authors: Reid J. W.
Published: January 2008

Two previously undescribed species of Copepoda are members of the interstitial community of the sandy bed of a stream in northern Virginia. Diacyclops albus n.sp. shares with D. languidus, D. languidoides, and D. nanus the combination of biarticulate rami of leg 1 and endopodite of leg 2, the remaining rami of the swimming legs being triarticulate. Diacyclops albus differs from these congeners in having one rather than two terminal spines on the leg 4 endopodite article 3, as well as in other characters. Parastenocaris palmerae n.sp. differs from North American congeners in having the medial margin of leg 5 strongly convex proximally and concave distally in both sexes; in addition, the male of no other known North American species has leg 4 with a multiply incised endopodite similar to that of the male of P. palmerae.
Sex ratios of Corophium volutator (Pallas) (Crustacea: Amphipoda) in Bay of Fundy populations
Authors: Schneider Saul D. , Boates J. Sherman , Forbes Mark
Published: January 2008

Previous work on the tube-dwelling intertidal amphipod Corophium volutator (Pallas) has shown that adult sex ratios are female-biased for populations along the Bay of Fundy, Canada. The causes of these biased sex ratios, and many other aspects of the life history of this important prey species, are unknown. Some authors have suggested that biased sex ratios for adults may be due to differential predation on adult males by migrant shorebirds. Such differential predation is not expected for juvenile C. volutator, which differ in behaviour from adult males. In this study, we first demonstrate an accurate method of sexing juvenile C. volutator that is based on sex differences shown by adults. This method will enable more detailed ecological studies of C. volutator. We then show that sex ratios are female-biased for juvenile C. volutator, which is probably a more important determinant of a biased sex ratio for adults than is differential shorebird predation on adult males. We demonstrate that biased sex ratios also appear to occur for newly hatched C. volutator, indicating that some form of asexual reproduction (e.g., automixis) may exist within Bay of Fundy populations of C. volutator.
A new genus of Lumbriculidae (Oligochaeta) from Korea
Authors: Brinkhurst R. O. , Rodriguez P. , Tae-Soo Chon , Tae-Sung Kwon
Published: January 2008

Lamprortus orientalis Rodriguez gen.nov., sp.nov. is identifiable as a member of the Lumbriculidae by virtue of the prosoporous male ducts, but is unique in the family, as it is consistently hologynous. The elongate atria, single vas deferens on each atrium, and spermathecae located in the post-ovarian segment indicate a relationship to Lamprodrilus and related genera distributed from Siberia through eastern Asia to western North America.
Recovery from the effects of subchronic pentachlorophenol exposure on the growth of juvenile bluegill sunfish (Lepomis macrochirus)
Authors: Samis Andrew J. W. , Colgan Patrick W. , Johansen Peter H.
Published: January 2008

Exposure of juvenile bluegill sunfish (Lepomis macrochirus) to 48 and 173 μg/L pentachlorophenol (20 and 72% of 96-h LC50, respectively) for 22 days produced a significant reduction in food conversion efficiency measured over the last 10 days of exposure. A 22-day recovery period in untreated water caused food conversion efficiency values to increase so that there was no longer a significant difference between previously exposed and control fish. For bluegill sunfish, exposure to sublethal levels of pentachlorophenol can decrease food-conversion efficiency, but recovery from this state of reduced growth is rapid when fish are placed in a toxicant-free environment. Although other studies have found that a number of biochemical indicators of pentachlorophenol exposure cause long-lasting changes, this study used a new method of measuring food conversion over a very short period to show that food-conversion efficiency, which integrates many biochemical and physiological effects, recovers quickly.
Thermal tolerance in the tree lizard (Urosaurus ornatus) from a desert population and a low montane population
Authors: Smith Geoffrey R. , Ballinger Royce E.
Published: January 2008

We studied the thermal tolerance of two populations of the tree lizard Urosaurus ornatus from a desert environment in southwestern New Mexico and a low montane environment in southeastern Arizona. In general, there were no differences in thermal tolerance between the two populations. Desert individuals tended to have higher panting thresholds in the summer than low montane individuals, whereas the reverse held for late summer and fall. Males had lower critical thermal maxima than females in the low montane population, but there was no difference in the desert population. Thermal tolerance varied from month to month, tolerances being highest during the summer. Thermal tolerance was related to body size (measured as both snout–vent length and body mass), explaining up to 39% of the variance.
Effects of winter on the papillar morphology of the rumen in reindeer calves
Authors: Soveri Timo , Nieminen Mauri
Published: January 2008

