bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual downstream swimming speed during the natural smolting period among young of Baltic salmon (Salmo salar)
Authors: Fängstam Hasse
Published: July 2008

The individual downstream swimming behaviour of two-summer-old salmon from the Ume River hatchery stock was monitored throughout the natural smolting period in May–June. The experiment was performed in an artificial-stream tank (diameter 11 m) equipped with a passive integrated transponder (PIT) tag monitoring system. The swimming speed of individual fish in relation to water velocity and the porportion of time during which an individual fish showed active versus passive displacement were investigated using a total of 224 sexually immature fish and previously mature males, individually PIT tagged. At peak migration fish swam downstream at an average speed of about double the water velocity, indicating active downstream migration. No differences in downstream swimming speed between migratory and nonmigratory fish were observed. However, migratory and nonmigratory fish used considerably different proportions of the total time swimming faster than the water current, 10% for migratory fish but only 0.1% for nonmigratory fish. Migratory smolts covered about 25% of their total downstream displacement by means of active downstream swimming: 3.3 km out of 13.5 km in 24 h. Thus, the study clearly shows that active downstream swimming is an important part of the migratory repertoire of salmon smolts.
Dispersal in varying environments: the case of phoretic uropodid mites
Authors: Athias-Binche Françoise
Published: July 2008

Phoresy is a dispersal strategy in which one animal actively seeks out and attaches to another animal for transport. Phoretic dispersal is vital in many groups of mites that live in specialized microhabitats or unpredictable environments. This study deals with phenotypic plasticity and its relationship to initiation of the migration behaviour in a uropodid mite, Allodinychus flagelliger (Berlese), which inhabits dead wood. The deutonymphs are bimorphic, one morph being sedentary and the other, phoretic morph ensuring migration. Immigration and emigration were estimated for a 5-year period. Migration took place every year, as a result of obligate seasonal phoresy. The phoronts emigrated in spring attached to xylophagous insects. They immigrated in autumn, when their hosts built their galleries. The average annual emigration rate significantly increased as a function of the progressive decomposition of the dead wood, while immigration tended to diminish in the late stages of wood ageing. As a consequence, the deme finally declined and became extinct. Thus, the rate of emigration was manipulated by the deme in response to local conditions. It appeared not to be genetically fixed. The involvement of pleiotropic genes is possibly implied in the activation of migratory behaviour or the production of phoronts. The immigration rate is not fixed, because the arrival flow depends on heterospecific carriers. On the other hand, the rate of production of sedentary morphs did not vary and seemed to be genetically fixed.
Age-specific reproduction in female sea otters (Enhydra lutris) from south-central Alaska: analysis of reproductive tracts
Authors: Bodkin James L. , Mulcahy Dan , Lensink Calvin J.
Published: July 2008

We estimated age at sexual maturity and age-specific reproductive rates by examining carcasses and reproductive tracts from 177 female sea otters (Enhydra lutris). Carcasses were recovered from south-central Alaska, primarily from western Prince William Sound, as a result of the T/V Exxon Valdez oil spill in 1989. We found 65% of our sample to be sexually mature. Sexual maturity was first attained at age 2. The proportion of sexually mature animals increased from 30% at age 2 to 100% at age 5. Annual reproductive rates increased from 22% at age 2 to 78% at age 5 and remained relatively stable (75–88%) through to age 15. The sex ratio (♀:♂) of 49 fetal sea otters was 18:37 and differed significantly from parity. Females younger than 8 tended to produce more female fetuses, while older mothers did not. Our estimates of the reproductive characteristics of female sea otters obtained by examination of reproductive tracts were similar to those reported in the literature based on in situ observations of marked individuals.
Le genre Therea Billberg, 1820: position phylogénétique, nouvelles espèces, répartition, valence écologique (Dictyoptera, Blattaria, Polyphaginae)
Authors: Grandcolas Philippe
Published: July 2008

The genus Therea Billberg, 1820 is redefined as a monophyletic taxon belonging to the group Ergaula + Eucorydia + Therea + Cryptocercus in the subfamily Polyphaginae Kirby, 1904. Three new species, T. regularis, T. defranceschii, and T. hyperguttata, are described as well as T. petiveriana (Linnaeus, 1758) and T. nuptialis (Gerstaecker, 1861). The known distribution of the genus in India extends from dry deciduous forests to more humid formations (between latitudes 19 and 10° N). The species live in areas with mean annual rainfall ranging from 500 to 3800 mm.
Intense grazing by voles (Microtus pennsylvanicus) and its effect on habitat quality
Authors: Bergeron Jean-Marie , Jodoin Louise
Published: July 2008

Meadow voles (Microtus pennsylvanicus) were housed in fenced plots to simulate the effects of crowding on qualitative and quantitative changes of vegetation. Within one summer they reached density levels equivalent to 1000–1300 voles/ha and were removed from the plots during the fall. Biomass yields were estimated during fall and the following spring to assess the immediate effects of grazing and plant recovery before the new growth period. Significant reductions in yields of green biomass were registered in fall (15%) and in the following spring (52%) in the grazed plots. Dead matter was also reduced by intense grazing (> 7%). Biomass quality was estimated from measures of protein, total phenolics, and total nonstructural carbohydrates (TNC). Protein and phenolics in green biomass samples did not vary in the fall and spring collections but TNC varied significantly between grazed and ungrazed plots during both sampling periods. Intense grazing by voles during one summer of high density imposes quantitative changes on meadows that are still noticeable the following spring while most of the nutritive constituents of vegetation are affected little by grazing. These results support the idea that voles do not induce defensive mechanisms in heavily grazed plants.
Intercolony differences in the summer diet of Thick-billed Murres in the eastern Canadian Arctic
Authors: Gaston Anthony J. , Bradstreet Michael S. W.
Published: July 2008

