bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of feeding thyroid hormones on saltwater tolerance and growth rate of Atlantic salmon
Authors: Refstie Terje
Published: August 2008

Two experiments, involving the addition of thyroid hormones to the diet of salmon parr (Salmo salar) were carried out. The prime purpose of these experiments was to study the effect of feeding thyroid hormones on saltwater tolerance. Saltwater tolerance is interrelated with size and therefore growth rate was investigated. In experiment I three different thyroid preparations were used: thyroid extract, 3,5,3′-triiodo-L-thyronine (T3), and thyroxine (T4). Each thyroid preparation was fed to two different sizes of fish with two different concentrations in the diet. T3 gave the best overall results, both for saltwater tolerance and growth rate. No interaction was found between fish size and concentration of thyroid hormone in the diet. In experiment II three different concentrations of T3 in the diet were fed to salmon parr of two different ages. Feeding T3 improved saltwater tolerance and growth rate of 7-month-old fish but had a negative effect upon growth for 19-month-old fish. For the 7-month-old fish 10 mg T3/kg dry food gave the best effect on saltwater tolerance, while 1 mg T3/kg dry food was enough to improve growth. It is concluded that it is possible to induce smoltification in underyearling Atlantic salmon out of season by feeding thyroid hormones.
Digenean parasite communities in flatfishes of the Scotian Shelf and southern Gulf of St. Lawrence
Authors: Scott J. S.
Published: August 2008

Prevalence of digenean parasites in four major flatfishes of the Scotian Shelf and southern Gulf of St. Lawrence, American plaice (Hippoglossoides platessoides), yellowtail flounder (Limanda ferruginea), witch flounder (Glyptocephalus cynoglossus), and winter flounder (Pseudopleuronectes americanus), is compared between hosts in relation to geographic distribution, season, feeding behavior, and fish length. The 13 parasite species indicate overlap of feeding habits among hosts but also considerable diversity in feeding behavior, supporting the evidence from examination of stomach contents. Prevalence of digeneans in different final hosts varied between geographic areas and may be used to characterize the populations of the comparatively sedentary flatfish populations. Seasonal variation in prevalence was consistent from area to area but differed between parasites, from the expected increase in summer in some, concomitant with increased feeding, to a winter increase in others, probably related to a seasonal change of diet. Fish length had little effect on parasite prevalence in yellowtail flounder and witch flounder but had a notable effect on plaice and winter flounder from the Gulf of St. Lawrence, again apparently related to change of diet.
Selected skeletal morphology and pathology of moose from the Kenai Peninsula, Alaska, and Isle Royale, Michigan
Authors: Peterson Rolf O. , Scheidler Joseph M. , Stephens Philip W.
Published: August 2008

Age-specific parameters of growth and incidence of skeletal pathology were determined for moose populations at Kenai, Alaska, and Isle Royale, Michigan, primarily from skeletal remains of wolf-killed animals. Growth patterns, determined from the metatarsus, were similar for the two populations, with cessation of growth after the third summer. Kenai moose were consistently larger than Isle Royale moose after the first summer, with an average asymptote for metatarsal growth 3% greater. Size of Isle Royale calves was inversely correlated with winter severity prior to birth. The incidence of debilitating arthritis and periodontal disease increased with age, with a similar age of onset among female moose from both populations. Coxofemoral arthritis (degenerative joint disease) occurred more often among old (> 10 years) female moose from Isle Royale than from Kenai, probably contributing to a generally shorter life span. Periodontal disease occurred at a similar rate in both populations, despite a far greater rate of incisiform tooth wear in Kenai moose. The study furnished base-line data for a determination of trends in population quality and physical condition.
Disruptive selection: a tail color polymorphism in Acris tadpoles in response to differential predation
Authors: Caldwell Janalee P.
Published: August 2008

Previous workers have noted that cricket frog tadpoles of the genus Acris have black tail tips. My initial collections of Acris crepitans tadpoles from various localities in Kansas revealed a polymorphism in tail color associated with habitat type: ponds primarily have black-tailed tadpoles, whereas lakes and creeks have mostly plain-tailed forms. Collections of potential predators from these localities showed that the black-tailed pond populations co-occur with a high density of the aeshnid dragonfly larva, Anax Junius, and led to the hypothesis that the black tail functions as a deflection mechanism to divert the attack of the Anax larva to the tail of the tadpole and away from the more vulnerable head and body. Plain-tailed tadpoles are found primarily in lakes and creeks where fish are the major predators. Tail damage data from natural populations and data from predator–prey experiments support the hypothesis. Disruptive selection is most likely the mechanism responsible for maintenance of this polymorphism. Gene exchange occurs as adult frogs migrate from one habitat type to another, but selection on tadpoles by different predator regimes is habitat specific.
Mayfly communities in a Laurentian watershed (Insecta; Ephemeroptera)
Authors: Harper P. P. , Harper Françoise
Published: August 2008