To study papillar morphology as a nutritional indicator, samples were taken from five areas of the rumen of reindeer calves (Rangifer tarandus tarandus L.) in late April 1986 (group 1, n = 6); early May 1987 (group 2, n = 6); December 1986 (group 3, n = 9); and November 1987 (group 4, n = 6). The reindeer in groups 3 and 4 were allowed to graze freely under natural conditions, mainly feeding on lichens, while those in groups 1 and 2 were kept in pens and fed with lichens. The reindeer had shorter papillae at all five points in the rumen in spring, and the mean and areal papillar volumes and the papillar surface area in the caudal blind sacs were smaller than in the animals studied in early winter. The papillae were shorter in the caudal blind sacs than in the other parts of the rumen. The highest number of papillae was usually found in the atrium or the caudal blind sacs, whereas the mean papillar volume and papillar surface area were greater in the dorsal and ventral walls. Even relatively low amounts of lichens, which are rich in easily soluble carbohydrates, seem to be sufficient to produce volatile fatty acids for the papillae in order to avoid their regression to any great extent. The even, dense distribution of ruminal papillae in the reindeer resembles the pattern found in other ruminants, which are classified as concentrate selectors.
Influence du mode de vie sur les caractéristiques pondérales et structurales du squelette chez les amphibiens anoures
Authors: Castanet Jacques , Caetano Maria Helena
Published: January 2008

To specify the influence of a permanent aquatic life on skeletal mass and bone structure in anuran amphibians, the general and regional masses of the skeleton, as well as several histomorphometric indices of the bones (porosity, corticodiaphyseal index, density) were compared in four ranid species, two predominantly aquatic (Rana perezi and R. esculenta) and two more terrestrial (R. temporaria and R. dalmatina). The relative mass of the skeleton (as a percentage of the total body mass) is significantly lower in aquatic forms. This difference is not a phenomenon of intra- or inter-specific allometry between skeletal mass and body mass (size effect). Rather, it reflects a selective reduction of skeletal volume (low corticodiaphyseal index values and higher porosity), in particular in the autopodia, pectoral girdle, front limbs, and vertebral column of aquatic forms. These results reinforce the idea that habitat and mode of life are selective factors producing a more or less developed skeleton in anurans. Whether a lighter skeleton is a permanent adaptative feature or a reversible response in predominantly aquatic anurans remains to be tested.
Modulation of ovarian function by various indolamines during the sexually active phase in the Indian palm squirrel, Funambulus pennanti
Authors: Haldar C. , Singh Savita
Published: January 2008

We studied the effects of four indolamines (melatonin, 5-methoxytryptamine, 5-methoxytryptophol, and 5-methoxytryptophan) on ovarian activity in a tropical rodent, the Indian palm squirrel (Funambulus pennati), during the sexually active phase. Injection of the four 5-methoxyindoles at a dose of 20 μg/0.1 mL per animal every evening for 30 days reduced ovarian mass in both intact and pinealectomized animals. Intact animals treated with 5-methoxyindoles had a lower uterine mass than the intact controls. On the other hand, the uterine mass of pinealectomized animals treated with 5-methoxyindoles did not differ from that of their respective controls. Plasma estradiol levels showed a similar pattern to ovarian masses. We conclude that the effect of 5-methoxyindoles in the female palm squirrel is independent of the pineal gland and that 5-methoxytraptophol and 5-methoxytryptophan are more potent than melatonin.
Revision of the species ofRidgeiafrom northeast Pacific hydrothermal vents, with a redescription ofRidgeia piscesaeJones (Pogonophora: Obturata = Vestimentifera)
Authors: Southward Eve C. , Tunnicliffe Verena , Black Michael
Published: January 2008

