bluuebunny/crossref_metadata_2025 huggingface dataset:
Responses by dabbling ducks and aquatic invertebrates to an experimentally manipulated cattail marsh
Authors: Murkin Henry R. , Kaminski Richard M. , Titman Rodger D.
Published: August 2008

The responses of dabbling ducks (Anas spp.) and aquatic invertebrates to artificially created cover:water ratios (i.e., 30:70, 50:50, and 70:30) in an overgrown cattail (Typha latifolia) habitat were studied from April to June 1978, on the Delta Marsh in south central Manitoba. Invertebrate populations were not affected by cover–water treatments, but significant temporal changes in population levels occurred. Between 20 May and 9 June, invertebrate levels were higher than during the previous 3 weeks and were higher than levels on the control area of uncut cattail. Dabbling duck pair densities correlated positively with invertebrate levels on treatment areas. Waterfowl behaviour also changed with the increased invertebrate levels. The highest densities of dabbling duck pairs were associated with 50:50 plots, which supports the hypothesis of maximum avian use and production during the "hemi-marsh" phase of the marsh cycle. Explanations for this phenomenon are discussed.
Oogenesis and protandry in the purple-hinge rock scallop, Hinnites giganteus, in upper Puget Sound, Washington, U.S.A.
Authors: Laurén Darrel Jon
Published: August 2008

The annual reproductive cycle of female purple-hinge scallops, Hinnites giganteus, from upper Puget Sound, Washington, U.S.A., was investigated. Gametogenesis occurred in January, vitellogenesis in February, and spawning in June. Spawning was incomplete and development continued until September, but a second spawning did not occur. Based upon wet weight tissues indices, it is proposed that nutrients are stored in the adductor muscle but are transferred to the gonad during the active reproductive season. Phagocytic transfer of nutrients from atretic oocytes probably contributes to gametogenesis. Examination of paraffin sections during February revealed the presence of oocytes in male gonads. Furthermore, female whole body wet weight was significantly greater than male whole body wet weight, and females were more abundant than males. It is suggested that this results from consecutive sexuality, i.e., protandry.
The morphology of the kidney in young adult anadromous sea lampreys, Petromyzon marinus L., adapted to seawater. I. General morphology and fine structure of the renal corpuscle and the proximal segments
Authors: Youson John H.
Published: August 2008

The morphology of the opisthonephric kidney of young adult anadromous sea lampreys, Petromyzon marinus L., was examined at regular intervals during the gradual acclimation of these recently metamorphosed individuals to full-strength seawater. No alteration of the renal corpuscle, the ciliated neck segment, or the proximal pars convoluta and pars recta segments is observed through 40% seawater, but dilation of ventral tubules, the accumulation of a white precipitate, and specific fine structural changes in the cells of the proximal segments are noted in 60% seawater. The ultrastructural alterations are more conspicuous in 80 and 100% seawater and may reflect the involvement of the proximal segment in secretion, likely magnesium and sulphate ions. Flattening of the epithelium in proximal segments, enlargement of lateral intercellular spaces in the recta segment, and apparent increases in numbers of intermediate segments at levels of 80% seawater is more obvious in animals adapted to 100% seawater. The smaller cross-sectional area of the renal corpuscle in animals adapted to 80 and 100% seawater compared with the area in lower salinity might explain the previously found reduced glomerular filtration rate which accompanies seawater acclimation in anadromous lampreys.
Fecundity and ovarian cycles of the Antarctic krill Euphausia superba (Crustacea, Euphausiacea)
Authors: Denys C. J. , McWhinnie M. A.
Published: August 2008

The fecundity and ovarian cycles of Euphausia superba were studied using three approaches: (i) counting ovarian eggs at several stages of maturity; (ii) counting eggs spawned by individual animals in the laboratory; and (iii) observing the time sequence of ovarian changes by sequential sampling of a laboratory-maintained population. Ovarian egg counts show that the number of eggs per female is directly proportional to body length and inversely proportional to the stage of maturity. Observations of laboratory-maintained animals indicate that spawning is biphasic, occurring in two closely spaced bursts. Maximum total yearly brood size for females 30–50 mm in length is estimated to be approximately 2200–8800 eggs and is directly proportional to body length. After spawning is complete, the ovary reorganizes and reverts to a juvenile appearance within 6 weeks. Reorganization is followed by a prolonged reproductive diapause.
Development of the sheep–canid cycle of Sarcocystis tenella
Authors: Dubey J. P. , Speer C. A. , Callis G. , Blixt J. A.
Published: August 2008

Thirty-seven sheep were inoculated orally with 104 to 66 × 106Sarcocystis tenella sporocysts from dogs or coyotes and necropsied between 1 and 276 days postinoculation (DPI). Two single zoites were found in submucosal arteries of small intestines of lambs 3 and 6 DPI. At 9 to 21 DPI, numerous first-generation meronts were found in mesenteric arteries, intestinal blood vessels, and occasionally in other organs. First-generation meronts were 37.0 × 27.3 μm in sections and 54.4 × 46.6 μm in smears. At 16 to 40 DPI, second-generation meronts were found in capillaries of several organs; renal meronts were 20.6 × 12.0 μm in sections. Merozoites were found in peripheral blood at 14 to 16 DPI and at 25 to 32 DPI. Earliest sarcocysts were found at 35 DPI and contained one to three metrocytes. At 40 DPI, sarcocysts were up to 97 × 10 μm and contained 1 to 13 metrocytes. Bradyzoites formed between 52 and 66 DPI. At 75 DPI, sarcocysts had cross-striated walls and were infective for coyotes. Dogs and coyotes fed infected meat shed sporocysts in feces 9 to 10 days later. Gamonts were found in the small intestine between 8 and 21 h postinoculation and sporulation was completed within 8 days.
Occurrence of Cryptocotyle lingua (Creplin, 1825) (Digenea: Heterophyidae) in the rock gunnel, Pholis gunnellus (L.)
Authors: Gorman Andrea M. , Moring John R.
Published: August 2008

