bluuebunny/crossref_metadata_2025 huggingface dataset:
Anaerobic exercise in teleost fish
Authors: Jones David R.
Published: August 2008

In teleost fish, high speed ("burst") swimming is performed anaerobically while sustained performance is aerobic. The degree to which anaerobic energy production contributes to swimming performance in the steady exercise zone (swimming maintained for 2 to 200 min) in unknown. The relationship between oxygen consumption or scope for activity and swimming speed (U), the repayment of an oxygen debt during recovery from fatigue, and the reduction in maximum sustained speed (critical velocity, Ucrit) by reduced environmental oxygen or lowered blood haemoglobin suggest that steady performance in salmonids is aerobic. In salmonids, sufficient power is provided from the oxygen consumed to swim steadily at least at 80% of Ucrit. On the other hand, depending on the temperature, aerobic power output in cyprinids is only sufficient to reach 30–50% of Ucrit. Aerobic relationships holding for salmonids do not apply to cyprinids. In fact, high respiratory quotients early in exercise along with glycogen depletion and lactate accumulation rates in muscle during vigorous swimming suggest that steady performance in cyprinids is worthy of further examination.
The vasa deferentia of the male reproductive system of Calpodes ethlius (Hesperiidae, Lepidoptera)
Authors: Lai-Fook J.
Published: August 2008

The vasa deferentia of Calpodes ethlius are distinguishable into upper and lower regions, each of which consists of expanded and narrower tubular portions. The expanded region of the upper vas deferens is lined by a phagocytic epithelium while the narrower region is lined by a granular secretory epithelium. The expanded region of the lower vas deferens is a true seminal vesicle since it is always full of sperm bundles; it is lined by a nongranular secretory epithelium which extends to the junction with the duplex ejaculatoris. Distinctly different cells occur at the junctions of the three epithelia with each other. The entire vas deferens is surrounded by one or two thin muscle layers.
Structure of the accessory glands and duplex of the internal male reproductive system of Calpodes ethlius (Hesperiidae, Lepidoptera)
Authors: Lai-Fook J.
Published: August 2008

The paired accessory glands of Calpodes ethlius are long, blind tubes which open into the ductus ejaculatorius duplex (duplex) at a constriction. They are held closely together to each other by tracheoles. Combined light and electron microscopy suggests that there are at least six regions. These regions are identified by the fine structure of their epithelia and their luminal contents, characterized by some preliminary histochemistry. A structurally uniform merocrine secretory cell is found throughout the length of the gland. However, the differences that occur do so in the apical surface structure, especially the microvilli and the occasional bleb indicating apocrine activity. The other major element is an apocrine secretory cell with highly modified mitochondria and apical region. The latter consists of compartments which are filled with glycogen and organelles and which protrude into the lumen. The merocrine secretions include a variety of globular structures of varying sizes and densities and two filamentous elements in addition to the matrix. The U-shaped duplex is very short and joined to the accessory glands, vasa deferentia, and simplex. Its epithelium consists of a single cell type; however, there are obvious signs of asynchronous secretory activity in adjacent areas within the duplex. There are also some suggestions of apocrine activity although the epithelium is largely merocrine. The lumen contains, in addition to its own secretions, secretions of the vasa deferentia, apyrene sperm, and eupyrene sperm bundles. The latter are confined to the areas around the openings of the vasa deferentia.
Overcoming sampling bias in studies of terrestrial gastropods
Authors: Boag D. A.
Published: August 2008

Permanent plots, in the form of square masonite boards (30 × 30 cm), were placed in a variety of habitats as a means of sampling the fauna of living gastropods on a bighorn sheep range in southwestern Alberta. Fourteen species of gastropods, ranging in age from newly hatched young to overwintered adults, were found adhering to the undersides of these boards. The number of individuals found on plots was increased in some habitats by wetting them the day before inspection. In comparing this method with other sampling procedures, I concluded that the problem of differential visibility and fragility was resolved when using these boards. Furthermore, since all gastropods recorded were living individuals, there was no need to rely on the remains of dead animals (shells) as in sifted samples, with the inherent problem of deciding which shells were from animals recently dead. The use of permanent plots enables one to sample the exact location repeatedly without destroying it and thereby to compare numbers of individuals of each species in both space and time.
Interactions among pyruvate concentration, pH, and Km of pyruvate in determining in vivo Q10 values of the lactate dehydrogenase reaction
Authors: Walsh Patrick J. , Somero George N.
Published: August 2008

The interactions among pyruvate concentration, the apparent Michaelis constant (Km) of pyruvate, and intracellular pH on the Q10 of the lactate dehydrogenase (LDH) reaction of white skeletal muscle of the fish Gillichthys mirabilis were studied. Experimentally determined values for pyruvate concentration and Km of pyruvate (measured under both constant pH and variable (=biologically realistic) pH were used to estimate in vivo Q10's over acclimation time courses and in acute temperature-change situations. Temperature-dependent changes in pyruvate concentration were large. The 25 °C acclimated fish had approximately twice the pyruvate concentration of 15 °C acclimated specimens, and acute temperature changes also led to higher pyruvate levels at higher temperatures. These temperature-dependent changes in pyruvate concentration prevent temperature-dependent variation in the Km of pyruvate from having Q10-reducing influences. Rather, during acclimation a relatively stable ratio of Km: [substrate] is maintained. This is viewed as important for the preservation of correct regulatory capacity for the muscle LDH reaction.
Nestling house wrens: weight and feather growth
Authors: Zach Reto
Published: August 2008

