bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiac performance of an isolated heart preparation from the dogfish (Squalus acanthias): the effects of hypoxia and coronary artery perfusion
Authors: Davie Peter S. , Farrell Anthony P.
Published: August 2008

An isolated preparation of the heart of the spiny dogfish, Squalus acanthias, was developed that allowed control of filling and output pressures and perfusion of the coronary arteries. Cardiac output and stroke volume, but not frequency, were dependent upon atrial filling pressure. The mean maximum cardiac power output of 1.76 mW/g ventricle mass was achieved at high stroke volumes and moderate output pressures (29 cmH2O). When stroke volume was set at half of its measured maximum, increases in output pressure did not affect stroke volume up to pressures near 46 cmH2O, at which point cardiac power output was 1.4 mW/g ventricle mass. In the absence of coronary perfusion, hypoxic perfusion of the heart lumen reduced maximum power output by 38% at 58 ± 3.4 torr and by 64% at 7.7 ± 0.8 torr. Perfusion of the coronary circulation with air-saturated saline or red cell suspensions had no effect on hearts pumping air-saturated saline or hypoxic [Formula: see text] saline, but significantly increased the maximum power output of the hearts pumping severely hypoxic [Formula: see text] saline.
A new hypothesis concerning attachment of parasitic nematodes (Spirurida: Acuarioidea) to the upper alimentary tract of birds
Authors: Bartlett Cheryl M.
Published: August 2008

A gelatinous caplike structure found in vivo around the anterior end of two species of acuarioid nematode parasites (Skrjabinocerca prima Shikhobalova, 1930 and Skrjabinoclava inornatae Wong and Anderson, 1988) is described, termed a "pileus," and suggested as the means by which the nematodes attach to the oesophageal and proventricular mucosa of their bird hosts (Recurvirostra americana and Catoptrophorus semipalmatus inornatus, respectively). Nematodes were embedded in host tissues to the depth of the posteriormost extent of the pileus, which corresponded to the posteriormost extent of the cuticular cordons on the external surface of the anterior end of the nematode. Each cordon, C-shaped in cross section, may serve as a conduit that allows liquid nutrients in the lumen of the alimentary tract to seep into the nematode's mouth, thus enabling the parasite to feed when tightly sealed by the pileus into host tissues.
Inhibition of smolting in precocious male chinook salmon, Oncorhynchus tshawytscha
Authors: Foote Chris J. , Clarke W. C. , Blackburn J.
Published: August 2008

The ontogeny of precocious maturation in chinook salmon from Nicola River, British Columbia, was examined in conjunction with the effects of such maturation on smoltification and growth. A high proportion (56%) of male parr matured as yearlings. The growth patterns of precocious males and nonmaturing individuals of both sexes differed significantly. Precocious males appeared to grow rapidly relative to nonmaturing individuals in the early spring, but thereafter displayed a decreasing specific growth rate. In addition, precocious individuals gained more weight per increment of body length than nonmaturing individuals. The seawater adaptability of precocious individuals was lower than that of nonmaturing individuals at the three monthly sampling periods and decreased steadily as maturation proceeded.
Haul-out behaviour of ringed and bearded seals in relation to defence against surface predators
Authors: Kingsley Michael C. S. , Stirling I.
Published: August 2008

The ringed seal, Phoca hispida, hauls out at the edge of self-maintained breathing holes or narrow cracks, either in fast ice or in the centre of large floes in pack ice, apparently because this reduces its vulnerability to capture by polar bears, Ursus maritimus. Antipredator behaviour of ringed seals at haul-out sites also includes lying facing both their breathing hole and downwind, and vigilance. The much larger bearded seal, Erignathus barbatus, hauls out on the edges of wide leads or large holes in the ice, or on the points of small ice floes, and also faces both the water and downwind. Ice-associated seals which are not threatened by surface predators do not show these behaviour patterns.
A daily cycle of apocrine secretion by the B cells in the hepatopancreas of terrestrial isopods
Authors: Hames C. A. C. , Hopkin S. P.
Published: August 2008

The ultrastructure of the two cell types of the hepatopancreas of the terrestrial isopods Oniscus asellus and Porcellio scaber was examined at hourly intervals in animals habituated to a 16 h light: 8 h dark cycle. The ultrastructure of the B cells undergoes substantial changes which are repeated every 24 h. This 'B cell cycle' can be divided into two stages. During the first, 'extrusive' stage, which begins about 1 h before the onset of the light period, the contents of the B cells apical to the nuclei are voided into the lumen of the hepatopancreas. The second, 'restitutive,' stage begins about 10 h after the onset of the light cycle. The B cells swell in size by the accumulation of the new material until the next extrusive stage. The ultrastructural appearance of the S cells was similar at all stages of the daily and moult cycles; they were never observed to void any material into the lumen of the hepatopancreas. The differences between the rates of turnover of the contents of the S and B cells have important implications for understanding the dynamics of accumulation and loss of metal pollutants in terrestrial isopods.
Sudanonautes kagoroensis, a new species of freshwater crab (Decapoda: Potamoidea: Potamonautidae) from Nigeria
Authors: Cumberlidge Neil
Published: August 2008