Pholis gunnellus, collected at Schoodic Peninsula, Maine, during 1980 and 1981, is reported as a new natural second intermediate host of Cryptocotyle lingua. Mature flukes were recovered 5–20 days after feeding metacercariae teased from adult gunnels to laboratory-reared chicks; mice were refractory. The prevalence of infected Littorina littorea (11.1%) harboring pleurolophocercous cercariae was significantly greater than L. obtusata (0.9%) from the same site.
The adaptive significance of a complex caudal adaptation in the tropical gekkonid lizard Lygodactylus klugei
Authors: Vitt Laurie J. , Ballinger Royce E.
Published: August 2008

The tail of the Brazilian gekkonid lizard, Lygodactylus klugei, exhibits a suite of characteristics associated with both tail retention and tail loss adaptations. Tails are specialized for locomotion, possess specialized cutaneous glands, and are high in lipid and energy content. Tail loss in a natural population, however, is high and presumably associated with escape from predation via tail autotomy. The importance of the presence of a complete tail both functionally and for future predator escape is reflected by rapid regeneration of a tail complete with specialized functionally important structures.
Étude de la synthèse de la vitellogénine chez les mâles intersexués d'Orchestia gammarellus (Pallas) (crustacé amphipode). Effets de la greffe d'un ovaire
Authors: Ginsburger-Vogel Thomas , Meusy Jean-Jacques
Published: August 2008

In intersex males of Orchestia gammarellus (Crustacea, Amphipoda), vitellogenin is sometimes present in the haemolymph, but almost always in small amounts. However, no significant synthesis of vitellogenin can be shown in our experimental conditions. After the grafting of an ovary, vitellogenin becomes abundant, and a high level of synthesis, though subnormal, is observed in nearly half the cases. At the same time, secondary vitellogenesis occurs in the graft. The androgenic gland of the intersex male cannot prevent the ovary from functioning normally.
The effects of mebendazole on the growth and development of Caenorhabditis elegans
Authors: Spence Andrew M. , Malone Kathleen M. B. , Novak Marie M. A. , Woods Robin A.
Published: August 2008

Mebendazole inhibits the growth, reproductive capacity, and motility of Caenorhabditis elegans. Maximum reduction of length (50%) and volume (80%) was observed at 6.25 μg/mL mebendazole. At this concentration vulva formation was delayed by 18 h and egg production was reduced from 8 eggs/worm per hour to less than 1. The critical period for the effect of mebendazole on length was from 40 to 50 h after hatching. The drug did not affect the viability of eggs, larvae, or adults. L1 and L2 larvae were motile in the presence of mebendazole (6.25 μg/mL); paralysis became apparent during the L3 and was complete in L4 and adult stages. Paralysed worms coiled into a ring and moved feebly and spasmodically. The first two moults occurred at the same time in control and treated worms, the L3/L4 and L4/adult moults were delayed by less than 1 h in the presence of the drug. Evidence is presented that these observed effects are caused by mebendazole and were not the consequence of partial starvation resulting from paralysis.
Spring breeding of a northern temperate crayfish, Orconectes rusticus
Authors: Berrill Michael , Arsenault Michael
Published: August 2008

In southern Ontario in the springs of 1980, 1981, and 1982 the crayfish Orconectes rusticus bred explosively when water temperatures rose above 4 °C. Copulations occurred frequently as sexually mature males and females wandered over the substrate at night. Males fought with each other and interrupted copulating pairs. In 1980 and 1981, females began to sequester themselves and extrude their eggs 11–12 days after copulations began. Males then gradually wandered and fought less, began feeding, and the breeding period ended approximately 4 weeks after the initiation of frequent copulations. In 1982, a delayed spring resulted in a far shorter breeding period. Laboratory experiments indicated that although a rise in water temperature initiated breeding events, including egg extrusion, the degree of necessary temperature increase may be inversely correlated with the duration of lengthening photoperiod to which females are exposed. Females which did not copulate in spring extruded eggs which were mostly infertile, emphasizing the importance of spring copulation in this northern orconectid.
Phenetic affinities of males of the army ant genus Dorylus (Hymenoptera: Formicidae: Dorylinae)
Authors: Barr David , Gotwald Jr. William H.
Published: August 2008

Multivariate analyses of males of 25 species of the Old World army ant genus Dorylus were used to investigate taxonomic structure inherent in the morphological data gathered. Results were compared both with the current subgeneric classification of this genus and with results from a similar study on the major workers. Males are phenetically more divergent than major workers. The subgenera Rhogmus, Alaopone, and Typhlopone appear deserving of continued individual status, but species of Anomma and Dorylus (s.s.) form one diverse taxon. Although the single species of Dichthadia is relatively distinctive in this study, a conservative classification would place it with species of Dorylus (s.s.).
Effects of smelter emissions on metal levels in the plumage of ruffed grouse near Sudbury, Ontario, Canada
Authors: Rose George A. , Parker G. H.
Published: August 2008

