bluuebunny/crossref_metadata_2025 huggingface dataset:
Myxobolid parasites (Myxozoa: Myxobolidae) infecting fishes of western Montana, with notes on histopathology, seasonality, and intraspecific variation
Authors: Mitchell Lawrence G.
Published: March 2009

Cypriniform and salmonid fishes of the Columbia River drainage of western Montana harbor five members of the myxozoan family Myxobolidae. Myxobolus muelleri inhabits Ptychocheilus oregonensis (northern squawfish), Mylocheilus caurinus (peamouth), Richardsonius balteatus (redside shiner), and Catostomus macrocheilus (largescale sucker). Cysts appeared in gills, musculature, subcutis, and visceral mesenteries. Unencysted spores infiltrated mesenteries and viscera. Spore size and shape in the various tissues and hosts were highly varied. Muscle and subcutaneous cysts were associated with connective tissue proliferation and muscle degeneration; cyst rupture was associated with diffuse inflammation and rodlet cell proliferation. Infection prevalence in muscles and kidneys was high in adult and juvenile hosts (78–100%) throughout the year. Seasonal prevalence of gill and subcutaneous infections fluctuated markedly. Cysts of Myxobolus dujardini occurred in gills of the northern squawfish, peamouth, and redside shiner. Unicauda sp. was found in the eye capsule, gall bladder, mesenteries, and kidney of northern squawfish. Henneguya zschokkei occurred in intermuscular connective tissue of Prosopium coulteri (pygmy whitefish) and Prosopium williamsoni (mountain whitefish). Myxobolus sp. occurred in the gills of Catostomus catostomus (longnose sucker).
The effects of five fish anaesthetics on acid–base balance, hematocrit, blood gases, cortisol, and adrenaline in rainbow trout
Authors: Iwama George K. , McGeer James C. , Pawluk Mark P.
Published: March 2009

Some physiological aspects of five fish anaesthetics in rainbow trout were investigated. The effects of benzocaine, 2-phenoxyethanol, MS-222 (Sandoz), metomidate, and carbon dioxide gas (CO2) on acid–base regulation, hematocrit, blood gases, and cortisol and adrenaline concentrations were determined in resting rainbow trout fitted with chronic catheters in the dorsal aorta. A severe hypoxia developed with the cessation of breathing in deep anaesthesia. This was accompanied by a rise in blood [Formula: see text] and adrenaline concentration, and a fall in blood pH. Blood bicarbonate concentrations remained unchanged and cortisol concentrations declined with time. There was a transient increase in hematocrit coinciding with the increase in adrenaline concentrations.
A limpet shell shape that reduces drag: laboratory demonstration of a hydrodynamic mechanism and an exploration of its effectiveness in nature
Authors: Denny Mark
Published: March 2009

As the velocity of flow increases, smooth, symmetrical objects such as spheres and cylinders exhibit an abrupt transition from a laminar to a turbulent boundary layer. As a consequence, these shapes experience a substantial reduction in fluid-dynamic drag at velocities above the transition. The possibility was explored that this form of drag reduction operates in benthic marine organisms, and a single individual limpet has been found that exhibits the phenomenon in a laboratory flume. When the limpet's anterior end is oriented upstream, the shell shows a sudden 40% reduction in drag at a water velocity of 1.6 m/s, a velocity that is commonly encountered on wave-swept shores. It is unlikely, however, that this drag-reduction mechanism operates effectively under field conditions because flow is often from a direction inappropriate for drag reduction and the presence of upstream objects can abolish the effect. Furthermore, drag is much less likely to act as an agent of disturbance than is lift, so any reduction in drag is unlikely to enhance survivorship. The likelihood that drag reduction via an abrupt boundary-layer transition is ineffective under natural conditions may help to explain why many benthic organisms do not have "typical" low-drag shapes.
Fetal growth of Northwest Atlantic harp seals, Phoca groenlandica
Authors: Stewart R. E. A. , Stewart B. E. , Lavigne D. M. , Miller G. W.
Published: March 2009