Six models were tested for weight and feather growth of nestling house wrens (Troglodytes aedon). For weight growth, the logistic model with an asymptote A of 10.4 g and a growth-rate constant K of 0.52 day−1 was best. Curves for weight growth of individuals varied, and some birds had pronounced weight recession. Growth of primary feather 10 followed the Gompertz model with A and K equal to 18.8 mm and 0.32 day−1, respectively. Growth of rectrix feather 6 could best be described by the von Bertalanffy model with a forced A value of 32.5 mm and K equal to 0.12 day−1. Fitting of the models to rectrix feather length was complicated because fledging occurred when growth was only 37% complete as opposed to 84% complete for primary feather growth. The variation among broods of growth parameters and nestling time ranged up to 54.5%. First and second broods did not differ significantly in these parameters and brood size could not account for much of the observed variability. Weight growth and primary feather growth were linked, but this was not the case for weight and rectrix, or for primary and rectrix feather growth. Some birds that failed to fledge had depressed growth. Weight growth and recession are particularly well suited for investigating natural and man-made environmental stresses such as gamma radiation.
The transmission and development of Cosmocephalus obvelatus (Nematoda: Acuarioidea) of gulls (Laridae)
Authors: Wong P. L. , Anderson R. C.
Published: August 2008

Cosmocephalus obvelatus (Creplin, 1825), found in the oesophagus of ring-billed gulls (Larus delawarensis Ord), from Lake Ontario developed to the infective stage in the haemocoel of the amphipods Crangonyx laurentianus, Hyalella azteca, and Gammarus fasciatus. At 20 °C the first moult occurred 10 days and the second 18 days postinfection. Infective larvae given to laboratory-reared herring (Larus argentatus) and ring-billed gulls entered the proventriculus of the birds and moulted 3.5 days postinfection. Five days postinfection, fourth-stage larvae were found attached to the posterior third of the oesophagus. The fourth moult occurred 11 days postinfection and worms were found throughout the oesophagus. Females were gravid 27 days postinfection. Various developmental stages are described. Infective larvae became encapsulated on the mesentery of experimentally infected goldfish (Carassius auratus) and a shiner (Notropis sp.). Infective larvae were found in various fish collected in waters adjacent to the gull colony. Regular examination of adult gulls indicated birds acquired infections soon after arriving from the wintering grounds. There was little evidence transmission occurred in the latter regions. Young-of-the-year birds acquired infections by (1) regurgitation of fourth-stage larvae and adult worms along with food during feeding by parents and (2) from infective larvae contained in the fish given to them by the parents. Prevalence in 28-day-old birds had reached 100%. Intensity (including all stages) in fledglings 35–42 days old on July 3 was 15.7 (6–38).
Ultrastructure of the larval antenna of Tenebrio molitor L. (Coleoptera: Tenebrionidae): structure of the trichoid and uniporous peg sensilla
Authors: Bloom J. W. , Zacharuk R. Y. , Holodniuk A. E.
Published: August 2008

The antenna of the final instar larva of Tenebrio molitor has three segments. The reduced third (terminal) segment bears a large trichoid sensillum, four uniporous peg sensilla, one blunt tipped peg sensillum, and one papillate sensillum. The second segment bears a very large multiporous placoid sensillum, three uniporous peg sensilla, one blunt-tipped peg sensillum, and one papillate sensillum. The numbers and arrangement of these sensilla are usually stereotyped, but variations occur.The trichoid sensillum is a long, thin, unsocketed, aporous hair. It is innervated by two (sometimes one) bipolar neurones and has five sheath cells. The three sheath cells which distally delimit the large sensillar sinus have extremely elaborate microvillate inner borders. The uniporous peg sensillum is a short, stout, socketed peg with a single terminal pore. It is innervated by two to six (usually six) bipolar neurones. The dendrite from one of these always ends as a tubular body in the base, while the dendrites from the others extend to the tip of the peg. This sensillum has a small sensillar sinus and only four sheath cells. The inner sheath cell of both types of sensilla forms a cylindrical, nonlapped sleeve around the dendrite bundles.
Effects of thyroid hormones and prolactin on food intake and weight changes in young male reindeer (Rangifer tarandus tarandus)
Authors: Ryg Morten , Jacobsen Endre
Published: August 2008

Yearling male reindeer were treated with thyroid hormones and prolactin to see if reported seasonal variations in these hormones could participate in the control of the growth cycle in Cervidae. Both prolactin and thyroid hormone injections were followed by increased food intake. The effect was not additive, and no interactions were seen. Weight gain decreased after treatment with thyroid hormone, alone or in combination with prolactin. Weight gain increased in animals treated with prolactin alone. We conclude that changes in prolactin secretion may be important for the regulation of the growth cycle, but that the role of changes in thyroid hormone secretion is unclear.
Tissue specific isozymes of alanopine dehydrogenase in the channeled whelk Busycotypus canaliculatum
Authors: Plaxton William C. , Storey Kenneth B.
Published: August 2008