This work investigated geographical and temporal variability in the metal content of the plumage of wild populations of ruffed grouse (Bonasa umbellus), especially as affected by the emissions of the nickel–copper smelters at Sudbury, Ontario. Levels of copper, nickel, and iron in plumage in the postmoult condition (6, 1, and 35 μg∙g−1, respectively) did not differ between birds from a site highly contaminated with metals and an uncontaminated control site. Such levels were thought to reflect endogenous incorporation of minerals during the period of feather growth and are termed base levels. Plumage in the premoult condition, having been subjected to exogenous influences during the feather year, showed gains in metal content of 7- to 20-fold over base levels at the contaminated site. As further evidence of exogenous influence, grouse retrices exposed in vitro to the atmosphere at the contaminated site showed linear time-related gains of metals. Models were developed to describe feather metal content as a simultaneous function of duration of exposure to the environment and reciprocal of distance from the pollution sources. Implications about the use of feather chemistry to identify natal areas of wildfowl and the biological monitoring of metal fallout are discussed.
Mate selection strategies by male mites in the absence of intersexual selection by females: a test of six hypotheses
Authors: Everson Peter R. , Addicott John F.
Published: August 2008

Male Tetranychus urticae Koch (Acarina: Tetranychidae) search for and tend quiescent female deutonymphs, and upon emergence the tending male mates with the female. The potential for severe intrasexual selection among males, with little or no opportunity for intersexual selection on males by females, makes the T. urticae system well suited for testing hypotheses of optimal male mating behavior. We propose six hypotheses for the mate selection behavior of male T. urticae. The hypotheses can be divided in two groups: those that assume that male behavior is genetically fixed and those that assume that males vary their choice of females in response to extrinsic variables such as the number of females, number of males, or leaf condition. Our results show that males differentially tend those females that are closest to eclosion, so that an hypothesis of random mate selection must be rejected. The mate selection behavior of males is affected by the number of females present on a leaf, but not by the number of males or the leaf condition. Therefore, hypotheses of fixed mate selection behavior are rejected, as are the hypotheses of minimizing the probability of being forced to accept a cotender and mate selection based upon energetic constraints. We conclude that males use a behavioral strategy based primarily on minimization of the time invested in each copulation.
Photoperiodic induction of diurnal locomotor activity in Microtus montanus, the montane vole
Authors: Rowsemitt C. N. , Petterborg L. J. , Claypool L. E. , Hoppensteadt F. C. , Negus N. C. , Berger P. J.
Published: August 2008

Some microtine species are nocturnal in the summer and diurnal in the winter. This activity shift has been induced in Microtus montanus in the laboratory using photoperiod alone as a cue. The shift from nocturnal to diurnal activity involves modifying the intensity and timing of short activity bouts. This phenomenon may be a mechanism for avoiding harsh microclimates.
Humpback whales (Megaptera novaeangliae) off the west coast of Greenland
Authors: Perkins Judith S. , Bryant Peter J. , Nichols George , Patten Donald R.
Published: August 2008

An assessment of humpback whales off west Greenland during July and August 1981 was made by fluke photoidentification and strip census methods, in order to determine whether these animals constitute a separate stock or an extended summer range of a stock already identified in the northwest Atlantic. Of 25 individuals sighted, 13 flukes were photographed. None matched whales previously identified in northern feeding areas, but one matched a whale photographed on Silver Bank just north of Hispaniola in the Caribbean in February 1981. Thirty-seven humpbacks were photographed later along the Labrador–Newfoundland coasts. Six of these whales (16%) matched individuals previously identified in the northwest Atlantic. West Greenland humpbacks were not evenly spaced, but were concentrated over the edges of offshore banks. Distribution was unrelated to zooplankton densities, but was positively correlated with large flocks of greater shearwaters. These findings, together with two observations of lunge feeding, confirmed that the humpbacks were eating small fish, probably Ammodytes sp. Our results suggest the possibility of a discrete feeding stock of humpbacks, probably numbering less than 200 whales, off west Greenland which, like other feeding stocks in the northwest Atlantic, breed and calve on Silver and Navidad banks in winter.
Sécrétions protéiques du tissu adipeux chez Rhodnius prolixus (Stål). Étude immunochimique
Authors: Chalaye D. , Hadj-Idris A. E. Queiroz
Published: August 2008

The proteins present in saline extracts or culture medium of the fat body from fifth-instar larvae or adults of Rhodnius prolixus were examined. Immunochemical analyses show six or seven antigens common to both the haemolymph and the fat body of adults. Continuous gradient gel electrophoresis reveals that most of haemolymph proteins are found in the fat body extract and incubation medium. The three predominant adult haemolymph fractions (lipoprotein 5, glycoprotein 3, and vitellogenin) are identified in the fat body of both female and male adults but no vitellogenin is found in the fifth-instar larvae fat body. Vitellogenin synthesized and secreted in vitro by the adult fat body consists mostly of protein A which is a 260 000 molecular weight lipoglycoprotein. The larger complex of 500 000 (protein B) is mainly found in haemolymph and ovocytes.
Changes in protein composition of bovine spermatozoa during epididymal maturation
Authors: Yoo Bong Y. , Ji Inhae , Ji Tae H.
Published: August 2008