A freshwater crab, Sudanonautes kagoroensis n.sp., is described and illustrated on the basis of 57 specimens from seven localities in the guinea savanna zone of central Nigeria. The taxonomic relationship of S. kagoroensis to other freshwater crabs from Nigeria belonging to this genus is discussed and its ecology and distribution are described. Seven species of Sudanonautes Bott, 1955 are now known from Nigeria.
The comparative ultrastructure of spermatozoa from five branchiobdellidans (Annelida: Clitellata)
Authors: Ferraguti M. , Gelder S. R.
Published: August 2008

The ultrastructure of mature spermatozoa from five species of branchiobdellidans is described. The species come from four genera, and the three major families in the Branchiobdellida (Annelida: Clitellata) are all represented. The spermatozoa of Branchiobdella pentodonta and B. astaci (Branchiobdellidae) have a very long helical acrosome and a helical marginal fiber surrounding the flagellum, whereas those of Xironogiton instabilis show a twisted acrosome similar to that found in some oligochaetes. Bdellodrilus illuminatus (Bdellodrilidae) is extremely atypical, with no true acrosome, and with a long helical end-piece. Cambarincola fallax (Cambarincolidae) has an acrosome with a helical ridge on the acrosome tube, as in hirudineans, but shares with Branchiobdella spp. a helical marginal fiber around the flagellum. The spermatozoan characters in these species display a mixture of oligochaete and hirudinean features, as well as some autapomorphies, thus dispelling the idea that branchiobdellidan spermatozoa are very similar. Although a unique model cannot yet be defined for branchiobdellidan spermatozoa, a number of characters do show promise. These observations are still too few to allow any inference of evolutionary polarity in the Branchiobdellida or Clitellata, but they do suggest the possibility of using the comparative ultrastructure of the spermatozoa as an additional tool for studying branchiobdellidan phylogeny.
The coronary and luminal circulations of the myocardium of fishes
Authors: Davie Peter S. , Farrell Anthony P.
Published: August 2008

There are two routes to supply oxygen to the myocardium of fishes, an oxygen-poor luminal supply and, in some fishes, an additional oxygen-rich coronary circulation. When present in teleost fishes, coronary vessels penetrate the myocardium to differing degrees. Elasmobranchs have coronary vessels throughout the myocardium. The different distributions of the coronary vessels reflect solutions to the problem of oxygen diffusion from the luminal blood to various parts of the heart, especially the outer layers of large ventricles. By examining cardiovascular data derived from in vivo experimental perturbations, such as exercise and environmental hypoxia, and from in vitro studies with perfused hearts, we discuss the extent to which luminal venous blood obviates the need for a coronary circulation and the extent to which the coronary circulation supplements the luminal oxygen supply. The oxygen content of the venous blood surpasses the maximal demand of the working heart and so the likely limitation of the luminal blood is the venous partial pressure of oxygen [Formula: see text] which in part determines the oxygen gradient to the mitochondria. The threshold venous [Formula: see text] is between 6 and 16 torr. Whether the coronary circulation is perfused in all species of fishes under resting conditions is not clear. Experimental data support the idea that there are species differences in the relative dependence on the coronary circulation. Coronary perfusion becomes relatively more important in situations where venous [Formula: see text] decreases and myocardial oxygen demand stays the same or increases, e.g., sustained aerobic exercise, environmental hypoxia, and the recovery period after exercise. Observations in vivo and in vitro support the idea that the pressure-generating potential of the heart, as opposed to the potential for flow output, is much more sensitive to changes in coronary blood flow. Coronary blood flow is more likely to be controlled through modulation of a large coronary vasodilatory reserve than through variations in perfusion pressure. Studies on coronary vasoactivity in fishes are limited; nonetheless, species differences are apparent.
Calcium transport and the regulation of cardiac contractility in teleosts: a comparison with higher vertebrates
Authors: Tibbits Glen F. , Hove-Madsen Leif , Bers Donald M.
Published: August 2008

Active teleosts such as the salmonids must vary cardiac output severalfold over a wide range of temperatures. Myocardial contractility, an important determinant of cardiac output, must be maintained and regulated in these species under conditions that are cardioplegic to mammals. Contractility is determined primarily by the magnitude and rate of calcium delivery to the myofilaments. In mammals, a relatively small Ca2+ influx across the sarcolemma (SL) triggers the release of a larger pool of calcium from the sarcoplasmic reticulum (SR). In teleosts and other lower vertebrates, release of Ca2+ from the sarcoplasmic reticulum appears to be less important than in mammals, based primarily on the following findings: (i) electron micrographs of the ventricles of these species indicate that the sarcoplasmic reticulum is relatively sparse, and (ii) ryanodine, an alkaloid that blocks Ca2+ release from the sarcoplasmic reticulum, has little impact on steady-state tension generation. This would suggest that myofilament Ca2+ delivery is controlled primarily by calcium influx across the sarcolemma, which presumably occurs through the voltage-dependent L-type calcium channel. In the absence of a prominent role for Ca2+ release from the sarcoplasmic reticulum under most physiological conditions, therefore, it follows that that the rate of mechanical relaxation is determined primarily by the rate of efflux of calcium across the sarcolemma. The trans-sarcolemmal Ca2+ efflux is determined by two SL proteins: Na+–Ca2+ exchange and the Ca2+ pump. However, there may be conditions in the hearts of active teleosts in which SR Ca2+ release is of physiological consequence. The contribution of these transport systems to the delivery and removal of Ca2+ from the myofilaments with each beat is discussed.
Two new species of coccidia (A picomplexa: Eimeriidae) from Eumeces fasciatus (Sauria: Scincidae) in Arkansas
Authors: Upton Steve J. , McAllister Chris T. , Trauth Stanley E.
Published: August 2008

