bluuebunny/crossref_metadata_2025 huggingface dataset:
Cystidicoloides ephemeridarum (Linstow, 1872) (Nematoda) in speckled trout, Salvelinus fontinalis, from southern Ontario
Authors: Greenwood S. J. , Baker M. R.
Published: March 2009

The seasonality of infection and histopathology of Cystidicoloides ephemeridarum were studied in speckled trout, Salvelinus fontinalis, from the Rocky Saugeen River, Ontario. Ten trout were examined each month between May and October of 1985 and 1986 (total of 120 fish). Prevalence was 100% during both sampling years. The mean intensity followed the typical seasonal trend for this parasite in salmonids from the Northern Hemisphere. In both years it increased from May to reach a maximum in June and then declined considerably in July and August. This decline levelled off in September and October. Histopathological examination revealed that worms were unattached in the lumen of the transitional (curved) and pyloric regions of the stomach. These worms were often found within the bolus of food consumed by the host. No nematodes were found feeding on host tissue and there was little evidence of pathogenicity. Infrequently, superficial disruptions of the mucosal epithelium occurred adjacent to worms located close to the stomach lining, but underlying tissues appeared unaffected.
Influence of oxygen concentration on the distribution of Mysis relicta Lovén in a eutrophic temperate lake
Authors: Sherman R. K. , Lasenby D. C. , Hollett L.
Published: March 2009

The lower depth limit of a Mysis population in Crystal Lake, southern Ontario, gradually moved upward through the summer stagnation period, generally following a position just above the 1.0 mg/L dissolved oxygen isopleth. Mysis held in bioassay chambers demonstrated a 16-h LC50 value of 1.0 mg dissolved oxygen/L. Avoidance chamber experiments revealed that Mysis could detect and move away from areas of low dissolved oxygen concentrations. It is suggested that Mysis, which has been used as an indicator of oligotrophic conditions, could survive in a mesotrophic or eutrophic lake that undergoes oxygen depletion in the hypolimnion by moving upward in the water column.
The adaptive significance of dorsal spine variation in the fourspine stickleback, Apeltes quadracus. V. Temporal variation
Authors: Blouw D. M. , Hagen D. W.
Published: March 2009

We investigated temporal variation in polymorphisms for the number of dorsal spines in the fourspine stickleback, Apeltes quadracus, and in the ninespine stickleback, Pungitius pungitius, to complement studies based on geographic variation. The changes in spine number that occurred over a 10-year period at Daigle Inlet, New Brunswick, are small relative to geographic variation among sites in the Maritime Provinces. However, some statistically significant changes occur in both species: they take place at or near reproduction; there is no evidence that they are related to selection by predators or any other environmental factor that we measured; and they tend to be followed by reversals that damp the net change. Contrary to expectation, based on spatial relationships, spine numbers in A. quadracus and P. pungitius do not covary predictably over time. The results show that events at or near reproduction play a role in determining local morph frequencies. Our main finding is that spine number is surprisingly stable for both species, and we conclude that it is constrained to local equilibrium values.
The effects of ureteral resistance on gull urine composition and flow rate
Authors: Hughes Maryanne R.
Published: March 2009

The effects of ureteral resistance on the ionic and osmotic composition of urine were examined in five anesthetized Glaucous-winged Gulls, Larus glaucescens, orally loaded with 0.075 M NaCl. One ureter was cut caudad to the kidney and the cloaca was opened to expose the contralateral ureteral papilla. The [Na] of urine leaving the kidney (renal urine) was less than plasma [Na] and positively correlated with flow rate. Renal urine [Cl] was less than plasma [Cl] at flow rates less than 50 μL min−1, but higher than plasma [Cl] at greater flow rates and was positively correlated with flow rate. Renal urine [K] was greater than plasma [K] at all flow rates, but markedly so below 20 μL min−1. Ureteral transit did not affect ion concentrations, but decreased (P < 0.01) urine volume and increased (P < 0.001) osmotic concentration, suggesting that the rapid flow of fluid through the renal tubules reduced isosmotic NaCl uptake and addition of osmotically active substances. Glomerular filtration was determined by inulin clearance rate in four anesthetized gulls as 4.88 ± 0.27 mL min−1 kg−1. The percentage of filtered Na, Cl, and water reaching the ureters was 0.83, 1.04, and 1.76, respectively. The ureter may influence the ureteral urine composition by regulating the rate of passage of urine through the kidney.
New and described species of Skrjabinoclava Sobolev, 1943 (Nematoda: Acuarioidea) of the proventriculus of nearctic waders (Aves: Charadriiformes) with a review of the genus and a key to species
Authors: Wong P. L. , Anderson R. C.
Published: March 2009