The tissues of the channeled whelk Busycotypus canaliculatum displayed activities of three glycolytic dehydrogenases, alanopine dehydrogenase (ADH), octopine dehydrogenase (ODH), and lactate dehydrogenase (LDH). ADH and ODH were present in all seven tissues (hepatopancreas, gill, kidney, and mantle, ventricle, foot, and proboscis muscles) tested. ADH was the major cytosolic dehydrogenase activity in all tissues except proboscis, while ODH was present in high activities only in the four muscular tissues. Significant LDH activity occurred only in the two muscles which perform sustained work, ventricle, and proboscis.Tissue specific isozymes of ADH were identified. Three forms, specific for hepatopancreas, gill–kidney, and muscle tissues, were separable by isoelectrofocusing (pI's 5.69, 5.58, and 5.93, respectively), chromatofocusing, and polyacrylamide gel electrophoresis. The three isozymes differed kinetically showing significant differences in apparent Km's for L-alanine (e.g., 8.84 ± 0.03, 10.64 ± 0.40, and 13.12 ± 0.65 mM for hepatopancreas, ventricle, and gill, respectively) and even greater differences in apparent Km's for glycine (619 ± 55, 1412 ± 115, and 2542 ± 230 mM for the above three tissues, respectively). The ratios Km(gly)/Km(ala) averaged 70, 192, and 132 for the three isozymes, hepatopancreas, gill–kidney and muscle, respectively.The physiological functions of ADH isozymes in the whelk may be similar to those of the M and H isozymes of LDH in vertebrates or the muscle and brain specific isozymes of ODH in cephalopod molluscs.
Metazoan parasites of cod, Gadus morhua L., in Canadian Atlantic waters
Authors: Appy R. G. , Burt M. D. B.
Published: August 2008

From July to September 1975, 739+ Atlantic cod, Gadus morhua L., were collected in the Bay of Fundy, Nova Scotia shelf, and southern Gulf of St. Lawrence and were examined for metazoan paraties. Of 49 parasites recorded, 10 were considered more or less specific to cod or related gadid hosts, 9 were considered accidental infections, and the remaining majority of parasites were apparently capable of infecting a wide range of unrelated marine fishes. The general lack of strict host specificity of enteric parasites of northern marine fishes results in a very diverse parasite fauna in fish such as cod which have very broad feeding habits.Metazoan parasites recorded from cod were mostly arctic–boreal transatlantic and amphiboreal species. No species endemic to the northwestern Atlantic were found. However, among all metazoan parasites which are restricted to gadid hosts, there are more endemic species in the North Atlantic, particularly the northwestern Atlantic than present in the North Pacific. This distribution surely reflects the large number of endemic gadid genera and species in the North Atlantic and the probable Atlantic–Arctic origin of the Gadidae.
Growth, biomass, and production of juvenile Atlantic salmon (Salmo salar L.) in two Miramichi River, New Brunswick, tributary streams
Authors: Randall R. G. , Paim U.
Published: August 2008

The production rate of juvenile Atlantic salmon (Salmo salar) was estimated at four sites in two tributary streams of the Miramichi River, New Brunswick, during the period September 1976 to October 1978. Annual production ranged between 0.27 and 5.12 g∙m−2∙year−1. Growth was largely restricted to a 4-month period in early summer. Among the four sites, age 0+ salmon attained a mean weight of between 0.95 and 3.50 g by the end of their first growing season (September) and densities in July ranged between 0.3 and 3.1 fry∙m−2∙Age 1+ parr grew to mean weights between 4.95 and 12.45 g by September, and June–July densities ranged between 0.03 and 0.6 parr∙m−2. Marking information indicated that most parr remained in the study sites from July to September, but larger proportions of migrant parr were recorded in October. Production during summer was directly and positively related to initial population densities. Production rates at these sites were lower than most other recorded values for juvenile Atlantic salmon. Biomass of salmon may have been below the carrying capacity of the environment at all four sites.
Effects of group density on call rate, phonokinesis, and mating success in Palmacorixa nana (Heteroptera: Corixidae)
Authors: Aiken R. B.
Published: August 2008

Little information exists on the effects of density on the calling of acoustic insects. In the field, density of Palmacorixa nana males varies markedly. In the laboratory, such variation appears to be a result of males forming groups around each other. When males aggregate, the number of spontaneous calls per male per minute increases exponentially. Females show a phonokinetic preference for the mean call rate of the densest male aggregation. Males show a phonokinetic preference for the less dense aggregations. Females always preferred the greatest acoustic power. Phonokinetic responses of male and female P. nana to groups of conspecific males were consistent with an assessment of the reproductive costs and benefits of associating with a group. As density increased, both the costs and benefits to males of associating with a group increased. In denser aggregations, males had more copulations per mounting attempt but had more agonistic interactions and mating interference from other males.
The honeycombed species of Chydorus (Cladocera, Chydoridae): comparison of C. bicornutus and C. bicollaris n. sp. with some preliminary comments on faviformis
Authors: Frey David G.
Published: August 2008