Two new species of coccidia were recovered from the intestinal contents of Eumeces fasciatus from Arkansas and are described. Oocysts of Eimeria fasciatus sp.nov. sporulate endogenously and are cylindrical, 34.9 × 16.2 (32.0–36.2 × 15.2–17.4) μm, shape index (length/width) 2.2 (1.9–2.3). Micropyle and oocyst residuum absent; polar granule present. Sporocysts ellipsoidal, 12.0 × 8.7 (10.4–13.2 × 8.0–9.4) μm, without Stieda or substieda bodies; shape index 1.4 (1.1–1.5). Sporozoites each contain a single spherical posterior refractile body. This coccidian was found to infect the biliary epithelium. Oocysts of Isospora scinci sp.nov. sporulate exogenously and are subspherical, 26.5 × 24.3 (21.6–31.2 × 18.2–27.2) μm; shape index 1.1 (1.0–1.2). Micropyle, oocyst residuum, and polar granule absent. Sporocysts ovoidal, 14.9 × 10.4 (12.0–16.0 × 9.4–11.6) μm, with Stieda and substieda bodies; shape index 1.4 (1.2–1.6). Sporozoites each with anterior and posterior refractile bodies. The site of infection of this species was not determined.
Studies on the life history of some species of Protocalliphora (Diptera: Calliphoridae)
Authors: Bennett Gordon F. , Whitworth Terry L.
Published: August 2008

The rate of development of the larvae, postfeeding larvae, puparia, and adults of 10 species of Protocalliphora were studied and differences noted in the rates of development and (or) survival. Larvae of Protocalliphora were photonegative and strongly influenced by thigmotactic stimuli. The method of feeding of the larva is described. Metamorphosis was completed more quickly at higher temperatures than at lower temperatures. Survival of purparia at temperatures of 7 °C or lower was poor and indicated that this stage was not adapted to withstand low temperatures and probably did not survive the winter. Adult Protocalliphora females were longer lived than males, surviving for an average of 70–100 days, with some individuals surviving for over 250 days under laboratory conditions. Adults fed readily on a sugar–protein diet, crushed berries, and certain species of flowers, but most species did not feed on any form of carrion. Adults mated readily in captivity, but none of the seven species tested crossbred. Spermatozoa remained motile in the seminal receptacles for over 100 days. Eggs were laid on a few occasions, but the factors determining egg production were not studied. Adult Protocalliphora were strongly photopositive and became quiescent in the dark. Adult flies rarely became active until a threshold temperature of 15.5 °C; different species had differing threshold temperatures. Adults successfully overwintered in a single field trial.
Contrasts in development and smolting of genetically distinct sympatric anadromous and nonanadromous Atlantic salmon, Salmo salar
Authors: Birt Tim P. , Green John M. , Davidson William S.
Published: August 2008

Parameters associated with the parr–smolt transformation were compared in cultured 1+ anadromous and nonanadromous Atlantic salmon derived from wild broodstock collected in Gambo River, Newfoundland. Progeny of nonanadromous salmon were significantly longer at swim-up than progeny of anadromous salmon, although consistent differences in growth performance were not observed during most of the 1 st year of development. Anadromous salmon grew more rapidly than nonanadromous salmon in the spring months during the smolting period. Distinct differences were noted between groups in seasonal levels of body silvering, gill Na+–K+ ATPase activity, and size and number of gill chloride cells. Most male nonanadromous salmon matured as "post-smolts," whereas maturation was not observed among female nonanadromous nor among either sex in the anadromous group. Differences between anadromous and nonanadromous salmon were not observed in seasonal levels of body moisture, plasma Na+ and Cl−, condition factor, or salinity tolerance. Differences noted between groups are probably genetic in nature and suggest that the two forms of salmon in Gambo River represent separate breeding populations.
The time of day of egg laying by the Brown-headed Cowbird and other icterines
Authors: Scott David M.
Published: August 2008

I present data on the time of day of oviposition for 16 species of icterines to evaluate the idea that laying exceptionally early in the morning by the brood parasite, the Brown-headed Cowbird (Molothrus ater), is a specialization for parasitism. This cowbird, the earliest known layer among icterines, typically lays before sunrise (sunrise −9.14 ± 2.52 (SE) min, n = 36). Another brood parasite, the Shiny Cowbird (Molothrus bonariensis), also sometimes lays before sunrise. The best-known nonparasitic icterines, the Red-winged Blackbird (Agelaius phoeniceus) and the Common Grackle (Quisacalus quiscula), lay shortly after sunrise. Fragmentary records show that several other icterines lay within an hour or so after sunrise. Data are inadequate to conclude that early laying by Brown-headed Cowbirds has arisen as an adaptation for parasitism. The Brown-headed Cowbird at London, Ontario, lays earlier than most local passerines, as is shown by new data on oviposition by seven host species arranged in order of increasing lateness of oviposition: Agelaius phoeniceus, Dendroica petechia, Melospiza melodia, Cardinalis cardinalis, Vireo olivaceus, Dumetella carolinensis, and Turdus migratorius.
Anatomy, ultrastructure, and functional morphology of the metathoracic tracheal defensive glands of the grasshopper Romalea guttata
Authors: Whitman Douglas W. , Billen Johan P. J. , Alsop David , Blum Murray S.
Published: August 2008