The diet of Thick-billed Murres collected near six colonies in the eastern Canadian Arctic comprised invertebrates (84% of 23 462 items) and fish (16%). Adult diets differed significantly among colonies, both within the Low Arctic (Hudson Strait), between Low and High Arctic (Lancaster Sound – Baffin Bay), and between Low-Arctic colonies and a colony close to the High/Low Arctic boundary (Davis Strait). Murres from the High Arctic took more invertebrates, fewer fish, and a smaller number of species overall than those from the Low Arctic. Diets were more diverse in the Low Arctic than in the High Arctic, in keeping with the greater number of prey taxa available at lower latitudes. Similarity indices show that diets at High-Arctic colonies were more similar to one another than was true for other colonies. Differences among Low-Arctic colonies suggest variation in the relative abundance of different nekton components within Hudson Strait.
Do urinary urea nitrogen and cortisol ratios of creatinine reflect body-fat reserves in black-tailed deer?
Authors: Parker Katherine L. , DelGiudice Glenn D. , Gillingham Michael P.
Published: July 2008

Urinary ratios of urea nitrogen:creatinine and cortisol:creatinine have been used as indices of the nutritional and physiological health of cervid populations. These ratios are used to monitor temporal trends in dietary protein and (or) energy deprivation, and changes in net catabolism of endogenous protein as body-fat reserves are depleted. Over a 2-year period, we compared urine chemistries of free-ranging and captive Sitka black-tailed deer (Odocoileus hemionus sitkensis) to examine seasonal and locational differences. We also determined body composition of all deer using tritiated water. Elevated urea nitrogen and cortisol ratios of creatinine did not consistently reflect individual animal body condition as measured by declining fat content in our free-ranging animals. Instead these urinary ratios more likely reflect immediate dynamics between fat depletion, protein catabolism, and energy intake rather than long-term changes in body-fat reserves.
Glycerol and water balance in a near-isosmotic teleost, winter-acclimatized rainbow smelt
Authors: Raymond James A.
Published: July 2008

Rainbow smelt, Osmerus mordax, have previously been shown to produce high concentrations of glycerol in winter to avoid freezing, becoming almost isosmotic in a marine environment when temperatures reach the freezing point of seawater. Here it is shown that osmotic water losses, as shown by drinking rate, decrease dramatically in winter as a result of the increased osmolality. Urine flow also appears to decrease in winter in response to reduced drinking. Glycerol is lost through the skin and gills, and probably through intestinal discharge, at total rates ranging from 3.5 to 9.5 mg∙100 g−1∙h−1. Combined permeabilities to glycerol of the gills and skin in the head were in the range 0.9–2.6 × 10−7 cm∙s−1. Glycerol concentrations, efflux, and permeability of the gills were comparable to those for urea in marine elasmobranchs. However, mechanisms for conserving the two osmolytes may differ.
Restudy of Spirura infundibuliformis McLeod, 1933 (Nematoda: Spiruroidea) from Spermophilus richardsonii, with observations on its development in insects
Authors: Anderson R. C. , Barnes E. T. , Bartlett C. M.
Published: July 2008

A redescription is provided of Spirura infundibuliformis from the stomach of ground squirrels, Spermophilus richardsonii, in southern Alberta, Canada; Spirura leucurusi Babero, 1973 is regarded as a synonym. Spirura infundibuliformis is distinguished from most members of Spirura by the presence of 9–13 pairs of preanal papillae; 20 other species described in the genus have only 4, rarely 5, pairs. Spirura infundibuliformis developed at ambient temperatures (20–30 °C) to the infective stage in 11–12 days in grasshoppers common on the prairies (Melanoplus infantilis, Aeropedellus clavatus, Aulocara elliotti, and Camnula pellucida), where the ground squirrels were collected, as well as in laboratory-reared crickets (Acheta pennsylvanicus).
Schistosoma mansoni – Biomphalaria glabrata: dynamics of the sporocyst population in relation to the miracidial dose and the host size
Authors: Gérard Claudia , Moné Hélène , Théron André
Published: July 2008

The rate of invasion of snails and percentage of the digestive gland occupied by daughter sporocysts decrease when the snails are larger and the miracidial dose is smaller. Growth of the sporocyst population is influenced not only by the miracidial dose, but also by the changes in the growth rate of the host. The larger the host and (or) the smaller the miracidial dose, the more significant is the volume occupied by the sporocyst population. Biomass- and (or) density-dependent regulatory mechanisms of different patterns intervene to limit the volume of parasites. Rapid colonisation and intensive exploitation of the host correspond to an immature plurimiracidial system, whereas progressive colonisation and less exploitation correspond to a mature monomiracidial system. The results are discussed in terms of possible demographic strategies that can be used to optimize parasite fitness in various environments.
Regulation of phosphofructokinase and the control of cryoprotectant synthesis in a freeze-avoiding insect
Authors: Holden Clark P. , Storey Kenneth B.
Published: July 2008

