bluuebunny/crossref_metadata_2025 huggingface dataset:
Summer foraging patterns and diet selection of muskrats inhabiting a fen wetland
Authors: Lacki Michael J. , Peneston William T. , Adams Kenneth B. , Vogt F. Daniel , Houppert Joseph C.
Published: August 2008

Foraging patterns, dietary preference, and diet quality of muskrats (Ondatra zibethicus) were studied at an alkaline fen in northern New York, from May 1985 to August 1986. Cattail (Typha latifolia) was the most prominent plant food item in the diet of muskrats. Feedbed surveys indicated that muskrat foraging bouts decreased from the lakeshore denning area with distance into the fen. This pattern of reduced feeding activity was associated with declines in both open water travel routes (i.e., sluiceways) and cattail biomass. Muskrats preferentially selected the core of the cattails. Tissue assays showed core tissue to contain low amounts of lignin and only moderate levels of cellulose, suggesting that muskrats were selecting the plant part most easily digested. Nitrogen and phosphorus levels in cattail samples from all sampling locations in the fen were similar, suggesting that muskrats concentrated their foraging movements for reasons other than maximizing diet quality. These data suggest that predator avoidance behavior strongly influenced muskrat foraging movements, and that muskrats attempted to maximize feeding efficiency within the constraint of access to available open water escape routes.
Photoperiod and its effect on incidence of sexual maturity in pink salmon (Oncorhynchus gorbuscha)
Authors: Beacham Terry D. , Murray Clyde B.
Published: August 2008

Pink salmon (Oncorhynchus gorbuscha) were reared for 15 months after fry emergence under three photoperiod regimes. About 50% of males matured in a photoperiod that had two periods of declining day length within the 15-month study period. No males matured in photoperiods having only one period of declining day length, and no females matured in any photoperiod. The rate of change of day length is likely of greater importance than the amplitude of change in inducing sexual maturation in males.
The effects of mating on the fine structure of neurosecretory caudodorsal cells in Helisoma duryi (Mollusca)
Authors: Khan Hamid R. , Ashton Mary Lou , Mukai Spencer T. , Saleuddin A. S. M.
Published: August 2008

The hermaphroditic snail Helisoma duryi does not lay eggs if raised as a virgin in isolation or when castrated. The fine structure of its neurosecretory caudodorsal cells (CDC), which produce the putative egg-laying hormone, was studied in reproductively inactive virgin and castrated snails and compared with that of the reproductively active mated snails, using electron microscopy, tannic acid incubation technique, and electron microscope autoradiography after injection of [3H]leucine. The CDC of virgin and castrated snails accumulate large numbers of elementary granules and appear synthetically inactive, whereas the CDC of mated snails contain fewer elementary granules and possess features characteristic of increased protein synthesis. The flattened cisternae of the rough endoplasmic reticulum of the CDC of the virgins become swollen 3 h after first mating. In tannic acid incubated tissues, more released granules were seen in CDC from snails 12 h after first mating than in CDC from virgin and castrated snails. Autoradiography showed more silver grains on the CDC from snails 12–48 h after first mating than on those from snails 3–6 h after first mating. It is suggested that, in Helisoma, mating provides a stimulus to the CDC for increased protein synthesis and release of the putative egg-laying hormone.
Isospora albogularis sp.nov. (Apicomplexa: Eimeriidae) from the yellow-headed gecko, Gonatodes albogularis (Reptilia: Gekkonidae)
Authors: Upton Steve J. , Freed Paul S.
Published: August 2008

A new species of isosporan was recovered from the fecal contents of three of five yellow-headed geckos, Gonatodes albogularis, collected from Liberia, Guanacaste Province, Costa Rica. Sporulated oocysts of Isospora albogularis sp.nov. are subspherical, 29.5 × 26.9 (26.4–32.0 × 22.4–30.8) μm, with a shape index (length/width) of 1.1 (1.0–1.3). A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are ovoid, 14.9 × 10.8 (13.6–16.0 × 10.2–11.4) μm, with a shape index of 1.4 (1.3–1.5). Both Stieda and substieda bodies are present, and the end opposite to the Stieda body is normally tapered slightly.
Limb skeletal variation in the Jemez Mountains salamander, Plethodon neomexicanus
Authors: Dwyer Christine M. , Hanken James
Published: August 2008

We examine limb skeletal variability in Plethodon neomexicanus, a geographically isolated species of plethodontid salamander endemic to the Jemez Mountains of New Mexico, U.S.A. Data are derived from a series of 25 specimens prepared as whole mounts stained for bone and cartilage. Only 25% of hind limbs display the derived hind limb phalangeal formula 1-2-3-3-1, once considered characteristic of this species; two hind limb and one forelimb phalangeal formulae are reported for the first time. In addition, there are six variant carpal and tarsal patterns as well as the two predominant, primitive mesopodial patterns that are typical of most other species of Plethodon as well as of many other plethodontid genera. Limb skeletal variability in P. neomexicanus is among the highest recorded for urodeles and may represent an ancient and widespread polymorphism in the genus Plethodon.
Home range and movements of postfledging American black ducks in eastern Maine
Authors: Frazer Catherine , Longcore Jerry R. , McAuley Daniel G.
Published: August 2008