Reproductive organs, fetuses, and newborn pups of Northwest Atlantic harp seals (Phoca groenlandica) were collected from 1977 to 1984. These data were used to describe development and fetal growth in terms of biomass and energy, and to estimate the timing of gestational events. The mean pupping date in the Gulf of St. Lawrence was March 2. After the pups were weaned, females mated and conceived around March 12–14. Suspended development of the embryo lasted until early June and implantation took place in August. Fetal mass was more useful in assessing fetal growth than were linear body measurements because it could be used for a greater range of fetus sizes and had lower variance. After implantation, fetuses grew approximately 0.10 g⅓∙d−1 until they were born the following March. Caloric content and caloric density of the fetus increased during active gestation. Caloric density increased most in the last 2 months, which is consistent with an increased deposition of lipids.
Interaction between effects of low pH and low ion concentration on mortality during early development of medaka, Oryzias latipes
Authors: Chulakasem Weerawan , Nelson Jay A. , Magnuson John J.
Published: March 2009

Eggs and fry of medaka, Oryzias latipes, were incubated continuously from shortly after fertilization until 7 days after hatching using a factorial design with four water conductivities (9, 16, 28, and 49 μS/cm) and four pH levels (4.2, 4.5, 5.6, or 6.6). Results on survival suggest that only during hatching can independent effects of pH and ionic strength be statistically separated. Mortalities of encapsulated embryos and fry were determined by interactions between pH and ionic strength. Sensitivity to dilute, low pH water was greatest in freshly fertilized eggs and 1- to 4-day-old fry. Egg mortality occurred within a day after water hardening, whereas fry mortality occurred more gradually over the 3 days following hatching. Dilute, low pH water did not influence oxygen consumption or calcium content of eggs, yet impeded normal developmental increases in both calcium content and metabolic rate in fry. Results are discussed mechanistically with respect to causes of the mortality, and two explanatory models are proposed. Speculation that patterns of interaction in multivariate analyses can be indicative of physiological mechanisms also is entertained.
Ulcers associated with larval Anisakis simplex B (Nematoda: Ascaridoidea) in the forestomach of harbour porpoises Phocoena phocoena (L.)
Authors: Smith John W.
Published: March 2009

Anisakis simplex B larvae and adults occurred in the forestomach of 7 of 10 Phocoena phocoena found drowned in cod nets in the winters (November–January) of 1977–1978, 1980–1981, 1981–1982, and 1983–1984, along the Scottish east coast. A cluster of third- and fourth-stage larvae was found in one large, crater-like ulcer in the wall of the ventral "hemisphere" of the forestomach in five porpoises. A sixth infected animal had one large ulcer bearing a larval nematode cluster, plus, at a separate site in the ventral hemisphere, an aggregation of six very small ulcers, three of which contained larvae. The remaining infected porpoise harboured a large multiple ulcer at a single site in the ventral hemisphere, each of its five craters bearing a cluster of larvae. Adult male and female nematodes were apparently "free" in the forestomach lumen. One third-stage larva of Contracaecum sp. was the only other parasite found in the gastrointestinal tract of the 10 porpoises. Whiting (Merlangius merlangus) was the dominant prey item, and may have been the source of A. simplex B infection.
Two new species of soil moss eutardigrades (Tardigrada) from Canada
Authors: Manicardi Gian Carlo
Published: March 2009

Two new species of Tardigrada, Macrobiotus bondavallii and Isohypsibius bertolanii, from a soil moss sample taken from a pine forest near Whitehorse (Yukon Territory, Canada) are described. Some environmental–morphological relationships in soil-dwelling tardigrades are considered.
Effect of pinealectomy on the testicular response of the freshwater snake Natrix piscator to different environmental factors
Authors: Haldar C. , Pandey R.
Published: March 2009

The effects of different humidity, photoperiod, and temperature regimes on the testicular function of the tropical water snake Natrix piscator were investigated in both sham-operated and pinealectomized snakes. Moderate humidity (50 ± 5%) had no effect on the testis, but high humidity (85 ± 5%) increased the testicular weight and activity of sham-operated snakes after 3, 6, and 9 weeks. Exposures to 14L:10D or 24L:0D and high temperature (42 ± 2 °C) inhibited testicular weight and activity in sham-operated snakes, whereas exposure to 10L:14D or 0L:24D and a low temperature (20 ± 2 °C) had no effect. Pinealectomized snakes did not respond to any of these experimental conditions, but their testicular weight remained the same as that of the pinealectomized controls under natural environmental conditions. The pineal gland showed an opposite response to that of the testes. Pineal gland weight decreased under high humidity and increased under 14L:10D, 24L:0D, and high temperature. These findings suggest that the ecofactors humidity, photoperiod, and temperature play a role in the regulation of testicular function in this snake, and that the pineal gland is implicated in the mediation of these factors.
Mating increases the synthetic activity of the neurosecretory caudodorsal cells of Helisoma duryi (Mollusca: Pulmonata)
Authors: Mukai S. T. , Saleuddin A. S. M.
Published: March 2009