Examination of vestimentiferan worms attributed to the genus Ridgeia from more than 50 vent sites in the northeast Pacific indicates that only one species is present. We amalgamate Ridgeia piscesae Jones and R. phaeophiale Jones under the name R. piscesae and include other forms previously suspected to be different species. Allozyme evidence supports the hypothesis that the populations belong to a highly plastic phenotype. The distance data indicate no substantial genetic differences among populations along Juan de Fuca Ridge and across a transform fault to the northern Gorda Ridge. Morphological data indicate that the original distinction of two species on the basis of obturacular saucer number and tube colour was based on the extremes of a continuum of characteristics that relate to animal size, levels of predation, and probably vent fluid conditions. The intriguing effect of habitat on phenotype in this abundant vent animal requires further investigation now that the taxonomy is better understood.
Population dynamics of two species of intestinal helminth in oystercatchers (Haematopus ostralegus)
Authors: Goater C. P. , Goss-Custard J. D. , Kennedy C. R.
Published: January 2008

The cestode Micrasomacanthus rectacantha and the trematode Psilostomum brevicolle are the two most common intestinal helminths of oystercatchers, Haematopus ostralegus, on the Exe estuary, England. Each was present in 57 of 60 birds, in numbers ranging from 1 to 9833 and from 1 to 182, respectively. Cockles (Cerastoderma edule) were used as paratenic host by M. rectacantha and as second intermediate host by P. brevicolle. Over 90% of the transmission of M. rectacantha from intermediate hosts occurred in winter, between cockles and juvenile birds. Exposure to M. rectacantha was highest in cockles from muddy sites, where up to 80% of older cockles were infected with 1–14 larvae. Exposure to P. brevicolle was similarly high at one sandy site. Juveniles also made up > 90% of the birds present on the estuary in summer, when significantly more worms were gravid. Estimates based on the numbers of uterine eggs per individual P. brevicolle showed that 8 % of the total Exe population of oystercatchers (ca. 200) contributed 51% of the eggs to the estuary. The results implicate host age, host feeding preference, and host population structure as important factors determining variation in helminth abundance in birds.
Variation in the feeding kinematics of mole salamanders (Ambystomatidae:Ambystoma)
Authors: Beneski Jr. John T. , Larsen Jr. John H. , Miller Brian T.
Published: January 2008

High-speed cinematography was used to investigate the prey-capture kinematics of six species of mole salamanders (Ambystomatidae). We compared the feeding behavior of the subgenus Ambystoma (A. californiense and A. macrodactylum) with that of the subgenus Linguaelapsus (A. mabeei, A. texanum, A. annulatum, and A. cingulatum). Prey capture by all six species is characterized by a 3-part gape cycle (a period of rapid mouth opening prior to extraoral tongue protraction, followed by a period of relatively stable gape angle during extraoral tongue protraction and retraction, followed by a period of rapid mouth closure), a tongue-extension cycle (protraction and retraction), and anterior head–body displacement. Among the six species, two distinct modes of prey capture are evident: (1) the Ambystoma mode (A. californiense, A. macrodactylum, A. mabeei, and A. texanum), and (2) the Linguaelapsus mode (A. annulatum and A. cingulatum). Most differences in prey-capture kinematics between the two modes are primarily differences of degree rather than the addition or loss of unique behaviors, and include a general reduction in the gape angles and a general increase in the elapsed times associated with specific events in the Linguaelapsus mode. We hypothesize that these differences are primarily the result of a prolonged period of tongue protraction in the Linguaelapsus mode during which the glandular tongue pad is fitted to the prey. In addition to differing from each other, the gape profiles of the ambystomatid subgenera differ markedly from the 4-part gape profiles of plethodontids and salamandrids.
Spatial organization of a lynx population
Authors: Poole Kim G.
Published: January 2008

I examined the home-range relationships and spatial organization of an untrapped lynx (Lynx canadensis) population in the southern Northwest Territories, Canada. I determined annual home ranges and static and dynamic interactions among 30 radio-collared adult lynx from April 1989 to April 1993. Densities of snowshoe hares (Lepus americanus), the main prey, declined during winter 1990–1991. There was extensive range overlap between sexes, and between certain pairs of female lynx. Ranges among most males and among other individual or pairs of females were more exclusive. Most intrasexual dynamic interactions indicated neither attraction nor avoidance, suggesting that home-range boundaries were maintained by passive means. Two male–female pairs showed some positive attraction during the early part of the first winter of low hare density. Home ranges of three male and three female lynx monitored for 3 consecutive years were stable. Spatial organization broke down during winter 1991 – 1992, when all resident lynx died or dispersed; this was concomitant with the first full winter of low hare density. Spatial organization observed prior to low hare densities may be described as a land-tenure system, based on prior residency, and may have served to regulate the density of this untrapped population during peak prey levels.
Buccal capsule of Zeldia punctata (Nemata: Cephalobidae): an ultrastructural study
Authors: Baldwin J. G. , Eddleman C. D.
Published: January 2008

