bluuebunny/crossref_metadata_2025 huggingface dataset:
The antennal sensilla of the carnivorous "phantom" larva of Chaoborus crystallinus (De Geer) (Diptera, Nematocera)
Authors: Nicastro Daniela , Smola Ulrich , Melzer Roland R.
Published: July 2008

The prehensile antennae of larval Chaoborus crystallinus are equipped with seven sensilla that comprise 24 sensory cells. Analysis of their ultrastructure indicates that they represent either mechano-or chemo-receptors. The main chemosensory input is established by a compound sensillum, S15 ("sensory cone" with 15-sensory cells), that is located at the tip of the antennal article (outer ventral claw). Exteroreceptors are the "middle claw" of the antenna, and a small sensillum trichodeum at half the length of the antennal article. Proprioreceptive mechanoreceptors are found in the proximal and distal regions of the antennal article. Comparison of sensillar arrangement and ultrastructure indicates that the ancient sensillar equipment of the culicid type is still present within the highly specialized catching apparatus of C. crystallinus. Compared with Culicidae, chemosensitive input is reduced, while proprioreceptive, mechanosensory input is highly developed. Larvae of Culicidae and Chaoboridae appear to possess a homologous set of antennal senilla that show specializations connected to the different functions of the antennae.
Anophryocephalus inuitorum sp.nov. and A. arcticensis sp.nov. (Eucestoda: Tetrabothriidae) in ringed seals (Phoca hispida hispida) and harp seals (Phoca groenlandica) from high-latitude seas of eastern Canada and the Arctic basin
Authors: Hoberg Eric P. , Measures Lena N.
Published: July 2008

Anophryocephalus inuitorum sp.nov. and A. arcticensis sp.nov. are described from ringed seals (Phoca hispida hispida) in the eastern Canadian Arctic; the latter species is also reported from harp seals (Phoca groenlandica) in the Gulf of St. Lawrence. Anophryocephalus inuitorum is most similar to A. skrjabini, but can be distinguished by fewer testes (14–27) and smaller dimensions of the strobila, neck (3.0–5.9 mm long), and cirrus sac (31–70 μm long), diameter of the genital atrium (44–68 μm), and length of the male canal (23–42 μm long). Anophryocephalus arcticensis resembles A. nunivakensis in the structure of the scolex, but is readily distinguished by a longer neck (8.9–14.7 mm), an elongate cirrus sac (60–98 × 44–73 μm) with a substantially thicker muscular wall, a more globular vitelline gland, and larger embryophores (29–41 μm long) and oncospheres (24–34 μm long). These are the first species of Anophryocephalus to be described from phocines in the eastern Canadian Arctic, and are included in a revised key for the genus.
Metabolism ofD-[1-13C]glucose in livers ofMeriones unguiculatusinfected withEchinococcus multilocularis
Authors: Novak Marie , Modha Ashok , Lee Jonathan , Buist Richard , Blackburn Barry
Published: July 2008

Following administration of [1-13C]glucose, sequential13C nuclear magnetic resonance (NMR) in situ spectra were obtained from the liver of uninfected jirds (Meriones unguiculatus) and those infected with Echinococcus multilocularis over a period of 2 h. Quantitative evaluation of the flow of labelled carbon through the liver at 80 and 120 min after glucose administration revealed that although the percentage of labelled glucose utilized by the liver was the same for both groups, glycogen synthesis differed. At both times, the livers of infected animals had incorporated a smaller percentage of the [1-13C]glucose into glycogen labelled at C1and a larger percentage into the C6position of glucose/glycogen. In another experiment, identical with respect to the substrate administered, NMR analysis of perchloric acid extracts revealed that the livers of infected animals had lower concentrations of labelled glucose and glycogen and higher concentrations of labelled alanine and lactate than those of uninfected controls. Concentration differences were also noted for some of the unlabelled metabolites. Echinococcus multilocularis cysts contained the same labelled metabolites as the livers but the concentration of lactate was much higher. Parasite cysts also contained labelled acetate.
Life cycle of a sea louse, Caligus elongatus von Nordmann, 1832 (Copepoda, Siphonostomatoida, Caligidae)
Authors: Piasecki W. , MacKinnon B. M.
Published: July 2008

Caligus elongatus, known as a sea louse, is a very important pathogen of sea-farmed Atlantic salmon (Salmo salar). The life cycle of C. elongatus was examined under laboratory conditions. The observations were made at 10 °C, with ambient photoperiod. Small Arctic char (Salvelinus alpinus) kept in full-salinity seawater were used as experimental host fish. They were infected individually by offspring of several C. elongatus females. The hosts were killed at consecutive time periods after infection and developmental stages of the parasite were recovered. The life cycle consists of 8 stages: 2 nauplii, 1 copepodid, 4 chalimi, and adult. A separate preadult stage does not occur. The copepodid is infective and all subsequent stages live on fish. The time at which a particular stage is attained by 50% of individuals in a cohort (T50) was as follows: chalimus I, 7.1 days post infection (dpi); chalimus II, 11.4 dpi; chalimus III, 14.0 dpi; chalimus IV, 17.6 dpi; adult, 24.7 dpi. The generation time was 43.3 days. The females can lay eggs at least twice. The males die after copulation (38–54 days after hatching). Overwintering females show signs of diapause.
A quantitative assessment of the reproductive biology ofCyclonaias tuberculata(Bivalvia: Unionidae)
Authors: Haggerty Thomas M. , Garner Jeffrey T. , Patterson George H. , Jones Jr. Lannis C.
Published: July 2008