In the lubber grasshopper Romalea guttata, the respiratory system produces, stores, and delivers a phenolic defensive secretion. The exudate is secreted by a glandular epithelium surrounding the metathoracic spiracular tracheal trunks. Embedded in the glandular tissue are multiple secretory units, each comprised of a basal secretory cell and an apical duct cell. Secretory cells have numerous mitochondria, a tubular, smooth endoplasmic reticulum, well-developed Golgi bodies, and a microvillilined vesicle thought to transfer secretion to the intracellular cuticular duct of a duct cell. Ducts empty into the metathoracic tracheal lumina where the exudate is stored behind the closed metathoracic spiracle. Tactile stimulation elicits secretion discharge, which begins when all spiracles except the metathoracic pair are closed and the abdomen is compressed. Increased hemostatic and pneumatic pressures drive air and secretion out of the spiracle with an audible hiss. Both metathoracic spiracles discharge simultaneously. The secretion erupts first as a dispersant spray, then as an adherent froth, and finally assumes the form of a slowly evaporating repellent droplet. Discharge force and number vary with eliciting stimuli, volume of stored secretion, and age, disturbance state, and temperature of the insect. Molting grasshoppers are unable to discharge because the stored exudate is lost with the shed cuticle. The advantages and limitations of a tracheal defensive system are discussed.
Intraspecific patterns of resource use by fathead minnows in a small boreal lake
Authors: Price Christopher J. , Tonn William M. , Paszkowski Cynthia A.
Published: August 2008

An isolated, single-species assemblage of fathead minnows (Pimephales promelas) was studied to identify patterns of feeding and diel activity among three life-history groups (adult males, adult females, and juveniles). Minnows were collected from inshore and offshore stations during monthly (May–August) 24-h sampling periods. Minnows appeared flexible in their choice of food items, concentrating their feeding on invertebrate taxa, such as emerging chironomid pupae, that were temporarily available, as well as on relatively large and vulnerable microcrustaceans, such as Daphnia. Adult males, larger than females and juveniles, consumed the amphipod Hyallela azteca to a greater extent than the two smaller-bodied groups. Patterns of habitat use and activity were also consistent with behavioral flexibility. Prior to the breeding season, when all three groups were abundant, the population displayed intraspecific differences in diel activity; adults were typically active at night, when chironomid pupae were most abundant, whereas juveniles were primarily day active. Later, as catches of males declined, spatial and temporal patterns of females and juveniles were similar and diet overlap was high. Characteristics of both the fish population and their prey interact to shape patterns of resource use in fathead minnows.
Histopathology of cytoplasmic polyhedrosis virus (Reoviridae) infection in corn earworm, Helicoverpa zea (Boddie), larvae (Insecta: Lepidoptera: Noctuidae)
Authors: Bong C. F. J. , Sikorowski P. P.
Published: August 2008

Histopathology of cytoplasmic polyhedrosis virus (CPV) infection in the larval midgut of the corn earworm, Helicoverpa (=Heliothis) zea (Boddie) is described. Small polyhedral inclusion bodies (PIB) are observed in columnar cells of the midgut 1 or 2 days after treatment with CPV. Virions are partially or completely occluded in a polyhedral matrix to form PIB at the periphery of the virogenic stroma. PIB are dodecahedral in shape with a hexagonal outline and measure from less than 1 to 4 μm in size. Virions measure about 50 nm in diameter. Microvilli of infected columnar cells are not affected until immediately prior to rupture of the cell. Some infected columnar cells ruptured to release PIB into the gut lumen 2 or 3 days after infection. PIB are also released into the lumen by extrusion of heavily infected columnar cells. Mitochondria and rough endoplasmic reticulum deteriorate as infection progresses, and in many cells with advanced infection, the nucleus is obscured. PIB are found in goblet cells 5 days after infection. Infected goblet cells degenerate to such an extent that only a few of the original microvillus-like cytoplasmic projections and cell organelles are left. The implications of CPV infection in integrated pest management of the corn earworm are discussed.
Reproductive biology of the quillback, Carpiodes cyprinus, in a small prairie river
Authors: Parker Brian R. , Franzin William G.
Published: August 2008

Quillback (Carpiodes cyprinus (Lesueur)) spawning migrations were monitored in 1984 and 1985 in the Ochre River, Manitoba. Quillback migrations were limited by both water temperature and discharge. Upstream spawning migrations began after water temperatures reached 5 °C but only when discharges were high. Quillback migrated up to 32 km upstream from Dauphin Lake during periods of high discharge but only 2–3 km upstream if discharges were low. Quillback probably are annual spawners and spawned from mid-April to mid-June at water temperatures between 7 and 18 °C. Fecundity ranged from 46 600 to 360 000 ova in females of 912–3410 g wet weight. Fecundity had a linear relationship to quillback wet weight. Relative gonad weight, ova diameter, and dry weight of ova all increased with increasing female weight. Fertilized ova hatched after 13–17 calendar days or 220.7–229.8 degree-days. The mean total length of newly hatched larvae was 7.95 mm. Tubercle distributions were similar to previously described patterns except that, in addition, Dauphin Lake quillback bore tubercles on the dorsal surface of the head, the anal and caudal fins, and the cornea of the eye.
Purification of an agent causing growth inhibition in anuran larvae and its identification as a unicellular unpigmented alga
Authors: Beebee Trevor J. C.
Published: August 2008