Phosphofructokinase (PFK) from larvae of the freeze-avoiding gall moth Epiblema scudderiana was purified 711-fold using ATP-agarose affinity chromatography to a final specific activity of 23 U/mg protein. The native molecular mass of the enzyme was 420 000 ± 20 000 Da. The enzyme showed an optimum pH of 8.13 ± 0.21 at22 °Cand 8.19 ± 0.11 at5 °C. Arrhenius plots of PFK activity showed a sharp break at 9 °C. S0.5 values for fructose 6-phosphate showed positive thermal modification, decreasing with decreasing assay temperature; the opposite was true for ATP-Mg2+. PFK was activated by fructose 2,6-bisphosphate, AMP, and inorganic phosphate; activator effects were temperature-dependent. The enzyme was inhibited by ATP-Mg2+, citrate-Mg2+, and phosphoenolpyruvate. The positive effects of low temperature on enzyme kinetic properties would promote PFK activity to channel glycolytic carbon flow into the production of glycerol during cold-stimulated cryoprotectant synthesis.
Plasma levels of sex steroids in three species of pipefish (Syngnathidae)
Authors: Mayer Ian , Rosenqvist Gunilla , Borg Bertil , Ahnesjö Ingrid , Berglund Anders , Schulz Rüdiger W.
Published: July 2008

The pipefishes (Syngnathidae) are marine teleosts in which the males brood the young. In some species sex-role reversal occurs when, contrary to the usual pattern, females compete more intensely than males for access to mates. This paper reports an investigation of the sex hormones of males and females to see whether they deviate from the "normal" teleost pattern. To that end, plasma levels of the androgens testosterone (T), 11-ketotestosterone (OT), 11β-hydroxytestosterone, 11-ketoandrostenedione, and 11β-hydroxyandrostenedione (OHA), together with 17α-hydroxy-20β-dihydroprogesterone (17,20-P) and 17β-estradiol (E2), were measured by means of radioimmunoassay in three species of pipefish: Nerophis ophidion, Syngnathus typhle, and Syngnathus acus. Plasma levels of OT, the dominant circulating androgen in breeding males of most teleost species, was found to be highest in breeding males and low or non-detectable later in the brooding males. This observed decline in male OT levels from the prespawning to the postspawning (=brooding) period is in general agreement with what has been found in other teleosts. In both breeding and brooding S. acus males, T was quantitatively the dominant androgen, whereas OHA was the major androgen in S. acus females, as well as in the females and breeding or brooding males of both S. typhle and N. ophidion. In breeding S. acus and S. typhle males the levels of T, OHT, and OT were higher than in corresponding brooding males and females. The 17,20-P level was below detection limit. E2 was also usually non-detectable, but was most consistently found in breeding Syngnathus males.
Individual variation in predation on fur seals by southern sea lions (Otaria byronia) in Peru
Authors: Harcourt Robert
Published: July 2008

Southern sea lions (Otaria byronia) were observed to prey on juvenile and adult female South American fur seals (Arctocephalus australis) at Punta San Juan, Peru (15°22′S, 75°12′W) between October 1987 and December 1988. Over the course of the study there were 165 attacks on fur seals with 33 seals killed. While both adult male and subadult male sea lions captured and killed fur seals, adult female and juvenile sea lions never acted aggressively towards fur seals. Adult males attacked fur seals on 82.4% of the occasions when they were present at the rookery, subadults on 52% of occasions. Distinctive pelage characteristics allowed some of the male sea lions to be individually identified, and differences in hunting success were observed between adults and subadults, and between five identifiable adults who hunted on at least five occasions. Motivation for attacks differed for subadults and adults, with subadult males using captured fur seals as female sea lion substitutes, guarding them from others and copulating with them, whilst adult sea lions hunted fur seals as food. However, only a small proportion of adult sea lions hunted fur seals, and with differing rates of success.
Acclimation to seawater of dwarf nonanadromous Atlantic salmon, Salmo salar
Authors: Birt Tim P. , Green John M.
Published: July 2008

The ability of nonanadromous Atlantic salmon to regulate hydromineral balance in seawater was assessed by determining plasma Na+ and Cl− concentrations, gill Na+–K+ ATPase activity levels, and gill chloride-cell length in fish exposed to gradually increasing salinity. Plasma ion levels were much higher in nonanadromous salmon exposed to seawater than in anadromous smolts in the same condition, and in both forms held in fresh water. This indicates a lower level of hypoosmoregulatory ability in the nonanadromous form. The activity of gill Na+–K+ ATPase was low in nonanadromous salmon at the beginning of the experiment but increased in response to elevated external salinity. Mortality approached 100% despite increased enzyme activity levels. Salmon retained in fresh water did not exhibit increased enzyme activity. Anadromous smolts exposed to the same conditions exhibited somewhat elevated yet nonlethal plasma ion concentrations. Gill chloride cells increased in size in salmon exposed to seawater and decreased in size in fish held in fresh water. Hypoosmoregulatory inability and a general suppression of the smolting process in some stocks of nonanadromous salmon may be associated with sexual maturation at a young age. However, this is not universal, since nonanadromous salmon in some other stocks mature later yet show clear evidence of reduced smolting.
Mitochondrial DNA variability in Ontario and New York rainbow trout (Oncorhynchus mykiss)
Authors: Danzmann Roy G. , Ferguson Moira M. , Arndt Steven K. A.
Published: July 2008