Two hundred and thirty-three purple wartyback unionids (Cyclonaias tuberculata) were collected approximately monthly over a 31-month period from Kentucky Reservoir (Tennessee river mile 201.3), Tennessee, between August 1988 and February 1991. An equal sex ratio and only one case of hermaphroditism were discovered. Histological examinations showed that spermatogenesis and oogenesis occurred throughout the year except during late summer and early fall. "Typical" spermatogenesis was most evident between May and July. Spawning occurred between early spring (March–April) and late summer (August). Brooding variation among females was shown by the presence of embryos in the suprabranchial chambers and gills between early April and late August. Brooding was short term, as indicated by mature larvae being found in the outer demibranchs between early July and late August. Full demibranchs were never found, possibly indicating that the study took place during years of poor reproductive performance.
Intraspecific variation in wing loading affects habitat use by little brown bats (Myotis lucifugus)
Authors: Kalcounis Matina C. , Brigham R. Mark
Published: July 2008

Morphological constraints have been linked to habitat partitioning by different species of animals. Interspecific differences have been explored, but less is known about the relationship between individuals of the same species. The purpose of this study was to determine if habitat use by little brown bats (Myotis lucifugus) varies with body mass of individuals. From aerodynamic theory, we predicted that bats with higher body mass will have higher wing loadings, should be less manoeuvrable, and thus tend to forage in areas where there are fewer obstacles to detect and avoid (clutter). Habitat was ranked into four zones based on the degree of clutter, and habitat use was assessed by measuring the time that males and non-reproductive, pregnant, lactating, postlactating, and artificially loaded females spent in each habitat zone. To test the assumption that a selective advantage accrues to bats foraging in clutter, we measured the availability of flying insects in cluttered and open habitats. Insect trap samples revealed a higher density of insect prey in more cluttered habitats. Body mass was positively correlated with wing loading. Overall, males were smaller than females with respect to mass and wing loading; however, these differences did not translate into differential habitat use. As predicted, there was a significant relationship between individual wing loading and habitat use, with heavier bats (greater wing loading) foraging in less cluttered areas.
Influence of habitat structure on the escape tactics of the lizard Psammodromus algirus
Authors: Martin Jose , López Pilar
Published: July 2008

We examined the escape responses of a population of lizards (Psammodromus algirus) in relation to reasonal variation in the habitat caused by the presence or absence of leaves in deciduous shrubs under which the lizards seek refuge against predators, and, within a season, relative to the microhabitat occupied. Approach and flight distances of lizards were significantly longer in early spring (when most bushes were without leaves) than in summer. Within a season, approach and flight distances were also longer in microhabitats with less vegetation cover. Lizards ran to refuges (patches of leaf litter under bushes) similar in characteristics but further than the nearest one available from their initial location. This suggests that misleading the predator is also crucial to escaping successfully. Escape responses were independent of ambient temperature. Lizards showed flexibility in their antipredator behaviours that may be related to predation risk assessment.
The effect of maternal mass on litter size and offspring survival in the hispid cotton rat (Sigmodon hispidus)
Authors: Campbell Michael T. , Slade Norman A.
Published: July 2008

We tested the proposition that maternal body mass affects litter production and recruitment in the cotton rat (Sigmodon hispidus) in Kansas. We also addressed hypotheses about why cotton rats in Kansas are larger and more fecund than conspecifics in Texas. We livetrapped cotton rats on both control and food-supplemented grids. Pregnant females were briefly confined until parturition; their pups were weighed and toe-clipped, then mother and young were returned to the site of capture. Subsequent trapping revealed survival of the offspring, i.e., ability of mothers to recruit pups into the population. Heavier mothers on both sets of grids gave birth to larger, heavier litters and had more pups survive to recruitment. The percentage of pups surviving was not related to maternal mass or to pup mass, so the increased recruitment resulted primarily from heavier mothers' having more rather than heavier pups. Mothers on the supplemented grids bore larger and heavier litters than their same-mass counterparts on the control grids. Despite their larger litters, lighter (ca. 100 g) mothers on the supplemented grids recruited fewer pups than their same-mass counterparts on control grids. Because heavier female cotton rats are more fecund, our results are consistent with the hypothesis that cotton rats in Kansas are larger than in those in Texas because of selection for increased litter size in Kansas. Seasonality in Kansas restricts the number of breeding opportunities and provides a nutrient pulse that supports rapid reproduction in the growing season.
Fluctuating asymmetry in the skeleton of the American kestrel, Falco sparverius: a test of the consequences of sexual size dimorphism
Authors: Bortolotti Gary R. , Gabrielson Joan R.
Published: July 2008