In Helisoma duryi, virgin snails lay significantly fewer eggs than mated snails. It is generally accepted that in basommatophoran pulmonates, the neurosecretory caudodorsal cells located in the cerebral ganglia produce a hormone that regulates egg laying. The synthetic activity of the caudodorsal cells in Helisoma has been measured in vitro and in vivo using tritiated leucine. Virgin and castrated snails (reproductively inactive) showed significantly reduced levels of [3H]leucine incorporation compared with first-mated snails (24 and 48 h postmating). This increase in synthetic activity following mating was corroborated by autoradiography at the light microscope level which localized transport of caudodorsal cell neurosecretory proteins to the cerebral commissure, the neurohaemal area. Mating triggers an increase in synthetic activity of the caudodorsal cells.
Travel in alpine terrain: energy expenditures for locomotion by mountain goats and bighorn sheep
Authors: Dailey Thomas V. , Hobbs N. Thompson
Published: March 2009

We used indirect calorimetry to measure energy expenditure for locomotion by three mountain goats (Oreamnos americanus) and five bighorn sheep (Ovis canadensis) in response to variation in level of activity, slope of travel, and snow conditions. The energetic increment of standing over lying averaged 26% for the two species. We could detect no difference between species in the net cost of travel on level surfaces [Formula: see text]. Energy expended by bighorn sheep and mountain goats for lifting 1 kg of body weight one vertical metre on a 21.5° slope (ca. 37 J/(kg∙m)) exceeded the highest cost documented for quadrupeds. Energy expended walking down a 21.5° slope exceeded energy expenditure for horizontal locomotion, or was recovered inefficiently (ca. 25% recovery of potential energy). The relative increase in the net cost of locomotion in snow achieved an asymptote when sinking depth exceeded 1.2–2.0 times brisket height. The slope of the relative increase in the net cost of locomotion as a function of sinking depth/brisket height was lower for mountain goats than for any North American ungulate studied to date. Consequently, mountain goats were less efficient than other species when snow was shallow, but were more efficient when it was deep. We explain this result on the basis of interspecific differences in locomotory behavior and foot loading.
Feeding performance in aquatic postmetamorphic newts (Urodela: Salamandridae): Are bidirectional flow systems necessarily inefficient?
Authors: Miller Brian T. , Larsen Jr. John H.
Published: March 2009

There are two basic designs of suction-feeding mechanisms in aquatic salamanders. Premetamorphic salamanders use a unidirectional flow system in which water is drawn into the mouth anteriorly and expelled posteriorly through the gill slits. Postmetamorphic salamanders use a bidirectional flow system in which water enters and then exits through the mouth. It has been suggested that bidirectional flow results in an inefficient feeding mechanism. To test this hypothesis, we compared the structure of the feeding system and the proficiency of aquatic prey capture among postmetamorphic individuals from (i) predominantly terrestrial (Tylototriton verrucosus), (ii) amphibious (Pleurodeles waltl, Cynops pyrrhogaster, Notophthalmus viridescens, Taricha granulosa, and Paramesotriton hongkongensis), and (iii) aquatic (Pachytriton brevipes) species of newts (family Salamandridae). Ossification of the hyolingual skeleton, size of the labial lobes, and taper of the snout increase with increasing preference for an aquatic habitat. All species studied except T. verrucosus captured prey in water. Feeding efficiency was similar among all the amphibious species; each was highly successful at capturing immobile prey (90–98%), successful at capturing mobile prey (40–58%), and less successful at capturing evasive prey (18–23%). Fully aquatic P. brevipes was highly successful in taking immobile (100%) and mobile (90%) prey and successful at capturing evasive prey (65%). We attribute the superior feeding performance of this newt to several morphological specializations of its feeding system, including a strongly tapered snout and greatly enlarged labial lobes. We reject the hypothesis that bidirectional flow is always inefficient for prey capture by metamorphosed salamanders. The degree of feeding proficiency in water is influenced by the morphological and behavioral attributes of aquatic salamanders, rather than just by the presence or absence of gill slits and, hence, by unidirectional flow.
Adaptive, genetically based differences in life history between estuary and freshwater threespine sticklebacks (Gasterosteus aculeatus L.)
Authors: Snyder Randal J. , Dingle Hugh
Published: March 2009