We detected 142 six-base restriction sites and 30 haplotypes using 34 enzymes in a survey of mitochondrial DNA (mtDNA) variability in rainbow trout (Oncorhynchus mykiss) from various hatchery sources in Ontario and New York state, and one naturalized population in Lake Ontario. Five major phylogenetic groupings were identified, with the most divergent grouping (assemblage B) differing on average by 0.63% site divergence from other haplotypes; the two most divergent haplotypes differed by 15 site changes. All haplotypes detected in steelhead occur in the phylogenetic assemblage most closely related to chinook salmon (O. tshawytscha). The New York hatchery stocks have markedly lower mtDNA variability than the naturalized population from Ontario. Similarly, the Ontario and New York fish appear to have reduced mtDNA diversity relative to western fish. Significant heterogeneity in mtDNA haplotype frequencies was observed among most Ontario and New York populations examined. Some mtDNA haplotypes were unique to specific populations suggesting their utility as potential markers for genetic stock identification.
The effect of larval brooding on the filtration rate and particle-retention efficiency of Pyganodon cataracta (Bivalvia: Unionidae)
Authors: Tankersley Richard A. , Dimock Jr. Ronald V.
Published: July 2008

Following fertilization, the outer demibranchs of the unionid mussel Pyganodon cataracta undergo extensive morphological changes to accommodate approximately a million shelled glochidia larvae within the ctenidial water tubes which serve as brood chambers. The effect of larval incubation on particle filtration and quantitative selection was determined by comparing clearance rates and particle retention efficiencies of adult mussels during brooding and nonbrooding periods. Particle clearance rates for gravid females were significantly lower than those for nongravid females and were as much as 54% lower than those of males collected simultaneously. Females brooding larvae were less efficient at retaining particles <5 μm than were males or nonbrooding females. Both particle clearance and retention spectra were nearly identical for males and females collected during nonbrooding periods. The effect of larval brooding on the activity of gill cilia on excised gill tissue was assessed by determining the beat frequency of the laterofrontal cirri and the pattern of transport of fluorescently labeled latex microspheres by frontal cilia. The metachronal beat of cirri on marsupial gills was significantly lower than on nonmarsupial gills of both males and females but did not differ between reproductive seasons. Particles were transported faster by frontal cilia on nonmarsupial and nongravid gills vs. gravid marsupial gills, suggesting that the reduction in particle clearance and retention by brooding females resulted from functional changes in the ciliature of the marsupial demibranchs.
Social behavior of alpine marmots (Marmota marmota): seasonal, group, and individual variability
Authors: Perrin Catherine , Coulon Jacques , Berre Michel Le
Published: July 2008

The composition and social interactions of three family groups of Marmota marmota were observed during a study in the Vanoise National Park (French Alps) from mid-June to late September. Interactions between members of the same group were mainly cohesive, which confirms the social nature of this species. Social interactions between marmots from different family groups were rare and agonistic. The rate of social interactions decreased as the season progressed, probably in relation to a shift in allocation of energy to preparation for hibernation. Some cohesive interactions increased just before immergence, when marmots restricted their activity to the main burrow system. Rates of social interactions differed between groups and between individuals. Fewer agonistic acts, more play-fighting, and persistence of play-fighting late in the active season among immatures suggest the influence of an ontogenetic component. The most agonistic of the studied groups included an adult male that had recently immigrated. He focused most of his agonistic acts on three 2-year-old males, of which two dispersed during the season. Social events characteristic of each group, individual variability, and level of familiarity between group members influence the quality of social interactions and the dispersal of immatures. Social relationships between familiar individuals are amicable and can facilitate the retention of immatures in their natal group as well as their recruitment by emigrant adults.
Reexamination of Corvospongilla novaeterrae (Porifera, Spongillidae), an environmentally restricted freshwater sponge from eastern Canada
Authors: Reiswig Henry M. , Ricciardi Anthony
Published: July 2008

Corvospongilla novaeterrae (Potts, 1886) (Demospongiae, Spongillidae) is known only from a few acidic lakes on the eastern coast of Canada. It is considered by some to be a sexual hybrid and thus an invalid species. This assumption is based upon an erroneous interpretation of C. novaeterrae's highly variable gemmoscleres and the abundant of foreign spicules (predominantly those of Duosclera mackayi) in the type specimens. We have examined a new specimen from Nova Scotia that has no foreign spicules and fits the original species description. We evaluate three hypotheses concerning this species' status: (1) it is a hybrid of Corvomeyenia everetti and another species; (2) it is an unusual ecomorphic form of C. everetti resulting from atmospheric inputs of sea salts; (3) it is a valid Corvospongilla species, closely related to C. seckti, C. volkmeri, and C. boehmi. Corvospongilla novaeterrae's morphologically variable gemmoscleres are quite similar to those of C. seckti, C. volkmeri, and C. boehmi, and appear to be evolutionary transients between birotulates and amphioxea (as in Radiospongilla and Pectispongilla). Other characters linking C. novaeterrae with other Corvospongilla species include (i) large gemmules (diameter > 1000 μm) with simple multiple foramina, (ii) a weakly developed or absent pneumatic layer, (iii) the size and shape of the birotulate microscleres, and (iv) the predominantly rod-shaped, tangentially arranged gemmoscleres. Evidence supports the acceptance of C. novaeterrae as a valid, environmentally restricted species.
Color pattern variation in Lake Erie water snakes: inheritance
Authors: King Richard B.
Published: July 2008