Fluctuating asymmetry, i.e., random, subtle departures from perfect bilateral symmetry, is believed to be a measure of developmental noise. The more physical stress an organism has undergone, the greater the asymmetry. We investigated the degree of fluctuating asymmetry in bones of the American kestrel (Falco sparverius) as a test of the developmental consequences of sexual dimorphism in size. The "cost of rearing" hypothesis predicts that females, because of their larger size, will suffer food shortages more often than males and hence show greater asymmetry. In contrast, the "female dominance" hypothesis predicts that females will be under less developmental stress because their size gives them an advantage when they compete with their brothers for limited food while in the nest. Significant fluctuating asymmetry was detected for all characters of both sexes; however, differences between males and females only approached statistical significance. We suggest that the degree of among-broods variation is so great that the role of gender in influencing developmental stability may be relatively small.
Horizontal and vertical movements of telemetered rainbow trout (Oncorhynchus mykiss) in Lake Washington
Authors: Warner Eric J. , Quinn Thomas P.
Published: July 2008

In summer and fall 1989, six rainbow trout (Oncorhynchus mykiss) were tracked in Lake Washington with ultrasonic transmitters for a total of 349 h to determine their movements in relation to the distribution of possible prey species. The trout moved primarily in the nearshore area at an average velocity of 12.4 cm/s (~ 0.25–0.3 body lengths/s). Five of the six fish made one more rapid (>1 body lengths/s) excursion across the lake, then continued moving in the nearshore zone. The trout were generally inactive, staying close (<50 m) to shore at night, and became more active near dawn; however, the highest average velocities were at dusk. They spent over 90% of their time in the top 3 m of the water column and 10% in brief (2 min), shallow (mean 6.6 m) dives. Dives occurred most frequently at dawn and during the day (0.8/h), less often near dusk (0.5/h), and seldom at night (0.1/h). The depth distribution and movement patterns suggest that the trout were feeding on Daphnia pulicaria during the day, in both nearshore and offshore areas, supplementing this diet with nearshore fishes such as prickly sculpins (Cottus asper). Predation on pelagic planktivores (longfin smelt, Spirinchus thaleichthyes, and juvenile sockeye salmon, Oncorhynchus nerka) was unlikely because the trout were primarily found nearshore and near the surface, whereas the planktivores are primarily offshore and closer to the bottom.
Morphological changes in rainbow trout (Oncorhynchus mykiss) gill epithelia following repeated intermittent exposure to chloramine-T
Authors: Powell Mark D. , Speare David J. , Wright Glenda M.
Published: July 2008

Chloramine-T is a widely used prophylactic and therapeutic agent in freshwater aquaculture. This study examined the effects of repeated intermittent exposure of healthy rainbow trout (Oncorhynchus mykiss) fingerlings to sublethal concentrations of chloramine-T (0, 5, 10, or 20 mg/L) twice weekly in 1-h pulses at 11 °C for 4 weeks in a replicate-tank facility. Gills were excised from subsamples of fish prior to exposure and at the end of the 4-week experimental period. Tissue was fixed and processed for light microscopy and transmission and scanning electron microscopy. The gill epithelium from fish treated with 10 and 20 mg/L chloramine-T appeared swollen and vacuolated, with extensive intercellular edema. There was a significant reduction in the number of lamellar mucous cells and an apparent increase in the numbers of chloride cells. Chloride cells from both the base of the lamella and the lamellar surface of gills exposed to chloramine-T had a significant increase in the area of the apical plasmalemma after treatment with 10 and 20 mg/L, and a reduction in the thickness of the apical plasmalemma-associated glycocalyx. These morphological changes are consistent with a compensatory mechanism for the remedial uptake of ions, suggesting that chloramine-T increased epithelial ion permeability coincident with a possible influx of water leading to intercellular edema. Chloride cell proliferation and intercellular edema may also have affected gas exchange across the branchial epithelium.
Vasichona opiliophila n.sp., an ectosymbiotic ciliate (Chonotrichia; Exogemmida) on the maxillae of the snow crab, Chionoecetes opilio
Authors: Taylor David M. , Lynn Denis H. , Gransden Scott G.
Published: July 2008

Vasichona opiliophila n.sp. is described from the basal endites of the maxillae of the snow crab, Chionoecetes opilio. This is the first report of these chonotrich ciliates from the Northwestern Atlantic. The genus Vasichona Jankowski, 1972 is redefined and the genus Cryptochona Jankowski, 1973 is considered to be a junior synonym of Vasichona because the relative size of the oral flap is not a stable character.
Patterns of leaf and stomatal development explain ovipositional patterns by the gall midge Cystiphora sonchi (Diptera: Cecidomyiidae) on perennial sow-thistle (Sonchus arvensis)
Authors: DeClerck-Floate R. A. , Steeves T. A.
Published: July 2008

The gall midge Cystiphora sonchi oviposits through the stomata of perennial sow-thistle (Sonchus arvensis) leaves, and requires tissues that are conducive to gall formation. To determine if these requirements affect ovipositional choice, egg distribution patterns among and within sow-thistle leaves were related to patterns of leaf and stomatal development. Our study showed that C. sonchi prefers to oviposit into leaves that are in the final stages of growth, when mature stomata are available and tissues are still responsive to the gall-forming stimulus. The youngest and oldest leaves within plants were avoided by ovipositing females. Cystiphora sonchi egg distribution within leaves generally reflected the availability of mature stomata, which develop from tip to base in young S. arvensis leaves. Hence, mature stomata, and C. sonchi eggs, were more frequent at the tip of young leaves. By the later stages of leaf development, the basipetal pattern of growth was no longer apparent, and mature stomata and C. sonchi eggs were more evenly distributed within leaves.
Validation of daily growth increments in otoliths of Anguilla rostrata (Lesueur) elvers
Authors: Martin Michael H.
Published: July 2008