Growth-inhibition mechanisms affecting amphibian larvae were investigated using five species of anurans (Rana temporaria, Rana esculenta, Bufo bufo, Bufo calamita, and Xenopus laevis) in the laboratory. Inhibition was selective for detritus-feeding rather than filter-feeding larvae, was not otherwise species-specific, and was mediated by unicellular organisms passed via coprophagy between tadpoles. These unicells were isolated and purified almost to homogeneity (in batches of > 107) by Percoll density gradient centrifugation and caused growth inhibition in a dose-dependent manner when added to tadpoles in culture. Ultrastructural, toxicological, and nucleic acid hybridisation studies indicated that the unicell was an unpigmented alga, probably of the genus Prototheca. Inhibitory cells were visualised by electron microscopy in the intestinal lumen, an environment in which no morphologically distinct life stages were identified. The relevance of these studies to interspecific competition between wild populations of anurans is discussed.
Effect of oil pipeline construction on the benthic invertebrate community structure of Hodgson Creek, Northwest Territories
Authors: Young Robert J. , Mackie Gerald L.
Published: August 2008

During the ice-free seasons of 1984 and the winter and summer of 1985, we determined the effect of winter oil pipeline construction on benthic invertebrates of Hodgson Creek, Northwest Territories. Total suspended sediments increased from < 2 mgL−1 to > 300 mg L−1 at sampling stations downstream of the pipeline right-of-way during construction, with peak concentrations exceeding 3000 mg L−1. A concurrent increase in benthic invertebrate drift density from 2.6 to 37.6/100 m−3 was observed downstream of construction. The effects of pipeline installation were observed up to 5 weeks following the end of construction. Following the spring snowmelt in 1985, no significant difference in standing crop, species richness, or functional group composition between stations upstream and downstream of the pipeline right-of-way was observed. We concluded that the negative impact of pipeline construction was limited to the period between construction and spring ice breakup. The frequency and magnitude of spate events were sufficient to remove accumulated sediment. Thus, the impact of natural perturbations in Hodgson Creek was greater than the effect of pipeline construction on benthic community structure.
Oocyte recruitment and spawning chronology in pike, Esox lucius, and muskellunge, Esox masquinongy
Authors: Lebeau Bernard
Published: August 2008

During the reproductive cycle, the progression of oogenesis differs markedly between northern pike, Esox lucius Linnaeus, and muskellunge, Esox masquinongy Mitchill. Both species have group-synchronous ovaries but have different oocyte recruitment strategies. Pike is a single spawner, developing eggs in a single clutch annually, whereas muskellunge is a fractional spawner, producing two clutches of eggs per year. During the spawning period in large female muskellunge, oocyte counts indicate that the second clutch of eggs is equally important to the first. An event portrait of the spawning period for muskellunge is provided, whereby arrival of adults to a spawning site, egg yield, and hatching success agree with the fractional spawner concept. A hypothesis of the temporal sequence of evolutionary relationships in recruitment of oocytes for esocoid fishes is presented. The reproductive strategy of muskellunge belongs to a common esocoid ancestor, whereas that in pike is derived and unique. The significance of this divergence in closely related species remains consistent with the ecological theory that evolution of reproductive strategies is adaptive to diverse environmental conditions.
Swimming behavior of juvenile giant scallop, Placopecten magellanicus, in relation to size and temperature
Authors: Manuel J. L. , Dadswell Michael J.
Published: August 2008

Juvenile scallops (shell height 4–35 mm) were stimulated to swim in an aquarium using a whelk, and their swimming was recorded and analyzed using a videocassette recorder. Scallops ascended in the water column in straight, spiral, or twisting patterns, and the majority never swam horizontally. Two types of swimming were observed. Stable swimming, with a consistent body angle (the angle that the scallop makes with the horizon), was recorded over the size range of scallops examined. In stepwise swimming, the body angle alternated between steep (98 ± 13 (SD)) and more horizontal angles (51 ± 9°). Stepwise swimming was observed among the smaller (mean ± SD = 8 ± 3 mm) scallops. Maximum and mean velocities were positively correlated with both shell height and temperature. Clap rate (Cr) increased with increasing temperature (Cr = 0.29T (°C) + 1.3). Body angle expressed a significant relationship with shell height. Below 10 mm shell height the mean angle was 82°; between 30 and 35 mm the mean angle was 38°.
Hatching, growth, ion accumulation, and skeletal ossification of brook trout (Salvelinus fontinalis) alevins in acidic soft waters
Authors: Steingraeber Mark T. , Gingerich William H.
Published: August 2008