The hypothesis that color pattern variation in Lake Erie island water snake (Nerodia sipedon) populations results from the opposing effects of natural selection and gene flow requires that this variation have a genetic basis. To determine whether color pattern variation is genetically based, data on the color pattern of wild-caught females and their captive-born offspring were used to estimate heritability of and correlations among four color pattern components. These data, and the results of two laboratory crosses, were also used to test for major locus influences on color pattern. Heritabilities of color pattern components estimated from sib analysis were significantly greater than zero for all four color pattern components, ranging from 0.34 to 0.79. Phenotypic and genetic correlations among color pattern components were positive, ranging from 0.24 to 0.55 (phenotypic correlations) and from 0.40 to 0.82 (genetic correlations). However, inheritance of color pattern was not strictly quantitative. Rather, a major locus appeared to influence color pattern, with alleles at this locus possibly determining whether snakes had regular (mainland-like) or reduced color patterns. Allele frequencies at this locus may have influenced the rate at which island and mainland water snake populations initially differentiated from each other, and may explain the lack of reduced-pattern morphs under similar selective regimes elsewhere.
Variations in the feeding success and behaviour of Galápagos sperm whales (Physeter macrocephalus) as they relate to oceanographie conditions
Authors: Smith Sean C. , Whitehead Hal
Published: July 2008

The feeding success of sperm whales off the Galápagos Islands, Ecuador, was examined over 5 study years; 1985, 1987, 1988, 1989, and 1991. A total of 160 days were spent following sperm whales at sea. The defaecation rates of sperm whales were used as an indication of feeding success. The recorded acoustic click rates of sperm whales were used as an indication of aggregative and foraging behaviour. Significant variation in feeding success occurred temporally over periods of days, months, and years. Feeding success also varied spatially with geographic area. Feeding success was inversely related to sea surface temperature (SST). The foraging and associative behaviour of sperm whales also varied with feeding success, SST, and by year. Variations in the feeding success and behaviour of Galápagos sperm whales can likely be attributed to changing oceanographic conditions in the waters surrounding the Galápagos archipelago.
Hunger and age effects on searching behavior of three species of predatory mites (Acari: Phytoseiidae)
Authors: Zhang Zhi-Qiang , Sanderson John P.
Published: July 2008

The effects of hunger level and adult age on searching behavior by the predatory mites, Phytoseiulus persimilis Athias-Henriot, Typhlodromus (= Metaseiulus) occidentalis Nesbitt, and Amblyseius andersoni (Chant), in patches of the twospotted spider mite, Tetranychus urticae Koch, were studied in the laboratory by continuous observation. Foraging responses such as patch giving-up time, patch time, and searching efficiency by female predators were affected strongly by hunger level and weakly by age; in some responses, the effects of hunger level changed with age. Effects of hunger level and age on various responses differed among predator species. In spite of the interspecific variation, starvation generally increased predator giving-up time and thus increased the duration of patch visits. Total patch time was correlated with the duration of visits rather than the number of visits. Predators that spent more time in prey patches also encountered and attacked more prey. Prey encounters and attacks increased patch time by an increment in time as a result of prey handling and by increasing the giving-up time. With successive visits to the prey patch, the strength of predator responses waned either because of habituation to patch cues or because of satiation after feeding. Host plant influence on predator behavior was stronger in the generalist A. andersoni than in the specialist P. persimilis.
Feeding variability among individual aquatic predators in experimental channels
Authors: Wotton Roger S. , Wipfli Mark S. , Watson Luke , Merritt Richard W.
Published: July 2008

Experiments were conducted in experimental channels to study feeding variability through time and between conspecific individuals of four species of lotic predators. Large and small Rhyacophila dorsalis (Trichoptera: Rhyacophilidae) were given black fly larvae, mainly Simulium ornatum (Diptera: Simuliidae) of two size classes during laboratory feeding trials lasting up to 5 days. Acroneuria lycorias (Plecoptera: Perlidae) were also given black fly larvae (Prosimulium fuscum, S. venustum) during 11-day laboratory feeding trials. Paragnetina media (Perlidae) and Isoperla signata (Plecoptera: Perlodidae), were supplied with a mixed prey assemblage of black fly larvae and mayfly nymphs, Baetis flavistriga (Ephemeroptera: Baetidae), and Epeorus vitrea (Heptageniidae), for 9 days in field experiments. There was significant variability in the consumption of prey among individuals of R. dorsalis, this being true for both large and small predators. Significant among-predator and day-to-day feeding variability also occured with A. lycorias, P. media, and I. signata. Our experiments showed that there are significant differences in prey consumption among individual predators within a given species, and these differences need to be considered when planning, and interpreting, future studies on predator – prey interactions, particularly those conducted in experimental streams.
Revision of Indo-Pacific Priolepis species possessing a reduced transverse pattern of cheek papillae, and predorsal scales (Teleostei; Gobiidae)
Authors: Winterbottom Richard , Burridge Mary
Published: July 2008