Electrophoretic evidence is presented that the protein composition of bovine spermatozoa may change during epididymal maturation. Ejaculated spermatozoa appear to acquire two new protein species, Mr 71 000 and Mr 36 000, which were absent in epididymal spermatozoa. In contrast, a protein band of Mr 50 000 which was present both in caput and cauda epididymal spermatozoa was not found in ejaculated spermatozoa.
Metabolism at the pyruvate branch point in the radula retractor muscle of the whelk, Busycon contrarium
Authors: Ellington W. Ross
Published: August 2008

The radula retractor muscle of the whelk Busycon contrarium contains high activities of both octopine dehydrogenase (~500 μmol∙min−1∙g wet weight−1) and strombine dehydrogenase (~150 μmol∙min−1∙g wet weight−1). Experiments were conducted with in vitro radula muscle preparations to assess under what physiological conditions these dehydrogenases function. Alanopine–strombine accumulated during anoxia, postanoxic recovery, and potassium-induced contractures in radula retractor muscles. No significant accumulation of octopine was observed. Although the accumulation of alanopine–strombine was significant, it was quantitatively small when compared with the production of succinate. Thus, it appears that alanopine–strombine formation has only an accessory role in cytoplasmic redox balance in B. contrarium radula retractor muscle. The physiological role of octopine dehydrogenase in this system remains unclear.
Feeding in tornaria larvae and the development of gill slits in enteropneust hemichordates
Authors: Gilmour T. H. J.
Published: August 2008

The food-collecting and waste-rejecting systems of the tornaria larval stages of enteropneust hemichordates are similar to those of larval and adult lophophorates and adult pterobranch hemichordates. Water entering the oral grooves is deflected towards the mouth and the impetus of heavy, potentially inedible particles may take them across the flow lines of the water currents inferred from the movements of suspended particles to impinge on cilia which reject them into the outgoing water currents. Lighter, potentially edible material remaining suspended in the deflected water currents is intercepted by cilia on an oral hood which is similar in structure and function to the preoral lobe of the actinotroch larvae of phoronids. Excess water carried into the mouth by cilia on the dorsal surface of the esophagus is rejected via lateral grooves which develop into pouches prior to metamorphosis. Following metamorphosis the pouches make contact with the body wall to form gill slits which continue to allow water to escape from the pharynx. This finding that the function of allowing excess water to escape is performed by lateral grooves in the esophagus of tornariae supports previous speculations on the evolution of gill slits and provides further evidence for relationships between lophophorates, hemichordates, and chordates.
Talitroidea (Crustacea, Amphipoda) and the driftwood ecological niche
Authors: Wildish D. J.
Published: August 2008

The three known marine and freshwater talitroids occupying the driftwood niche are listed, and an ecological niche classification for Talitroidea is proposed. Characteristic adaptations of the supralittoral driftwood species to their environment are presented and compared with adaptations shown by other littoral and terrestrial talitrids. It is suggested that the driftwood niche is preadaptive for talitrid terrestrial life.
Seasonal dynamics and ecological strategies of the pitcher plant chironomid, Metriocnemus knabi Coq. (Diptera: Chironomidae), in southeast New Brunswick
Authors: Paterson C. G. , Cameron C. J.
Published: August 2008

In southeast New Brunswick the chironomid, Metriocnemus knabi, an inhabitant of the aquatic system contained within the leaves of the pitcher plant, Sarracenia purpurea, show seasonal fluctuations in numbers related to emergence and colonization, but density is usually correlated with the potential volume of the leaves. Females from a May emergence oviposit into overwintered leaves and produce a generation which emerges in August prior to the deterioration of the leaves. The progeny of the August emergence develop in leaves of the current summer growth and do not emerge until the following July. Ovipositing by this generation can be into overwintered or newly opened leaves. Larvae that begin development in overwintered leaves, which show progressive deterioration during the later summer and autumn, migrate to younger leaves that have not achieved complete colonization. The July emergence produces the generation which emerges the following May. Thus, there appears to be two cohorts in the population, each of which produces three generations every 2 years. This unusual life cycle tends towards maximizing use of the living habitat which also has a seasonal pattern of growth and senescence.
Life history and movements of anadromous brook charr, Salvelinus fontinalis, in the St-Jean River, Gaspé, Quebec
Authors: Castonguay Martin , FitzGerald Gérard J. , Côté Yvon
Published: August 2008

A comparison between an anadromous and a freshwater lake population of brook charr showed that anadromous charr had a lower mean length at age 2+ and 3+, a greater longevity, a greater maximal length and a greater length and age at first maturity than the freshwater population. A biased sex ratio towards females occurred only in the anadromous population. The first 2 or 3 years in the life cycle of anadromous charr is spent in the river, followed by an intermediate period of a year in the salt wedge area and then by a 2- or 3-month period in salt water before returning to the river. Bigger charr started upstream migration earlier in the season than smaller charr. Migration peaks in 1979 were synchronized with the new moon. Fish movements in the estuary were greater during spring tides than neap tides. Diel activity was highest in the day in the estuary whereas the inverse situation occurred in the river. From tags returns, it was concluded that anadromous brook charr had a strong homing tendency.
Aquatic feeding by moose: seasonal variation in relation to plant chemical composition and use of mineral licks
Authors: Fraser D. , Thompson B. K. , Arthur D.
Published: August 2008