Chydorus bicornutus and C. faviformis are presently confined to the glaciated region of the northeastern United States and adjacent Canada where they quite commonly occur together. Chydorus bicollaris n. sp., in contrast, is presently confined to the Coastal Plain from Florida to New Jersey, where it just barely overlaps C. bicornutus and can co-occur with it. Chydorus faviformis and C. bicollaris are completely allopatric. A redistribution of all three species during successive glaciations and interglaciations is postulated.Chydorus bicornutus differs markedly from other species included in Chydorus. Chydorus bicollaris is somewhat more like Chydorus, but differs significantly in characters shared by members of the sphaericus complex. Chydorus faviformis quite closely resembles members of the sphaericus complex, including the male, which loses its honeycomb pattern on reaching maturity. These marked differences in morphology suggest that the three species are less closely related to one another than their sharing of a honeycombed exterior might suggest.Scanning electron micrographs of specimens in process of molting show the honeycomb pattern of the new exoskeleton collapsed and containing many complex wrinkles, which disappear as the animal subsequently expands. The functions of this bizarre exterior are unknown, including the vast difference in size of the lateral horns of bicornutus.
Structure and innervation of the swim bladder musculature in the weakfish, Cynoscion regalis (Teleostei: Sciaenidae)
Authors: Ono R. Dana , Poss Stuart G.
Published: August 2008

The striated swim bladder muscles of the weakfish Cynoscion regalis are deep red in color but cannot be classified histologically as having typical red fibers. The muscle fibers are homogeneous and average 29.6 ± 5.3 μm in diameter, one-fifth the diameter of the adjacent hypaxialis fibers. Each muscle fiber contains thin, ribbonlike myofibrils which are radially arranged around a central core of mitochondria, glycogen, and sarcoplasmic reticulum. Myofibrils are extremely regular in pattern. Triads occur at the Z line. Numerous mitochondria and muscle nuclei are located at the periphery of each muscle fiber. The muscle fibers are multiply innervated with motor endplates distributed along their entire lengths. Well-developed folding of the postsynaptic membrane, not previously reported in fishes, is present at the motor endplate.
Aspects of spatial and temporal cooccurrence in the life history stages of the sibling hakes, Urophycis chuss (Walbaum 1792) and Urophycis tenuis (Mitchill 1815) (Pisces: Gadidae)
Authors: Markle Douglas F. , Methven David A. , Coates-Markle Linda J.
Published: August 2008

The amount of coexistence in the sympatric sibling species, Urophycis chuss and U. tenuis, appears to be a function of ontogeny, with each life history stage showing different probabilities of interspecific encounters. Demersal juveniles coexist the least since U. chuss is inquiline with scallops and U. tenuis is in nearshore shallows. In U. tenuis there is also intraspecific segregation, with older juveniles and young adults bathymetrically segregated from the youngest demersal juveniles in summer.Relatively more coexistence is seen between neustonic juveniles. However, they show some seasonal and pronounced diel differences in availability to neuston nets (U. chuss predominates during the day and U. tenuis during night). The greatest coexistence is seen between adult U. chuss and adolescent to adult U. tenuis.Over its life, U. tenuis tends to move into deeper water while U. chuss is relatively stenotopic, its distribution largely a reaction to temperature. The life history strategy of U. tenuis is "get big quick," a goal achieved, in part, through delayed maturation (relative to U. chuss). The strategy of U. chuss seems to be avoid predation, concentrate growth in the juvenile stage, and "get mature quick." We speculate that both species' life histories may be subordinate to getting the demersal juveniles into the right nursery area at the right time.
A difference in production and associated events in two races of spruce grouse
Authors: Keppie Daniel M.
Published: August 2008

Analyses are given for several parameters in the production of juvenile spruce grouse in a local population in southwest Alberta (Canachites canadensis franklinii), 1970–1975, and in northeast New Brunswick (C. c. canace), 1975–1980. Canachites c. canace exhibited greater clutch size, nest success, proportion of females with broods and production of juveniles. Hatchability of eggs, average brood sizes, and mortality rates of juveniles were similar. Differential nest success appeared to be a primary influence on the difference in production of juveniles. In autumn, canace exhibited a substantial net reduction in juveniles as a consequence of dispersal, but not franklinii. Densities of juveniles in winter were similar. Speculation is provided about the differences in production and their association with other aspects of life history, notably the quality of juvenile stock.
Development of Turgida turgida (Rudolphi, 1819) in the common field cricket (Acheta pennsylvanicus Burmeister)
Authors: Gray J. B. , Anderson R. C.
Published: August 2008

Several species of orthopterans and coleopterans were experimentally infected with Turgida turgida. The common field cricket, Acheta pennsylvanicus, was the most suitable host. Eggs of T. turgida usually hatched in the ileum of crickets. Larvae were observed in the wall of the ieum 4 h postinfection. Larvae became encapsulated in the gut wall and moulted twice. At 30 °C the first moult occurred 5 days and the second one 10 days after infection. Larvae are described in detail. The intensity of T. turgida in crickets could be augmented by challenge infections.
The migration of humpback whales along the northeast coast of Newfoundland
Authors: Whitehead Hal , Silver Randi , Harcourt Patricia
Published: August 2008