We monitored the movements of 97 female and 15 male juvenile American black ducks (Anas rubripes) in the vicinity of Moosehom National Wildlife Refuge in eastern Maine and southwestern New Brunswick from September through mid-December, 1985–1987. Movements were described by estimating home ranges and radial movements from the primary roost marsh. Overall home range sizes averaged 4987 ha (range 54 – 28 070 ha), and maximum distances moved from the roost averaged 9.9 km (range 0.9–42.8 km). Home ranges were linear (linearity index 2.8), and home range area and distance of movements from the roost both increased monthly. Ducks that used >15% riverine habitat had larger home ranges and moved greater distances from the roost than ducks using <15% riverine wetlands. Movements did not differ between ducks usually alone and those usually in flocks. Juvenile black ducks moved in small flocks and were often alone (34% of 355 observations). Most ducks showed fidelity to one roost-marsh complex from September until migration in late November. Daily and seasonal movement patterns were similar to those predicted for refuging systems.
Comment—Evolution of insect wings: a limb exite plus endite model
Authors: Trueman J. W. H.
Published: August 2008

Kukalová-Peck has provided evidence that insect wings evolved from primitively moveable exite lobes of leg podomeres proximal to the coxa. Reinterpretation of previous experimental findings suggests that this hypothesis, as currently formulated, is only partly correct. The costal–subcostal field is derived from an epicoxal exite, but the radial–medial and cubital–anal fields of the wing have arisen from epicoxal endite and (or) subcoxal exite and endite lobes. Wings thus have a complex origin: limb exite plus endite.
A comparison of fuel preferences of mitochondria from vertebrates and invertebrates
Authors: Moyes C. D. , Suarez R. K. , Hochachka P. W. , Ballantyne J. S.
Published: August 2008

Knowledge of tissue-specific mitochondrial properties is important in understanding cellular aerobic energy metabolism. Studies employing isolated mitochondria offer the advantage of direct and controlled manipulation of extramitochondrial conditions, while minimizing disruption of interactions between mitochondrial enzymes, transporters, and membranes. In this review, we compare the oxidative properties of mitochondria isolated from liver, heart, and skeletal muscle of vertebrates and invertebrates. The observed differences between tissues and species in the capacities for mitochondrial oxidation of fatty acids, ketone bodies, pyruvate, and amino acids reflect fundamentally different adaptations for the assimilation, storage, and utilization of metabolic fuels.
Seasonal endocrine changes in Baltic salmon, Salmo salar, immature parr and mature male parr. I. Plasma levels of five androgens, 17α-hydroxy-20β-dihydroprogesterone, and 17β-estradiol
Authors: Mayer Ian , Lundqvist Hans , Berglund Ingemar , Schmitz Monika , Schulz Rüdiger , Borg Bertil
Published: August 2008

Plasma levels of the androgens testosterone (T) and 11-ketotestosterone (OT), the progestin 17α-hydroxy-20β-dihydroprogesterone (17,20-P), and the estrogen 17β-estradiol (E2) were measured by radioimmunoassay in monthly samples from immature parr (mostly females) and mature male parr of Baltic salmon, Salmo salar. The parr belonged to the Umeälven stock, northern Sweden, and were kept at ambient photoperiod and temperature throughout their rearing period. The sampling began in February at the end of their 2nd year and continued until December. 11β-Hydroxytestosterone (OHT), 11β-hydroxyandrostenedione (OHA), and 11-ketoandrostenedione (OA) were measured at selected times only. The levels of OT, T, and 17,20-P were low in mature and immature fish from February until the summer; in the immature fish they remained low for the entire period. There were only minor differences in steroid levels between mature and immature fish before and during the first half of smoltification (May). This was also the case for OHT, OHA, and OA. In the mature fish, the levels of T and OT started to rise in June. T peaked in August–October, and OT in September–October. Both androgens dropped to a very low level in December. OT displayed the highest levels of all androgens in the reproductive season. 17,20-P rose to a high level in October, peaked in November, and was still high in December. E2 levels were relatively high in winter, declined during spring in both groups, and rose again in autumn. The poorer adaptability to seawater that has been observed in mature vs. immature fish could not be explained by differences in steroid levels at the time of smoltification.
Ontogeny and sexual dimorphism of sonic muscle in the oyster toadfish
Authors: Fine Michael L. , Burns Noelle M. , Harris Thomas M.
Published: August 2008

Previous work has shown that neurons in the sonic motor nucleus of the oyster toadfish, Opsanus tau, grow larger in males than in females and increase in size and number for 7–8 years. In order to correlate postnatal motoneuron development with growth of target muscle fibers, we examined the ontogeny of sonic muscle growth. Both the swim bladder and attached sonic muscles increased in size for life and were, respectively, 20 and 44% larger in males than in females. The muscle and swim bladder grew at an equivalent rate in males, whereas in females, muscle growth did not keep up with bladder growth. The number of muscle fibers increased about 16-fold (31 000 to 488 000), and mean minimum fiber diameter increased almost 3-fold (11.5 to 28.6 μm) as fish grew. Fibers were 15.3% larger in females than in males (adjusted means of 21.9 and 19.0 μm, respectively), but males had 47% more fibers per muscle (adjusted means of 307 000 and 209 000). Muscle fibers also exhibited morphological changes. Most of the fibers in two juveniles had yet to differentiate the core of sarcoplasm characteristic of sonic muscle, whereas the largest cells in mature males and females tended to have multiple pockets of sarcoplasm and a contractile cylinder split into fragments. Multiple pockets in large fibers and the presence of smaller fibers in males than females are interpreted as adaptations for increased speed and fatigue resistance.
Distribution of polar bears (Ursus maritimus) during the ice-free period in western Hudson Bay
Authors: Derocher Andrew E. , Stirling Ian
Published: August 2008