Mayfly communities were investigated in a series of four lakes, two beaver ponds, and 13 streams in a Laurentian watershed. Forty-five taxa were collected mostly through emergence trapping of adults (76 trap-years). Q and R analyses were used to show similarities between the stations and associations between the species. The middle reaches of the mainstream harbour the richest communities which are an assemblage of a few ubiquitous species (Baetis gr. pygmaeus, Stenonema modestum, Habrophlebia vibrans, and Paraleptophlebia volitans), lotic species (Baetis flavistriga, B. pluto, Stenonema vicarium, and Heptagenia pulla) some of which show a restricted distribution (Paraleptophlebia adoptiva, P. Ontario, Leucrocuta hebe, and Stenacron interpunctatum heterotarsale), and also lentic species (Eurylophella verisimilis, Leptophlebia cupida, Cloeon simplex, C. rubropictum, Centroptilum album, and Stenacron interpunctatum frontale). The headwater streams contain no distinct element, except perhaps Siphlonurus typicus, but rather the more resistant or dispersive species from the mainstream, mainly Ephemerellidae and Leptophlebiidae. The lower reaches of the mainstream are characterized by the addition of a few typical river species, Serratella sordida and Epeorus vitreus. Lacustrine communities are less diverse, comprising mostly the lentic species from the streams plus a distinctive element (Stenacron interpunctatum canadense, Callibaetis ferrugineus, and Hexagenia limbata occulta). Only Leptophlebia cupida colonizes the bog lake, and no species occur in the beaver ponds. Most congeneric species are either spatially or temporally segregated. The sections of the mainstream produce an average of some 1000 adult mayflies/m2 per year; other streams are less productive and the lakes even less so (less than 100/m2). The seasonal succession of the species and the emergence patterns of the dominant species are illustrated; a classification of emergence patterns is attempted on the basis of the present data and of other recent studies.
A new nonparasitic species of Holarctic lamprey, genus Eudontomyzon Regan 1911 (Petromyzontidae), from Greece
Authors: Vladykov Vadim D. , Renaud Claude B. , Kott Edward , Economidis Pános S.
Published: August 2008

A new nonparasitic lamprey, Eudontomyzon hellenicus, from the Struma and Loúros river basins in Greece, is described and illustrated. The holotype (No. NMC 77-1773) is deposited in the National Museum of Natural Sciences, Ottawa, Canada. From all species of the same genus, E. hellenicus differs in the following characters: (1) small metamorphosed size (maximum total length (TL) 159 mm), (2) fewer trunk myomeres (52–62, averaging 57.4), (3) poorly developed lingual laminae cusps, (4) short and few (2–5) velar tentacles, and (5) extremely short urogenital papilla, even in spawning males. Furthermore, a nonfunctional intestinal tract in metamorphosed individuals of our species separates it from parasitic E. danfordi. The description is based on a study of 64 metamorphosed specimens, 13 transforming individuals and 237 ammocoetes.
Decreased day length and light intensity as factors inducing reproduction in Gammarus lacustris lacustris Sars
Authors: March B. G. E. de
Published: August 2008

Gammarus lacustris cultures were maintained in the laboratory under different light and temperature conditions during a 5-year period. Reproduction occurred only in adults which had been held at a short day length (12 h light) or in dim light for several weeks. Changes in photoperiod are the most consistent seasonal changes in temperature and arctic ecosystems, hence the response to light ensures regular annual reproduction in spite of unusual climatic conditions.
Experimental studies on acarine predator–prey interactions: the distribution of search effort and the functional and numerical responses of predators in a patchy environment (Acarina: Phytoseiidae)
Authors: Eveleigh Eldon S. , Chant D. A.
Published: August 2008

Laboratory experiments revealed that Phytoseiulus persimilis distributed its search effort in relation to prey density in a patchy environment, whereas Amblyseius degenerans distributed its search effort randomly among patches of prey. The main factor responsible for the aggregative response of P. persimilis was the length of its first visit to the patches. Although the functional responses of both predators changed with time, only those of P. persimilis closely reflected changes occurring in its distribution of search effort. The spatial complexity of the environment did not affect the overall predation rates of P. persimilis but it reduced its reproductive output. However, the predation rates of A. degenerans were adversely affected, suggesting that its fecundity would also be reduced in a spatially complex environment. Phytoseiulus persimilis distributed its progeny among patches containing relatively high prey densities and avoided ovipositing in the patch containing fewest prey. Neither species foraged optimally and possible reasons for this are discussed.
A world review of the soleiger species group in the genus Typhlodromus Scheuten (Acarina: Phytoseiidae)
Authors: Chant D. A. , Shaul E. Yoshida
Published: August 2008

A redefined soleiger species group in the genus Typhlodromus Scheuten is proposed. Typhlodromus subsoleiger (Wainstein), T. tetramedius Zaher &Shehata, T. ostiolatus (Athias-Henriot), and T. amaliae (Ragusa &Swirski) are synonymized with T. talbii Athias-Henriot; and T. incognitus (Wainstein &Arutunjan) and T. trimediosetus Xin et al. are synonymized with T. soleiger (Ribaga). A new species, Typhlodromus triporus, which was previously attributed to T. soleiger, is proposed. Characters for the group are described. Keys to the adult females of the five species in the group and descriptions of each species are provided.
Bakernema yukonense n. sp. (Nematoda: Criconematidae) with keys to the species of Criconemella and Discocriconemella
Authors: Ebsary B. A.
Published: August 2008