Humpback whales migrate along the northeast coast of Newfoundland in summer. Individuals were identified which moved from St. Vincent's on the south coast to Bonavista Bay on the northeast coast, and from there to southern Labrador. The mean migration rate northward along the northeast coast in summer was estimated to be 1.2° latitude per month, although animals moved through a study area at the end of the Bay de Verde Peninsula at about twice this rate. The animals arriving at Bay de Verde in early July, when humpback densities were higher, were on average larger than those arriving either earlier or later. Over periods of more than 1 day there was no evidence for consistent companionships (other than mothers with their 1st-year calves), and only one animal appeared to have a preferred range within the Bay de Verde study area, although some whales preferentially returned to certain stretches of the coastline in different years.
Structure and function of feeding in larvae of Nebria (Coleoptera: Carabidae)
Authors: Spence John R. , Sutcliffe James F.
Published: August 2008

The larval head capsule and mouthparts of Nebria species are adapted for capturing prey which have rapid escape responses and for efficient fluid feeding. Larvae discover prey by tactile contact and capture them by impalement on their long, sickle-shaped mandibles. In capturing prey, the mandibles appear to act as a snap trap triggered by contact with four specialized nasale spines and (or) two hairs projecting from the lateral margins of the frontale into the space embraced by the mandibles. Larvae egest proteolytic enzymes onto captured prey and shred the prey's cuticle through action of the mandibles against a heavy ventral nasalar spine. A mastication cycle involves rotation of the food bolus and periodic squeezing to extract liquified body contents of the prey. Probable chemo- and mechano-sensilla suited to mediate feeding are distributed on the mouthparts. Liquid food is strained through hairs and acanthae of the preoral chamber while being drawn into the cibarium by contraction of powerful cibarial dilators. Cibarial constrictors are not present and food is forced into the pharynx by natural elasticity of the cibarial walls. Larval mouthparts are highly specialized for fluid feeding while those of adults of Nebria are adapted for consuming solid food.
Geographic variation in caribou on the Canadian arctic islands
Authors: Thomas D. C. , Everson P.
Published: August 2008

Analyses of body, leg bone, skull, and pelage data indicated a cline in the characters of caribou (Rangifer tarandus) from central Boothia Peninsula to the western Queen Elizabeth Islands. The main difference between the skulls of barren-ground caribou (R. t. groenlandicus) on central Boothia Peninsula and the more northerly Peary caribou (R. t. pearyi) was a shorter muzzle in the latter. Pelage tone was markedly lighter in Peary caribou and they were smaller in most body measurements, most notably in the length of long bones. Two major populations of Peary caribou were identified: one on the western Queen Elizabeth Islands (Parry Islands), the other on Somerset and Prince of Wales islands. Differences in skull size and form suggest that each population was composed of two or more subpopulations. The larger and darker R. t. groenlandicus occurred on north-central Boothia Peninsula and the two subspecies and apparent intergrades were present in winter on northern regions of the peninsula. The morphological similarity of Peary caribou on Somerset and Prince of Wales islands is explained by interisland movements resulting in genetic mixing. The same is true for caribou on the western Queen Elizabeth Islands and that population apparently has little genetic interchange with the other.
Sterile matings at the beginning of the breeding season in Clethrionomys rufocanus and Microtus agrestis
Authors: Westlin Lilian M.
Published: August 2008

Female Clethrionomys rufocanus and Microtus agrestis were captured in Sweden at the beginning of their breeding seasons in 1978 and 1981 and were examined for evidence of sterile matings. Dissection, gross examination, and histological studies revealed that approximately 90% of the captured females had ovulated. These ovulations were most likely caused by mating because all investigated microtines have induced ovulation. All mated females of both species had experienced at least one sterile ovulation. Possible explanations of the phenomenon are discussed. Male C. rufocanus captured in the same period did not differ in sexual status from males captured later in the breeding season.
Larval and adult characters of Frickius Germain, its relationship to the Geotrupini, and a phytogeny of some major taxa in the Scarabaeoidea (Insecta: Coleoptera)
Authors: Howden H. F.
Published: August 2008

Adults and larvae of the scarab beetle Frickius variolosus Germain are described. Frickius and Taurocerastes Phil. are considered sister genera. Both adult and larval characters show these to be most closely related to the geotrupine genus Ceratotrupes Jekel and they are placed in the tribe Geotrupini. A phylogeny is presented for the four tribes of the Geotrupinae, nine subfamilies of Scarabaeidae, and the Passalidae and Lucanidae based on analysis of 39 adult and larval characters.
Jumbo spotted form of least cisco Coregonus sardinella in lakes of southern Yukon Territory
Authors: Lindsey C. C. , Kratt L. F.
Published: August 2008

Four lakes on the upper Yukon River drainage contain a strikingly spotted jumbo form of least cisco, with fork lengths up to 452 mm, larger than all previously known lacustrine or anadromous forms. The jumbo fish, with high gill raker counts (48–52), are probably nonmigratory. They may in each lake represent parallel responses to high dissolved solids, little competition, and unusually favourable conditions for growth. Available material is insufficient to establish whether small specimens in these lakes are young or slow-growing individuals of the jumbo spotted form, or whether the lakes contain two sympatric populations.
Factors determining temporal division of labor in honeybees
Authors: Winston Mark L. , Punnett Elizabeth Neilson
Published: August 2008