Nine new species of Skrjabinoclava Sobolev, 1943 are described from the proventriculus of waders (Charadriiformes) in North and South America, and one species (S. tupacincai Freitas and Ibanez, 1970) is redescribed. The nine new species are as follows: (1) Skrjabinoclava hartwichi n.sp. from Arenaria melanocephala; (2) Skrjabinoclava kritscheri n.sp. from Limosa fedoa; (3) Skrjabinoclava bakeri n.sp. from Calidris mauri (type host), C. alba, C. alpina, C. minutilla, C. pusilla, Catoptrophorus semipalmatus, and Limnodromus sp.; (4) Skrjabinoclava morrisoni n.sp. from Calidris pusilla; (5) Skrjabinoclava inornatae n.sp. from Catoptrophorus semipalmatus inornatus; (6) Skrjabinoclava wilsoniae n.sp. from Charadrius wilsonia wilsonia; (7) Skrjabinoclava scmipalmatae n.sp. from Charadrius semipalmatus; (8) Skrjabinoclava pusillae n.sp. from Calidris pusilla; and (9) Skrjabinoclava mycrsi n.sp. from Calidris alba (type host) and C. alpina. Reliable specific characters were noted in the morphology of spicules which make possible the identification of many species. The species of Skrjabinoclava in European waders need to be investigated and in particular the morphology of S. horrida, the type of the genus, needs to be clarified. Taxonomic notes are provided on 13 other previously described species, i.e., S. horrida (Rudolphi, 1809), S. aculeata (Creplin, 1825), S. decorata (Solonitzin, 1928), S. cincli (Yamaguti, 1935), S. solonitzini Sobolev, 1943, S. longifuniculata Sobolev, 1952, S. halcyoni Ryzhikov and Kokhlova, 1964, S. alii Ali, 1968, S. brevispicula Bondarenko and Daiya, 1971, S. amaurornae Schmidt and Kuntz, 1972, S. rallae Schmidt and Kuntz, 1972, S. venusta (Schmidt and Kuntz, 1972), and S. thapari Freitas, 1953. All species so far recorded in the genus occur in the proventriculus of birds, mainly waders, except S. thapari which has been reported in the stomach of Procyon cancrivorus.
Convergent evolution of jaw-opening muscles in lepidosirenid lungfishes and tetrapods
Authors: Bemis William E.
Published: March 2009

Lepidosiren and Protopterus have a jaw-opening muscle which is topographically and functionally similar to the depressor mandibulae of salamanders. The similarity is so close that it poses the question whether the lepidosirenid jaw-opening system is homologous to that of tetrapods. New information presented here confirms that the muscle is absent in Neoceratodus forsteri, the living sister species of Lepidosiren and Protopterus, and paleontological evidence shows that the muscle was absent in phylogenetically primitive lungfishes. There are also developmental differences between the mandibular depressor of lepidosirenids and the depressor mandibulae of tetrapods. Based on this, I conclude that the mandibular depressor of lepidosirenids has evolved independently from the functionally equivalent muscle of amphibians.
Parasites of burbot, Lota lota (family Gadidae), from the Ford River in the Upper Peninsula of Michigan
Authors: Muzzall Patrick M. , Whelan Gary E. , Peebles C. Robert
Published: March 2009

Of 128 burbot, Lota lota, collected from the Ford River in August 1983, 1984, November 1984, and May 1985, 121 were infected with at least one of the following parasites: Azygia sp., Crepidostomum farionis, Posthodiplostomum sp., Cystidicoloides tenuissima, Haplonema hamulatum, Raphidascaris acus, Neoechinorhynchus pungitius, Neoechinorhynchus saginatus, Myzobdella lugubris, Elliptis sp., Epistylis sp., Myxobolus sp., and Trichodina sp. Of the helminths found, R. acus and H. hamulatum had the highest prevalence and mean intensity, respectively. The prevalence of Myxobolus sp. decreased with burbot age. The prevalence of Epistylis sp. and Elliptis sp. and the prevalence and mean intensity of H. hamulatum and R. acus increased with burbot age. Taxonomically, the helminth fauna consisted of 263 (24%) trematodes, 741 (67%) nematodes, and 96 (9%) acanthocephalans. Using Brillouin's index, the mean diversity value ± 1 SD of counted helminths in infected burbot was 0.302 ± 0.333; the mean evenness was 0.303 ± 0.295.
Seasonal changes in the activity budget of captive ermine, Mustela erminea L.
Authors: Robitaille Jean-François , Baron Georg
Published: March 2009

The duration and location of behavior patterns in ermine (Mustela erminea L.) kept in outdoor enclosures were recorded over a 1-year period. The behavior patterns were grouped into five functional behavioral categories: exploration, comfort behavior, feeding behavior, nest care, and locomotion. Exploration and locomotion occurred mostly on the ground, whereas comfort behavior, feeding behavior, and nest care occurred in the nest. Total activity, outdoor activity, locomotion, and exploration were correlated with ambient temperature. Variations in monthly activity budgets over the year suggest the influence of two factors: the physiological reproductive state and the ambient temperature. The relevance of the observed behavioral strategies to energy economy in the ermine is discussed.
Form and function of the tooth crown structure in gekkonid lizards (Reptilia, Squamata, Gekkonidae)
Authors: Sumida Stuart S. , Murphy Robert W.
Published: March 2009

The shapes of gekkonid teeth are examined in detail using scanning electron microscopy. The teeth are found to have lingually tilted cusps similar to those reported in caecilians and extinct dissorophoid amphibians. In most species, teeth possess two cusps separated by a concave sulcus, but in (at least) one species, teeth have four well-developed cusps. Because the cusps are weakly developed or absent in large or noninsectivorous geckos, we suggest that the observed arrangement of cusps aids smaller species in grasping hard-bodied prey. The cusps of most gekkonid teeth possess well-developed median tips which are more pronounced than those of amphibians with bicuspid teeth. The shapes of these teeth may be of value in phylogenetic investigations.
Aggression and exploitation as mechanisms of competition in larval salamanders
Authors: Walls Susan C. , Jaeger Robert G.
Published: March 2009