A new species of Bakernema from the Yukon, Canada is described and illustrated. Bakernema yukonense n. sp. differs from B. inaequale by more body annules, longer stylet, and by the open vulva and straight vagina. The generic diagnosis of Bakernema is also emended. Emendations to the lists of Criconemella and Discocriconemella species are provided. The following new combinations are proposed: Criconemella alticola, C. canadensis, C. lineolata, C. medani, C. neoaxestis, C. obtusicaudata, C. onostris, C. parareedi, C. sphaerocephaloides, C. tescorum, C. vallicola, Discocriconemella theobromi, and D. lamottei. The following are new synonyms: Criconemella malusi with Criconemella antipolitana, Macroposthonia coomansi and Criconemoides rihandi with Criconemella tescorum, Nothocriconema montanus with Criconemella zavadskii, Discocriconemella inarata with C. discus, and Discocriconemella barberi with D. limitanea. Nothocriconemoides is considered to be a synonym of Criconemella and Acrozostron a synonym of Discocriconemella. Keys to Criconemella and Discocriconemella species are provided.
Canadian species of Tobrilus (Nematoda: Tobrilidae) with description of three new species
Authors: Ebsary B. A.
Published: August 2008

Nine species of Tobrilus in Canada, including three new species, are described and illustrated. Tobrilus filipjevi n. sp. differs from T. longus by the greater distance between the pocket teeth and by the longer spicules. Tobrilus parapellucidus n. sp. differs from T. pellucidus by the more posterior vulva, male with 10 supplements, and by the ductus ejaculatorius beginning closer to supplement 1. Tobrilus sablensis n. sp. differs from T. allophysis by having greater body length, larger stoma, and greater distance between the pocket teeth in the female. In the male the papillae are absent between supplements and the spicules are longer. The female of T. hopei is described for the first time and has a concentric vaginal musculature similar to T. longus, but differs by greater body length and more widely spaced pocket teeth. Other species in Canada include T. aberrans, T. pellucidus, T. hopei, T. longicaudatus, T. longus, and T. breviductus. Keys to the Canadian males and females are provided. The species T. longicaudatus is proposed as a new species and named T. gagarini n. sp.
The transmission and development of Paracuaria adunca (Creplin, 1846) (Nematoda: Acuarioidea) of gulls (Laridae)
Authors: Anderson R. C. , Wong P. L.
Published: August 2008

Paracuaria adunca (Creplin, 1846) Anderson and Wong, 1981 of the gizzard of ring-billed gulls (Larus delawarensis Ord) developed to the infective stage in the amphipods Hyalella azteca, Crangonyx laurentianus, and Gammarus duebeni. At 18–20 °C the first moult occurred 10 days and the second 18 days postinfection. Worms developed in the proventriculus of experimentally infected gulls, the third moult occurred 2.5 days and the fourth 5 days postinfection. In 8 days immature adults were found under the gizzard lining near the proventriculus. Females found 16 days postinfection had larvated eggs. Developmental stages in amphipods and gulls are described. Prevalence and intensity of P. adunca were studied in adult and juvenile gulls at the Eastern Headland (Leslie Spit) of the Outer Toronto Harbour, Lake Ontario. The low mean intensity (1.6) in adult birds examined on April 2 suggests that there was little or no transmission of the parasite on the wintering grounds of the gulls. Intensity and prevalence increased in adult birds on the breeding grounds from April 2 to June 25 and larval stages were found in the birds. Prevalence in young-of-the-year birds increased with age of the birds. Intensity reached a high of 3.2 (1–6) in 35- to 42-day-old-birds (July 3). Infective larvae became encapsulated on the mesentery of experimentally infected goldfish (Carassius auratus). Infective larvae of P. adunca were found in the mesentery of fish (Culaea inconstans, Notropis hudsonius, Semotilus atromaculatus) collected in waters adjacent to the breeding grounds. Paracuaria adunca was transmitted experimentally to geese (Anser anser) and ducks (Anas platyrhynchos) but few worms were recovered from the few birds that became infected.
Avian Haemoproteidae. 17. The haemoproteids of the avian family Cracidae (Galliformes); the guans, curassows and chachalacas
Authors: Bennett Gordon F. , Gabaldon Arnoldo , Ulloa Gregorio
Published: August 2008

The haemoproteids of the avian family Cracidae (Galliformes) are reviewed. Haemoproteus cracidarum n. sp. is described. Haemoproteus rotundus ortalidum Gabaldon &Ulloa, 1978 is emended to Haemoproteus ortalidum and the species is redescribed. This latter haemoproteid is unique in that it is the only dimorphic haemoproteid known and it possesses several other characteristics which are unknown among other haemoproteids. Other haemoproteid records from the Cracidae are summarized.
The effects of preload, after load, and epinephrine on cardiac performance in the sea raven, Hemitripterus americanus
Authors: Farrell A. P. , MacLeod K. , Driedzic W. R.
Published: August 2008

The preparation of the in situ heart was accomplished without any physical disturbance to the heart. The heart generated an intrinsic rhythm which was steady throughout the experiment and apparently was derived from the sinoatrial pacemaker. The power output developed by the in situ heart at physiological preloads and after loads was comparable to in vivo values. The effect of increasing preload (0 to 3 cmH2O) was a fourfold increase in stroke volume with little or no change in heart rate. When after load was changed (25 to 45 cmH2O) heart rate was unchanged and stroke volume was usually maintained. As a consequence, cardiac output was maintained by intrinsic factors alone at a higher work load. Epinephrine (10−9 to 10−5 M) in the perfusate produced relatively weak positive chronotropic and inotropic effects. The increase in cardiac output produced by epinephrine was small compared with the intrinsic changes evoked when preload was raised.
Fine structure and neurophysiology of a gustatory sensillum on the ovipositors of Metasyrphus venablesi and Eupeodes volucris (Diptera: Syrphidae)
Authors: Henderson D. E. Hood
Published: August 2008