The distribution and movements of polar bears (Ursus maritimus) during the ice-free period in western Hudson Bay were studied using mark and recapture and radiotelemetry locating of animals of known age and sex collected between 1966 and 1987. Polar bears segregated themselves by age, sex, and reproductive status. Adult males occupied coastal areas. Family groups and pregnant females occupied areas farther inland. Subadult females and males occupied similar habitats which overlapped with those of adult males. Avoidance of conspecifics, energy conservation, philopatry, denning habitat, and habitat selection appeared to influence observed patterns. A southward shift in the population was evident early in the ice-free period and was followed by a return movement northward during October and November. This may be due to ice-formation patterns which permit earlier access to the sea ice along the north coast and hunting habitat to the northeast. All bears moved less than bears on the sea ice, and movements were consistent with a strategy of energy conservation. Most bears appear to have travelled directly from the sea ice to the study area and remained until the sea ice reformed. Little exchange with adjacent populations and a high degree of philopatry were evident for all age and sex groups; this may be a function of the distribution of denning habitat, the winter distribution of sea ice habitat and seals, and the noncompetitive conditions that prevail during the ice-free period which make dispersal of limited benefit.
Vigilance behaviour and use of rocks by Columbian ground squirrels
Authors: MacHutchon A. Grant , Harestad Alton S.
Published: August 2008

During June and July 1986 at Skull Mountain, British Columbia, observations of Columbian ground squirrels (Spermophilus columbianus) were conducted to examine the relationship between vigilance behaviour and use of rocks. Most vigilance behaviour (looking and scanning) of Columbian ground squirrels occurs near burrows, and rocks near burrows are used to increase the distance of visibility, particularly following alarm calls. During both nonalarm and postalarm periods, adults and juveniles do not differ in the frequency of use of rocks, but do differ in how they allocate their time while on rocks. During nonalarm periods adults use rocks more for vigilance than do juveniles, whereas juveniles spend more time in other activities such as grooming and playing. After alarms, adults and juveniles on rocks spend almost equal amounts of time vigilant, but adults spend more time scanning (vertical posture with forepaws raised off the ground) while juveniles spend more time looking (head raised, but with forepaws on the ground). Ground squirrels use rocks more frequently during postalarm periods than during nonalarm periods and they prefer high rocks close to burrows. The observed patterns of rock use for vigilance behaviour suggest that risk of predation is an important constraint on the spatial and temporal allocation of activities by ground squirrels.
Transmission electron microscopic study of antennal sensilla of the female black fly, Simulium arcticum (IIL-3; IIS-10.11) (Diptera: Simuliidae)
Authors: Sutcliffe J. F. , Kokko E. G. , Shipp J. L.
Published: August 2008

The innervation and internal ultrastructure of the antennal flagellar sensilla of female Simulium arcticum (cytotypes IIL-3 and IIS-10.11) are described from transmission electron micrographs. Two types of contact chemosensilla and at least four types of olfactory sensilla (sensilla trichodea, two or more types of sensilla basiconica, grooved pegs) were found. These correspond to sensillar types previously described from scanning electron micrographs of the antennae of these species. In addition, possible thermo- and hygro-receptive sensilla coeloconica are described from the antennal tip. The sensory complement of the simuliid antenna is compared with those of certain other dipterans, and possible roles of these sensilla in host location and other behaviours are discussed.
Development of the lateral palatal brush in larvae of Aedes aegypti (L.) (Diptera: Culicidae)
Authors: Fry K. M. , McIver S. B.
Published: August 2008

Light and electron microscopy were used to observe development of the lateral palatal brush in Aedes aegypti (L.) larvae. Development was sampled at 4-h intervals from second- to third-instar ecdyses. Immediately after second-instar ecdysis, the epidermis apolyses from newly deposited cuticle in the lateral palatal pennicular area to form an extensive extracellular cavity into which the fourth-instar lateral palatal brush filaments grow as cytoplasmic extensions. On reaching their final length, the filaments deposit cuticulin, inner epicuticle, and procuticle sequentially on their outer surfaces. The lateral palatal crossbars, on which the lateral palatal brush filaments insert, form after filament development is complete. At the beginning of development, the organelles involved in plasma membrane and cuticle production are located at the base and middle of the cells. As the filament rudiments grow, most rough endoplasmic reticulum, mitochondria, and Golgi apparatus move to the apex of the epidermal cells and into the filament rudiments. After formation of the lateral palatal brush filaments and lateral palatal crossbars, extensive organelle breakdown occurs. Lateral palatal brush formation is unusual in that no digestion and resorption of old endocuticle occurs prior to deposition of new cuticle. No mucopolysaccharide secretion by the lateral palatal brush epidermis was observed, nor were muscle fibres observed to attach to the lateral palatal crossbars, as has been suggested by other workers.
The effect of diet on lipid deposition in Peromyscus maniculatus
Authors: Mawhinney Kimberley , Millar John S.
Published: August 2008