There are 10 Indo-Pacific species of Priolepis with a reduced transverse pattern of sensory papillae and scales in the predorsal midline. Nine of these, including three new species, are described here. Priolepis aureoviridis is known from the Hawaiian, Johnston, and Caroline islands; P. cinctus ranges from South Africa and the Red Sea to Japan and Tonga; P. eugenius is endemic to the Hawaiian islands; P. inhaca is found from the East African coast to Taiwan and the Society Islands; P. limbatosquamis is confined to the Hawaiian islands and Johnston Island; and P. squamogena is known from Howland Island southeastwards through the Society and Marquesas islands to Pitcairn Island. Of the three new species, P. agrena is known from the Philippine Islands and the northern Great Barrier Reef and P. pallidicincta ranges from Sulawesi through Guam and the Gilbert Islands to Fiji, whereas P. triops is known only from Fiji and the Society Islands. The remaining species, P. RW sp. 20, is known from the Austral and Easter islands and Lord Howe Island. This species will be described by D.F. Hoese and H.K. Larson. There is currently no information indicating that the species of the P. cinctus grade form a monophyletic assemblage.
A new species of Priolepis (Teleostei; Gobiidae) from the Kermadec Islands, southwest Pacific Ocean, with comments on relationships
Authors: Winterbottom Richard , Burridge Mary
Published: July 2008

Priolepis psygmophilia is described from four specimens from the Kermadec Islands in the southwest Pacific Ocean. The new species lacks scales in the predorsal midline and has a very faintly developed pattern of bars on the head and a reduced transverse pattern of cheek papillae, and thus apparently falls into the P. semidoliatus clade. However, the strongly outlined scale pockets indicate that it may be related to the portion of the P. cintus grade that shares this characteristic. If so, its relationships seem to lie with P. limbatosquamis (Hawaii) and an undescribed species (P. DFH sp. 3) from Lord Howe Island and eastern Australia, and another (P. RW sp. 20) from Lord Howe, Easter, and Austral islands, in which the predorsal midline scalation is reduced or absent. Thus, scales in the predorsal midline appear to have been lost independently in the P. cinctus grade and P. semidoliatus clade. There are now 29 Indo-Pacific species of Priolepis (of which 3 remain to be described by other workers), and 4 Atlantic species.
Phocid and cetacean blueprints of muscle metabolism
Authors: Hochachka P. W. , Foreman III R. A.
Published: July 2008

Large seals, such as northern and southern elephant seals and Weddell seals, are able to dive for unexpected lengths of time and to enormous depth. The current dive-duration record is 120 min (recorded for the southern elephant seal); the current depth record is 1.5 km (recorded for the northern elephant seal). Equally striking is the widespread observation that these seals, when at sea, spend close to 90% of the time submerged and often at great depth. For practical purposes, these species can be viewed as true mesopelagic animals when they are at sea. Analysis of current knowledge indicates that enzyme adaptations in chronic hypobaric hypoxia are directed mainly towards up-regulation of metabolic efficiencies. Evidence that similar metabolic adjustments are utilized by seals was obtained by profiling the maximum enzyme activities of four phocid species (harbor seal, Weddell seal, crabeater seal, leopard seal) and one cetacean (fin whale). In the seals, the patterns obtained were strikingly similar to those of hypobaric hypoxia adaptations. The extensive enzyme data obtained on seals, however, showed notably different patterns from those found in whale muscles. The data from the large seals were consistent with the concept that low power output but high-efficiency metabolic functions of skeletal muscles coupled with inherently low (and potentially further suppressible) metabolic rates constitute strategic biochemical components in the design of a mesopelagic mammal.
The protein requirement for maintenance in the White-crowned Sparrow, Zonotrichia leucophrys gambelii
Authors: Murphy Mary E.
Published: July 2008

Assumptions about potential mismatches between protein demand and protein availability are implicit in many hypotheses pertaining to the ecology of wild birds. However, few direct measures of the protein requirements of wild birds have been made. I evaluated the requirement for protein for maintenance of a wild granivorous passerine, the White-crowned Sparrow (Zonotrichia leucophrys gambelii). I estimated protein requirement from measures of endogenous nitrogen (N) loss, N balance, and changes in body mass in wintering adult birds. The experimental birds were kept indoors at 23 °C (8.5 h light: 15.5 h dark) and fed semisynthetic diets that differed only in their concentrations of protein (0–17.3%) and starch, which were reciprocally adjusted. The amino acid profiles of the protein in the diets were identical and were formulated to match the average amino acid profile of the mixed proteins of a diet containing grains, seeds, insects, and fruits. In White-crowned Sparrows, the protein requirements for maintenance of body mass (366 mg/d) and a positive N balance equal to that of birds ingesting the acclimation diets (436 mg/d) were 7.3 and 8.7% protein, respectively, in a diet containing 12.4 kJ apparent metabolizable energy per gram dry mass. The estimated minimum maintenance requirement for protein for N equilibrium, derived from regressing N excretion on N intake, equalled 264 mg protein/d, or ca. 5.3% dietary protein. Measures of endogenous N loss (endogenous urinary N loss plus metabolic fecal N loss) equalled 14.7 mg N/d, indicating that White-crowned Sparrows need to replace at least 92 mg body protein/d. Dietary protein content had little influence on the birds' utilization of dietary energy and daily metabolized energy. The apparent contradiction in the requirement for a positive N balance to maintain body mass is discussed.
The essential amino acid requirements for maintenance in the White-crowned Sparrow, Zonotrichia leucophrys gambelii
Authors: Murphy Mary E.
Published: July 2008