A typical uniporous contact chemosensillum was identified on the ovipositor of two aphidophagous syrphids, Metasyrphus venablesi (Cn.) and Eupeodes volucris O.S. (Diptera: Syrphidae). Fine structural study of the sensillum of M. venablesi revealed one mechanosensitive and five chemosensitive neurons. Single sensillum recordings from both species showed ovipositor sensititivy to various compounds characteristic of the oviposition site including aphid honeydew, sucrose, the amino acids alanine and tryptophan, an oxidation product of tyrptophan (indoleacetaldehyde), and water.
Fish embryo culture: rhombencephalic neuritic outgrowth in explanted axial cords from the zebrafish Brachydanio rerio (Hamilton-Buchanan)
Authors: Laale Hans W.
Published: August 2008

Fifteen stage 17 axial cords from the zebrafish Brachydanio rerio were stripped of epidermis and separated from their yolk spheres. Posterior halves, from the mid-rhombencephalic level to the caudal knob, were maintained in nutrient medium for 30 days at 24 ± 2 °C. The study describes preliminary observations on rhombencephalic neuritic outgrowth and associations with non-neural cells from 7 to 30 days of culture. Nerve fiber bundles increased in number and complexity with time and displayed heterogeneous branching behaviour. Frequent multiple close contacts with individual non-neural cells were observed, but selectivity of attraction to specific target cells was not verified. The findings are compared with similar contacts reported for mammalian tissues in vitro.
Circannual cycles of molt in ground squirrels
Authors: Joy Janet E. , Mrosovsky N.
Published: August 2008

Molt was studied in thirteen-lined ground squirrels (Spermophilus tridecemlineatus) from Kansas and Michigan. In constant laboratory conditions molt showed circannual cycles and generally occurred during the weight gain phase of the circannual body weight cycle. Molt in the Kansas ground squirrels began at a slightly later phase of the body weight cycle and ended at an earlier phase of the body weight cycle than in the Michigan ground squirrels. The relative portions of the body weight cycle spent molting was close to 35% in both populations. Molt is not dependent on the circannual body weight cycle, but is under control of the same circannual system.
Vadicola aprostatus gen. nov., sp. nov., a marine oligochaete (Tubificidae; Rhyacodrilinae) from British Columbia
Authors: Baker H. R.
Published: August 2008

Vadicola aprostatus gen. nov., sp. nov., a marine tubificid (Annelida; Oligochaeta) from intertidal habitats of British Columbia (usually coarse sand without obvious freshwater influence), is characterized by an internal projection in the ejaculatory duct and a lack of prostate cells on the atria. Vadicola aprostatus is placed in the subfamily Rhyacodrilinae.
Predation on painted turtle nests: nest survival as a function of nest age
Authors: Snow Jonathan E.
Published: August 2008

This study examined the relationship between nest age and predation rate in painted turtles (Chrysemys picta). Eighty-one intact nests were found; 33 were eventually preyed upon during the study. New nests (less than 72 h old) do not appear to have a greater risk of predation than older nests. The majority (55%) of nests preyed upon were older than 72 h. Nests were divided into two groups: the first 41 of the season's nestings and the remaining 40 nestings. The proportion of nests preyed upon did not differ significantly between the two groups. Predators appeared to have made more frequent daily visits during the time the latter group of nests were being constructed. The average age of nests preyed upon in each group was 13.7 and 2.7 d, respectively; these averages are significantly different. Identifiable predators included skunks (Mephitis mephitis), raccoons (Procyon lotor), foxes (Vulpes fulva), and chipmunks (Tamias striatus) that accounted for 23, 4, 4, and 5, respectively, of the nests preyed upon.
Annual cycles of activity and body composition in Spermophilus townsendii mollis
Authors: Rickart Eric A.
Published: August 2008

Data on activity scheduling and body composition in Spermophilus townsendii mollis Kennicott were collected over a 4-year period in northwestern Utah. Yearly variation in emergence scheduling was associated with variation in late winter warming patterns. Sex differences in patterns of growth and seasonal body composition were attributed to reproductive biology. These included (1) a decline in female lipid during reproduction, (2) a 2- to 3-week delay in the onset of female fattening relative to males, (3) a decrease in female water content during late lactation, (4) sex differences in rates of weight loss during dormancy, and (5) sexual dimorphism in juvenile growth and fattening phenology. The initiation of seasonal fattening coincided with the appearance of seeds in the diet and associated increases in dietary caloric value. Experimental supplements to the diet increased fattening rates in field populations. These observations support the hypothesis that yearly fattening and immergence schedules are influenced by variation in the quality of food resources.
Variation in the size and shape of introduced starlings, Sturnus vulgaris (Aves: Sturninae), in New Zealand
Authors: Ross Howard A. , Baker Allan J.
Published: August 2008