We investigated the mechanisms of competition between two species of larval salamanders, Ambystoma talpoideum and Ambystoma maculatum. A laboratory experiment revealed that A. maculatum suffered higher mortality during early periods of larval growth when raised with its congener, A. talpoideum, than it did when combined with conspecifics. Ambystoma maculatum had no effect on the survivorship of A. talpoideum. However, A. maculatum inhibited the growth of A. talpoideum as well as that of conspecifics. This inhibition of growth may be evidence of exploitative competition for food. In a second experiment, A. talpoideum was more aggressive (a form of interference competition) than A. maculatum to both conspecific and heterospecific larvae. These results suggest that coexistence between these two species of larval salamanders results from a trade-off between exploitative and aggressive superiorities.
Diel periodicity in density of Ephemeroptera nymphs on stream substrata and the relationship with drift and selected abiotic factors
Authors: Casey Richard J.
Published: March 2009

The diel periodicity in density of Ephemeroptera nymphs on an undisturbed stream bottom was documented by direct observation. The study was conducted in a second-order Rocky Mountain foothill stream in Alberta. Observations were made for 24-h periods, twice during a new moon and twice during a full moon; the times of the dark and light periods were noted. Nocturnal observations were made using a red light. The abundance of drifting nymphs, incident light, percent cloud cover in the sky, and water temperature were recorded to determine if they were related to the observed diel periodicity on top of the substratum. The taxonomic groups of Ephemeroptera nymphs examined were Cinygmula, Heptageniidae (Cinygmula and Epeorus), Baetis, Baetis–Ameletus, Ameletus, Drunella coloradensis Dodds, and total fauna (all groups including minor taxa). In response to the artificial light used for observations, total fauna, Cinygmula, and Baetis nymphs were not affected by the light, and the nymphs were not found to be negatively phototactic. Total fauna and Heptageniidae nymphs exhibited a diel periodicity between 24-h periods; the Baetis–Ameletus group also had a diel periodicity. Cinygmula, Baetis, and D. coloradensis nymphs did not exhibit a diel periodicity. Most taxonomic groups were at greater densities on the top of the substratum in the dark period than in the light period. For small and large size classes of nymphs examined, only the small Heptageniidae and Baetis–Ameletus nymphs showed a diel periodicity in density. Drift of the common groups of nymphs was aperiodic and not statistically correlated with the diel density of nymphs on the substratum. In general, incident light, percent cloud cover, and water temperature were not correlated with the diel density of the taxonomic groups on the top of the substratum.
Growth and physiological condition of black ducks reared on acidified wetlands
Authors: Rattner Barnett A. , Haramis G. Michael , Chu Diane S. , Bunck Christine M. , Scanes Colin G.
Published: March 2009

Acid deposition has been identified as one of several possible factors contributing to the decline of some waterfowl populations in North America. In an effort to examine the effects of acidification on black duck (Anas rubripes) recruitment, growth and physiological condition were monitored in ducklings foraging for a 10–day trial (days 10–20 of life) on acidified (pH 5.0) and circumneutral (pH 6.8) fish-free emergent wetlands. Acidification of these wetlands suppressed phytoplankton and algal growth, and reduced invertebrate biomass. Ducklings maintained on acidified wetlands grew poorly compared with ducklings reared on circumneutral wetlands, as evidenced by lower final body weight and culmen and tarsus length. Plasma growth hormone concentration was elevated and triiodothyronine levels were lower in stunted ducklings, in part substantiating impairment of growth-regulating processes. Ducklings exhibiting poor growth tended to have lower hematocrit, lower plasma protein, glucose, and cholesterol concentrations, and higher uric acid levels, presumably reflecting alterations in metabolism and development due to inanition. These findings suggest that acid deposition may lower food production in wetlands and ultimately impair duckling growth, condition, and survival.
Electron microscopic study of sperm head differentiation in the lizard Agama stellio
Authors: Al-Hajj Hameed , Janakat Suha , Mahmoud Fahmi
Published: March 2009

Early differentiation of the spermatid of Agama stellio is demonstrated by two anterior nuclear depressions, occupied by two proacrosomal vesicles, which fuse to form one vesicle. Later, this vesicle exhibits an acrosomal granule in its midposterior portion. The space between the posterior acrosomal membrane and the nuclear envelope is occupied by a subacrosomal fibrous layer which later exhibits a subacrosomal granule posterior to the acrosomal granule. The acrosomal vesicle and the nuclear depression flatten and later elongate. The acrosomal granule spreads and assumes the inverted V shape of the acrosomal vesicle, and the subacrosomal material assumes a feathery shape capping the nuclear prolongation. The subacrosomal granule on top of this feathery material forms a long, cross-striated subacrosomal rod which extends towards the tip of the acrosome. The chromatin material undergoes condensation into spirally oriented fibers, which eventually become homogeneous and dense. This process is accompanied by a change in the orientation of the manchette microtubules, which initially occur as rings around the nucleus and are eventually found parallel to the longitudinal axis of the nucleus.
Seasonal occurrence of Cyathocotyle bushiensis Khan, 1962 (Digenea: Cyathocotylidae) metacercariae in the intermediate host Bithynia tentaculata L. (Gastropoda: Prosobranchia)
Authors: Ménard L. , Scott M. E.
Published: March 2009