The ultrastructure of the buccal capsule of the microbivorous soil nematode Zeldia punctata demonstrates important differences and possible homologies with that of the nematode Caenorhabditis elegans. In Z. punctata the buccal capsule wall is separated into an anterior to posterior series of six cuticular rhabdions. The most anterior, rhabdion 1, the cheilorhabdion, is continuous with the body-wall cuticle and is produced by the adjacent syncytial hypodermis (=epidermis). Rhabdion 2 is underlain by a stack of two nonpharyngeal arcade synctyia and, in this respect, resembles the prorhabdion of C. elegans. Rhabdion 3 includes six electron-lucent rods and is surrounded by muscle designated ma, whereas rhabdions 4 and 5 are characterized by an electron-lucent marbling and each is surrounded by three muscles designated mb and mc, respectively. In Z. punctata the dorsal gland opens into the lumen of the buccal capsule near the base of rhabdion 5, whereas in C. elegans it occurs farther posteriorly, near the base of the buccal capsule. Rhabdion 6 is electron dense and is surrounded by the md muscles. The ma and mb muscles in Z. punctata are hypothesized as homologues of the epithelial cells e1 and e3 in C. elegans, but alternative testable hypotheses are also proposed.
Winter mortality and the function of larval hibernacula during the 14-year life cycle of an arctic moth,Gynaephora groenlandica
Authors: Kukal Olga
Published: January 2008

Larvae of the arctic moth Gynaephora groenlandica stop feeding and spin silk hibernacula before the peak of summer season in the Canadian High Arctic Archipelago. This study examines the function of these hibernacula in relation to the biotic and abiotic mortality factors of parasitism and temperature. Winter mortality of 10% among larvae in cages on the tundra was compared with previous results on parasitism (56% mortality). Prior to winter, the cages were used to record larval behaviour and the location of hibernacula. The majority of the larvae (81%) spun hibernacula, most of which were concealed between the stems of arctic heather, Cassiope tetragona. Fewer hibernacula were found on the primary host plant, arctic willow, Salix arctica, than on C. tetragona or Dryas integrifolia, which formed the dominant plant cover. Nearly one-half of all the larvae that spun hibernacula made joint hibernacula with other larvae. Frequency of larvae sharing hibernacula declined with increasing numbers of larvae per cage. At low population density about half of the larvae occupied communal hibernacula, whereas only one-quarter of the larvae at high density shared hibernacula. In most cases only 2 larvae spun a common hibernaculum, 3 larvae shared hibernacula less frequently, and greater numbers of larvae were rarely found in a single hibernaculum. Unlike the high excess body temperatures usually achieved through thermoregulation by feeding larvae and pupae, temperatures within hibernacula were nearly identical with those of the surrounding substrate over 18 h and rose < 5 °C during the afternoon. This study suggests that larval hibernacula lower summer and winter mortality of G. groenlandica larvae. Hibernacula are an effective barrier to parasitism, which is the primary mortality factor. Furthermore, the behavioural shift from feeding to spinning hibernacula may prevent energy depletion by inducing metabolic depression during mid to late summer, which may be essential for winter survival.
Relationship between the spatial distribution of freshwater mussels (Bivalvia: Unionidae) and the hydrological variability of rivers
Authors: Maio Joanne Di , Corkum Lynda D.
Published: January 2008