Life history theory predicts that migratory fishes should delay reproduction, be larger at maturity, and have higher fecundities than nonmigrants. We tested this hypothesis by comparing life histories of laboratory-reared estuary and freshwater threespine sticklebacks (Gasterosteus aculeatus L.) from the Navarro River, California. We also estimated phenotypic correlations and genetic variance (broad-sense heritabilities) for reproductive characteristics of these fish. The more migratory estuary sticklebacks delayed reproduction, were larger at first reproduction, and had higher fecundities than the freshwater fish. We found no significant differences in interclutch interval or average size of eggs. The body size – fecundity relationship did not differ among these populations, unlike the findings in previous reports comparing anadromous and freshwater threespine sticklebacks. We found significant levels of genetic variance for age and size at first reproduction in both populations, and for fecundity in the freshwater population. The estuary and freshwater sticklebacks did not differ in average number of fin rays, gill rakers, or lateral plates, indicating that differentiation in life history has not been accompanied by significant changes in these characteristics. These results provide evidence of genetic divergence between these populations with respect to life histories, and the nature of these differences suggests that adaptation to different migratory life-styles has occurred.
The Coccidia (Apicomplexa: Eimeriidae) of Testudines, with descriptions of three new species
Authors: McAllister Chris T. , Upton Steve J.
Published: March 2009

Three new species of Coccidia (Apicomplexa: Eimeriidae) are described from turtles in Texas, U.S.A. Oocysts of Eimeria texana sp.n. were found in 2/8 (25%) Texas cooters, Pseudemys texana, and are bent-cylindrical or elongate, 20.5 × 8.4 (17.6–23.2 × 7.2–9.0) μm (mean, range), with a smooth, thin, single-layered wall. A micropyle is absent but an oocyst residuum and polar granule are present. Sporocysts are ovoid, 8.1 × 4.7 (7.0–8.8 × 4.0–5.4) μm, with a Stieda body and sporocyst residuum. Oocysts of Eimeria cooteri sp.n. were recovered from 3/8 (37.5%) Pseudemys texana and are ellipsoid or bent-cylindrical, 25.9 × 10.9 (22.6–28.0 × 9.6–12.8) μm, with a single-layered wall. A polar granule and oocyst residuum are present but a micropyle is absent. Sporocysts are elongate, 14.9 × 5.3 (12.8–16.0 × 4.8–6.6) μm, with an elongate Stieda body capped by tiny knob-like thickenings and covered by a thin membrane; sporocyst residuum present. Oocysts of Eimeria stylosa sp.n. were harbored by 2/16 (12.5%) red-eared sliders, Trachemys scripta elegans, and are ovoid, 16.5 × 13.1 (14.4–17.6 × 12.0–14.4) μm, with a single-layered wall. Each end of the oocyst bears conical projections ca. 4.0 μm long. A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are ellipsoid, 11.1 × 5.8 (9.6–14.4 × 5.4–7.2) μm, with a small Stieda body and sporocyst residuum. A table of the more than 30 species of Coccidia of turtles is presented.
Structure, ultrastructure et essai d'interprétation fonctionnelle de l'appareil génital femelle d'Hemidiaptomus ingens provinciae et de Mixodiaptomus kupelwieseri (Copepoda, Calanoida). II. L'aire génitale
Authors: Cuoc Corinne , Arnaud Jean , Brunet Michel , Mazza Jacques
Published: March 2009

The genital area in Hemidiaptomus ingens provinciae and Mixodiaptomus kupelwieseri is made up of several external and internal solidary cuticular components, which connect the genital ducts with the outside. Its outer part, which is located on the ventral side of the genital segment, is delimited by an ovoid cuticular fold and by two swelling processes, one dorsal and the other ventral. The center is occupied by two operculums, which are separated from a median wall by two crescent-shaped genital apertures. The inner part of the area essentially includes two U-shaped ducts by which the oviducts are connected to the genital apertures. During egg laying, to allow oocytes and oviductal secretions to be carried out through the genital apertures, the ducts take a more or less circular section, owing to the contraction of muscles attached to their wall. At this stage, the genital area is entirely masked by a temporary external seminal receptacle. The genital area assumes a double function in reproduction: first, in stocking spermatozoa in the seminal receptacle, and second, in allowing oocyte laying and fecondation as they are pushed into the ovisac.
Reversal of apparent feeding preferences of bumble bees by aggression from Vespula wasps
Authors: Thomson James D.
Published: March 2009