Cyathocotyle bushiensis Khan, 1962 (Digenea) has been associated with late-summer duck mortality in southern Quebec. In an attempt to relate these die-offs with seasonal availability of the infective metacercariae to the ducks, two intermediate host (Bithynia tentaculata L.) populations were regularly sampled in 1984 and 1985. Prevalence varied between 5.3 and 57.3% at the South River, and between 9.1 and 49.7% at Lake St. Francis over the period of the study. Maximum abundances at the two localities were 1.38 and 1.66 metacercariae per snail, respectively. No close link between availability of metacercariae and periods of duck mortality was found, as the total prevalence and abundance of the cysts decreased through the summer, probably as a consequence of snail recruitment and low cercarial transmission rates, and increased in the autumn. Prevalence and abundance of metacercariae increased with snail age, estimated by both size and annual growth lines, and the metacercariae were found to be aggregated in the snail population. Comparison of infection levels reached at the end of the two sampling seasons by two year classes of B. tentaculata suggested that transmission of cercariae was higher in 1984 than in 1985. This was supported by the results of exposure of sentinel snails in an infected area during the 2 years of the study: transmission was detected in 1984 but not in 1985. In addition to C. bushiensis metacercariae, the sentinel snails acquired Sphaeridiotrema globulus (Rudolphi, 1814), another potential duck pathogen, in both years. The peak rate of transmission of S. globulus metacercariae occurred in August.
Feeding behaviour of Great Blue Herons at Creston, British Columbia
Authors: Forbes L. Scott
Published: March 2009

Great Blue Herons (Ardea herodias) at Creston, British Columbia, used three feeding behaviours: standing, walking slowly, and feetfirst diving. The prey taken differed with each behaviour. Standing herons took a higher proportion of active prey than herons walking slowly did; herons walking slowly took more sedentary prey than standing herons did. Herons diving feetfirst took dead and dying fish made available by a summer kill. The diet range of herons diving feetfirst was narrower than that of herons standing and walking slowly. The sizes and species of prey taken by herons reflected in part the abundance of prey. The gross and net energetic return of feetfirst diving was higher than that of walking slowly, which in turn was higher than that of standing. The herons appeared to be constrained from using more profitable feeding behaviours.
Cytotaxonomy of four European species in the Eusimulium vernum group (Diptera: Simuliidae)
Authors: Hunter Fiona F.
Published: March 2009

The polytene chromosomes of four closely related Eusimulium (Roubaud) morphospecies from Europe have been examined. These are Eusimulium vernum (Macquart), E. costatum (Friedrichs), E. cryophilum (Rubtzov), and E. carpathicum (Knoz). Interspecific comparisons indicate that vernum and costatum are homosequential in chromosomal banding pattern; however, costatum does differ from vernum in possessing a conspicuous chromocenter. Both species may have B chromosomes, but these are not identical. Three kinds of vernum populations are found: pure X0Y0 (with undifferentiated X and Y chromosomes), pure X0Y1 (with males heterozygous for IIS-1 ve), and mixed X0Y0/X0Y1 populations. Only two European vernum cytotypes are indicated. Eusimulium cryophilum and E. carpathicum share a suite of autosomal polymorphisms as well as a fixed paracentric (IL-2) and a fixed pericentric (IIIP-1) inversion with respect to the vernum "Knebworth" standard. They differ from one another by three fixed inversions (IIS-1, IIIS-3, and IIIS-4). It is argued that at least two siblings, cryophilum A and cryophilum B, exist within cryophilum s.l. Sections 86B and 91C in the long arm of chromosome III appear to be extremely labile for breakage and reunion phenomena because several tandem or near-tandem inversions occur in this area. A cytophylogeny of the taxa under study is presented.
Étude de la réponse à l'amputation des phalanges chez la souris : rôle morphogénétique des épithéliums, stimulation de la chondrogenèse
Authors: Revardel Jean-Louis , Chebouki Farida
Published: March 2009

The third phalanx of the mouse regenerates through epimorphosis, as it does in Urodela: dedifferentiation, growth, and redifferentiation. This capability would be due to the local persistence of embryonic characteristics in the dermis and the skeleton and to the morphogenetic action of developing epithelia. The amputation of the second phalanx results in scarring and in the formation of bony callosities. When stimulated by extracts of scarring epithelium or by growth hormone, these callosities, which constitute a model of tissue regeneration, can proliferate as do the chondroblastic regenerates in Anura.[Journal translation]
Copper rockfish (Sebastes caurinus) and quillback rockfish (Sebastes maliger) habitat in the Strait of Georgia, British Columbia
Authors: Richards Laura J.
Published: March 2009

Densities of copper rockfish (Sebastes caurinus) and quillback rockfish (Sebastes maliger) differ significantly among sites in the northern Strait of Georgia. To determine whether among-site density differences are associated with habitat characteristics of the sites, rockfish densities and habitat characteristics were measured at 12 sites during SCUBA surveys in 1984 and 1985. Quillback rockfish densities were greater in areas of high relief, broken rock, and high percentage cover of flat-bladed kelp, especially on deep transects. Copper rockfish densities were also greater in high relief areas, but effects of other habitat characteristics were not significant. Copper rockfish appeared to be more widely distributed than quillback rockfish over the range of habitats and depths surveyed.
Social behaviour of feeding finback whales off Newfoundland: comparisons with the sympatric humpback whale
Authors: Whitehead Hal , Carlson Carole
Published: March 2009