Activity of moose (Alces alces) was studied at aquatic feeding areas and at natural, sodium-rich licks during four periods covering late May to early September. Aquatic feeding increased from period 1 (late May and early June) to period 2 (late June and early July) and had declined by late July. Major activity at mineral licks occurred earlier in the season than aquatic feeding, especially for males. Chemical composition of aquatic plants showed no seasonal changes corresponding to the peak of aquatic feeding in period 2, although the sodium content of some species declined in period 3. We suggest that moose in the study area are attracted to sodium sources from late May to mid-July, that aquatic feeding replaces use of licks in June as the most sodium-rich aquatic plants become abundant, and that both activities decrease in midsummer because of declining attraction to sodium.
Systematics and zoogeography of three new nematode parasites of the frog Breviceps sylvestris sylvestris FitzSimons from South Africa
Authors: Baker M. R.
Published: August 2008

Hedruris transvaalensis n. sp. (Habronematoidea), the first Hedruris species recorded from Africa, belongs to a group within the genus found only on the Gondwanaland continents and characterized by fused, slender, and nontwisted spicules. It is distinguished from other Hedruris species by possessing spicules exceeding 350 μm in length. Oswaldocruzia robusta n. sp. (Trichostronglyoidea) is easily differentiated from all other species in the genus by its large body size, relatively large intestinal cells, the disposition and size of the bursal rays, spicule morphology (distal end with three branches, two of which are divided into eight or nine sharp processes), and shape of the female tail (distal half in form of spike). It is not closely related to other endemic African Oswaldocruzia spp., which form a homogeneous group. Entomelas sylvestris n. sp. (Rhabditoidea), the first Entomelas species recorded from sub-Saharan Africa, is distinguished from other Entomelas species by the division of the buccal capsule into two parts. Its presence in a frog confirms the wide and sporadic distribution of Entomelas in diverse amphibian and reptilian hosts. This suggests Entomelas is a relict and ancient group.
Daily measurements of variation in weight loss of eggs of seven passerine species before and during natural incubation
Authors: Manning T. H.
Published: August 2008

The eggs of one or more clutches of seven passerine species were weighed each day from the day they were laid until hatching. In all seven, the rate of weight loss increased during incubation. This increase was more rapid in the early stages, leading to curvilinear regression. Linear regression was, however, highly significant and explained over 80% of the variation in four species. Curvilinear regression was significant in two other species. The weight loss curve of a single unfertilized Barn Swallow, Hirundo rustica, egg was similar to that of the rest of the clutch until they commenced to pip. The daily weight loss of five unincubated eggs also increased with time. Shell damage was suspected to be the cause of sudden increases in weight loss of individual eggs. A simultaneous drop in weight loss by six clutches was probably caused by high humidity. Other decreases in weight loss may have been caused by rain. Mean weight loss from water vapour conductance through the shell as a percentage of initial egg weight was 0.9 ± 0.08 during the laying period, 12.0 ± 0.72 during the laying period plus the incubation period prior to pipping, and an estimated 14.6 ± 0.85 for the laying period and the whole incubation period.
Experimental infection of American kestrels, Falco sparverius, with Trichinella pseudospiralis Garkavi, 1972, and T. spiralis
Authors: Meerovitch E. , Chadee K. , Bird D. M.
Published: August 2008

Trichinella pseudospiralis Garkavi, 1972, but not T. spiralis was shown to be infective to American kestrels, Falco sparverius. A maximum of only 5.1% of the larvae administered were able to develop to the adult stage in the intestine. In vitro release of newborn larvae by female worms, recovered on days 10 and 15 postinoculation, was low. Adult worms were eliminated from the intestine by day 25 postinoculation. Few muscle larvae were first observed on day 20 postinoculation; their number increased with time but was never as high as in similarly experimentally infected mice.
The physiological responses of the rainbow trout to strenuous exercise: interactions of water hardness and environmental acidity
Authors: Graham Mark S. , Wood Chris M. , Turner Jeffrey D.
Published: August 2008

Cannulated adult rainbow trout were subjected to 6 min of exercise stress in four different water conditions: hard water ([Formula: see text] as CaCO3), control pH ([Formula: see text]); artificial soft water [Formula: see text], control pH; hard water, acid pH [Formula: see text]; and artificial soft water, acid pH. Physiological changes and postexercise mortalities were monitored over a 12-h recovery period. The physiological responses to exercise stress were qualitatively similar in all treatments and are discussed in detail. At control pH, water hardness had minimal influence on the magnitude of physiological response and postexercise mortality. When fish were exercised in hard water at acid pH, the symptoms of postexercise acidosis were actually ameliorated slightly and there was no increase in mortality. However, acid exposure in soft water greatly exacerbated most of the postexercise disturbances and caused a doubling of mortality.
Antennal sensilla of some aphidophagous Syrphidae (Diptera): fine structure and electroantennogramme study
Authors: Henderson D. E. Hood , Wellington W. G.
Published: August 2008