The presence of daily growth increments in otoliths was validated for Anguilla rostrata. Elvers were captured at the freshwater–seawater interface of the Annaquatucket River, Rhode Island, immersed in a tetracycline hydrochloride solution to mark their otoliths, and maintained in stream aquaria for 10 or 20 d. Increment counts outside the tetracycline mark generally underestimated the number of days since marking by less than 5%. This underestimation was probably due to the time required for tetracycline incorporation after administration.
Erythrodynamics in fish: recovery of the goldfishCarassius auratusfrom acute anemia
Authors: Houston Arthur H. , Murad Ajmal
Published: July 2008

Goldfish (Carassius auratus) were rendered anemic through immersion in phenylhydrazine∙HCl, a cohort of [3H]thymidine-labelled erythrocytes was established, and recovery followed over a 234-d period. Red blood cell (RBC), hemoglobin (Hb), and hematocrit (Hct) levels increased in biphasic fashion during recovery, rapid increases to plateau values being followed by more modest increases to levels equalling those observed prior to treatment. During the initial rapid phase of response, increased ventilatory and cardiovascular activities probably compensated for deficits in oxygen-carrying capacity but, by elevating blood O2tension, may have suppressed erythropoiesis. Continuing slow increases in RBC, Hb, and Hct may point to some as yet unidentified alternative mechanism for stimulating red cell formation. During maturation, mean erythrocytic volume decreased, while mean erythrocytic hemoglobin level increased. Cycles of division of circulating juvenile erythrocytes occurred at roughly 56-d intervals, but did not appear to play a major role in elevating blood O2-carrying capacity. Division and karyorrhexis or cell breakdown were loosely correlated. Under the conditions employed, red cell half-life was approximately 80 d.
The effects of winter food addition on the population dynamics ofClethrionomys rutilus
Authors: Schweiger Sabine , Boutin Stan
Published: July 2008

Peaks in red-backed vole (Clethrionomys rutilus) populations are associated with high survival in the previous winter and we tested the hypothesis that winter persistence is determined by food supply. We supplied sunflower seeds to voles in a replicated design during winter in two consecutive years. The study began when voles were at peak density and the pattern of change was one of decline to low density over the first winter followed by constant low densities. Food addition increased persistence of individuals slightly in the first winter and significantly in the second winter. Despite higher numbers in spring and greater production of young on food grids, densities did not increase to a peak in autumn. We conclude that the food additions created local patches of high density, but these were too small to have widespread effects on vole dynamics in the area.
Influence of primary prey on home-range size and habitat-use patterns of northern spotted owls (Strix occidentalis caurina)
Authors: Zabel Cynthia J. , McKelvey Kevin , Ward Jr. James P.
Published: July 2008

Correlations between the home-range size of northern spotted owls (Strix occidentalis caurina) and proportion of their range in old-growth forest have been reported, but there are few data on the relationship between their home-range size and prey. The primary prey of spotted owls are wood rats and northern flying squirrels (Glaucomys sabrinus). Wood rats are larger and heavier than flying squirrels, and their population densities tend to be much greater than those of flying squirrels. We present data indicating that the home ranges of spotted owls are smaller where their diet consists predominantly of wood rats than where it consists predominantly of flying squirrels, and the proportion of the diet consisting of wood rats and flying squirrels explained significant variation in home-range size. We also found a significant correlation between home-range size and abundance of wood rats. These data indicate that prey species are a better predictor of home-range size than the proportion of older forest within spotted owl home ranges in the Klamath Province of northwestern California and southwestern Oregon, an area that is predominantly late-successional forest. Differences in habitat use were also related to prey species. Where spotted owls foraged for wood rats, the results indicated a preference for habitat edges, but where they utilized flying squirrels no such patterns were apparent.
Seasonal change in feed intake, body composition, and metabolic rate of white-tailed deer
Authors: Worden Karol A. , Pekins Peter J.
Published: July 2008

Winter is a critical time of year for white-tailed deer (Odocoileus virginianus) in northern regions because their food consumption does not meet their daily energy demands. We measured feed intake, fasting metabolic rate (FMR), and body composition of five captive adult female white-tailed deer from September 1991 through March 1992 in New Hampshire to investigate the relationships between FMR and feed intake to fat deposition and mobilization. Deuterium oxide dilution was used to estimate monthly body composition, indirect respiration calorimetry was used to measure monthly FMR, and metabolizable energy intake (MEI) was calculated from daily feed intake. Mean percent body fat increased from 9.1 ± 1.5 to 24.9 ± 4.4% from September to December, and then declined through March. Mean percent body protein did not change during the study (range 20–21%). Mean MEI peaked during September and October (171.9 ± 8.1 and 168.7 ± 10.3 kcal∙kg body mass−0.75∙d−1, respectively), and declined 54% by February. Mean FMR ranged from 79 to 90 from October through March. Correlations between MEI or FMR and change in body fat were weak. It was estimated that intake rates of free-ranging deer were only 90–110% of winter FMR, and that deer with 20% body fat could balance their daily energy expenditure (1.7 × FMR) with fat stores for about 3 months, or the period of time during which MEI was depressed in captive deer.
Paralysis as a defence response to threatening stimuli in harp seals (Phoca groenlandica)
Authors: Lydersen Christian , Kovacs Kit M.
Published: July 2008