Finback whales off Newfoundland and Labrador formed groups of between 1 and 10 animals, with smaller groups being found more frequently. The number of whales in a group was closely related to the horizontal size of the prey schools on which the whales were feeding. Associations between individual finbacks were generally of short duration. In these respects finback social behaviour was similar to that of the humpback whales that frequently fed on the same prey schools as the finbacks. However, finbacks moved faster than the humpbacks, stayed further apart from conspecifics, and, unlike the humpbacks, were never observed to perform energetic above-water displays. Differences in speed and manoeuvrability between the two species may explain why they rarely formed interspecific groupings.
The absorptive surfaces of Nectonema sp. (Nematomorpha: Nectonematoidea) from Pandalus montagui: histology, ultrastructure, and absorptive capabilities of the body wall and intestine
Authors: Skaling Barbara , MacKinnon B. M.
Published: March 2009

The histology, ultrastructure, and absorptive capabilities of the body wall and intestine of the juvenile stages of Nectonema sp. (Nematomorpha: Nectonematoidea) that parasitize the shrimp Pandalus montagui in Passamaquoddy Bay, New Brunswick, were examined using histological, histochemical, ultrastructural, and in vitro labeling techniques. The body wall consists of a multilayered cuticle that rests on, and is produced by, a thin cellular hypodermis. The intestinal tract consists of a minute mouth, a cuticularized oesophagus, and a blind-ending intestine consisting of a lumen surrounded at different places by two, three, or four elongated cells. These cells consists of a maximum of two "absorptive" cells with microvillar luminal surfaces, and a maximum of two "secretory" cells, which contain numerous electron-dense granules. Acid and alkaline phosphatases and nonspecific esterases were detected in the outer layers of the body wall (cuticle and hypodermis) and in the intestinal cells. Such enzymes appear to be related to absorption of nutrient substances. Autoradiography experiments using [3H]leucine showed that following incubation in [3H]leucine-labeled seawater, leucine was concentrated in the hypodermis and the intestinal cells. Similar results were obtained when worms were incubated first in [3H]leucine-labeled seawater and then chased in nonlabeled L-leucine. Uptake of [3H]leucine was inhibited by L-leucine when worms were incubated in a seawater solution of [3H]leucine and excess L-leucine. In vitro absorption of [3H]leucine provides evidence that a carrier-mediated transport system operates across both the cuticle and the intestine of Nectonema sp.
The polytene chromosomes of Simulium (Ectemnaspis) ignescens Roubaud and the related species Simulium "C," both from Colombia
Authors: Duque Sofia , Hoyos Paulina Muñoz de , Rothfels Klaus
Published: March 2009

The paper describes the polytene chromosomes of Simulium (Ectemnaspis) ignescens from Colombia and compares them with those of a sympatric undescribed species designated Simulium "C." The two species share the entire banding sequence of chromosome arms IS, IL, and IIIS. Their IIIL arms differ by a single fixed inversion, but their second chromosomes exhibit multistep arrangement differences that were not completely resolved. The nucleolar organizer of S. ignescens is in the base of IIIS, that of Simulium "C" in the base of IS. Polymorphisms in IIS of S. ignescens exhibit partial sex linkage; no sex differential segments were demonstrated in Simulium "C." Common autosomal polymorphisms of both species involve preferentially chromosome III. Preliminary studies indicate that the chromosome maps of S. ignescens can serve as standards for other neotropical Simulium Latreille species including the important vectors of Onchocerca volvulus and Mansonella ozzardi.
Morphometric and meristic variability among North American Atlantic salmon (Salmo salar)
Authors: Claytor Ross R. , MacCrimmon Hugh R.
Published: March 2009

To investigate the morphometric and meristic variation of Atlantic salmon (Salmo salar) in North America, juveniles from 16 anadromous and 5 nonanadromous populations were collected from an area extending from Labrador to New York state. The findings from the analysis of these characters were supplemented by an examination of malate dehydrogenase variation on a subset of specimens from selected populations. Newfoundland – Labrador and Gaspé – Maritime populations were found to belong to distinct regional stocks. This conclusion was supported by the accuracy of the morphometric discriminant function and a discontinuity in Mdh-3,4(100) allele frequencies. The lack of a clinal relationship between morphometric characters, latitude, longitude, and number of degree-days above 7 °C also suggested a pattern of distinct regional stocks. Considerable overlap among populations was found for meristic characteristics, and these were considered unsuitable for stock identification purposes. While no somatic differences were found between anadromous and nonanadromous populations, there were significant differences in Mdh-3,4(100) frequencies. The congruence of morphometric and malate dehydrogenase characteristics in delineating regional stocks emphasizes the importance of a multiple character approach in solving stock identification problems.
Continuous, deep diving in female northern elephant seals, Mirounga angustirostris
Authors: Boeuf Burney J. Le , Costa Daniel P. , Huntley Anthony C. , Feldkamp Steven D.
Published: March 2009