An animal's nutritional status depends on (i) nutrient availability, (ii) its nutritional needs, and (iii) physiological, metabolic, morphological, and behavioral compensations that avert or minimize discrepancies, if any, between the first two factors. Of the factors determining nutritional status, the actual nutritional needs of wild animals have received the least attention by biologists. I report the requirements for each of the essential amino acids (EAAs) for maintenance of a small granivorous passerine, the White-crowned Sparrow (Zonotrichia leucophrys gambelii). I measured the maintenance requirements of wintering, adult sparrows under thermoneutral conditions, using synthetic diets that differed only in their concentrations of the EAA being investigated. I estimated EAA requirements on the basis of (i) changes in body mass, (ii) daily food intake, and (iii) N balance in birds fed different concentrations of the EAAs in diets containing 12% protein and 12.4 kJ apparent metabolizable energy per gram dry mass. For the most part, estimates of requirements based on these three indices were in agreement. The estimated requirements for the EAAs (mg/kJ basal energy expenditure), based on integrating the results from the above three indices, were as follows: Arg = 0.39, His = 0.11, Lys = 0.29, Ile = 0.27, Leu = 0.38, Val = 0.24, Met in the absence of Cys = 0.38, Phe in the absence of Tyr = 0.39, Thr = 0.19, and Tip ≤ 0.07. Cys and Tyr could supply about half of the above requirements for Met and Phe, respectively. Except for Lys and His, these requirements are consistent with those reported for adult domestic roosters.
The life cycle of Podmosta macdunnoughi (Ricker) in the Lower Laurentians, Quebec (Plecoptera: Nemouridae), with a discussion on embryonic diapause
Authors: Harper P. P. , LeSage L. , Lauzon M.
Published: July 2008

Podmosta macdunnoughi (Ricker) is a small nemourid stonefly distributed over the glaciated areas of eastern Canada and northern New England, but more abundant in the boreal zone. In the outlet stream of Lake Pitt in the Lower Laurentians of Quebec, near the southern edge of its range, the species has a univoltine cycle. The adults emerged in late April and early May. The eggs, however, did not hatch till September and the first nymphs were collected in October. Growth continued throughout the winter and ended just before the emergence period. Though a wide range of sizes was present during the winter, there was a resynchronisation of the population before emergence and a short emergence period due to rapid growth of the smaller nymphs. Mature female nymphs were larger than males. The significance of the embryonic diapause in this northern species is discussed.
Clutch size and initiation date of ospreys: natural patterns and the effect of a natural delay
Authors: Steeger Christoph , Ydenberg Ronald C.
Published: July 2008

We studied the breeding performance of ospreys (Pandion haliaetus) in southeastern British Columbia from 1987 to 1990. Clutch size, brood size, and the number of young fledged per nest all declined significantly as clutch initiation date was delayed. The quality of later born young as measured by growth rate and the number of fault bars in rectrices did not seem to be reduced. Behavioural observations of the flight-hunting performance of six focal males demonstrated that food availability did not decline in the course of the nestling period. Clutch initiation of some osprey pairs was naturally delayed when their nests were occupied by Canada geese (Branta canadensis). Nest occupation delayed clutch initiation by 9.4 days on average, and reduced clutch size by 0.2 eggs. Osprey pairs possessing an alternate nest were not delayed by the presence of geese in their primary nest, and did not reduce clutch size, suggesting that the clutch size reduction was a direct response to the delay, rather than to the presence, of geese. The results do not support the reduced food availability or reduced breeding commitment hypotheses for seasonal clutch size decline. The data conform to the predictions of the hypothesis that the optimal clutch size is set by a trade-off between the declining reproductive value of later hatched nestlings and the delay required to be able to enlarge the clutch.
Sex identification of polar bears from blood and tissue samples
Authors: Amstrup S. C. , Garner G. W. , Cronin M. A. , Patton J. C.
Published: July 2008

Polar bears (Ursus maritimus) can be adversely affected by hunting and other human perturbations because of low population densities and low reproduction rates. The sustainable take of adult females may be as low as 1.5% of the population. Females and accompanying young are most vulnerable to hunting, and hunters have not consistently reported the sex composition of the harvest, therefore a method to confirm the sexes of polar bears harvested in Alaska is needed. Evidence of the sex of harvested animals is often not available, but blood or other tissue samples often are. We extracted DNA from tissue and blood samples, and amplified segments of zinc finger (ZFX and ZFY) genes from both X and Y chromosomes with the polymerase chain reaction. Digestion of amplified portions of the X chromosome with the restriction enzyme HaeIII resulted in subdivision of the original amplified segment into four smaller fragments. Digestion with HaeIII did not subdivide the original segment amplified from the Y chromosome. The differing fragment sizes produced patterns in gel electrophoresis that distinguished samples from male and female bears 100% of the time. This technique is applicable to the investigation of many wildlife management and research questions.
Effect of stimulus train duration and cycle frequency on the capacity to do work in the pectoral fin muscle of the pumpkinseed sunfish, Lepomis gibbosus
Authors: Luiker Eric A. , Stevens E. Don
Published: July 2008