Brook trout eyed eggs and subsequent alevins were exposed to pH 5.0, 6.5, and 7.0 in soft reconstituted water and to pH 8.2 in hard well water for up to 72 d. Hatching was delayed and hatching success reduced (p < 0.05) in eyed eggs exposed to pH 5.0 and 6.5. Alevin growth was not affected. Fish in all treatments rapidly accumulated monovalent ions in a similar pattern and in the order of Na+ > K+ > Cl− during yolk absorption and early exogenous feeding. Whole-body monovalent ion concentrations were reduced for short periods during yolk absorption in alevins exposed to pH 6.5 and throughout most of the experiment for those exposed to pH 5.0. Whole-body Mg2+ concentrations were not affected by treatment pH and remained near their median hatch level throughout the exposure. The whole-body concentration of Ca2+ was reduced in fish exposed to pH 5.0, particularly near the end of the experiment. Calcium accumulation in fish was influenced by the interaction of pH and time at pH 5.0 but not at the other pH levels. Alevins exposed to pH 5.0 experienced delayed ossification of skeletal structures associated with feeding, respiration, and locomotion that usually persisted for up to 10 d. The detection of skeletal abnormalities early in life might aid in identifying fish populations at risk in acidified waters.
Measurement of weasel body size
Authors: Johnson Donald R.
Published: August 2008

Body size of long-tailed weasels (Mustela frenata) and short-tailed weasels (Mustela erminea) collected in northern and central Idaho was indexed using cranial length, zygomatic width, cranial mass, body mass, and body length (total less tail) as size variables. In comparison with the other variables, body length had lower and sometimes nonsignificant correlations with principal component 1 (PC1) scores of principal component analysis, suggesting that its further use as an index of body size for these species is inappropriate. Young males (6–9 months of age) of one or both species, similar in body size to adult females, occurred in all regions sampled. Because body size alone is not a reliable method of separating juvenile males from adult females, specimens identified as male lacking the baculum or tag information independently confirming sex are possibly misclassified.
Plasma testosterone concentrations of captive male hooded seals (Cystophora cristata)
Authors: Noonan L. M. , Ronald K. , Raeside J.
Published: August 2008

Plasma testosterone concentrations of two captive male hooded seals of known ages were determined for a period of 1.5–5.5 years. Concentrations of testosterone were elevated and seasonally associated with reproductive behaviour and development of the musk odour. Profiles of plasma testosterone suggest that the breeding season of the male extends over several months, thus facilitating the development of a polygynous mating system.
Does game cropping serve conservation? A reexamination of the African data
Authors: Macnab John
Published: August 2008

Commercial culling of wildlife species in natural habitats (game cropping) or in fenced areas (game farming) has been suggested as a means of conserving such species in North America. An alternative hypothesis proposes that such exploitation may have an adverse impact on these species and other species associated with them. Commercial exploitation uses the precedent of African cropping projects originally set up for conservation. This review examines the biological and economic evidence from Africa in the light of these two hypotheses. The biological evidence is now seen to suggest that domestic ungulates are more productive than wild species in medium-rainfall natural habitats of Africa. Game farming, which provides luxury products (meat), and services (tourism, hunting) to foreigners, is more productive than game cropping which tries to provide cheap meat to low-income native peoples. The economic evidence in favour of cropping is drawn from culling programs for management in national parks, and from private ranches in southern Africa. However, these park culling schemes subsidized costs and were not intended for profit, whereas private ranches sold to luxury markets and were subsidized by tourism and sport hunting. Although many private game farms are a commercial success, their value for conservation is limited. There may also be some negative effects on conservation.
Cranial strength in relation to estimated biting forces in some mammals
Authors: Thomason J. J.
Published: August 2008

The mammalian skull has proven to be remarkably plastic during ontogeny and phylogeny in response to the demands of mastication. I examine whether the bending strength of the skull in some mammals correlates with the maximal loads imposed through the masticatory apparatus. The approach is analytical, using the methods of beam theory. Cranial strength is estimated from the second moment of area and other geometrical measurements made from 20–30 transverse CT scans through the skulls of 20 opossums (Didelphis virginiana), and through single skulls of five felid and five canid genera of different sizes. Maximal biting forces were first estimated from areas on the dried skulls bounding the spaces filled in life by the jaw-adducting muscles. These estimates were then adjusted with reference to forces recorded in vivo or, for other specimens, to estimates based on dissections of the jaw muscles. Stress distribution in the face, and peak stresses, were calculated for each animal. Stress levels are low (5–35 MPa) compared with peak stresses in limb bones (40–100 MPa), which correlates with the lower in vivo strains in cranial bones reported in the literature. Stress estimates are in a range that is plausible, which supports the validity of the procedure. Patterns of stress distribution along the face are comparable within each group of animals. Peak stress is independent of size for the carnivorans, but decreases with increasing skull length in D. virginiana. High bending strength of the skull is a consequence of cranial form in mammals; having to enclose the brain, for example, increases the bending strength of the skull. Furthermore, factors such as stiffness or shear and torsional strength may be more important than bending strength. However, bending stress levels appear to be closely regulated, as in other bones that have been studied. The threshold for optimising bending strength and weight is simply at a different level.
Synthèse et exocytose de chlorocruorine et mise en réserve du fer par le tissu périvasculaire d'un annélide polychète
Authors: Ouaghi El Mahjoub , Grasset Michèle
Published: August 2008