The free-ranging dive pattern of seven adult female northern elephant seals (Mirounga angustirostris) was obtained with time–depth recorders during the first 14 – 27 days at sea following lactation. The instruments were recovered and mass gain at sea determined when the animals returned to the rookery at Año Nuevo, California, to molt. The seals gained a mean of 76.5 ± 13.9 kg during a mean of 72.6 ± 5.0 days at sea. The mean dive rate was 2.7 ± 0.2 dives/h and diving was virtually continuous during the entire period at sea. Mean dive duration was 19.2 ± 4.3 min with the longest submersion lasting 48 min. Mean surface interval between dives was 2.8 ± 0.5 min, so that only 14.4% of the recorded time at sea was spent on the surface. Surface intervals did not vary with the duration of preceding or succeeding dives. Modal dive depth for each female was between 350 and 650 m. The maximum dive depth was estimated at 894 m, a depth record for pinnipeds. The deep, nearly continuous dive pattern of female northern elephant seals differs from the dive pattern of other pinnipeds and appears to serve in foraging, energy conservation, and predator avoidance.
The anterior nervous system in the praesoma of five species of the genus Neoechinorhynchus (Acanthocephala: Neoechinorhynchidae) from turtles
Authors: Gee Randall J.
Published: March 2009

The nerve pathways in the praesoma are described for five species of Neoechinorhynchus from turtles, based on light microscopy of serial transverse, sagittal, and longitudinal sections stained with Ehrlich's acid haematoxylin. The route from the cerebral ganglion to the musculature and sense organs of the proboscis and body wall for 11 nerves, 5 paired and 1 single, the presence and structure of the Stützzelle, and its association with the neck sense organs are described. A comparison with the nervous system in the praesoma of Paulisentis fractus and Neoechinorhynchus cylindratus is given.
Breeding biology of tree swallows in relation to wetland acidity
Authors: Blancher Peter J. , McNicol Donald K.
Published: March 2009

We examined aspects of the breeding biology of tree swallows (Tachycineta bicolor) in relation to the pH, presence or absence of fish, and dissolved organic carbon concentration in 51 wetlands adjacent to nest boxes northeast of Sudbury, Ontario. Wetland pH was positively related to swallow clutch size, the total volume of eggs in a clutch (clutch volume), the number of fledglings per successful nest, and several measures of nestling size and growth. Swallows breeding near wetlands where fish were present laid earlier, but had smaller eggs and clutch volumes and slower growth of primary feathers than swallows breeding near fishless wetlands. Organic carbon concentrations were poorly related to the reproduction of swallows. These results are discussed in relation to possible mechanisms for the effects of wetland acidity on avian reproduction.
The distribution of plerocercoids of Diphyllobothrium dendriticum (Nitzsch) in sockeye salmon (Oncorhynchus nerka) smolts from Great Central Lake, British Columbia
Authors: Ching Hilda Lei
Published: March 2009

Sockeye salmon (Oncorhynchus nerka) from Great Central Lake, Vancouver Island, British Columbia, were sampled in May of 1986 and 1987 to study the locations and sizes of plerocercoids of Diphyllobothrium dendriticum. In 1986, 93% of 59 smolts were infected with a total of 222 plerocercoids (mean intensity ± SE, 4.0 ± 3.4; range, 1–15). In 1987, 77% of 168 smolts were infected with a total of 341 plerocercoids (mean ± SE, 2.6 ± 1.8; range, 1–9). More than 75% of the infected fish contained one to three plerocercoids, which were more often found free in the musculature than encysted in the viscera. Plerocercoids occurred most frequently in the midepaxial and midhypaxial musculature and encysted on the stomach and pyloric ceca. Plerocercoids varied in body length: those from the stomach area were <2 mm, and those in the viscera and musculature were 3–10 mm (a few from the musculature were >10 mm).
Lernanthropinus nematistii sp.nov. (Lernanthropidae) and Caligus tenuifurcatus Wilson, 1937 (Caligidae), siphonostomatoid copepod parasites of roosterfish (Nematistius pectoralis Gill, 1864) from the Sea of Cortez
Authors: Deets Gregory B. , Benz George W.
Published: March 2009

Two roosterfish, Nematistius pectoralis Gill, 1864, from the southern Sea of Cortez were examined for parasitic copepods. The male and female of Lernanthropinus nematistii sp.nov. and Caligus tenuifurcatus Wilson, 1937 are described. Lernanthropinus nematistii sp.nov. is distinguished from its congeners by a bifid process near the tip of the brachium of the second maxilla. Caligus tenuifurcatus is distinguished from other species by the number and location of the flat, dentiform basal processes on the three most medial setae of the second exopod segment of leg 1.
A laboratory study of the vulnerability of prey to predation by three aquatic insects
Authors: Fuller Randall L. , DeStaffan Peter A.
Published: March 2009

The vulnerability of three different prey (Baetis spp., Ephemerella spp., and Simulium spp.) to predation by Nigronia serricornis (Megaloptera) and Paragnetina media and Agnetina capitata (both Plecoptera) was studied in recirculating Plexiglas chambers. When each prey was tested individually, Simulium was least vulnerable to predation by A. capitata and equally vulnerable with Ephemerella to P. media and N. serricornis. Baetis was the most vulnerable to predacious stoneflies while Baetis and Ephemerella were equally vulnerable to N. serricornis. When prey were tested in mixed assemblages, similar trends in prey vulnerability were seen, except that Ephemerella was more vulnerable than Simulium to P. media and N. serricornis. Our data suggest that Ephemerella is less vulnerable than Baetis to predation by stoneflies; however, they were equally vulnerable to N. serricornis, possibly because of differences in feeding behavior and morphology between stoneflies and N. serricornis. Significantly more Simulium larvae moved to the sides and ceiling plates of the experimental chambers versus the control chambers; this differential movement suggests that the presence of predators may have stimulated escape to an apparently predator-free refuge.
Actinomycin D, cycloheximide, and tunicamycin inhibit vitamin A induced proximodistal duplication during limb regeneration in the axolotl Ambystoma mexicanum
Authors: Scadding Steven R.
Published: March 2009