Hydrological variability refers to the differences in the patterns of flow among rivers. Drainage basins in southwestern Ontario and southeastern Michigan were selected a priori using records of flow variability. Hydrological variability was then used as a macrohabitat measure of mussel habitat. The distribution and relative abundance of mussels were determined in drainage basins of two hydrologically different types, three event responsive (i.e., hydrologically flashy) and three stable (i.e., hydrologically stable). Eleven event and 10 stable sites were sampled once each from 18 to 30 August 1993. Fifteen species of unionids were found in the study area (13 in event rivers and 9 in stable rivers), with different relative abundances in each regime. Multivariate analyses revealed that there are distinct mussel communities based on the hydrological variability of the river. Amblema plicata, Pyganodon grandis, and Fusconaia flava characterized event sites and Elliptio dilatata, Lampsilis radiata, and Lasmigona costata characterized stable sites. We propose that some unionids can be associated with river types with specific hydrological features and their distribution can be predicted using flow-related stream attributes.
Demographic and reproductive attributes of dispersers in two populations of the subterranean rodent Ctenomys talarum (tuco-tuco)
Authors: Malizia Ana I. , Zenuto Roxana R. , Busch Cristina
Published: January 2008

The demographic and reproductive characteristics of dispersers in the fossorial rodent Ctenomys talarum, the tuco-tuco, were studied by removing animals from two experimental plots. Data on dispersers' attributes were compared with those of resident and transient individuals from previous capture–mark–release and removal studies performed in the same localities. Average weekly dispersal by tuco-tucos was 2.38% (range 0–5.75%) at Necochea and 5.75% (range 0–15.75%) at Mar de Cobo. The low proportion of dispersers reflects their fossorial habit. At Mar de Cobo, the sex ratios of dispersers and transients showed a 1:1 relationship, whereas residents showed an excess of females. All groups did not differ from a sex ratio of 1:1 at Necochea. At both localities, dispersers did not differ qualitatively from residents in age composition, litter size, or body mass. Transients and dispersers of both populations were characterized by a higher proportion of immature individuals than residents. We conclude that dispersal may be an important factor regulating the C. talarum population and may counteract the restrictions imposed by its subterranean habitat.
Influence of wind speed on sage grouse metabolism
Authors: Sherfy Mark H. , Pekins Peter J.
Published: January 2008

We measured the effect of wind speed on the metabolic rate of six adult sage grouse (Centrocercus urophasianus) with indirect respiration calorimetry at ambient temperatures above, near, and below the lower critical temperature. There was a significant effect (P < 0.05) of temperature on metabolic rate at all wind speeds, and a significant effect (P < 0.05) of wind speed on metabolic rate for temperatures ≤ 0 °C. Wind speed had a more pronounced effect on metabolism at temperatures below the lower critical temperature for sage grouse. Metabolic rates measured at wind speeds of ≥ 1.5 m/s were significantly higher than those measured at wind speeds < 1.5 m/s. Multiple regression analysis of wind speed (u; m/s) and temperature (Ta; °C) on metabolism (MR; mL O2∙g−1∙h−1) yielded the equation MR = 0.0837 (u) − 0.0248 (Ta) + 0.5444. The predicted cost of thermoregulation at conditions of −5 °C and u = 1.5 m/s was about 1.5× standard metabolic rate; half the increase was due to wind. Measurements of wind speed in sagebrush (Artemisia spp.) stands indicate that such habitat effectively reduces wind speed to < 1.5 m/s. Microhabitat value should be recognized in the management of sagebrush stands.
Winter habitat use by ptarmigan, snowshoe hares, red foxes, and river otters in the boreal forest – tundra transition zone of western Quebec
Authors: St-Georges Mario , Nadeau Simon , Lambert Daniel , Décarie Robert
Published: January 2008

We investigated species–habitat relationships of the midsized fauna inhabiting the transition zone between the boreal forest and forest tundra of subarctic Quebec. Data were collected during a winter aerial track survey of 46 randomly selected 25-km2plots. The presence of species tracks and habitat variables were recorded for each 1-km section of riparian edge habitat within a plot. Sections of non-riparian habitat were also surveyed. Logistic regression was used to construct habitat models for ptarmigan (Lagopus spp.), snowshoe hares (Lepus americanus), red foxes (Vulpes vulpes), and river otters (Lutra canadensis). Species' habitat type selection was studied by comparing use and availability. Kendall's correlation coefficients were computed to analyze interrelations between variables. Significant logistic regressions were obtained for each species. The index of rank correlation between the observed responses and predicted probabilities for all pairs of observations ranged from 0.67 for ptarmigan to 0.84 for river otters. Species abundance was negatively associated with latitude except for that of snowshoe hare, which showed a stronger negative link with open habitat. For all species, distribution was not proportional to the frequency of occurrence of habitat types. Non-riparian habitat was either avoided or not significantly preferred by all species. Herbivorous species and river otter selected edge habitats along watercourses. Our study suggests that differences presented by the forest tundra and boreal forest are of importance for wildlife.
Scanning electron microscopy, whole-mount histology, and histochemistry of two anodontine glochidia (Bivalvia: Unionidae)
Authors: Pekkarinen M.
Published: January 2008