In field experiments, the nectar and pollen levels of Aralia hispida inflorescences were independently manipulated. In the absence of Vespula spp., Bombus spp. workers (the primary pollinators) appeared to prefer nectar-enriched inflorescences, learning their locations and visiting them at a higher rate, but did not respond to variation in pollen. In the presence of Vespula, however, Bombus appeared to prefer inflorescences with more pollen, showing no response to nectar variation. Vespula responded strongly to nectar level, aggressively patrolling the nectar-enriched plants and preventing Bombus from feeding.
Preliminary findings of restriction fragment differences in mitochondrial DNA among killer whales (Orcinus orca)
Authors: Stevens Tracy A. , Duffield Deborah A. , Asper Edward D. , Hewlett K. Gilbey , Bolz Al , Gage Laurie J. , Bossart Gregory D.
Published: March 2009

A preliminary assessment of mitochondrial DNA restriction patterns in the killer whale (Orcinus orca) was conducted using 10 captive North Atlantic killer whales from the southeastern coast of Iceland, a captive-born offspring of one of these whales, and 9 North Pacific killer whales. No restriction pattern variation was seen among these whales, using the enzymes BamH I, Bgl II, Hinf I, Kpn I, or Pvu II. Restriction pattern variation was found using the enzyme Hae III. This restriction endonuclease distinguished the North Atlantic killer whales (type 1) from the North Pacific killer whales. The North Pacific killer whales were further differentiated into two groups: those originating from the "resident" communities of the Vancouver Island region (type 2), and those from the "transient" community of Vancouver Island, as well as those stranded along the Oregon coast (type 3). The observed Hae III restriction pattern differences suggest that mitochondrial DNA analysis will be a valuable technique for investigating regional and local distributions of maternal lineages among killer whale pods, especially in the North Pacific.
Aspects of the phytogeny of the Trematoda Rudolphi, 1808 (Platyhelminthes: Cercomeria)
Authors: Brooks Daniel R. , Bandoni Susan M. , Macdonald Cheryl A. , O'Grady Richard T.
Published: March 2009

Systematic analyses of various familial- and suprafamilial -level groups of trematodes are evaluated using phylogenetic systematic methods, and the results are compared with previous phylogenetic systematic studies of the major trematode groups. Within the Aspidobothrea, the Aspidogastridae and Multicalycidae are sister-groups, the Stichocotylidae is the sister-group of those two, and the Rugogastridae is the sister-group of those three, based on a suite of 15 morphological characters with a consistency index of 84.6%. No autapomorphy is yet known for the Multicalycidae. Characters newly considered within the digeneans produced the following modifications in the phylogenetic systematic analysis presented by D. R. Brooks, R. T. O'Grady, and D. R. Glen (1985. Can. J. Zool. 63: 411–443): (i) the fellodistomes are a paraphyletic assemblage within the superfamily Gymnophalloidea, order Strigeiformes: (ii) the Campulidae is transferred to the suborder Acanthocolpata, order Plagiorchiformes, from the superfamily Fascioloidea, order Echinostomatiformes; (iii) the suborder Troglotrematata is the sister-group of the Renicolata plus the Plagiorchiata; (iv) the Plagiorchiata is divided into two infra-suborders: the possibly paraphyletic Plagiorchiatea plus the Opecoelatea, including the superfamilies Opecoeloidea and Microphalloidea; (v) the superfamily Telorchioidea includes the Ochetosomatidae and Telorchiidae but not the Urotrematidae. Characters used by authors in critiques of other portions of the phylogenetic tree support rather than conflict with the tree when analyzed phylogenetically. Aspidobothreans appear to have been associated primitively with chondrichthyans, with host-switching to teleosts and turtles in the Aspidogastridae. Digeneans appear to have been primitively associated with the sister-group of chondrichthyans, the stem group leading to all the rest of the gnathostomous vertebrates. The plesiomorphic life cycle pattern for trematodes appears to be the mollusc–vertebrate two-host cycle. Because complex life cycle ecology evolved before the complex developmental programs in digeneans the evolution of digeneans occurred under conditions of conservative ecology and innovative ontogeny.
Observations on gray whale (Eschrichtius robustus) utilization patterns in the northeastern Chukchi Sea, July–October 1982–1987
Authors: Clarke Janet T. , Moore Sue E. , Ljungblad Donald K.
Published: March 2009