Starlings were introduced into New Zealand from Great Britain between 1860 and 1880. Substantial numbers of birds, released at many points in the country, have given rise to populations now occurring throughout New Zealand. Morphometric variation in 16 characters, including 8 derived size and shape variables, was assessed statistically in eight samples totalling 384 adults. Univariate analyses revealed that all 16 characters of males but only 9 of females varied significantly among localities. Discriminant analysis confirmed that character variation was essentially haphazard among localities. The degree of sexual dimorphism did not covary with latitude. Both among and within localities, a three-dimensional shape vector, involving bill length, tail length, and middle toe length, was associated with many linear size variables, but not with overall size as represented by the geometric mean of external characters or with body weight. The size of females was more closely aligned with environmental variables than was size of males, but males showed a greater association between interlocality and intralocality character variability. The greatest differences between the sexes was in geographic variation of bill size and shape, suggesting intersexual ecological differentiation.
Étude des relations entre les communautés piscicoles et les différents habitats d'une rivière nordique: notion d'habitat optimal
Authors: Savard Louise , Moreau Guy
Published: August 2008

A complete linkage cluster analysis using the physical characteristics of the sampling sites has revealed the existence of five groups corresponding to five habitat types nonequally distributed in a northern Quebec river. According to the results of discriminant analysis using the relative abundance of the fish species present, these habitats support populations which differ by the relative abundance of species and not by the presence or absence of some particular species. A habitat is first characterized by a species living preferentially in this habitat, then by the other species inhabiting the area in an opportunistic way, and finally by some satellite species which do not seem to have any marked requirements. A habitat is considered as optimal for a species first if this species inhabits this area preferentially to others and secondly if this use is more advantageous for growth or condition factor. This seems to be confirmed for two of the most abundant species, northern pike (Esox lucius) and lake whitefish (Coregonus clupeaformis), both of which have a higher condition factor and a better growth in the part of the river where their optimal habitat is more frequently found.
Summer diet of the narwhal (Monodon monoceros) in Pond Inlet, northern Baffin Island
Authors: Finley K. J. , Gibb E. J.
Published: August 2008

Stomach contents of 73 narwhals (Monodon monoceros) taken in Pond Inlet during June to September 1978–1979 were examined. Arctic cod (Boreogadus saida) and Greenland halibut (Reinhardtius hippoglossoides) comprised 51% and 37%, respectively, of the diet by weight. Arctic cod contributed 57% in 1978 but only 29% in 1979. Squid (Gonatus fabricii) beaks were abundant but not representative of recent intake. Deepwater fish (halibut, redfish (Sebastes marinus), and polar cod (Arctogadus glacialis)), found primarily in male narwhals, indicate a deep diving (>500 m) capability. The largest measured weight of stomach contents was 10.1 kg and weights projected from otoliths did not exceed 19.6 kg. No selection of prey items by size was evident amongst various sex and age groups of narwhals. Feeding was most intensive at the ice edge and ice cracks but little feeding took place in the fiords during late summer. Blubber thickness declined in females but not in males during the summer. The significance of traditional summering areas appears to be related to calving requirements and not to feeding opportunities.
Why do meadowlarks switch song types?
Authors: Falls J. Bruce , d'Agincourt Lorraine G.
Published: August 2008

Singing of eastern and western meadowlarks, Sturnella magna and S. neglecta, was monitored during 85-min experiments in which 13 1-min bouts of recorded conspecific song were broadcast at irregular intervals. Both species tended to switch song types at the onset of playback. Song bouts of magna were shortened in playback periods, with multiple switches occurring; bouts of neglecta during playback were of normal length. Overall, bouts of magna were shorter than those of neglecta. When playback began, long bouts were more likely to end in a switch than shorter ones. Survivorship curves of completed bouts for both species followed a log-linear function; beyond a minimum length switching was independent of previous bout length. Lengths of successive bouts were positively associated in birds with short bouts (mainly magna) but not in birds with longer bouts (mainly neglecta). Switching was associated with long interbout intervals and with movements, although most switches occurred in short intervals without movements. These results are mainly consistent with the hypothesis that delivery of repertoires reduces habituation of listeners. This antihabituation mechanism is distinguished from other explanations for repertoires. A derivative explanation, that song variety serves as a graded signal of readiness to interact (inter- or intra-sexually), is suggested and predictions are discussed.
Résistance de l'œuf de carpe commune (Cyprinus carpio L. Cyprinidae) à des chocs thermiques chauds ou froids
Authors: Jaoul Annie , Roubaud Pierre
Published: August 2008

The resistance of common carp (Cyprinus carpio L.) eggs to hot and cold shock has been studied by measuring the survival rate during the course of an incubation at a constant temperature of 20 °C. When incubation was pursued in oxygen-saturated conditions, a 1-h-long thermal shock which occurred during the synchronous segmentation stage had no effect within the temperature range of 8–28 °C. At gastrula stage, this interval reached 0.3 °C and at the end of epiboly it reached 36 °C. With hypoxic incubation conditions, a 1-h postepibolic shock had no effect within the range of 1–36 °C. On the contrary, a 12 °C (or less) preblastulean cold shock or a 30 °C (or more) pregastrulean hot shock induced a significant loss of further resistance to hypoxy. An overoxygenation during the shock did not increase the embryonic resistance. During the synchronous segmentation, the sensitivity to cold shock varied occasionally, possibly in relation with the mitotic cycle. Sensitivity to thermal shock also depended on the gametes' fertility. The resistance to thermic shock was compared with the thermic profiles that are described to be optimum in laboratory conditions at constant temperature, or in natural conditions of development. Hypoxy or hyperoxy cannot be the determining factor in thermic-shock effects on carp eggs: several hypotheses were reviewed to explain the acquisition of an increasing resistance to the variation of the environmental temperature.
Identification of larval and juvenile Canadian Atlantic gadoids with comments on the systematics of gadid subfamilies
Authors: Markle Douglas F.
Published: August 2008