In this study we describe the behavioural and physiologial characteristics of a fear-induced paralysis response in harp seals (Phoca groenlandica). Of 382 pups tested, 328 (86%) displayed this passive defence response, and of 46 adult seals tested, 26 (57%) individuals exhibited paralysis. Gender had no effect, but among pups there was a signifiant increase with age in the proportion of individuals that performed the response (contingency table; G = 21.46, p = 0.002). During paralyses seals became rigid, the foreflipprs were brought into the sides of the body, the hind flippers were pressed closely together, and the neck was retracted so that the forehead was drawn into the fat sheath that encases the rest of the body. The animals would always urinate and often defecate. Physiologically speaking, paralyses had two phases. In pups, an apnoea phase preceded a period of hyperventilation. Adults alternated between these two phases more sporadically during a paralysis bout. Mean heart rates of pups during paralysis apnoeas were approximately 30 beats/min. During the hyperventilatory phase their heart rates escalated to values in excess of 150 beats/min. Respiration rates for the pups during hyperventilation ranged from 26 to 66 breaths/min. Heart rates of adults during apnoeas were more viable than those of pups, but the average value was similar (32 beats/min). The lowest heart rate recorded was 10 beats/min. Average heart rates of adults during breathing phases were lower than those of pups, ranging from 118 to 130 beats/min. A suite of lactation-related adaptations and ecological circumstances may explain the paralysis response in harp seals. Harp seals have evolved in the presence of polar bears. They are afforded some protection by giving birth in dense aggregations on unstable ice that is variable in geographical location, but pups are extremely vulnerable when a surface predator does enter the whelping patch, and available defence options are limited. The paralysis response may serve to disinterest the predator and so reduce the risk of incidental injury from traumatic, playful handling by a predator by protecting vital body parts.
Tube morphology and activity patterns related to feeding and tube building in the polychaeteMesochaetopterus tayloriPotts
Authors: Sendall K. A. , Fontaine A. R. , O'Foighil D.
Published: July 2008

Tube morphology and activity patterns related to feeding and tube building in Mesochaetopterus taylori Potts were examined using entire specimens and tubes. Tube orientation in situ at Patricia Bay, Vancouver Island, British Columbia, Canada, was typically L-shaped, and tubes were buried to and rarely coursing deeper than 30 cm, with only 1–2 cm of tube aperture exposed at the sand surface. Perforations were found in a distinctive thin-walled region at the buried apex of the tube, and were absent in the much thicker remaining tube length. Filter feeding using one or two mucus bags was observed, while posteriorly directed peristalsis in the abdominal segments generated a current from the exposed tube opening towards the buried tube apex. Thermistor-probe recordings of laboratory-held specimens showed feeding activity to be most prevalent during the day, one mucus bag, on average, being produced every 5.5 min. Mucus bags were also utilized to transport sand during excavation. Tube construction was noted to take place at the buried end of the tube, where old perforations were covered over and new perforations made as the tube was extended. The production of one sand casting per hour was noted in worms undertaking tube construction in laboratory aquaria. Our findings are compared with data available on other members of the Chaetopteridae.
Removing American crows and duck nesting success
Authors: Clark Robert G. , Meger Daryl E. , Ignatiuk Jordan B.
Published: July 2008

The American crow (Corvus brachyrhynchs) is reputed to be an important predator of duck eggs, but its potential impact has not been evaluated adequately. We removed breeding crows from their territories prior to and during the duck breeding season to test whether duck nesting success would increase. Nesting success in two removal areas did not differ from that of two control areas. Our results are consistent with several studies indicating that removal of one predator species from a community of predators, including corvids, does not lead to predictable increases in breeding success of game birds. Further work is needed to determine the relative importance of different predators and to learn why removal of one predator species is generally ineffective.
Effets à court terme de la disponibilité de nourriture, de la température et de la remise en suspension des sédiments sur les indices biochimiques de croissance du Mya arenaria (L.): une étude en milieu naturel
Authors: Mayrand Élise , Pellerin-Massicotte Jocelyne , Vincent Bruno
Published: July 2008

The purpose of this study was to assess the short-term variability of the biochemical indices of growth protein:DNA, protein:RNA, and RNA:DNA ratios, in Mya arenaria (L.) and to evaluate the short-term effects of some environmental factors on these indices. The RNA:DNA and protein:DNA ratios of the digestive gland were positively correlated with the resuspension of benthic organic matter and sedimentation of organic particles in the water column, respectively. The RNA:DNA ratio of the gills was also positively correlated with resuspension. Resuspended benthic organic material is suggested to provide an appreciable source of food for Mya arenaria, which would supplement the generally low contribution from sedimentation. Sediment temperature did not affect the tissue indices studied. This suggests that the physiological responses of intertidal animals tend to be independent of short-term temperature variations. The biochemical indices of the adductor muscle did not respond to any of the studied environmental parameters.
Life history, gonad state, and changes in functional sex ratio in the salt-marsh waterboatman, Trichocorixa verticalis (Fieber) (Heteroptera: Corixidae)
Authors: Aiken R. B. , Malatestinic N.
Published: July 2008