Honeybee workers perform tasks in an age-related sequence during their lifetimes, with young workers generally performing hive duties and older workers guarding the entrance. The relationship between the timing of brood care and foraging and the colony characteristics of worker population, age distribution, and brood care were examined in order to determine the influence of colony growth on the ontogeny of worker activities. Foraging age was strongly correlated with colony population but not with age distribution or brood area. The age when workers cared for brood was weakly correlated with colony population and not correlated with age distribution or brood area. The results suggest that the ages when tasks are performed depend in part on colony population and less on age distribution and brood area.
Experimental studies on acarine predator–prey interactions: effects of temporal changes in the environment on searching behaviour, predation rates, and fecundity (Acarina: Phytoseiidae)
Authors: Eveleigh Eldon S. , Chant D. A.
Published: August 2008

We examined the effects of temporal changes in the environment on the searching behaviour, predation rates, and fecundity of Phytoseiulus persimilis and Amblyseius degenerans in the laboratory. Phytoseiulus persimilis demonstrated an ability to respond quickly to changes in prey distribution in a patchy environment and maintained its searching efficiency despite these changes. In contrast, A. degenerans was rather insensitive to temporal changes in prey distribution and when it found a profitable patch its visits to other patches were restricted. Thus, this species was unable to maintain its searching efficiency in the changing environment. Phytoseiulus persimilis distributed its progeny in relation to the distribution of prey in the changing environment and avoided oviposition in patches without prey, whereas A. degenerans showed no such discrimination. The fecundity of both species was not adversely affected by changes in prey distribution although their fecundity was lower than when all of the prey were in a single patch and their dispersal was restricted.
Répartition des ressources et changements saisonniers de l'alimentation d'ombles de fontaine anadromes, Salvelinus fontinalis
Authors: Gaudreault Alain , Castonguay Martin , FitzGerald Gérard J.
Published: August 2008

Resource partitioning among anadromous brook charr in an estuary included habitat and prey-type partitioning. In spring and summer, juveniles were foraging in the upper estuary on crustacea and insects while adults were eating crustacea and fish in the lower estuary. In the fall, adult charr, which were all in the river, ate little. During winter, adult charr were found in the estuary and consumed crustacea and only a few fish. The relative weights of stomach contents were similar in summer and winter, showing for the first time the importance of winter feeding for this species.
Changes in physical condition of male mallards (Anas platyrhynchos) during moult
Authors: Young D. A. , Boag D. A.
Published: August 2008

The relationship between moult and physical condition was studied in adult male mallards (Anas platyrhynchos) collected between May and October on the Canadian Prairies in 1976. Body weight did not change significantly while birds were moulting. During the flightless period, however, there was a significant decrease in flight muscle weight, whereas leg muscle weight increased. Subcutaneous lipid depots, smallest in breeding birds, increased significantly during the prebasic body moult and decreased temporarily during the flightless period. Carcass lipid depots and total protein remained relatively constant throughout the moult. These data suggest that moulting male mallards did not encounter nutritional stress in south central Canada in 1976.
Seasonal, habitat, and sex-specific food habits of red-winged blackbirds: implications for agriculture
Authors: McNicol Donald K. , Robertson Raleigh J. , Weatherhead Patrick J.
Published: August 2008

Seasonal, habitat, and sex-specific food habits of red-winged blackbirds were studied by stomach analysis from March through October 1977 in eastern Ontario. The overall diet is nonspecialized, but within seasons, habitats, or sexes, specializations do occur. In early spring, males eat waste grain and seeds, with birds in agricultural habitats specializing more on the former, and in nonagricultural habitats on the latter. In the breeding season, both sexes in both habitats switch to insects, although waste grain remains an important component of the diet of birds in agricultural areas. Following breeding, birds move into agricultural areas and exploit both standing oats and corn, and then waste grains again late in the fall. Some of the insects and weed seeds in the birds' diet are potentially damaging to agriculture, so consumption by birds may have direct benefits to agriculture. A cost-benefit analysis, focussing on details of the quantities and economics of consumption by red-winged blackbirds of some of these insect and weed pests should be done before widespread control of blackbirds is attempted.
Description of parasitic stages of Hexamermis glossinae (Nematoda: Mermithidae) from Glossina in West Africa, with observations on the host–parasite association
Authors: Hominick W. M. , Croft S. L. , Kuzoe F. A. S.
Published: August 2008