The perivascular tissue of Sabella pavonina, a layer of brown cells covering ventral and lateral vessels, is characterized by three types of distinct inclusions in the cells: chlorocruorin vacuoles, ferritin particles and granules, and vacuoles containing both chlorocruorin and ferritin. The crystallization of chlorocruorin in trans-Golgian vesicles and the gathering of these into vacuoles suggests that this tissue is involved in the chlorocruorin synthesis and indicates that the terminal stage of this synthesis occurs in the Golgi apparatus. The basolateral exocytosis of this respiratory pigment in intercellular spaces and its transit to the lumen of the vessels are revealed. Alternating changes in chlorocruorin and ferritin contents of chloragocytes linked to ultrastructural variations in these cells, as observed in many sabella, led to the conclusion that the perivascular tissue play a role in both chlorocruorin synthesis and temporary iron storage.
Metabolic control of Argyropelecus hemigymnus photophores: effects of glucose and pyruvate
Authors: Mallefet J. , Baguet F.
Published: August 2008

Modifications in oxygen consumption and luminescence of isolated luminescent organs of the mesopelagic fish Argyropelecus hemigymnus following glucose and pyruvate administration were studied before and during light emission triggered by adrenaline. Isolated photophores (mean fresh weight 13.5 ± 0.9 mg) at rest, i.e., in the absence of light emission, in saline (20 °C) exhibit a respiration rate of 1.045 ± 0.082 (SE) nmol O2/min (n = 35). A significant decrease (p = 0.05) in oxygen consumption was observed after the addition of 5.5 mM glucose. Instead of the oxygen decrease usually observed as a result of control stimulations using adrenaline, photophores pretreated with glucose increased their oxygen uptake in response to adrenaline, and maximal light emission was reduced by 85% (p = 0.01). The addition of 5.5 mM pyruvate induced a significant transient increase (p = 0.05) in oxygen uptake of isolated photophores, though this treatment did not statistically modify the mean time course of oxygen consumption and light emission in response to adrenaline. The hypothesis of a hypometabolic state of the isolated photophores of A. hemigymnus during light emission is discussed.
The epidermis of Phoronis psammophila Cori (Phoronida, Lophophorata): an ultrastructural and histochemical study
Authors: Fernandez I. , Aguirre A. , Pardos F. , Roldán C. , Benito J. , Emig C. C.
Published: August 2008

The principal cell types of the trunk epidermis of Phoronis psammophila are categorized and described on the basis of their ultrastructural and histochemical properties. There are seven cell types: uniciliated supporting cells with a well-developed microvillar layer, fine-granule-containing cells with distinctive finger-like processes that contain vesicles and extend into the microvillar layer, and five types of generalized gland cells distinguished mainly by the fine structure of their secretory granules. Gland cells lack cilia but possess intact basal body complexes within the cytoplasm in close association with the Golgi complex. This is an unusual feature for gland cells, and suggests that they may have recently evolved from more typical ciliated epithelial cells. The secretory product of the gland cells contains either acidic mucopolysaccharides, which are mostly sulfated, or neutral mucopolysaccharides and protein. The possible functions of these cell types are discussed. The supporting cells are presumably involved in direct uptake of nutrients and (or) the protection and cleaning of the epidermis. The fine-granule-containing cells may help the animal adhere to the tube, whereas the gland cells probably function in the secretion of the tube.
Bear feeding activity at alpine insect aggregation sites in the Yellowstone ecosystem
Authors: Mattson David J. , Gillin Colin M. , Benson Scott A. , Knight Richard R.
Published: August 2008

Bears (Ursidae) were observed from fixed-wing aircraft on or near alpine talus in the Shoshone National Forest between 15 June and 15 September in 1981–1989. Bears fed on insect aggregations at 6 known and 12 suspected alpine talus sites, disproportionately more at elevations > 3350 m, on slopes > 30°, and on south- and west-facing aspects. While at these sites, bears almost exclusively ate invertebrates, typically army cutworm moths (Euxoa auxiliaris). Subadult grizzly bears (Ursus arctos horribilis) appeared to be underrepresented at the sites, and proportionate representation of adult females with young appeared to decrease between 15 June and 15 September. Overall, observations of bears at these sites increased between 1981 and 1989. We suggest that alpine insect aggregations are an important food source for bears in the Shoshone National Forest, especially in the absence of high-quality foraging alternatives in July and August of most years.
The biochemical characteristics and hatching performance of cultured and wild Atlantic salmon (Salmo salar) eggs
Authors: Srivastava Rakesh Kumar , Brown Joseph A.
Published: August 2008

The biological, morphological, and biochemical characteristics of Atlantic salmon (Salmo salar) eggs were examined as potential egg-quality criteria. In addition, the metabolic utilization of body stores during early development of cultured and wild Atlantic salmon was compared. Fertilization and hatching success and survival of developing embryos and alevins were recorded as a biological measure of egg quality. This measure was related to levels of protein, lipid, carbohydrate, dry matter, and ash as potential biochemical indicators, and to egg size, yolk-sac volume, and alevin size at hatching as potential morphological indicators of egg quality. Egg diameter and alevin length were positively correlated with egg weight and alevin weight, respectively, whereas egg diameter and weight were not correlated with alevin length and weight. Eggs collected from wild Atlantic salmon had higher protein, lipid, carbohydrate, and energy content, which declined simultaneously during development, and were associated with higher fertilization and hatching success and greater size and survival of embryos and alevins, than those collected from cultured stock. It is suggested that for egg-quality criteria, energy content of eggs can be used as a condition index for development and survival of salmonids.
Interspecific and intraspecific otolith variability in the genus Merluccius as determined by image analysis
Authors: Lombarte A. , Castellón A.
Published: August 2008