A total of 821 gray whales were seen during aerial surveys in the northeastern Chukchi Sea from July through October 1982–1987. Gray whale distribution extended from south of Point Hope to northeast of Point Barrow, Alaska, between 0.5 and 166 km offshore. Monthly abundance estimates (number of whales/survey hour) were highest in July (6.81) and lowest in October (0.40). Gray whales were usually in open water (82%, n = 670) or in light ice (16%, n = 134) and were seldom associated with heavy ice (2%, n = 17). Most whales were feeding (63%, n = 514), with the majority of the others swimming and diving (24%, n = 193) or forming part of a cow–calf association (9%, n = 72). One group of three whales was involved in sexual activity. Feeding whales were seen most often within 40 km of the shore, but also occurred offshore. Thirty-six gray whale calves were seen. Calf abundance (number of calves/survey hour) was significantly higher (p < 0.001) in July, when 92% (n = 33) of all calves were seen, than in any other month. Most cow–calf pairs were seen nearshore between Point Hope and Point Barrow. Monthly calf ratios (number of calves/number of whales) ranged from 0.09 in July to 0.00 in October, with an overall rate of 0.04.
Polymorphism in opioid modulation of the thermal responses of the land snail Cepaea nemoralis
Authors: Kavaliers Martin
Published: March 2009

The shell color and banding polymorphism of the land snail Cepaea nemoralis has been the subject of numerous ecological studies. Evidence is presented in this paper that differences in opioid modulation of thermal responses are associated with this shell polymorphism. It is shown that the effects of the prototypic opiate agonist, morphine, and prototypic antagonist, naloxone, on the aversive thermal ("nociceptive") responses of Cepaea vary with shell banding pattern and thermal micro-habitat. Of the three morphs examined, the shell type (yellow unbanded) with the highest basal response latency and morphine-induced "analgesia" was present at the warmest environmental temperatures, the shell type (yellow two-banded) with an intermediate basal response latency and morphine-induced analgesia was at sites of intermediate temperature, and the shell type (yellow five-banded) with the shortest response latency and lowest morphine sensitivity was present in the coolest micro-habitats. It is suggested that these differences in opioid modulation of thermal responses may contribute to the polymorphic thermal responses of natural populations of Cepaea.
Summer zooplankton distributions at the surface of the outer Bay of Fundy, eastern Canada
Authors: Brown R. G. B. , Gaskin D. E.
Published: March 2009

Copepods and cladocerans were collected, mainly in August, from the top 0.25 m of the water column in the outer Bay of Fundy, off Brier Island, Nova Scotia (ca. 44°15′N, 66°23′W) in 1975–1978, Deer Island, New Brunswick (ca. 45°00′N, 67°00′W) in 1977–1978, and Grand Manan Island, New Brunswick (ca. 44°40′N, 66°43′W) in 1981. In 1975–1977, the dominant species at the surface off Brier Island were stage CIV-I Calanus finmarchicus and CVI-V Pseudocalanus sp. The copepods Acartia spp., Anomalocera pattersonii, Centropages sp., Eurytemora spp., and Oithonia similis and the cladocerans Evadne sp. and Podon sp. also occurred regularly. The relative abundance of Calanus finmarchicus declined during the period July–October 1976, though the proportion of stages CVI-V increased. The relative proportions of Pseudocalanus sp., and of its stages CVI-V, both declined during the same period. The community at the surface was similar to that collected in other studies from subsurface tows in the Bay of Fundy as a whole, including Brier, Deer, and Grand Manan islands. This was not true of Brier Island in 1978: CVI-V Calanus finmarchicus predominated, and other species were scarce. Our samples from Deer and Grand Manan islands resembled those from Brier Island in 1978, though CVI-V Calanus finmarchicus predominated even more strongly. We discuss the differences between our samples from Brier Island in 1978 and 1975–1977, and between the latter and our New Brunswick data. However, there is no obvious explanation for most of these anomalies.
Paternal care in captive collared lemmings (Dicrostonyx richardsoni) and its effect on development of the offspring
Authors: Shilton Cathy M. , Brooks Ronald J.
Published: March 2009