Parasitic stages of Hexamermis glossinae from Glossina palpalis s. 1. and G. pallicera, which were collected immediately prior to the rainy season near Bouaflé, Ivory Coast, are described and illustrated. Specimens have an onchiostylet and were similar to Coccinellimermis coccinellae exochomi (Rubtzov, 1971) Rubtzov, 1978. Adults of Coccinellimermis are unknown. Possession of an onchiostylet is probably a specific rather than a generic character and Coccinellimermis is therefore a subjective junior synonym of Hexamermis. Results from 200 G. palpalis collected in a localized area showed that 5% of the flies were infected and that 12.3% of the males were parasitized compared with 2.1% of the females. Four of the 10 flies harbouring nematodes also harboured trypanosomes. Such concurrent infections were more frequent than expected since fewer than 10% of the 200 flies harboured trypanosomes. No correlation exists between age of the female flies, estimated by ovarian ageing, and length of the parasites. Infected females had fed and ovulated, and two carried a developing larva in the uterus. The life cycle of this mermithid is unknown, but all stages of the life cycle may occur where female flies larviposit.
Seasonal effects of photoperiod and temperature on spermatogenesis and male secondary sexual characters in the three-spined stickleback, Gasterosteus aculeatus L.
Authors: Borg Bertil
Published: August 2008

Effects of photoperiod (16 h light (L): 8 h dark (D) and 8 h L: 16 h D) and temperature (18 and 8 °C) on spermatogenesis and androgen-dependent kidney hypertrophy in the three-spined stickleback were studied in alternate months of the year. In winter 16 h L: 8 h D in combination with 18 °C stimulated secondary sexual characters, whereas in spring other regimes were also stimulatory. Spermatogenesis was more active and the kidney more suppressed in 8 h L: 16 h D at 18 °C than in other groups in winter. In the natural annual cycle spermatogenesis is quiescent from the beginning of winter until the end of the breeding season in summer. Decline of secondary sexual characters in July is accelerated by high temperature. High kidney epithelium is never found together with vigorous spermatogenesis, indicating androgen-inhibition as a major factor in the control of spermatogenetic activity.
Further studies on puffinosis, a disease of the manx shearwater (Puffinus puffinus)
Authors: Nuttall P. A. , Perrins C. M. , Harrap K. A.
Published: August 2008

Epizootics of puffinosis occurred on Skomer Island during the period from late August to mid-September 1978, 1979, and 1980. They affected shearwater fledglings in well-defined areas on the island which were the same for each of the 3 years of study. In contrast to previous reports puffinosis was also recorded in young chicks and full-grown birds.
Comment on Dr. Gilmour's views on feeding by hemichordates and lophophorates
Authors: Strathmann Richard R.
Published: August 2008

Observations on motion of captured particles, films of ciliary motion during particle capture, and physical theories of the motion of particles and water contradict substantial parts of Dr. Gilmour's accounts of ciliary feeding by hemichordates and lophophorates. (T. H. J. Gilmour. 1982. Feeding in tornaria larvae and the development of gill slits in enteropneust hemichordates. Can. J. Zool. 60. This issue.)
Effects of food and oxygen availability on habitat selection by guppies in a laboratory environment
Authors: Talbot André J. , Kramer Donald L.
Published: August 2008

Using the ideal free distribution model proposed in 1970 by S. D. Fretwell and H. L. Lucas, we investigated how local food and oxygen availability influenced the distribution of a group of guppies (Poecilia reticulata, Teleostei, Poeciliidae) among five habitats in a large tank. Our study differed from previous investigations of ideal free distributions in the larger number of habitats available, the presence of resource-free zones between habitats, the visual isolation of the different habitats, the availability of resources over an entire day rather than a short feeding period, and the systematic variation of a potential cost component (low oxygen). In our system, the ideal free distribution model was a poor predictor of fish distributions. Although the proportion of fish in a habitat was positively correlated with food supply, there were too few fish where the food supply was high and too many fish where the food supply was low to equalize average feeding rates in all habitats. The proportion of fish in a habitat was not affected by oxygen concentration, whether food was limited or superabundant. Large, stable differences in density occurred between habitats receiving identical treatments. Time spent by the fish in sampling alternative habitats and the ease with which some individuals could restrict the access of others to the habitats may have contributed to the failure of the ideal free distribution model. The effectiveness with which guppies use the surface film for respiration under hypoxic conditions may explain the lack of a dissolved oxygen effect. Our study demonstrates the need to understand conditions that promote or hinder the appearance of ideal free distributions before they can be used to predict the relationship between animal density and resource availability in nature.
Hematozoa of marine fish from Ungava Bay and adjacent northwestern Atlantic Ocean
Authors: Khan R. A.
Published: August 2008

Blood of marine fish and gastrointestinal contents of piscivorous leeches from Ungava Bay and northern Labrador were examined for hematozoans and compared with samples taken from southern Labrador during 1982–1983. A limited number of fish from Ellesmere Island in the Canadian Arctic were also examined for hematozoans. Prevalence of trypanosome and piroplasm infections was greater in fish taken from Ungava Bay than in those from northern or southern Labrador whereas hemogregarines infected more fish in the latter area. Similarly, prevalence of trypanosome infections in the leech Johanssonia arctica was correspondingly higher in samples from Ungava Bay and southern Labrador. Two additional species of leeches, Calliobdella nodulifera and Platybdella anarrhichae, from southern Labrador fish, harbored asexual stages of species of Haemogregarina. It is suggested that the prevalence of infections in fish is associated with leech abundance, which is higher in Ungava Bay and off the southern coast of Labrador. Two of 22 fish of two species from Ellesmere Island harbored hemogregarine infections. It is likely that a comprehensive study of hematozoans of arctic fish might provide information on their relationship to species that occur in the subarctic region of the Atlantic and Pacific Oceans.
Can voles (Microtus pennsylvanicus) be poisoned by secondary metabolites of commonly eaten foods?
Authors: Jean Yves , Bergeron Jean-Marie
Published: August 2008