The goal of our experiment was to elucidate the effect of stimulus duty cycle (the percentage of the cycle that the muscle was stimulated), phase (the relative timing of the imposed sinusoidal length change and stimulation), and muscle cycle frequency (the speed at which the muscle was cycled) on work and power in the pectoral fin muscle of a labriform swimmer, the pumpkinseed sunfish, Lepomis gibbosus. Stimulus train duration was varied from a twitch to a 40% duty cycle; cycle frequency was varied from 1 to 8 Hz. Work was calculated as the area of work loops produced by muscle contractions while the muscle was undergoing sinusoidal length changes. Maximum net work per cycle (6.2 J/kg) was produced at 1 Hz cycle frequency and a 32% duty cycle. Maximum power (26.7 W/kg) was produced at 5 Hz cycle frequency and a 16% duty cycle. As cycle frequency increased, the duty cycle and the stimulus train duration that produced maximum work decreased. The relatively long relaxation time compared with the length of time required to complete the whole cycle precluded the muscle from doing net positive work at high cycle frequencies.
Acute olfactory sensitivity of wild common carp, Cyprinus carpio, to goldfish hormonal sex pheromones is influenced by gonadal maturity
Authors: Irvine I. A. S. , Sorensen P. W.
Published: July 2008

To determine whether wild common carp (Cyprinus carpio) employ as pheromones the same gonadal hormones as goldfish, and whether their olfactory sensitivity is influenced by gonadal condition, the olfactory responsiveness of Mississippi River carp to gonadal steroids was measured by electro-olfactogram recording during two spawning seasons. Thirty-three gonadal steroids and two prostaglandins were tested. Of the steroids, only 17α,20β-dihydroxy-4-pregnen-3-one (17α,20βP), 17α,20βP-sulfate (17α,20βP-S), and androstenedione (A) were specifically detected with high sensitivity. 17α,20βP was the most potent compound, with a threshold concentration of 10−13 M, while 17α,20βP-S, and A had thresholds of approximately 10−10 M. This pattern of sensitivity matches that of the goldfish, which strongly suggests that these species share steroidal pheromone systems. The olfactory sensitivities and specificities of adult male and female carp to steroids were similar to each other and did not vary with season. However, juvenile fish were less sensitive than adults to 17α,20βP, 17α,20βP-S, prostaglandin F2α, and 15-ketoprostaglandin F2α, and more sensitive to both A and L-serine: the sensitivity of the carp olfactory epithelium to putative pheromones was apparently influenced by gonadal maturity and likely also by hormonal condition.
Underwater vocalizations of ice breeding grey seals
Authors: Asselin Sylvie , Hammill Mike O. , Barrette Cyrille
Published: July 2008

Grey seals (Halichoerus grypus) breed both on land and on the ice. In January 1991, 36 h of underwater recordings were made from Amet Island, located in ice-covered waters in the southern Gulf of St. Lawrence. All vocalizations were examined for spectral and temporal structure and then classified into 1 of 7 call types. The majority of calls consisted of guttural "rups" and "rupes" (frequency = 100–3000 Hz), and low-frequency growls (100–500 Hz). Other less common vocalizations were low-frequency clicks (3000 Hz), as well as loud knocks, similar to knocking vocalizations recorded in walrus, and which had not been described previously for grey seals. The total number of vocalizations and the number of specific call types showed seasonal variations. The rate of vocalizations increased with the intensity of social activity and with the number of agonistic behaviors during the progression of the breeding season. Comparisons between night and day showed some changes in the vocal repertoire. Low-frequency clicks were recorded more often during darkness (17.1% of calls) than in daylight (1.9%), and when ice cover was more extensive.
Body composition dynamics of ruddy ducks during wing moult
Authors: Hohman William L.
Published: July 2008

A method was developed for indexing moulting costs in waterfowl based on intensity of moult and proportional mass of feathers in seven feather regions (ADJMOLT). This method was then applied to an examination of relations between moulting costs and size-adjusted body mass and composition of postbreeding male and female ruddy ducks (Oxyura jamaicensis) collected in southwestern Manitoba, 30 July – 24 August 1985. Moderate to heavy moult (25 to > 50% of moulting feathers) was recorded in all feather regions. The intensity of down moult was greater in males than in females, but no differences between sexes in moult score by contour feather region, overall mean moult score, or ADJMOLT were detected. Relations between ADJMOLT and body fat (FAT), liver protein (LIVER), and size-adjusted body mass (ADJMASS), body protein (ADJPROT), and leg and breast muscle protein (ADJLEG and ADJBR, respectively) were not influenced by sex, but there was a sex effect on the relation of ADJMOLT to gizzard mass (GIZZWT). ADJPROT and ADJBR were negatively associated with ADJMOLT, whereas female GIZZWT was positively related to ADJMOLT. ADJMASS, ADJLEG, FAT, and LIVER were unrelated to ADJMOLT. Female ruddy ducks were structurally smaller and had less ADJMASS, ADJPROT, ADJLEG, and FAT than males, but there were no sex-related differences in ADJBR. I found no evidence of nutritional stress in post-breeding ruddy ducks, but argue that stress associated with moult in waterfowl is most likely to occur in females, especially small-bodied species that are primarily herbivorous.