An attempt to identify larvae and juveniles of Gaidropsarus led to a broader survey of gadoid morphology. Representative specimens of all gadoid families and all Canadian Atlantic gadid species were examined for selected morphological characters. The polarity of these character states was examined using a cladistic approach and led to the conclusion that the gadids are composed of three groups, recognized herein as subfamilies: Gadinae, Lotinae, and Phycinae. The most informative structure examined was the caudal skeleton, which showed three characters with an obvious primitive state in some gadids: presence of X and Y bones, 6 "primary" caudal fin rays, and low (<40) total caudal fin ray counts. Dorsal fin structure, which has been the basis of previous gadid systematic arrangements, is also shown to be informative, providing good evidence of relationship within gadines and phycines. The proposed groupings receive some additional support in the gross morphological similarity of their larvae.
The effects of hydrocortisone and thyroxine treatments on development of duodenal morphology, alkaline phosphatase, and sugar transport in chicken (Gallus gallus) embryos
Authors: Mallon D. L. , Betz T. W.
Published: August 2008

The ability of thyroxine (T4) and hydrocortisone (H), alone or together, to cause precocious duodenal development was tested in chicken embryos. Correlations in the levels of duodenal enzymic, structural, and absorptive properties were compared in intact and treated embryos. Duodenal alkaline phosphatase activity, morphogenesis, and sugar absorption develop together in untreated embryos. Precocious alkaline phosphatase activity, morphogenesis, and α-methylglucoside uptake were correlated after H and T4 treatments. These parameters also responded significantly to T4 treatments alone. The levels of the alkaline phosphatase activity in 16.5-day embryos were three times normal after H plus T4 treatment. No parameters changed significantly after H treatment alone. Parallel increases in alkaline phosphatase activity and morphogenesis probably reflect duodenal participation in sugar uptake functions, at least for duodenal maintenance. Adrenocorticoids and thyroid hormones could be involved in these aspects of normal duodenal development.
Distribution and postglacial dispersal of freshwater fishes of Labrador
Authors: Black Geoff A. , Dempson J. Brian , Bruce W. J.
Published: August 2008

The voluminous literature on the freshwater and diadromous fishes of Labrador is summarized in distributional maps. A total of 25 obligate freshwater spawning and one catadromous species has been reported. Fishes from Atlantic and Mississippi refugia probably invaded the region from the Great Lakes basin primarily via glacial Lake Barlow-Ojibway, crossing Quebec north of the Otish Mountain to the headwaters of the Churchill River system. Additional dispersal routes existed to the north and south. Euryhaline species from an Atlantic refugium first invaded coastal regions during postglacial depression and marine inundation. Remnants of these occur as landlocked populations. Labrador is divided into three major ichthyogeographic regions based on species distributions and dispersal opportunities. The Churchill River forms one region and is divided into three subregions. Upstream of Churchill Falls there is only one species, which dispersed across Quebec. Downstream areas, including accessible tributaries, have all of the common fishes present in Labrador. Less accessible watersheds south of Churchill River form the third subregion and are limited to fishes with better swimming abilities. The second major region is southeastern Labrador which has euryhaline fishes from Atlantic refugia and three species from Quebec. The third major region is loosely defined as northern Labrador (> 55°N) although it is one of decreasing numbers of species with increasing latitude.
Predation by three glacial opportunists on natural zooplankton communities
Authors: Nero Redwood W. , Sprules W. Gary
Published: August 2008

We examine the influence of three glacial opportunist predators, Mysis relicta, Limnocalanus macrurus, and Senecella calanoides, on natural zooplankton communities of central Ontario through a series of feeding experiments in small enclosures (23.6 L). Estimates of in situ clearance rates by M. relicta match previously determined rates, with the following gradation of values: Asplanchna sp. > daphnids and bosminids > Epischura lacustris > large cyclopoids, Chydorus sphaericus and small Diaptomus sp. > L. macrurus > S. calanoides. Clearance rates by M. relicta are similar for all daphnids and bosminids. Hypolimnetic species like Daphnia longiremis and Eubosmina longispina are apparently eliminated by M. relicta, while similarly vulnerable species survive because they have an epilimnetic refuge from M. relicta. Limnocalanus macrurus and S. calanoides prey primarily on copepods, Diaphanosoma spp., and rotifers in the hypolimnion. When both clearance rates and population densities of M. relicta, L. macrurus, and S. calanoides are taken into account, the total predatory impact of M. relicta is much larger than that of the two relict copepods. Based on a theoretical comparison of measured clearance rates by predators with estimated rates of prey recruitment, we conclude that differences in species composition and abundance between relict and nonrelict lakes described in a previous survey are due principally to predation by M. relicta.
Isolation of hepatopancreatic cell types and enzymatic activities in B cells of the crayfish Orconectes rusticus
Authors: DeVillez E. J. , Fyler D. J.
Published: August 2008