Intramarsupial glochidia of Anodonta anatina (L.) and Pseudanodonta complanata (Rossmässler) were studied in southern Finland. Material staining positively with periodic acid – Schiff's reagent (PAS), neutral lipid reserves, and acid phosphatase activity have different distributions in the mantle of the two species. Moreover, the mucous covering of the mantle of the two glochidia behaves differently on critical-point drying. The presence of microvilli with alkaline phosphatase activity on the mantle surface and acid phosphatase activity in the mantle cells in both glochidia suggest that the mantle plays a role in nutrient uptake and digestion and possibly also in electrolyte uptake. The primordia of the stomach, digestive diverticula, and intestine, at least in A. anatina glochidia, contain neutral lipids and exhibit acid phosphatase activity: In A. anatina glochidia, a microvillous layer with alkaline phosphatase activity continues from the ventral walls of the lateral pits to the suspected kidney diverticula. In both glochidia, there may be three pairs of rudimentary ganglia, which do not stain with methylene blue. The eight ciliated sense organs of the glochidia are methylene blue- and PAS-positive and they exhibit succinate dehydrogenase and acid phosphatase activity. In each mantle lobe, the enveloping cell of the dorsal ciliary organ is interconnected with those of the ventral triad via a cellular fold or "tract," and the ciliated central cells of the organs send axons towards each other.
Forage intake rates of ruffed grouse and potential effects on grouse density
Authors: Hewitt David G. , Kirkpatrick Roy L.
Published: January 2008

One hypothesis to explain low densities of ruffed grouse (Bonasa umbellus) in the southeastern United States is that available winter forages in the Southeast require more time to harvest than forages eaten in the central portions of the species' range, where grouse densities are greater. Longer foraging times could increase mortality rates through greater predation risk and higher energy expenditure. To test this hypothesis, we conducted trials with captive ruffed grouse to determine their maximum instantaneous rates of intake of various forages and used the results to estimate minimum foraging times for southeastern ruffed grouse consuming an average winter diet. Grouse in the Southeast must forage for > 100 min to meet their energy demands. Ruffed grouse in the central portion of the range rely heavily on aspen (Populus sp.) buds during the winter and can consume the same amount of metabolizable energy in 30–50 min. Thus, we present evidence that ruffed grouse in the southeastern United States must forage for longer periods to meet daily energy demands and therefore may experience higher winter mortality rates.
Survival of breeding male American woodcock in Maine
Authors: Longcore Jerry R. , McAuley Daniel G. , Sepik Greg F. , Pendleton Grey W.
Published: January 2008

We radio-marked 150 male American woodcock (Scolopax minor) during 1987–1989 and estimated period survival for 1 April – 15 June. Survival varied from 0.690 (1989) to 0.924 (1988), with a 3-year mean (95% confidence interval) of 0.789 (0.693–0.885). Woodcock were killed by raptors (n = 14, 53.8%), mammals (n = 1, 3.8%), or unknown predators (n = 5, 19.2%); six deaths (23.1%) were from miscellaneous causes, including three (11.5%) from entanglement in the transmitter harness. A composite survival estimate based on telemetry studies for the breeding, postbreeding, and wintering periods was 0.471 (0.789 × 0.923 × 0.647). The calculated survival rates were 0.881 for the spring migration period and 0.853 for the combined hunting and fall migration period. In a proportional hazards model, body mass at capture was not related to survival. Forest type (hardwood versus conifers) affected survival (P < 0.016), which was lower for woodcock using mostly conifer sites. Survival was related positively to mean snow depth in December (P < 0.038), negatively to snow depth in April (P < 0.046), and positively to minimum temperature in December (P < 0.054) and April (P < 0.066) in some analyses.