Vitamin A is known to cause proximodistal duplication of parts of the limb during limb regeneration in amphibians. The objective of this study was to investigate the cellular site of action of vitamin A when it causes this duplication in the axolotl Ambystoma mexicanum. Both forelimbs of larval axolotls were amputated through the radius–ulna, and treated with retinol palmitate by immersion for 10 days. Actinomycin D, cycloheximide, and tunicamycin were each applied to the right forelimb by implantation of a silastin block containing one of these antibiotics on days 2 and 6 postamputation. The left limb received a control silastin block at the same time. Actinomycin D and cycloheximide completely blocked the proximodistal duplication caused by retinol palmitate, and tunicamycin substantially inhibited the development of these duplications. These results suggest that retinol palmitate (i) induces duplication by switching on a gene (as it is antagonized by actinomycin D), (ii) requires protein synthesis (as it is antagonized by cycloheximide), and (iii) may effect glycoprotein synthesis (as it is antagonized by tunicamycin).
Passive solute and fluid transport in brook trout (Salvelinus fontinalis) urinary bladder epithelium
Authors: Marshall William S.
Published: March 2009

The passive transport of solutes across the brook trout (Salvelinus fontinalis) urinary bladder epithelium was examined in vitro in Ussing-style membrane chambers. The low transepithelial conductance (average 0.14–0.20 mS∙cm−2) and low mannitol permeability (6.9 ± 1.4 × 10−11 cm∙s−1, mean ± SE) indicate that both the transcellular and paracellular pathways have limited solute permeability. Fluid transport measurements in in vitro bag preparations indicate low hydraulic conductivity (1.6 ± 0.4 × 10−7 cm∙s−1∙atm−1; 1 atm = 101.325 kPa) and suggest that the absorbate is hyperosmotic, 5-fold more concentrated than the bathing solutions. Voltage clamping experiments with unidirectional 22Na+ and 36Cl− fluxes indicated that Na+ passive diffusion occurs primarily via a transcellular pathway, whereas the epithelium behaves as a simple resistive barrier to Cl−; thus, a diffusional portion of the Cl− flux may be paracellular. The balance of the Cl− serosa-to-mucosa flux is nonconductive and apparently represents anion exchange. Current–voltage relations were nonlinear as is typical of some tight epithelia. Bladder urine is highly hypotonic, with sodium, potassium and chloride contents of 2.00 ± 0.36, 0.76 ± 0.19 and 1.31 ± 0.20 mM, respectively. In addition to the previously demonstrated absorptive neutral NaCl active transport, present results indicate a barrier function of the urinary bladder epithelium in which hydraulic conductivity and ion and uncharged solute permeabilities are low. These characterisitics are in turn consistent with the production in vivo of a very dilute urine.
Further studies of the role of harbour seal (Phoca vitulina) pup vocalizations in preventing separation of mother–pup pairs
Authors: Perry Elizabeth A. , Renouf Deane
Published: March 2009

Calls of harbour seal (Phoca vitulina) pups, propagated simultaneously in air and underwater while the pups' heads were above the surface of the water, were recorded to examine in detail the differences between them and to determine if both versions are individually distinct. Although the airborne and underwater versions of the calls were different from one another, they were distinct for each pup on the basis of several physical parameters, primarily the frequency of the major harmonic. Interactions between the mothers and pups at the time of calling were observed to assess the role of the cries in maintaining mother–pup contact. Analysis of the variations in vocalizations and contextual data supported the hypothesis that the mothers use these vocalizations for individual recognition of their offspring and for ensuring that contact with them is maintained. It is postulated that differences between the aerial and underwater versions of calls increase the accuracy with which the mothers can locate their pups.
Growth in length and weight of northern brown bears: differences between sexes and populations
Authors: Kingsley Michael C. S. , Nagy John A. , Reynolds Harry V.
Published: March 2009

Growth curves were fitted to data on age, length, and spring weight for individuals from three populations of the brown bear, Ursus arctos, in northern Canada and northwest Alaska. Females reached 90% of asymptotic length before sexual maturity and before the age of first production. Their weight remained approximately in proportion to the cube of their length. Males reached 90% of asymptotic length 0.7 to 1.7 years later than females, and had asymptotic lengths 10–15% greater. Males continued their growth in weight even longer, and reached asymptotic weights 80–100% greater than females. Variation between these populations was small compared with the total range of variation in the species.
Embryology of intestinal caeca in the bluegill (Lepomis macrochirus)
Authors: Hossain Amjad , Dutta Hiran M.
Published: March 2009

Gastrointestinal caeca, which are unique structures of fish, are located at the junction between the stomach and intestine. The postembryonic development of caeca in the bluegill was traced in relation to the source of nutrition (endogenous, endoexogenous, or exogenous). During the mesolarval stage a constriction appears at the gastrointestinal junction, which first gives origin to bulges, which eventually become the stomach and the intestine. The gastrointestinal constriction deepens and obstructs the rapidly branching mucosa of the intestine. The obstructed mucosal folds extend outward and are transformed into caecal buds. It was found that both the formation and the number of the caeca are related to the magnitude of the gastrointestinal constriction and the degree of splitting of the obstructed mucosal folds. The absence of mucosal division in the stomach at the time of the caecal buds' origin also establishes that the caeca develop from the intestinal mucosal folds and not from the stomach.
Matching of cardiac oxygen delivery and fuel supply to energy demand in teleosts and cephalopods
Authors: Driedzic William R.
Published: March 2009