Lipid deposition in Peromyscus maniculatus was examined to test the hypothesis that phenotypic fat deposition is a consequence of diet composition. Eighty P. maniculatus were divided into four groups of 20 and maintained on experimental diets varying in fat and protein. After 30 days, the mice were killed, necropsied and analyzed for lipid deposition. Changes in diet quality were not reflected in major changes in total body lipid. Changes in gut dimensions were sufficient to compensate for differences in diet and enabled the mice to maintain the same levels of lipid deposition on all diets.
Electrophoretic characterization of Cryptosporidium parvum (KSU-1 isolate) (Apicomplexa: Cryptosporidiidae)
Authors: Tilley Michael , Upton Steve J.
Published: August 2008

Sodium dodecyl sulfate polyacrylamide gel electrophoresis, immunoblotting, lectin binding, and iodine-125 surface labeling of sporozoites were used to probe the coccidial pathogen, Cryptosporidium parvum. Analysis of silver-stained profiles of CsCl gradient purified, freeze–thawed oocysts revealed >50 bands, whereas profiles of anion exchange chromatography purified sporozoites displayed >40 bands. Surface iodination of sporozoites revealed about 20 surface proteins, the most heavily labeled of which had molecular masses of 18–20, 37–39, 48, 73–76, and 102–105 kilodaltons. Following electrophoresis and Western blotting, 4 of 12 different 125I-labeled lectin probes bound to blots and collectively revealed at least 19 bands to be glycosylated. Concanavalin A specifically recognized at least 14 bands, whereas Griffonia simplicifolia agglutinin I, Maclura pomifera agglutinin, and soybean agglutinin recognized 5–7 bands each. Of the five most heavily labeled surface molecules, the four with lowest molecular masses all appeared to be glycosylated. Immunoblotting with sera collected from two individuals 30 days after they passed oocysts revealed that the majority of parasite glycoproteins and surface molecules are immunogenic.
Does the lachrymal salt gland of Malaclemys terrapin have a significant role in osmoregulation?
Authors: Cowan F. Brian M.
Published: August 2008

Several reptiles possess glands capable of secreting fluids with sodium chloride as the major solute. Almost all studies have measured total sodium chloride secreted by these glands, not the concentration of ions. Thus, it has been difficult to evaluate the role of these glands in osmoregulation. The results reported herein on a large sample of Malaclemys terrapin indicate the lachrymal gland is capable of secreting tears with concentrations of sodium chloride exceeding 500 mM. However, the absolute amount of sodium chloride secreted and the generation of "free water" is relatively low, and the response to salt loading is somewhat inconsistent. Furthermore, the lachrymal gland responds consistently to the presence of irritating fumes not apparently related to osmo- or iono-regulation. The ionic and organic contents of the tears resulting from ionic and nonionic stimuli are similar, suggesting that the lachrymal gland is not a dedicated salt gland, but a gland differentiated to serve some other role, as in many other animals. The gland may be adapted to carry out that role with minimal water loss, as expected in euryhaline animal. The evidence indicates that the control of the lachrymal gland in M. terrapin is considerably more complex than that of other known salt glands.
Effects of low ambient pH and aluminum on plasma kinetics of cortisol, T3, and T4 in rainbow trout (Oncorhynchus mykiss)
Authors: Brown S. B. , MacLatchy D. L. , Hara T. J. , Eales J. G.
Published: August 2008

Plasma kinetics for cortisol, 3,5,3′-triiodo-L-thyronine (T3), and L-thyroxine (T4), and other blood parameters were examined in catheterized rainbow trout (Oncorhynchus mykiss) exposed for 7 days to a sublethal ambient pH of 4.7 (adjusted with H2SO4), an ambient pH of 4.7 plus Al (AlKSO4, 20 μmol/L), or an ambient pH of 7.7 (control). Sublethal pH alone increased the cortisol level and the plasma degradation rate but did not change the plasma clearance rate; it did not modify plasma T3 and T4 levels and their kinetics or hepatic microsomal 5′-monodeiodinase activity; it increased plasma glucose and decreased plasma Cl− and osmolality with no change in packed cell volume. Low pH in combination with Al increased the cortisol plasma level, plasma clearance rate and plasma degradation rate; it increased the T4 plasma degradation rate but decreased the T3 plasma clearance rate, T3 plasma appearance rate, and 5′-monodeiodinase activity by increasing Km and decreasing Vmax; it also increased plasma glucose and depressed plasma Cl− and osmolality but increased packed cell volume. We concluded that Al exacerbates the effects of low ambient pH to increase cortisol prodcntion and decrease T3 production. Depressed T3 production through 5′-monodeiodinase inhibition may contribute to the poor growth of Al-exposed fish.
Effects of low pH and low calcium concentration on the pulmonate snail Planorbella trivolvis: a laboratory study
Authors: Hunter R. Douglas
Published: August 2008