Antennal sensilla of Metasyrphus venablesi (Cn.) and Eupeodes volucris O.S. (Diptera: Syrphidae) were studied by scanning and transmission electron microscopy. Males and females both had four types of sensilla. Three of these, two multiporous pitted (mpp) sensilla (one round-tipped and one pointed) and a multiporous grooved peg sensillum, were also confirmed by scanning electron microscopy on the following species: Syrphus torvus O.S. (♂, ♀), Syrphus opinator O.S. (♂, ♀), Scaeva pyrastri (L.) (♂, ♀), Dasysyrphus amalopsis O.S. (♂), Xanthogramma flavipes Lw. (♀), Brachyopa perplexa Cn. (♀), Pipiza sp. (♂), and Xylota quadrimaculata Lw.(♀). The fourth mpp sensillum had thicker walls and fewer pores. All four types were located among dense noninnervated setae on the antennal bulb and are probably olfactory. Electroantennogramme (EAG) study revealed antennae of female M. venablesi to be sensitive to some components of the aphid–plant oviposition site complex, namely, some green plant volatile substances (6-carbon alcohols), crushed pea aphids, crushed carnation petals, methylsalicylate and amylacetate, and to be nonresponsive to honeydew and some of its components (tryptophan, indolealdehyde, and indoleacetaldehyde).
The effect of thermal effluent, before and after macrophyte harvesting, on standing crop and species composition of benthic macroinvertebrate communities in Lake Wabamun, Alberta
Authors: Rasmussen Joseph B.
Published: August 2008

The heated area of Lake Wabamun prior to macrophyte harvesting had higher submerged macrophyte production, greater amounts of plant detritus in the sediment, and a higher standing crop of benthic macroinvertebrates than the unheated area. Species composition of the benthic macroinvertebrate community was also much different in the heated area with the warmest areas supporting a community dominated by tubificid oligochaetes (Limnodrilus hoffmeisteri and Tubifex tubifex), and the moderately heated areas supporting a community dominated by large Chironomus species (Chironomus plumosus and Chironomus atroviridis). Benthos of the unheated parts of the lake consisted mainly of smaller chironomid species such as Chironomus maturus, C. (cf.) staegeri, Polypedilum nubeculosum, Cladotanytarsus spp., and Tanytarsus spp. The heated area was subjected to mechanical macrophyte harvesting which removed the majority of the submerged macrophytes. This reduced the amount of plant detritus within the sediment and also the standing crop of benthic macroinvertebrates in the heated area. Species composition of the oligochaete-dominated community was not affected by harvesting. Species composition of the Chironomus-dominated area was greatly affected by harvesting and became more similar to that of the unheated area; densities of the large Chironomus species were reduced to low levels, while the densities of smaller chironomid species increased.
Two new natatory asellote isopods (Crustacea) from the San Juan Archipelago, Baeonectes improvisus n. gen., n. sp. and Acanthamunnopsis milleri n. sp., with a revised description of A. hystrix Schultz
Authors: Wilson George D.
Published: August 2008

Two new species of asellote isopods from the waters surroundng the San Juan Archipelago are described and diagnosed. Baeonectes improvisus n. gen., n. sp. and Acanthamunnopsis milleri n. sp. belong to the highly evolved, natatory families Eurycopidae and Munnopsidae, respectively. Baeonectes, a circum-arctic and boreal shallow-water genus, also includes B. muticus (Sars), the type-species. The taxonomic concept of Acanthamunnopsis has difficulties that must be resolved before A. milleri can be described. To this end, the family Acanthamunnopsidae Schultz is invalidated and merged with the Munnopsidae; the genus Acanthamunnopsis Schultz is revised; and A. hystrix, the type-species, is redescribed with corrections and additions to the original description. The unusual presence of the bathypelagic genus Acanthamunnopsis in the surface waters of the San Juan Archipelago is discussed. Acanthamunnopsis milleri is tentatively postulated to be a deep resident of the open ocean that was carried landward into the Strait of Juan de Fuca by upwelled intrusions of cold, saline water.
Intra- and inter-specific competition between Barrow's goldeneye (Bucephala islandica) and bufflehead (Bucephala albeola)
Authors: Savard Jean-Pierre L.
Published: August 2008

Barrow's goldeneye and bufflehead pairs defend well-delineated territories from which they exclude conspecifics. Only the male defends the territory and does so even when the female is absent. However, after the young have hatched, females of both species defend brood territories from which they exclude conspecifics. Both species are also interspecifically territorial. Barrow's goldeneye and bufflehead drakes threatened and (or) attacked 15 and 11 species, respectively. However, 55% of Barrow's goldeneye interspecific encounters were with bufflehead and 52% of bufflehead encounters were with Barrow's goldeneye. Barrow's goldeneye drakes always excluded bufflehead from their territory whereas bufflehead drakes successfully excluded yearlings, females, and unpaired Barrow's goldeneye drakes but were usually dominated by paired males. Female Barrow's goldeneye excluded all bufflehead from the brood territory and were particularly aggressive toward bufflehead broods. Food and mates are the most likely defended resources in intraspecific encounters. In interspecific encounters diving ducks were more violently attacked than dabbling ducks indicating that food may be the defended resource. Interspecific aggression of Barrow's goldeneye toward bufflehead does not appear to be misdirected intraspecific aggression but rather a directed aggression toward a food competitor and may therefore be adaptive.
The fall phase of dispersal in juvenile spruce grouse
Authors: Schroeder Michael A.
Published: August 2008