The life history and sexual development of Trichocorixa verticalis were studied in salt-marsh pools in New Brunswick, Canada. Trichocorixa verticalis overwinters as an egg and the adults of the first summer generation appear in late June. The second summer generation appears as first-instar nymphs in mid-July. Males and females mature sexually about 1 month after eclosion, the first sexually mature females appearing 1 week before males. For most of the season, the numerical sex ratio is male-biased. The functional sex ratio (ratio of sexually mature males and females) is even more strongly male-biased. These results indicate that mate competition among males may be more severe than was initially apparent.
Taxonomy, ecology, and karyology of a new species of Phagocata from Spain, with a discussion on the phylogenetic systematics of the genus Phagocata s.l. (Platyhelminthes, Tricladida, Paludicola)
Authors: Sluys Ronald , Ribas Maria , Baguñà Jaume
Published: July 2008

The new species Phagocata ullala Sluys, sp.nov. is described from two localities in Spain, the Ebro delta and Pyrenean Massif. The species is characterized by brown dorsal pigmentation, principally ventral testes throughout the body length, vasa deferentia that fuse to form the ejaculatory duct in the proximal section of the cone-shaped penis papilla, and a basic haploid complement of 17 chromosomes. Animals from the Pyrenees may be polyploid, with complements of 4n, 8n, 10n, and 14n. At present, the genus Phagocata s.l. is diagnosed only by plesiomorphic features. The paper explores possible apomorphic characters of several groups within this genus. It is suggested that "Albiplanaria" and Atrioplanaria are monophyletic taxa and that together "Albiplanaria," Fonticola olivacea, and Phagocata s.str. form a monophylum.
Lack of an association between heterozygosity and growth rate in the wood frog,Rana sylvatica
Authors: Wright Michael F. , Guttman Sheldon I.
Published: July 2008

The effect of both multilocus and single-locus heterozygosity on growth rate was examined in a cohort of larvae of the wood frog, Rana sylvatica, collected from a pond during the later stages of premetamorphic development. Seven electrophoretically detected enzyme loci were used to determine individual heterozygosity, whereas the growth rate was measured as wet mass. In all cases, no significant correlation was found between multilocus heterozygosity and mass among larvae collected at intervals during the developmental period. In addition, multiple regression analyses indicated that no single locus had a demonstrable effect on growth rate. The results of this study, therefore, provide no evidence for a link between enzyme heterozygosity and growth rate during the later stages of premetamorphic development in wood frog larvae.
Composition of eggs of common eiders
Authors: Swennen C. , Meer J. Van der
Published: July 2008

The content of common eider (Somateria mollissima) eggs was studied in the colony on the Dutch island of Vlieland for 3 years. Mean wet mass was 108 g: ca. 9% shell, ca. 45% albumen, and ca. 45% yolk. Mean dry density (g∙cm−3) was 0.086 for shell, 0.069 for albumen, 0.094 for lean yolk, and 0.169 for yolk lipids. The average energy value of the egg content was estimated at 10.45 kJ∙cm−3, and 1087 kJ for the content of an average egg with a volume of 104 cm3. The average energy value of the shell membranes amounted to 15 kJ. The most common clutch size is 5 eggs, which means that, on average, 5510 kJ is directly invested in a clutch. Corrected for volume, total dry mass and dry mass of lean yolk, albumen, and fat differed among females. Corrected for volume, lean yolk mass decreased with clutch size; other components were not involved. This induced an increase in the ratio of lipid in the yolk to lean yolk with clutch size. Within a clutch, dry mass of the components varied isometrically with egg volume. Egg volume varies according to the laying sequence, those laid in the middle of the sequence being largest. Therefore, the amount of energy allocated to individual eggs in a clutch varies according to the same curvilinear relationship.
Contact rehydration in the terrestrial slugLimax maximusL. in the field
Authors: Matanock H. L. , Welsford I. G.
Published: July 2008

Specimens of Limax maximus were observed in the field between the hours of 10:00 p.m. and 2:00 a.m. as they entered a pool of rain water approximately 0.5 cm deep. Hemolymph was withdrawn from slugs before they entered the water and after they exited it. A significant proportion of the animals exhibited locomotion to the water source (i.e., orientation to water; 16/16) and retraction of the superior and inferior tentacles (13/16; χ2 = 6.25, p < 0.02), and there was a trend for animals in the water to flare the foot (11/16); these are all behaviors associated with contact rehydration. The mean hemolymph osmolalities of the two groups (i.e., 179 ± 29.6 (SD) mosmol∙kg H2O−1prior to entering the water versus 104 ± 29.8 mosmol∙kg H2O−1after exiting the water; n = 16) were significantly different from one another (t = 6.92, p < 0.001). Time spent in the water was inversely correlated with hemolymph osmolality (r2 = 0.715, p < 0.01). The calculated rate of change in hemolymph osmolality for the slugs was 3.7 mosmol∙kg H2O−1∙min−1. These data support the hypothesis that contact rehydration plays a role in regulating water balance in slugs in the wild.
Paddle cilia fixation artefacts in palliai organs of adultMytilus edulisandPlacopecten magellanicus(Mollusca, Bivalvia)
Authors: Beninger Peter G. , Potter Tracy M. , St-Jean Sylvie D.
Published: July 2008