The distributions of hepatopancreatic cell types, dissociated by mechanical disruption or collagenase digestion, were analyzed after gradient centrifugations on Percoll. B cells and intact residual vacuoles were isolated at an average density of 1.079 g/mL. F-cell densities were lower and variable, and lipid containing R cells were restricted to the tops of gradients. Lysates of peak fractions of B cells and vacuoles (84% purity) showed tryptic activity inhibited by N-p-tosyl-lysine chloromethyl ketone (TLCK) and α-amylase activity, providing direct evidence for the inclusion of these digestive enzymes.
Evidence of chemically mediated population recognition in coho salmon (Oncorhynchus kisutch)
Authors: Quinn Thomas P. , Tolson Graeme M.
Published: August 2008

To test the hypothesis that population-specific pheromones guide adult salmonids to their natal streams, juvenile and adult coho salmon (Oncorhynchus kisutch) were tested for chemosensory responses in two-choice tanks. Coho salmon from Quinsam and Big Qualicum rivers, British Columbia, Canada, distinguished their own population from the other. Tagging evidence indicates that straying between these two rivers and a third, geographically intermediate river seldom occurs. Thus, population-specific chemicals constitute a potential source of information for homing coho salmon, though their role vis-à-vis imprinted odors from other sources could not be evaluated.
Census of "Hawaiian" humpback whales (Megaptera novaeangliae) by individual identification
Authors: Darling James D. , Morowitz Harold
Published: August 2008

The numbers of humpback whales (Megaptera novaeangliae) that assembled in Hawaii in one winter and over the five winters from 1977 to 1981 were estimated by photographic identification of individual animals. Individual whales were identified by the black and white skin patterns on the underside of their flukes. Straight counts of identified individuals provide absolute minimum estimates, 521 in 1 year and 922 over 5 years. Calculations based on the number of repeat sightings of individuals were used to estimate total population size. These were based on the graph of the rate of discovery of "new," previously unidentified, whales and a form of the Bernoulli distribution, a theoretical distribution that estimates total numbers from multiple sightings of individuals in repeated sampling. The best estimates are 1000 in one winter and 2100 over five winters. The difference between one and five winters indicates that the population is not identical from year to year. Also, there are suggestions that the population increases in size over the winter period, and a small subpopulation may have a different behaviour pattern, possibly remaining in Hawaii longer, than the majority of animals.
Analysis of mitochondrial DNA in allopatric anadromous and nonanadromous Atlantic salmon, Salmo salar
Authors: Birt Tim P. , Green John M. , Davidson William S.
Published: August 2008

Analysis of mitochondrial DNA from allopatric anadromous and nonanadromous Atlantic salmon was conducted using restriction endonucleases. A variant fragment pattern was produced in a single nonanadromous specimen by one restriction enzyme. Fragment patterns produced by all other enzymes did not reveal any variation between or within populations. These results support the hypothesis that the two forms of salmon are very closely related.
Intestinal helminths of lesser scaup ducks: an interactive community
Authors: Bush Albert O. , Holmes John C.
Published: August 2008

This paper examines patterns in the linear distribution of helminths in the small intestine of each of 45 scaup. Over all birds, most common species of helminths were found in over half of the small intestine; their distributions overlapped broadly. In individual birds, each species occupied a more restricted, predictable part of the intestine; "core species" (those present in more than two-thirds of the birds) were more evenly distributed along the intestine than expected by chance and occupied almost all of it; "secondary species" (those in one- to two-thirds of the birds) were clumped in anterior and posterior portions of the intestine; and "satellite species" (those in less than one-third of the birds) were randomly distributed. For all common helminths, the range occupied in individual birds was significantly correlated with population size; however, overlap between adjacent species did not increase with increases in their total numbers. The intestinal helminths of scaup belonged to three guilds: small absorbers (paramucosal), large absorbers (mid-lumenal), and trematodes. The interactions noted above occurred both within and between guilds. The overall helminth community in scaup appeared to be saturated with species belonging to the two absorber guilds, but not with trematodes. Communities within individual scaup sampled this overall community and were often unsaturated. We conclude that the core and secondary species of absorbers provide a basic, interactive structure to the overall community and to most of the communities in individual birds. Trematodes and satellite absorber species provide stochastic elaborations.
Gastropod intermediate hosts of the meningeal worm Parelaphostrongylus tenuis in Pennsylvania: observations on their ecology
Authors: Maze R. J. , Johnstone C.
Published: August 2008

Gastropods from five elk foraging areas in north central Pennsylvania were collected from June to September 1981 and 1982 and examined for Parelaphostrongylus tenuis larvae. A total of 445 snails were found with a prevalence of infection of 16.2%. Seven species of snails were collected; larvae were found in six, and three represent new reports of naturally infected intermediate hosts of P. tenuis. These were Triodopsis albolabris, T. tridentata, and Ventridens intertextus. The prevalence of infection in each of these species was 20, 11.8, and 20.3%, respectively. Of 363 slugs, belonging to three species, only 1 (Deroceras laeve) was infected. One site, an old reclaimed strip mine, yielded 81% of the collected snails and 91.7% of the infected snails. This site was distinctive in its dense interwoven ground cover and soil of high calcium content and neutral pH.
Biochemical characterization of some raptor trypanosomes. II. Enzyme studies, with a description of Trypanosoma bennetti n. sp.
Authors: Kirkpatrick Carl E. , Terway-Thompson Cynthia A. , Iyengar M. Raja
Published: August 2008