We examined parental care in captive collared lemmings (Dicrostonyx richardsoni) to determine how this behavior differed between sexes and to test the hypothesis that presence of the male with the litter from parturition to weaning (17 d) would affect preweaning rates of growth, behavioral development, and body size and aggression at sexual maturity. Also, we tested whether stressing the litter, by removal of the female for 8 h/d, would alter the effect of the male on the development of pups. We compared four treatments: pups raised with mother only, pups raised with both parents, stressed pups raised with mother only, and stressed pups raised with both parents. Parental behavior was recorded from parturition to weaning. Preweaning development of pups was measured by rate of weight gain, age of eye opening, and development of thermoregulation and righting ability. Comparisons were made between stressed and unstressed litters raised with or without the sire. At 25 d, pups were weighed again and isolated, and at 60–75 d, their intrasexual aggressive behavior was measured. Presence of the sire did not alter behavior of the dam, and except for lactation, males and females cared equally for the pups. At weaning, stressed pups weighed less than unstressed pups, but this difference disappeared by 25 d. Presence of the sire had no effect on aggression of male or female offspring at 75 d. We concluded that the paternal care shown in this species is either an artifact of laboratory conditions or that it has effects, such as protection of offspring from infanticide or alleviation of thermal stress, that were not examined in this study.
The kinematics of larval salamander swimming (Ambystomatidae: Caudata)
Authors: Hoff Karin vS. , Huq Nisar , King V. Ann , Wassersug Richard J.
Published: March 2009

We studied the kinematics of straightforward, constant velocity swimming in larval Ambystoma mexicanum and Ambystoma maculatum. The larvae were filmed at 200–320 frames/s and their filmed images were digitized for computer analysis. The maximum sustainable velocity we recorded was 18.7 lengths/s, which compares favorably to the maximum speed reported for similarly sized anuran larvae. The Ambystoma, however, differed greatly from tadpoles in the form of the propulsive wave in their bodies. Specifically, the maximum amplitude at the tail tip, at swimming speeds >6 lengths/s, was exceptionally high, exceeding 30% of body length; at high speed, the position of minimum amplitude was well posterior to the otic capsules and produced considerable yaw at the head; and the length of the propulsive wave in the body shortened as speed increased. All of these features characterize poor mechanical efficiency during constant velocity swimming, and indeed two measures of efficiency (propeller efficiency and stride length) confirmed the locomotor superiority of tadpoles and sub-carangiform fishes to Ambystoma larvae. The drag induced by exposed gills and limbs may account in part for the inferior performance of the salamanders. Ambystoma larvae are designed for anguilliform movement among the rocks and vegetation of the substrate, and for high acceleration over short distances, such as those used during a lunge at prey. The mechanical inferiority of Ambystoma larvae during sustained, constant velocity swimming is consistent with their microhabitat shift away from open water situations in the presence of subcarangiform fishes.
Sperm masses and sperm transfer in a vestimentiferan, Ridgeia piscesae Jones, 1985 (Pogonophora: Obturata)
Authors: Southward Eve C. , Coates Kathryn A.
Published: March 2009

Discrete sperm masses, of irregular outline, 2–5 mm in their maximum dimension, were found on males and females of Ridgeia piscesae Jones, 1985 (Pogonophora: Obturata), hydrothermal vent tube worms from the Juan de Fuca and Explorer Ridges in the eastern North Pacific Ocean. Masses were found in tentacular and vestimental locations, often near the gonopores. The fine structure and size of spermatozoa from inside males are the same as in the masses and are distinctly different from described spermatozoa of perviate pogonophores. Maturation of the spermatozoa appears to be completed within the external sperm mass, after spawning. The sperm masses produced by males may be actively transferred to adjacent females of the densely aggregated animals found at the vent sites. In the females, these masses come to rest near the gonopores where fertilization may occur, just internal or external to the pores.
Diving and foraging behavior of leatherback sea turtles (Dermochelys coriacea)
Authors: Eckert Scott A. , Eckert Karen L. , Ponganis P. , Kooyman G. L.
Published: March 2009

Remote time–depth recorders (TDR) were deployed on six gravid leatherbacks nesting on Sandy Point, St. Croix. Dive behavior was monitored continuously for each turtle during internesting intervals ranging from 9 to 11 days. Dive duration averaged 9.9 min/dive (SD = 5.3, n = 5096); mean depth was 61.6 m (SD = 59.1, n = 5096). One turtle dived twice beyond the range of her TDR to depths we estimate >1000 m. Postdive surfacing intervals averaged 4.9 min/dive (SD = 13.1, n = 5090). Differences in mean dive depth, dive duration, and surface intervals among turtles were not attributable to differences in body size (length or mass). Distinct diel periodicity was observed in dive behavior; submergence intervals were longest at dawn, declined throughout the day, and were shortest at dusk. Night dives (19:00–04:59) were shorter, shallower, and more frequent than day dives (05:00–18:59). Dive depth was less variable at night than during the day. The dive pattern suggests nocturnal foraging within the deep scattering layer, a hypothesis that is corroborated by seasonal weight loss data.
The phenology and social biology of four sweat bees in a marginal environment: Cape Breton Island
Authors: Packer Laurence , Jessome Vincent , Lockerbie Cathy , Sampson Blair
Published: March 2009