Morphological variation in the sagittal otoliths of six species of the genus Merluccius was compared. The outlines of the otoliths were broken down numerically and classified according to numerical taxonomic methods. The results of this classification indicated that the specific characters of the sagittae emerge with individual growth, so that the otoliths from small individuals of various species exhibit plesiomorphic characters and are quite similar to one another. The otoliths from individuals longer than 20 cm can be classified into two geographic and phylogenetic groups: a Euro-African group (M. merluccius, M. capensis, and M. paradoxus) with plesiomorphic features, and an American group (M. bilinearis, M. productus, and M. gayi).
Histomorphological changes in epidermal structure of juvenile Arctic charr (Salvelinus alpinus L.) subjected to sustained exercise
Authors: Christiansen Jørgen Schou , Jobling Malcolm , Amin Anil B. , Ribe Hilde
Published: August 2008

Groups of sexually immature juvenile Arctic charr (Salvelinus alpinus L.) were subjected to exercising regimes equivalent to either ~0.0 (control), 1.0, or 2.0 body lengths per second for 63 days. The effects of the different treatments on the epidermal structure of individual fish were examined. Epidermal thickness, measured in micrometres, did not vary between treatments, but fish exposed to a water current equivalent to 2.0 body lengths/s had increased numbers of epidermal cell layers compared with control fish. There were no differences in the numbers of mucous cells per millimetre of cell layer irrespective of the treatment employed, but the increase in the numbers of cell layers exhibited by exercised fish appeared to have resulted in an increase in the numbers of mucous cells per square millimetre of cross-sectional epidermal area (i.e., cell concentration). The superficial mucous cells were significantly larger in exercised fish than in control fish. There were no differences in the sizes of the underlying mucous cells among treatments. The variations in epidermal structure could not be ascribed to differences in individual growth parameters, but appeared to be a consequence of the different exercising regimes imposed upon the fish.
Testing the Wildlink activity-detection system on wolves and white-tailed deer
Authors: Kunkel Kyran E. , Chapman Richard C. , Mech L. David , Gese Eric M.
Published: August 2008

We tested the reliability and predictive capabilities of the activity meter in the new Wildlink Data Acquisition and Recapture System by comparing activity counts with concurrent observations of captive wolf (Canis lupus) and free-ranging white-tailed deer (Odocoileus virginianus) activity. The Wildlink system stores activity data in a computer within a radio collar with which a biologist can communicate. Three levels of activity could be detected. The Wildlink system provided greater activity discrimination and was more reliable, adaptable, and efficient and was easier to use than conventional telemetry activity systems. The Wildlink system could be highly useful for determining wildlife energy budgets.
The winter environment of painted turtles, Chrysemys picta: temperature, dissolved oxygen, and potential cues for emergence
Authors: Crawford Kenneth M.
Published: August 2008

Water, bottom, and presumed hibernaculum temperatures and dissolved oxygen concentrations were examined over four winter seasons (1981–1985) in a shallow pond near Ann Arbor, Michigan, where a population of painted turtles, Chrysemys picta, overwinter. The minimum presumed hibernaculum temperature varied considerably from year to year (3.7–6.3 °C) and was correlated with the severity of the winter. Turtles hibernating at this site would not have been exposed to temperatures below freezing even in the severest winter. Ice covered the pond continuously for an average of 92 (56–117) days and subsequently, dissolved oxygen fell precipitously, the water becoming severely hypoxic (< 1 ppm O2) for an average of 43 (39–46) days. The timing of emergence varied annually (March 1 to April 14) and was correlated with the severity of the winter. Thus, it appears that photoperiod or a circannual rhythm is not a proximate cue for arousal. Emergence generally occurred after the ice cover was completely melted, when water and bottom temperatures were increasing steadily and the vertical temperature gradient had collapsed or reversed. The annual variability in physical conditions demonstrated in this study strongly suggests that studies involving hibernation in aquatic ecosystems are best conducted over several winters.
Importance of lake characteristics in structuring parasite communities of salmonids from insular Newfoundland
Authors: Marcogliese David J. , Cone David K.
Published: August 2008

Metazoan parasites of Salmo salar and Salvelinus fontinalis were studied at eight sites in insular Newfoundland. The locations included water bodies of various sizes (<1, 1–100, and >100 ha) and depths (<1, 1–5, and >5 m). Nine of 14 parasite species were salmonid specialists and generally had wider geographic distributions than the remaining generalists, with one exception (Echinorhynchus lateralis). The distributions of Crepidostomum farionis, Sterliadochona ephemeridarum, and E. lateralis appeared to be facilitated by the widespread distribution of intermediate hosts. Larval digeneans (Apophallus imperator, Diplostomum sp., and Tetracotyle sp.) were typically associated with shallow medium-sized lakes. Species using limnetic copepods as intermediate hosts (Philonema agubernaculum, Eubothrium salvelini, and Diphyllobothrium sp.) were most often found in fishes inhabiting the deeper lakes. Small ponds had low parasite richness (R = 5); medium and large lakes had similar richness (R = 9–11). Jaccard's index and cluster analysis revealed that fishes in the small ponds and deep lakes had inherently different parasites from fishes of the shallow medium-sized lakes, the latter containing fishes parasitized by larval digeneans. Based on the study it was concluded that lake depth is a fundamental factor determining the structure of parasite communities in salmonids in insular Newfoundland.