Five of the plant species most commonly eaten by meadow voles (Microtus pennsylvanicus) were tested for toxicity in laboratory conditions. These were timothy (Phleum pratense), bromegrass (Bromus inermis), reed phalaris grass (Phalaris arundinacea), white clover (Trifolium repens), and field horsetail (Equisetum arvense). Diets consisted of Purina Rabbit Lab Chow coated with increasing quantities of plant extracts. All but one diet in this study had no effect on growth or on liver and kidneys weights. The highest dose of reed phalaris grass forage (second growth) increased liver weight significantly, but such concentrations do not correspond to those in the diet of Microtus in nature. Therefore, we conclude that none of the plants tested can be considered to be toxic to voles. Our discussion stresses the importance of plant secondary metabolites particularly when voles are stressed by a nutritional imbalance.
Reproductive biology of the commercial sea cucumber Parastichopus californicus (Stimpson) (Echinodermata: Holothuroidea). I. Reproductive periodicity and spawning behavior
Authors: Cameron J. Lane , Fankboner Peter V.
Published: August 2008

The commercial sea cucumber Parastichopus californicus (Stimpson) has an annual reproductive cycle, with spawning occurring in the late spring through summer within the inland waters of southwestern British Columbia, Canada. The sexes are separate and occur at a 1:1 ratio within the population studied. Ovarian and testicular tubules regenerate and proliferate preceding the spawning season each year. Spawning is partially synchronous and may be mediated by an increase in the intensity and duration of insolation.
Prolonged and burst swimming in anadromous and freshwater threespine stickleback, Gasterosteus aculeatus
Authors: Taylor Eric B. , McPhail J. D.
Published: August 2008

Prolonged and burst, or "fast-start," swimming were measured in anadromous and resident freshwater sticklebacks. In prolonged swimming tests conducted at 5 body lengths/s, anadromous sticklebacks fatigued less easily than freshwater sticklebacks. Anadromous sticklebacks also had larger pectoral fins and less robust bodies than freshwater sticklebacks. At the start of a burst swimming sequence (kinematic stage 1), freshwater sticklebacks curved their bodies more than anadromous sticklebacks, but trailing-edge amplitudes were the same in both forms. During kinematic stage 2, freshwater sticklebacks had greater trailing-edge amplitudes than anadromous fish, but body curvature was the same in both forms. During burst swimming, freshwater sticklebacks attained both higher maximum and mean velocities than anadromous sticklebacks and also travelled a greater distance in the first 50 ms (2.67 vs. 1.98 cm). These results are discussed with respect to differences in habitat and life histories in the two forms of Gasterosteus.
A world review of the ecclesiasticus species group in the genus Typhlodromus Scheuten (Acarina: Phytoseiidae)
Authors: Chant D. A. , Yoshida-Shaul E.
Published: August 2008

A new ecclesiasticus species group in the genus Typhlodromus Scheuten is proposed. The group is characterized primarily by the presence of seta z6 on the podoscutum and setae S2, S4, and S5 on the opisthoscutum. It is composed of 17 species: T. sentus Pritchard and Baker, T. neosentus van der Merwe, T. acanthus van der Merwe, T. sennarensis El Badry, T. parva (Matthysse and Denmark) comb, nov., T. kuzini (Wainstein), T. relenta (Matthysse and Denmark) comb, nov., T. ecclesiasticus De Leon, T. scytinus Chazeau, T. prunusus van der Merwe, T. yokogawae Ehara and Hamaoka, T. operantis (Chaudhri) comb, nov.,T. loricatus (Wainstein) comb, nov., T. bregetovae (Wainstein and Beglyarov) comb, nov., T. neosoleiger Gupta, T. ignavus (Chaudhri) comb, nov., and T. niloticus El Badry. Typhlodromus vitreus (Chaudhri) comb. nov. is designated as a junior synonym of T. bregetovae. Two species, T. ignavus and T. niloticus, are designated as "species inquirendae" because of insufficient information on their characteristics. Various generic concepts relating to the species in this group are reviewed. The group is described and a key to adult females and descriptions of each species are provided.
A revision of the Nearctic species of the genus Pullimosina (Diptera, Sphaeroceridae)
Authors: Marshall S. A.
Published: August 2008

The genus Pullimosina Roháček is revised to include 13 Nearctic species in the 2 subgenera Pullimosina s. str. And Dahlimosina Roháček. Pullimosina yukonensis, P. hirsutiphallus, P. geminata, P. mcalpinei, P. umphreyi, P. vockerothi, P. woodi, and P. zayensis spp. n. are described as new. Pullimosina dahli (Duda), P. antennata (Duda), and P. pullula (Zetterstedt) are newly recorded from North America. Leptocera rara Spuler and Leptocera opacella Richards are placed into synonymy with P. heteroneura (Haliday). A key to the Nearctic subgenera and species of Pullimosina is provided, and their phylogenetic relationships are discussed.