The characteristics of the fall phase of dispersal for 41 female and 88 male juvenile spruce grouse (Dendragapus canadensis) were analyzed for data collected between 1965 and 1984 in southwestern Alberta. Females moved significantly farther than males. Reasons for this difference were sought in location of wintering areas, timing of brood breakup relative to that of brood hen migration, and distance moved by the migrating brood hen. Wintering areas, encompassing blocks of forest within which more than 80% of adults passed the winter, represented less than 15% of the study area. These areas were apparently also the destination for a high proportion (84%) of the juveniles. Distances moved are believed to be influenced by the location of the wintering areas in relation to the direction taken by juveniles after brood breakup occurs, as well as the timing of this event in relation to the timing of migration in adult hens. Brood breakup of juvenile males preceded that of females (median 4 and 15 September, respectively), and dates of brood hen migration overlapped those of brood breakup (median 13 September). Hence, longer distances moved during the fall phase of dispersal (and a greater disappearance rate) by juvenile females relative to males may be caused by their later median date of brood breakup and consequently the increased probability of their moving with their migrating brood hens. This possibility is supported by the observation of intact broods following the migratory paths of their mothers. The data suggest that once the brood breaks up, juveniles may stop at nearby wintering areas.
Freeze tolerant frogs: cryoprotectants and tissue metabolism during freeze–thaw cycles
Authors: Storey Kenneth B. , Storey Janet M.
Published: August 2008

Tissue-specific metabolism in the freeze tolerant frog, Rana sylvatica, was monitored over a course of 3 days of freezing exposure at −2.5 °C followed by 11 days of thawing at 3 °C. Freezing induced the rapid accumulation of glucose as a cryoprotectant with maximal levels of 257 μmol/mL in blood and 188, 140, 74, and 28 μmol/g wet weight in liver, heart, kidney, and leg muscle, respectively. Liver showed the fastest rate (20 μmol g−1 h−1 over the initial 7 h) and the shortest half time (5 h) for glucose accumulation. This plus the activation of liver glycogen phosphorylase and a 593 μmol/g decrease in liver glycogen indicated this organ as the major site of cryoprotectant production during freezing. Glucose accumulation was reversed when frogs were thawed (half time for clearance varying from 1.9 days in liver to 8.1 days in leg muscle) with glucose restored as liver glycogen. Extracellular freezing was also accompanied by a progressive accumulation of lactate and alanine as glycolytic end products indicating a reliance on fermentative metabolism during freezing and by a decline in energy status (ATP content and energy charge decrease) in tissues. Relative amounts of lactate and alanine accumulated varied dramatically between tissues: from heart, which produced only lactate, to leg muscle, which had an alanine:lactate ratio of 4.5:1. No other amino acids accumulated in tissues during freezing exposure, but alanine accumulation in leg muscle was inversely proportional to a decline in tissue aspartate, glutamate, and glutamine contents. When thawed, lactate and alanine were readily cleared from tissues and energy status was slowly restored.
Intercellular junctions in the larval epidermis of the colonial ascidian Distaplia occidentalis: a thin-section and freeze-fracture examination
Authors: Cavey Michael J. , Wood Richard L.
Published: August 2008

The larval epidermis of the colonial ascidian Distaplia occidentalis is a unilayered epithelium consisting of squamous and cuboidal or low columnar cells. The epidermal cells are laterally folded and interdigitated or overlapped. The occluding (tight) junctions and the close (gap) junctions that join the epidermal cells have been examined by transmission electron microscopy. In thin sections, the occluding junction is represented by focal fusions of the apposed plasmalemmata. Freeze-fracture replicas of the occluding junction show linear, anastomosing arrays of intramembranous particles on the protoplasmic faces of the cellular membranes. In thin sections of the close junction, the apposed plasmalemmata are mutually parallel and separated by a narrow intercellular cleft. Freeze-fracture replicas of the close junction reveal macular aggregations of intramembranous particles on the protoplasmic faces of the cellular membranes.
Trypanosome infection in salamanders (order: Caudata) from eastern North America with notes on the biology of Trypanosoma ogawai in Ambystoma maculatum
Authors: Woo Patrick T. K. , Bogart James P.
Published: August 2008

Using the haematocrit centrifuge technique, trypanosomes were detected in 85 of 971 (8.8%) salamanders. The prevalence ranged from about 1% (4 of 405) in 1984 to 26.1% (24 of 92) in 1981. Trypanosomes were found in Ambystoma maculatum, A. laterale, A. jeffersonianum × A. laterale triploid hybrids, and A. jeffersonianum. Detectable infections were not found in A. texanum, A. texanum × A. laterale hybrids, or Notophthalmus viridescens. Trypanosoma ogawai was isolated in A. maculatum and A. jeffersonianum and it was infective by blood inoculation. The trypanosome and its multiplication process in the salamander are redescribed. It multiplied by unequal binary fission and the progenies were a small epimastigote and a large trypomastigote. The trypanosome developed to the metatrypanosome stage in the crop of the leech Batracobdella picta in 9 days at 21 °C. Metatrypanosomes from leeches at 16 days after feeding were infective when inoculated into laboratory-raised salamanders.
Prototroch structure and innervation in the trochophore larva of Phyllodoce (Polychaeta)
Authors: Lacalli T. C.
Published: August 2008