Comparing electrophoretic mobility patterns of 14 enzymes of nine strains of cultured avian trypanosomes and two strains of cultured mammalian trypanosomatids revealed marked differences between the strains isolated from Falco sparverius and those isolated from other host raptors as well as among the avian trypanosomatids and the mammalian ones. These results supported the differentiation of two species of raptor trypanosomes based on other criteria: size, form, in vitro growth behavior, surface carbohydrate expression, lectin-mediated agglutination, and qualitative activity profiles of 19 enzymes. The results indicate that biochemical characteristics, particularly isoenzyme electrophoretic data, are useful and objective additions to the traditional criteria used to type and classify Trypanosoma spp. of birds. Trypanosoma bennetti n. sp. from F. sparverius is described as a new species, and the other avian trypanosome strains are identified as T. avium Danilewsky, 1885. A phylogenetic tree, constructed by methods of numerical taxonomy, revealed that T. bennetti n. sp. is distantly related to T. avium as well as to T. rhodesiense and Leishmania chagasi.
Falcaustra species (Nematoda: Kathlaniidae) parasitic in turtles and frogs in Ontario
Authors: Baker M. R.
Published: August 2008

Five Falcaustra species are reported from southern Ontario: F. inglisi (Anderson, 1964) Baker, 1980 from Rana catesbeiana and R. clamitans (new host record) of Algonquin Park; F. chelydrae Harwood, 1932 and F. wardi (Mackin, 1936) from Chelydra serpentina of Guelph; F. affinis (Leidy, 1856) from Chrysemys picta marginata (new host record) of Guelph; and F. catesbeianae Walton, 1929 from Rana catesbeiana of Long Point, Ontario. The last four species have not previously been reported in Canada. They are redescribed based on specimens from Ontario and museum specimens from North America. Examination of type specimens of Spironoura hylae Reiber, Byrd &Parker, 1940 and Spironoura spiculata Reiber, Byrd &Parker, 1940 revealed that they are synonymous with F. affinis. Type specimens of Falcaustra longespiculata Walton, 1927 from Terrapene Carolina of North America are shown to be lost. This species, which may be synonymous with F. affinis, is designated a species inquirenda.
Ceramotylenchus tesselatus n. gen., n. sp. and Pleurotylenchus minor n. sp. (Nematoda: Tylenchida) from Alabama
Authors: Ebsary B. A.
Published: August 2008

A new genus and species of Duosulciinae and a new species of Pleurotylenchus are described and illustrated. Ceramotylenchus tesselatus n. gen., n. sp. is distinguished by having a cuplike oral disc, two crenate lateral incisures, absence of lateral vulval flaps, and alternating rows of blocks on the head and body that gives a tilelike appearance. Pleurotylenchus minor n. sp. is distinguished from P. sachsi by a smaller body size, more posterior vulva, shorter stylet, laterally indented head annules, and by the lateral field that begins on the first body annule.
Effects of concomitant denervation and re-amputation through the regenerative forelimb outgrowth in Xenopus laevis froglets
Authors: Liversage Richard A. , Crawford Michael J. W. K. , McLaughlin Danielle S.
Published: August 2008

Normally innervated Xenopus laevis froglet forelimbs respond to amputational injury by forming a heteromorphic, cartilaginous spike outgrowth. However, denervation concomitant with amputation of the distal portion of a regenerate outgrowth performed at 1, 2, 3, 4, and 6 weeks after initial forelimb amputation resulted in the regression (resorption) of most, if not all, of the remaining portion of the regenerate tissues. These results indicate that, as in urodele amphibians, concomitantly denervated and amputated forelimb outgrowths of postmetamorphic froglets do not adjust sufficiently to denervation and fresh amputation to allow regeneration to recommence. Instead, progressive resorption of the remaining tissues of the regenerate occurs.
Ventral neurons in an abdominal ganglion of the locust Locusta migratoria, with properties similar to dorsal unpaired median neurons
Authors: Lange Angela B. , Orchard Ian
Published: August 2008

The presence of ventral neurons in the seventh abdominal ganglion of the locust Locusta migratoria, with properties similar to dorsal unpaired median neurons, are reported. These cells resemble dorsal unpaired median neurons in that they possess similar morphological and neurophysiological properties, show an affinity for neutral red, and contain octopamine. Octopamine-containing neurons of the unpaired median type are therefore not confined to the dorsal surface.
The association of 5-hydroxytryptamine, octopamine, and dopamine with the intrinsic (glandular) lobe of the corpus cardiacum of Locusta migratoria
Authors: Orchard I. , Martin R. J. , Sloley B. D. , Downer R. G. H.
Published: August 2008

The levels of 5-hydroxytryptamine, octopamine, and dopamine in the glandular lobe of the corpus cardiacum and its nerve tract, the nervi corporis cardiaci II, have been measured by high-performance liquid chromatography in Locusta migratoria. All three amines are present within the glandular lobe, but only octopamine and 5-hydroxytryptamine were detected within NCCII. Immunohistofluorescence using antibodies against 5-hydroxytryptamine reveals that 5-hydroxytryptamine immunoreactive fibres are present within the nervi corporis cardiaci II and within the anterior regions of the glandular lobe. A few fibres pass over the surface of the glandular lobe. The report therefore provides the first description of the relative levels of 5-hydroxytryptamine, octopamine, and dopamine in the glandular lobe and the first description of 5-hydroxytryptamine immunoreactive fibres within the locust corpus cardiacum.