Freshwater pulmonate snails (Planorbella trivolvis) were maintained in the laboratory in stream water with manipulated pH and Ca2+. Low pH treatments (4.6 and 4.7) resulted in significantly lower adult growth rates and reduced gross fecundity compared with circumneutral pH treatments (7.2 and 7.4) regardless of the Ca2+ level. None of the eggs laid in low pH treatments hatched, mostly because of developmental arrest (gastrula or earlier). Eggs in low Ca2+ treatments took longer to complete development and had a higher incidence of abnormality compared with eggs in the high pH, high Ca2+ treatment. Juveniles that successfully hatched from the low Ca2+ treatments grew very little and all died within 100 days whereas over 7.2% of those in the high Ca2+, circumneutral pH treatment were alive at day 100, some of which had become adults and were laying eggs. This study suggests that both low pH (4.6) and low Ca2+ (1–2 mg/L) are lethal to Planorbella trivolvis, with embryos and juveniles showing much greater sensitivity than adults. Given the ranges of the two variables used in this study (1000-fold for H+ and ca. 30-fold for Ca2+), pH has the greater negative impact and, when below 5.0, led to recruitment failure in P. trivolvis; a similar effect on other pulmonate species would be expected. Furthermore, a Ca2+ concentration as low as 2 mg/L alone, regardless of pH, would be sufficient to cause recruitment failure by reducing juvenile survival. These data suggest that increasing Ca2+ levels does not protect P. trivolvis from the effects of low pH.
Evaluation of the accuracy of 22Na and tritiated water for the estimation of food consumption and fat reserves in passerine birds
Authors: Gauthier Marc , Thomas Donald W.
Published: August 2008

We validated the use of 22Na and 3H for the measurement of food intake, total body water, and fat reserves in free-living passerines. The close correlation between sodium intake and blood sodium turnover (r2 = 0.98) and the narrow 95% confidence limits on the relationship (± 11% for Na consumption over 6.0 mmol) show that the 22Na technique may give precise estimates of food intake for individuals. The 3H technique does not provide precise measures of fat reserves in individuals because estimates of body fat have an error term ranging from 25 to 150%. However, it is sufficiently precise to allow the comparison of fat reserves between groups of birds. We provide a field test showing that adult Cliff Swallows have 60.3% lower fat reserves during a second breeding attempt compared with the first.
Use of winter feeding craters by snowshoe hares
Authors: Gilbert B. Scott
Published: August 2008

Snowshoe hares (Lepus americanus) in the southwest Yukon foraged in winter on ground vegetation by digging feeding craters in snow. Hares utilized at least three species: Dryas drummondii, Hedysarum mackenzii, and Lupinus arcticus. Hares dug feeding craters to reach these plants in snow up to 36 cm deep, and the area of these craters ranged from 140 to 2600 cm2. I recorded few craters after midwinter when snow depths reached 40 cm; the few craters dug at this time were in areas of shallow snow either beneath trees or in windswept areas. When hares had stopped digging craters, I established 11 small plots (1 × 1 or 1 × 2 m) where I removed snow to ground level. Hares moved in and used these areas to feed on D. drummondii and L. arcticus. I conclude that the vegetation was suitable for hares and speculate that hares stopped digging feeding craters because snow depth or snow density made it energetically uneconomical. The food value of these plants and their importance in the winter diet of hares needs further study.
Breeding seasons of oceanic birds in a subarctic colony
Authors: Hatch Scott A. , Hatch Martha A.
Published: August 2008

We studied the breeding seasons of marine birds on the Semidi Islands, western Gulf of Alaska, from 1976 to 1983. Distributions of laying or hatching observed in 11 species during 1–7 years are presented; less detailed information is available on the breeding schedules of three species. The combined laying period of 14 species lasted 3 months from mid-April to mid-July; the first eggs of the earliest and latest species were laid about 9 weeks apart. Mean laying dates varied by 2–16 days in nine species observed in 2 or more years. Although the egg-laying sequence of species was largely preserved from year to year, we found little evidence of concordant annual variation in breeding seasons. Species that fed lower in the food chain tended to breed earlier than those that fed at higher trophic levels. Early laying was correlated with longer laying periods, both within and between species. With the exception of three puffin species, birds with similar food habits exhibited less overlap in hatching and fledging dates than laying dates. A test for nonrandom dispersion of breeding times failed to find evidence for competitive avoidance of breeding overlap in piscivores or planktivores. Species may not have timed their egg laying to provide for maximum food availability during chick rearing. Rather, the comparative analysis of breeding schedules suggests that breeding times were determined more by the food requirements of laying females. Young females laying relatively late probably account for the right-skewed distributions of egg laying observed in this and other studies of colonial seabirds.
Components of breeding productivity in a marine bird community: key factors and concordance
Authors: Hatch Scott A. , Hatch Martha A.
Published: August 2008

We estimated components of annual breeding productivity for eight species of marine birds on the Semidi Islands in the western Gulf of Alaska. Mortality of eggs and young, caused primarily by avian predators, accounted for most of the annual variation in productivity. Failure to produce eggs, clutch size variation, and the hatchability of eggs were generally less important. The stage of breeding at which annual productivity was most strongly regulated differed among species. In murres, chick-rearing success accounted for the largest share of annual variation in overall productivity, whereas incubation success was the key factor in fulmars, kittiwakes, and puffins. Although avian predators were the dominant proximate cause of egg and chick losses in some species, food supply seemed ultimately responsible for variation in all the major components of productivity. Concordance of productivity among species was low for the marine bird community as a whole, but selected pairs of species exhibited a greater tendency for high and low productivities to occur in the same years. Compared with the same or similar species outside Alaska, Semidi Islands birds were in one of three categories: (i) species whose productivity was about the same as reported from other areas (fulmars and gulls), (ii) species with comparatively low productivity (murres, puffins, kittiwakes), and (iii) species with similar mean productivity but greater annual variation (cormorants). These patterns suggest that specialized consumers of forage fish experienced food shortages at the Semidi Islands and that surface feeders were more severely affected than divers.
Forced copulation in sympatric American black ducks and mallards in Nova Scotia
Authors: Seymour N. R.
Published: August 2008