The prototroch and prototroch nerve in trochophores of two Phyllodoce species are described at the ultrastructural level and interpreted with reference to the observed normal behavior of larvae during swimming. The prototroch is a complex structure consisting of four tiers of cells of which the second bears the main locomotory cilia. Cells in the other tiers also have cilia but are notable chiefly for the slender processes they send to the prototroch nerve and which evidently contribute to the sheath that surrounds the nerve. Neurociliary synapses were not observed, but the prototroch arrests when the frontal organ is touched and in response to cholinergic drugs. The arrests are only partial in that the cilia continue to beat, but in a restricted register. The mechanism responsible was not identified, but several possibilities are discussed. While the capacity to arrest could be intrinsic to the main trochal cells (i.e., tier 2), the absence of obvious regions of contact between these cells and the prototroch nerve increases the likelihood that the other tiers are also involved. The arrests could in fact result simply from physical interference between the cilia of adjacent tiers. The arrest response in Phyllodoce is compared with that seen in trochal bands in other spiralian larvae.
Description of the Macrocheles kraepelini species complex (Acari: Macrochelidae) with two new species
Authors: Walter D. E. , Krantz G. W.
Published: August 2008

Mite predators of synanthropic flies similar to Macrocheles kraepelini (Berlese) are described as a new complex of species belonging to the Macrocheles glaber species group. Two new species in the kraepelini complex are described, M. tantalus and M. hallidayi. The male of M. kraepelini is described for the first time. Information on the distribution and phoretic associations of all three species is presented. Macrocheles hallidayi and M. kraepelini are sibling species, which, when sympatric, differ in adult body size by the same ratio as the holarctic sibling species pair of M. perglaber and M. glaber.
Blackflies (Diptera: Simuliidae) of the Queen Charlotte Islands, British Columbia, with discussion of their origin and description of Simulium (Hellichiella) nebulosum n. sp.
Authors: Currie D. C. , Adler P. H.
Published: August 2008

A morphological and cytological study on blackflies of the Queen Charlotte Islands, British Columbia, revealed a total of 16 species in three genera: Prosimulium (6 species), Simulium (9 species), and Stegopterna (1 species). Included is a description of Simulium (Hellichiella) nebulosum n. sp. Notes on distribution and bionomics are provided for each species. AH species collected on the Queen Charlotte Islands are also found on the North American mainland. We conclude that the origin of the present-day simuliid fauna is best explained by post-Wisconsinan dispersal from mainland populations. This conclusion does not support the hypothesis of a continuously mild, Wisconsinan refugium on the Queen Charlotte Islands.
Body condition of willow ptarmigan parasitized by cestodes during winter
Authors: Thomas V. G.
Published: August 2008

Sixty-two adult male willow ptarmigan (Lagopus lagopus) were collected over 3 days in April 1979 from a single flock along the Hudson Bay coast of Ontario. Twenty-one ptarmigan contained cestodes (genus Raillietina) in the anterior of the small intestine and 41 were free of cestodes. Each ptarmigan was dissected into its principal voluntary muscles, liver, and intestinal components, and the entire body was subjected to neutral fat extraction. Parasitized willow ptarmigan had significantly heavier empty small intestinal weights than nonparasitized birds. All other variables pertaining to the fat–protein reserve status were very similar between the two groups. The larger small intestines of parasitized ptarmigan were shown, statistically, to be attributable to the presence of cestodes and not to effects of varying body size. There were significant correlations between the weight of the small intestine and the weight of cestodes (r = 0.677) and the volume of cestodes (r = 0.667) but not the number of cestodes (r = 0.414) in any given ptarmigan. The hypertrophic response was confined to the small intestine and was small (approximately 1.2 g of wet tissue) compared with the amount of intestinal hypertrophy that normally occurs with change of season and diet. This population of willow ptarmigan readily accommodates to cestodes with no detectable impairment of its winter nutrient and energy balance.
Winter habitat of northern leopard frogs, Rana pipiens, in a southern Ontario stream
Authors: Cunjak Richard A.
Published: August 2008

The winter habitat of northern leopard frogs (Rana pipiens) in a southern Ontario stream is described from underwater snorkeling observations. Rana pipiens were located beneath rubble (13–40 cm diameter) generally where water depths were greater than 85 cm and the mean mid-depth water velocities were 22.5 cm/s. Water temperatures during the winter ranged between 0.5 and 2.1 °C. Animals were quite torpid but still capable of swimming after being disturbed. Results from a limited marking study suggest that at least some R. pipiens remain in the same stream section throughout the winter months. Competition for similar winter shelters among various species of the stream community is suggested as a possible cause of reduced stream productivity where the availability of such habitats is limited.
The effects of saline gas composition and pH on haemodynamic stability in the perfused trout head preparation
Authors: Perry S. F. , Daxboeck C.
Published: August 2008

The effects of saline gas composition and pH on various haemodynamic properties of the perfused trout head preparation were evaluated. Increasing the concentration of saline CO2 from a "normal" level of 0.3 ([Formula: see text]; 1 Torr = 133.322 Pa) to 5.0% [Formula: see text] resulted in a significant elevation of input pressure (Pi) and a reduction in the ratio of dorsal aortic [Formula: see text] to anterior-venous flow [Formula: see text], whereas a reduction of pH, at constant [Formula: see text], had only a slight effect on [Formula: see text]. Altering the [Formula: see text] of the saline from 5 to 350 Torr while maintaining water normoxic (140 Torr) was without effect on input pressure or flow distribution in the gills.