Both fish and cephalopods have a single systemic ventricle which performs mechanical work at similar levels in the two groups of organisms. This example of convergent evolution is used to identify common features of cardiac oxygen delivery and fuel supply in relation to energy demand. Foremost, both groups of animals exhibit morphological alterations to enhance oxygen delivery to the myocardium. In cephalopods, the heart is positioned to directly receive oxygenated blood, and coronary arteries can be present in both fish and cephalopods. At the cellular level, oxygen extraction is facilitated by elevated concentrations of myoglobin in the hearts of fish, which face particularly acute low levels of extracellular oxygen. These features represent adaptations to meet the challenge of oxygen delivery. In temperate-zone teleosts and cephalopods, maximal in vitro activity of ATPase reflects maximal in situ oxygen demand. In both groups of animals, there is a linear relationship between maximal in vitro hexokinase and ATPase activities, and in temperate-zone teleosts a similar relationship exists between carnitine palmitoyl transferase and ATPase activities. These enzyme activities are interpreted to reflect adaptations in maximal capacities to utilize glucose and fatty acids in response to increased energy demand.
Limiting carbohydrate stores: alleviating the problem in the marathon runner, a hibernating lizard, and the neonate brain
Authors: Guppy M.
Published: March 2009

The marathon runner is always potentially short of carbohydrate, and the best runners use more lipid and thus conserve carbohydrate. It turns out that training enables more effective use of intramuscular lipid, thus bypassing the problem of transporting lipid fuels across cell membranes. The bobtail lizard (Tiliqua rugosa) hibernates in winter and relies on "on board" fuel supplies during this period. One way that the bobtail conserves carbohydrate is by having a dearth of those tisses that rely on carbohydrate for fuel and consequently produce lactate. This strategy is reflected in the low resting lactate turnover of the bobtail, which is only 0.1% of that of a mammal. The neonate rat brain encounters a profound hypoglycaemia in the first 3 h of life. It counters this problem by using lactate for the first 1–2 h, and ketones for the next 2 h. These three situations demonstrate (i) that carbohydrate depletion as a problem is widespread in the animal kingdom, (ii) that the solutions to the problem involve many biological systems, and (iii) that solutions are more constrained within than between species.
The Gusum case: a brass mill and the distribution of soil Collembola
Authors: Bengtsson Göran , Rundgren Sten
Published: March 2009

The sensitivity towards metal pollution of some population and community characteristics in Collembola was demonstrated based on observations at eight field sites along a transect from a brass mill. Samples were collected in coniferous forest soils at Gusum, southeastern Sweden, where a local brass mill has created a metal gradient in the surrounding area, with Cu and Zn concentrations in the mor (Oa + Oe) layer close to the mill at levels 50 times above background. Cu concentrations in whole animals increased exponentially in the vicinity of the smelter, but accumulation in body tissues was only observed at background sites. Neither species number, density, nor species diversity were linearly correlated with metal concentrations but instead showed a bell-shaped distribution. The vertical distribution of Collembola was clearly dependent on soil metal concentrations, and their densities at 2 – 10 cm depth were positively correlated with metal concentrations at 0–2 cm depth. The most pertinent information was gained from observations on the species composition. Tullbergia spp. and Onychiurus armatus (Tullberg) became more abundant in the polluted soils, whereas Folsomia quadrioculata (Tullberg) and Frisea mirabilis (Tullberg) generally disappeared. Folsomia fimetarioides (Axelson) became the dominant species in the polluted soil and seemed to have a distribution that was inversely related to that of Isotomiella minor (Schäffer). The general persistence of a high abundance of Collembola in the polluted soils and the more specific changes in species abundances may be due to quantitative and qualitative changes in food supply, low bioavailability of the metals, and efficient avoidance and detoxification capabilities in the animals.
Blood flow and volume distribution during forced submergence in Pekin ducks (Anas platyrhynchos)
Authors: Heieis M. R. A. , Jones David R.
Published: March 2009

Blood is the major oxygen store in ducks forced to dive, and underwater endurance depends on how much of this store can be used by oxygen-sensitive tissues such as the heart and brain. Arterial injection of macroaggregated albumin labelled with technetium-99 m, which is trapped and held by capillaries, showed that circulation in dives was restricted to the thoracic and head areas. However, tracing red blood cells labelled with technetium-99 m as they were injected during dives showed not only that the time required for the activity to reach equilibrium was 4–10 times longer than when labelled cells were injected into resting ducks but also that blood flow continued in the leg and visceral regions. Tracing red blood cells, labelled with technetium-99 m and mixed in the circulation before a dive, during the dive showed that labelled red blood cells were redistributed from the peripheral and visceral areas to the central cardiovascular area. Measurement of circulating red blood cell volume during and after diving showed that, on average, 75.24 ± 4.56% of the total red blood cell volume was circulated during forced submergence. Hence, in forced dives, red blood cell volume is positioned in such a manner that the heart and brain have access to the oxygen stored there, and the residual blood flow in the periphery ensures that most of the red blood cell volume is circulated.