Observations of primarily identifiable wild black ducks and mallards provided qualitative and quantitative descriptions of interactions within and between intraspecific, interspecific, and heterospecific pairs throughout the breeding season. The study was carried out in a watershed on the St. Lawrence estuary shore of Nova Scotia from 1972 to 1988. Attempted forced copulation and forced pair copulation were rare among black ducks at any time throughout the breeding period. Only two apparently successful forced copulations were observed. Territorial males chased both female black ducks and mallards, and these chases appeared motivated by hostility. Males that had left their mates/territories did not attempt forced copulation with other females. Females sometimes avoided strange males, particularly when they returned to territories from their nests. Paired males rarely approached females with broods. Male mallards chased both female mallards and black ducks, and did not appear to discriminate between species when attempting forced copulation. Male mallards were more persistent and vigorous in their chases than black ducks, and they attempted forced copulation, whether with black ducks or mallards, more frequently than male black ducks did. Apparently successful forced copulation between a male mallard and female black duck occurred on three occasions.
The ecology of Paleozoic terrestrial arthropods: the fossil evidence
Authors: Shear William A. , Kukalová-Peck Jarmila
Published: August 2008

The available fossil evidence for the ecology of terrestrial arthropods in the Paleozoic is reviewed and reinterpreted. Some original data are provided, derived mainly from the detailed morphology of mouthparts, genitalia, cuticular vestiture, and body form. Paleozoic chelicerates were more diverse than their modern descendants and were probably dominant ground-level and arboreal predators. Web-building spiders and highly diversified mites appear to have been absent. Paleozoic myriapods include possibly the earliest land animals, and as abundant detritivores, provided a major conduit for primary productivity into higher trophic levels. Paleozoic insects present many difficulties of interpretation, but appear to have been extraordinarily diverse and may have played quite different ecological roles from today's insects, viewed as a whole. It is postulated that herbivory, defined as predation on living plants, may have been rare in early Paleozoic terrestrial ecosystems, and that most primary productivity was funneled through detritivores and decomposers. In the late Paleozoic, the evidence for herbivory by insects, except for feeding on fructifications, is rare. Insects seem to have played a major part as a selective force on plant fructifications.
Distribution of radioiron in larval lampreys, Petromyzon marinus L., following administration of 55ferrous citrate
Authors: Hall S. J. , Youson J. H.
Published: August 2008

Light microscopic autoradiography and quantitative tissue analyses were used to examine the distribution of radioiron in larvae (ammocoetes) of the lamprey Petromyzon marinus L. over time following the injection of 55ferrous citrate (55Fe). It was found that a single intraperitoneal injection of 55Fe is an efficient method of introducing iron into ammocoetes, and radioiron retention within the body remained high throughout the 28-d experiment. Immediately after radioiron administration the isotope was transported in the serum fraction of the blood to sites of iron storage and elimination. The liver is the most important target organ for iron in ammocoetes, and radioiron acquired from the alimentary canal, skin, carcass, and blood contributed to the initial increase in this organ. Data indicated only temporary storage in the liver; between 3 and 16 d, radioiron was redistributed by the blood to the skin, kidney, alimentary canal, and carcass. Biliary transport of radioiron from the liver to the lumen of the anterior intestine may also explain the lowering of iron concentrations in the liver and the rise in levels in the alimentary canal during this interval. The redeposition of 55Fe in the liver at 16 d may signify longer-term storage of the metal in this organ. There is movement of radioiron in and out of the carcass tissues over time, and most of the radioactivity is localized in the adipose tissue. The epithelial cells of the proximal tubules of the kidney absorb and concentrate the radioiron presumably present in the glomerular filtrate. This concentration probably reflects both the absorption of iron bound to ferritin and a mechanism necessary for maintaining the high serum iron levels of ammocoetes. The release of mucus from iron-laden mucous cells of the skin and exfoliation of radioiron-laden epithelial cells in specific regions of the posterior intestine are possible routes for iron elimination. However, percent incorporation of the injected radioactivity was still high at the end of the experiment, indicating that iron excretion in ammocoetes is relatively low or that it is a slow process. These data support the notion that lampreys provide a useful animal model for the study of iron metabolism in vertebrates.
Eutardigrada from Vancouver Island, British Columbia, Canada, including a description of Platicrista cheleusis n.sp.
Authors: Kathman R. Deedee
Published: August 2008

Thirty-one species of eutardigrades were collected on five mountains on Vancouver Island, British Columbia, during July 1986 and July 1987. Three of the species found were new to science, including 1 species, Platicrista cheleusis n.sp., described herein and 2 species described elsewhere, and 21 others are new to British Columbia; 13 of these are also new to Canada.
The influence of sibling gender on the growth and survival of Great-tailed Grackle nestlings
Authors: Teather Kevin L.
Published: August 2008