To ascertain the nature of paddle cilia in adult marine bivalves, three scanning electron microscopic (SEM) fixation protocols were used to fix ciliated organs of the palliai cavity in the blue mussel, Mytilus edulis, and the giant scallop Placopecten magellanicus (Bivalvia: Mytilidae, Pectinidae). SEM examination concentrated on the various regions of the labial palps and gills in M. edulis, with supplementary observations of the osphradium and adjacent regions in P. magellanicus. A regular transect approach was used to examine all surfaces, both for thoroughness and to reveal any eventual patterns in distribution. Cilia with paddle-like expansions were observed on all surfaces when both hypotonic glutaraldehyde–cacodylate buffer and hypotonic Sörensen's buffer were used; no intra- or inter-individual pattern was evident. No expansions were present when isotonic glutaraldehyde–cacodylate was employed. We conclude that paddle cilia may be induced in adult marine bivalves by hypotonic fixation; this has wider implications for the other bivalve species in which such cilia have been reported, in addition to the numerous accounts of such structures in other taxa.
Spatial and temporal patterns of predation of simulated sage grouse nests at high and low nest densities: an experimental study
Authors: Niemuth Neal D. , Boyce Mark S.
Published: July 2008

We examined patterns of predation on 252 simulated sage grouse (Centrocercus urophasianus) nests placed at two densities around six active leks in southeastern Wyoming, U.S.A. Predation intensity, as measured by the frequency of multiple-nest predation events, was significantly greater at high-density sites, implying enhanced prey capture (functional and (or) numerical response) by predators. Significant spatial aggregation of nest predation further implies enhanced prey capture by predators at high prey densities. Predation varied significantly among sites, but there were no significant first-order differences in predation between densities. Predation was also significantly affected by year–density and site–year–density interactions. Several factors, including nest cover, prey defense mechanisms, study site location, nest location, year, search methods of predators, number of predators, and random encounter may inhibit or confound density-dependent nest predation. Enhanced prey capture provides a mechanism for density-dependent population regulation.
Fur increases the parasite drag for flying bats
Authors: Hassanloo Z. , Fenton M. B. , DeLaurier J. D. , Eger J. L.
Published: July 2008

We measured the drag (in grams) generated by air flowing at 5.02 m/s over blank plates and test plates to which bat skin and fur was glued, comparing drag values when air flowed with and against the "set" of the fur. Our samples included 37 specimens representing 27 species. There was a significant positive correlation between fur length and drag and significantly higher drag values when air flowed against rather than with the set of the fur. We found a significant tendency for bats with higher aspect ratios and higher wing loadings to have shorter fur, and the data from a naked bat (Cheiromeles torquatus) show that from an aerodynamic standpoint, bats would be better without fur. We conclude that the other benefits of fur, such as those relating to thermoregulation, communication, and crypsis, outweigh the costs of the drag it generates.
Comparative anatomy of the cardiac foramen ovale in the Pinnipedia
Authors: Macdonald Alastair A. , Dixon Christopher , Boyd Ian L.
Published: July 2008

The structure of the cardiac foramen ovale from eight genera of pinnipeds was studied using the scanning electron microscope. Specimens were obtained from fetuses or neonates of the Californian sea lion (Zalophus californianus), Antarctic fur seal (Arctocephalus gazella), walrus (Obenus rosmarus), grey seal (Halichoerus gryphus), ringed seal (Phoca hispida), bearded seal (Erignathus barbatus), Weddell seal (Leptonychotes weddelli), and crabeater seal (Lobodon carcinophagus). In each species, the structure that permits oxygenated blood from the placenta flowing in the caudal vena cava to pass directly into the left side of the heart, the foramen ovale, when viewed from the terminal part of the caudal vena cava had the appearance of the entrance to a short tunnel. A thin fold of tissue, the developed remains of the septum primum, projected from the caudal edge of the foramen ovale into the lumen of the left atrium. It constituted about 75% of the inner surface of the tunnel, and was generally unfenestrated. The wall of the interatrial septum contributed the "floor." The distal end of the tunnel was straight-edged. In most cases the septum primum was long enough to cover the foramen ovale. The siting of pulmonary veins in the roof of the left atrium appeared to be such that drainage from them after birth would press the septum primum over the foramen opening, thereby functionally closing it. Collapses of the tunnel was seen in all the neonatal seals, and in the 1-month-old neonate the fold of tissue was anchored to the interatrial septum along the surface of the crista dividens, which lay in the left atrium. Cellular protrusions and thread formation may play a role in the closure of the foramen ovale.
Day- and night-time prey availability for waterbirds in a tropical lagoon
Authors: McNeil Raymond , Díaz Oscar Díaz , A. Ildefonso Liñero , S. José R. Rodríguez
Published: July 2008