Growth and survival of Great-tailed Grackle (Quiscalus mexicanus) nestlings were monitored over 3 years to determine if greater food demands of sons influenced nestling success. I predicted that (i) the growth rates of nestlings would be lower in nests containing mostly males, and (ii) the chance of all nestlings in predominantly male broods fledging would be less than that in predominantly female broods. Sibling gender and the overall sex ratio of the brood had little effect on nestling growth. There was no evidence that starvation was more frequent if the oldest nestlings were males rather than females, although there was some evidence that broods of three containing two or three males were less likely to fledge all nestlings than those containing two or three females. Mass at fledging for both males and females was influenced most strongly by hatching sequence and to a lesser extent by egg mass and hatching date.
Population ecology of the freshwater mussel Anodonta grandis grandis in a Precambrian Shield lake
Authors: Huebner J. D. , Malley D. F. , Donkersloot K.
Published: August 2008

Anodonta grandis grandis is found in about half of 50 Experimental Lakes Area lakes surveyed but is abundant in only some of these lakes, including lake 377. Lake 377 is a typical small Precambrian Shield lake, 27.7 ha in area and 17.9 m in maximum depth, with [Ca2+] of [Formula: see text], conductivity of 25 μmho∙cm−1 (1 mho = 1 S), and alkalinity of [Formula: see text]. The water renewal time of approximately 187 days is shorter than that of most Precambrian Shield lakes. Bottom sediments in the sublittoral zone ranged from fine sand through granules to cobbles and boulders. Several species of possible glochidial host fish including yellow perch were collected from lake 377. The size of the mussel population, estimated by depth-stratified random sampling, was 36 800 ± 12 000 (± 95% confidence interval). Mean density was 0.133 mussels/m2 lake surface, and maximum density was 4.3 mussels/m2. Mussels were most abundant in the 1.5- to 3.1-m depth stratum. Mean lengths and weights in collections ranged from 77 to 87 mm and from 43 to 56 g, respectively. Maximum length and weight were 117.9 mm and 109.6 g, respectively. Based on external annuli, mussels live to 15+ years in lake 377. Flesh and shell averaged 25.1 and 23.2% of live weight, respectively. Calcium constituted 44.7% of the ash weight of shell. We estimated a standing dry weight biomass of mussels of 330–390 mg∙m−2 and dry weight production of 60 mg∙m−2∙year−1. This is [Formula: see text] of the estimated annual dry weight algal production. The shells of live mussels contain [Formula: see text] of the total calcium in lake 377. Despite oligotrophic conditions and low [Ca2+], lake 377 supports a substantial population of A. g. grandis growing at a moderate rate. Lake 377 may be a favourable habitat for this species because of its short water-turnover time.
Redescription of the leech Desserobdella phalera (Graf, 1899) n.comb. (Rhynchobdellida: Glossiphoniidae), with notes on its biology and occurrence on fishes
Authors: Jones Simon R. M. , Woo Patrick T. K.
Published: August 2008

Desserobdella phalera (Graf, 1899) n.comb. is redescribed. This glossiphoniid leech deposits cocoons directly onto the substratum and belongs, therefore, in the subfamily Glossiphoniinae. It has the following generic characters: diffuse salivary glands, two pairs of coalesced eyes, one pair of mycetomes, and subdivision of primary annuli in complete body segments. Desserobdella phalera is distinguished from its congener Desserobdella picta (Verrill, 1872) by having dorsal papillae and lateral metameric and dorsal colour markings. In addition, it has approximately 60 radiating papillae on the rim of the caudal sucker. Desserobdella phalera was found naturally on bowfin (Amia calva L.) and largemouth bass (Micropterus salmoides (Lacepède)) from Ontario, Canada, and on bowfin from Florida, U.S.A. Occurrence on bowfin is a new host record. Desserobdella phalera fed experimentally on nine species of fish.
The biology of Trypanosoma phaleri n.sp. from bowfin, Amia calva L., in Canada and the United States
Authors: Jones Simon R. M. , Woo Patrick T. K.
Published: August 2008

Between 1985 and 1989, 133 of 136 (98%) bowfin (Amia calva) collected from Lakes Ontario, Erie and Huron, Ontario, Canada, and from Sugg's Lake, Florida, U.S.A., were infected with a new species of trypanosome. Trypanosoma phaleri n.sp. was pleomorphic, developed to infective metatrypanosomes in the leech Desserobdella phalera, and was transmitted by D. phalera to laboratory-reared bowfin but not to Catostomus commersoni, Anguilla rostrata, Ictalurus nebulosus, Gasterosteus aculeatus, Salmo gairdneri, Perca flavescens, Stizostedion vitreum, or Carassius auratus. Trypanosoma phaleri n.sp. developed poorly in the leech Hemiclepsis marginata.
Factors mediating copulatory behavior and close-range mate recognition in the male gypsy moth, Lymantria dispar (L.)
Authors: Charlton R. E. , Cardé R. T.
Published: August 2008

Physical models incorporating various structural features of female gypsy moths, Lymantria dispar, were used to identify the specific factors that evoke conspecific male copulatory behavior and play a part in mate recognition. Models invested with virgin female wings or body scales elicited male copulatory responses comparable to those evoked by virgin females. The presence and diameter of models also influenced male copulatory reactions. Exposure to sex pheromone was necessary to prime copulatory behaviors but, by itself, was not sufficient to release these reactions. Males expressed copulatory behaviors most faithfully when the pheromone was supplemented with female abdominal scales applied to cylindrical models either comparable in size or larger than a female. To establish the nature of the cues that prompted copulatory reactions and the sensory basis of these responses, female scales were chemically and structurally altered and male sensory structures were selectively ablated. Solvent, acid, or base extraction of female abdominal scales did not diminish the copulatory response whereas pulverization of the scales eliminated it. Models impregnated with solvent extracts of female abdominal scales elicited copulatory behavior from a higher proportion of males than did controls without extracts, although the mean time spent attempting to copulate did not differ significantly. Males whose compound eyes, tympana, tarsal chemoreceptors, labial palps, or genitalia were ablated displayed fundamentally the same copulatory behaviors as their sham-operated counterparts whereas antennectomy eliminated mating behaviors. Taken together, these findings indicate that tactile cues associated with females serve as primary releasers of copulatory behavior for sex pheromone stimulated males and that chemicals affiliated with female body scales appear to play a relatively minor role in this process.
The rate and strength of byssal reattachment by blue mussels (Mytilus edulis L.)
Authors: Lee Carey Y. , Lim Shirley S. L. , Owen Michael D.
Published: August 2008

The rate of secretion and number of byssal threads by which blue mussels (Mytilus edulis L.) reattach were measured in circulating seawater and with the mussels exposed to currents between 10 and 20 cm/s. In circulating water, larger mussels secrete more byssal threads than small mussels and appear to do so more rapidly. If detached blue mussels are exposed to currents, this pattern is reversed; when exposed to high currents, small mussels reattach more rapidly than large mussels.
Cytotoxic effects of α-terthienyl on the midgut of the tobacco hornworm, Manduca sexta
Authors: Sen A. , Iyengar S. , Arnason J. T. , Craig D. A. , Philogène B. J. R. , Morand P.
Published: August 2008

The toxic effects of sublethal doses of α-terthienyl, a secondary metabolite of Asteraceae, was studied on the fifth instar larvae of Manduca sexta following continuous feeding for 24 h. Localized areas of damage to midgut epithelial cells were observed with swelling and rupture of both columnar and goblet cells. However, the midgut appears to recover from this damage and continue normal development, suggesting the ability of an oligophagous species like M. sexta to repair and recover from the effect of these toxins.
Home range size adjustments by the eastern chipmunk, Tamias striatus, in response to natural and manipulated water availability
Authors: Bowers Michael A. , Welch David N. , Carr Timothy G.
Published: August 2008

Capture–recapture techniques were used to study the spatial organization of a population of eastern chipmunks, Tamias striatus, over 16 weeks of an uncharacteristically dry summer and early fall. The objective was to examine the role of free water as a factor influencing home range size. Home range size was estimated for time periods of 1, 3, and 5 weeks. For animals captured more than two times, home range size estimates were not significantly correlated with the number of captures or body weight, nor did home ranges differ between males and females. Home ranges were relatively large in early summer, small in mid- to late-summer, and large again in the early fall. Home ranges were significantly smaller during the 8 weeks of greater-than-median precipitation than during weeks of less-than-median precipitation. Home ranges of 8 individuals out of 12 increased in size during a 3-week drought period relative to their pre- and post-drought home ranges. Differences in home range size between drought and nondrought periods were more pronounced for males than females. Comparison of home range size before and after the provision of supplemental drinking water showed that where water was added, chipmunks reduced the size of their home ranges significantly more than control (unwatered) chipmunks. These results identity water availability during certain years and seasons as a factor influencing home range size.
Costs of parental neglect in the brown noddy (Anous stolidus)
Authors: Morris Ralph D. , Chardine John W.
Published: August 2008

We observed several instances of attacks by conspecific adults on brown noddy (Anous stolidus) chicks that were associated with joint parental absence from the nest site. Attacks were by immediate neighbours and by single or pairs of brown noddy adults apparently prospecting for a nesting ledge. One instance of infanticide was observed and the ledge was subsequently occupied by a pair of noddies. We suggest some adaptive reasons for such behaviour.
A telemetric study of the home ranges and homing routes of copper and quillback rockfishes on shallow rocky reefs
Authors: Matthews Kathleen R.
Published: August 2008

Ultrasonic telemetry was used to investigate the home ranges and homing routes of 11 copper, Sebastes caurinus, and quillback, Sebastes maliger, rockfishes. Home ranges of four copper and quillback rockfishes were monitored to determine if movement occurred during the day, night, or strong current (7.4 km/h). As expected from previous conventional tagging work, home ranges were small (most <10 m2) on high relief reefs and considerably larger (within 4000 m2) on low relief reefs. No off-reef movement by copper and quillback rockfishes was detected on either reef type. To determine homing routes, the daily positions of seven copper and quillback rockfishes were monitored as they proceeded back to their home sites after experimental 500-m displacements from a high relief rocky reef to a low relief rocky reef. Six of the seven displaced copper and quillback rockfishes took from 8 to 25 days to return home; one quillback rockfish was followed for 16 days and lost, it was last located approximately halfway back to the original home site. Once displaced rockfish returned to their original capture site, no subsequent movement was detected, suggesting home site recognition. Homing seemed to consist of three phases: (i) initial movements along a bimodal northwest-southeast axis that are possibly associated with directional preferences in exploratory migrations, (ii) movement (westerly) towards the home reef, and (iii) the final location of the home site. Homing and exploratory migrations may be characteristic behaviors in the speciose rockfish group; the evolutionary advantage ensures rockfishes locate and utilize high quality habitats.