One of the main hypotheses formulated to explain why marsh birds, wildfowl, and shorebirds forage at night postulates that the birds prefer to feed at night because the feeding opportunities are most profitable then. To investigate this hypothesis, we compare day- and night-time availability and describe the diel abundance rhythm of swimming and benthic organisms inhabiting the shallow waters of a tropical lagoon complex in northeastern Venezuela. Three sampling techniques were used by day and by night: net sampling for swimming organisms, core sampling for those in the sediments (10 cm deep), and sight counts for organisms on the surface of substrata. Overall, in the case of swimming organisms, fishes, isopods, amphipods, shrimps (Penaeus spp.), and corixids were 3–30 times more abundant at night than during daytime. In general, infaunal organisms were about equally abundant during the day and the night, or slightly more abundant during the day. At the surface, isopods, amphipods, and polychaetes were greater than 10 times more abundant at night than during the day. However, gastropods were slightly more numerous during daytime on the substrata, while pelecypods were about equally numerous during day- and night-time. Fiddler crabs (Uca sp.) were generally more available during daytime. Considering all organisms together, the prey for marsh birds, wildfowl, and shorebirds were significantly more abundant at night. In conclusion, tactile-foraging species (e.g., spoonbills, skimmers, ibises, dabbling ducks, and several species of shorebirds) should profit by foraging only at night and resting during the day, and foraging during daylight only to top up a nighttime deficit. On the other hand, despite limited nighttime visual capacity, some sight-feeding species (e.g., herons, plovers) may take advantage of increased prey availability at night, at least on moonlit nights.
Day- and night-time parental investment by incubating Wilson's Plovers in a tropical environment
Authors: Thibault Michel , McNeil Raymond
Published: July 2008

With the use of a time-lapse video camera and infrared lamps, we quantified diurnal and nocturnal incubation sex roles in 17 pairs of Wilson's Plovers (Charadrius wilsonia cinnamominus) breeding in northeastern Venezuela. More than 82% of nests reached the hatching stage. Between the laying of the last egg and hatching of the first one, parents devoted 83% of their time incubating. Males spent more time incubating than females. Males incubated mainly at night and females mostly during daytime. Males also spent significantly more time incubating during daytime than did females during nighttime. During incubation, females relieved males at dawn and males relieved females at dusk. By relieving each other under conditions of low light intensity, parents probably reduced nest predation. Outside the breeding season, the Wilson's Plovers forage almost exclusively during nighttime. In contrast, during the breeding season, males foraged mainly during daytime low tides, probably as a consequence of their nocturnal nest attendance. During short daytime periods, on cloudy days, incubating plovers, particularly the females, abandoned their eggs to forage.
Postglacial evolution in lateral plate morphs in Norwegian freshwater populations of the threespine stickleback (Gasterosteus aculeatus)
Authors: Klepaker Tom
Published: July 2008

Norwegian freshwater stickleback populations were founded after the last glacial period, and the progressive uplift of the land has produced an age range (1000 – 13 000 years) of the stickleback habitats. Most of the freshwater populations of today have probably been formed by isolation of marine sticklebacks in the process of land uplift. The freshwater threespine stickleback is known for its great morphological variability. Three distinct morphs ("low," "partial," and "complete") are recognized on the basis of variation in the lateral row of plates. Among the Norwegian populations, all three morphs were found, but the low morph was by far the most common and occurred mostly in monomorphic populations. The presence of the complete and partial morphs was mostly restricted to young lakes near the sea. It is likely that the plate polymorphism in this region is a transitionary evolutionary stage from a founding population dominated by complete to a monomorphic low population. The hypothesis of a polytypic origin of the low morph is discussed, and an alternative hypothesis is proposed. Within each plate morph, the number of plates also varied, and populations with exceptionally low plate numbers were mostly confined to three different areas. Within these areas, populations with plateless specimens also occurred. These plateless specimens tended to inhabit old lakes. The low plate number and plateless populations were found in parts of Norway that were deglaciated early. The advanced plate reduction can therefore be a result of a longer period of isolation and freshwater evolution. Other populations may be on their way towards extreme plate reduction, but have not yet reached the level of platelessness.
Metabolic organization of liver and somatic muscle of landlocked sea lamprey,Petromyzon marinus, during the spawning migration
Authors: LeBlanc P. J. , Gillis T. E. , Gerrits M. F. , Ballantyne J. S.
Published: July 2008

The metabolic organization of liver and muscle of the landlocked sea lamprey, Petromyzon marinus, during the spring spawning migration was assessed by measuring activities of key enzymes for several metabolic pathways, the oxidative properties of mitochondria, and plasma concentrations of nonesterified fatty acids (NEFAs) and free amino acids. These determinations indicate that several metabolic sources are used to fuel the energy requirements of muscle. Lamprey muscle has a high capacity to oxidize lipids but the plasma NEFAs are lower than those reported for other species. Of the NEFAs measured in plasma, 18:0 was prominent, accounting for 23% of the total NEFA content of the plasma. High plasma concentrations of ketogenic amino acids and high levels of tissue ketogenic/ketolytic enzyme activities indicate that ketone bodies may also be a major fuel source for migrating sea lampreys. Based on mitochondrial oxidation and enzyme measurements, glutamine catabolism in somatic muscle of lampreys is less important than in other fish red muscle.