Augochlorella striata, Lasioglossum (Evylaeus) cinctipes, Lasioglossum (Evylaeus) comagenense, and Lasioglossum (Dialictus) laevissimum were studied on Cape Breton Island, Nova Scotia, throughout their flight season in 1987. The weather during the summer was unusually good, with above-average temperatures and hours of sunshine but very low rainfall. Conversely, the previous summer had been very poor for bees, with comparatively few days suitable for foraging, particularly in July. Augochlorella striata was basically solitary but some nests produced one or, at most, two workers, thereby becoming eusocial. In other localities, L. cinctipes is known to be eusocial with well-developed morphological and physiological caste differentiation. However, most foundresses observed in 1987 were extremely small, smaller than usual for workers elsewhere, and none of the more than 100 nests produced adult workers or a reproductive brood. Most foundresses were either survivors of the worker brood from the previous year or unusually small reproductive brood females produced as a result of the bad weather in 1986. Lasioglossum comagenense was solitary or semisocial with one to four females occupying a nest. Lasioglossum laevissimum exhibited significant levels of pleometrosis and an extended period of worker foraging in summer. A comparison of the productivities of these four species indicates the importance of a flexible social system in a marginal climate.
Nucleated red cell function: metabolism and pH regulation
Authors: Boutilier Robert G. , Ferguson Ralph A.
Published: March 2009

The full extent and apportionment of aerobic and anaerobic contributions to energy transduction for membrane pumps associated with cellular pH regulation are very poorly understood. One way of approaching this problem at the cellular level is by using the nucleated erythrocyte as a model cell. Indeed, the aerobic and anaerobic capacity of salmonid erythrocytes and their β-adrenergic mediated pH regulation offers a model "pH regulating system" for examining cellular strategies of response to acute and (or) chronic changes in oxygen availability. Much of our work has focused on the balance between metabolic energy production and the maintenance of erythrocytic pH through primarily or secondarily active ionic exchange mechanisms at the cell membrane. Upon adrenergic stimulation, a rise in cyclic AMP activates the Na+–H+ exchanger, leading to cell alkalinization and an elevation of intracellular Na+. The increased Na+ evidently stimulates Na+,K+-ATPase activity and the increased ATP consumption is matched with aerobic energy production. The pHi that is subsequently established appears to be set by levels of poly anionic phosphates.
The importance of metabolism in acid–base regulation and acid–base methodology
Authors: Pörtner Hans-Otto
Published: March 2009

Metabolism not only affects the acid–base status of an animal by means of proton stoichiometries but, by feedback regulation, acid–base parameters (pH, [Formula: see text], bicarbonate) influence metabolic rates and the pathways used. This leads to a significant contribution of metabolism to acid–base regulation under both aerobic and anaerobic conditions. The relationship between amino acid metabolism, urea synthesis, and [Formula: see text] excretion is discussed as an example important for steady-state metabolic acid–base regulation during aerobiosis. Generally, acid–base relevant metabolism may be regulated through the effect of acid–base disturbances on hormonal mediation, allosteric modulation of enzyme proteins, pH optima, and the levels of substrates or products, some of these being acid–base relevant substances like bicarbonate, CO2, inorganic phosphate, and NH3. During functional or environmental anaerobiosis the same relationships prevail. Metabolic proton accumulation is counterbalanced by phosphagen depletion and ammonia accumulation in adenylate catabolism. In addition, in integrated control of metabolic and acid–base status, long-term (mitochondrial) anaerobiosis leads to reductions in metabolic rate and increased removal of acidic groups. The importance of metabolic processes in acid–base methodology is discussed in terms of traditional concepts and recent developments.
Interaction between hypometabolism and acid–base balance
Authors: Lutz Peter L.
Published: March 2009

This review discusses the changes in acid–base balance that are produced during hypometabolism and the negative feedback role they play in maintaining the hypometabolic state. In prolonged hypometabolism, air-breathing animals consume internal stores of fat, protein, and carbohydrate, while glycogen is the primary fuel supporting anaerobic hypometabolism. Because the excretory processes are greatly reduced, the accumulation of waste products must be dealt with internally. Mitigating strategies to minimise acid–base disturbance are seen in higher buffer capacities, an acid shift in the pH optima of key enzymes, and the use of metabolic pathways that result in a reduction of net H+ production. In some hibernating animals, gut bacteria may play an important role in preventing [Formula: see text] accumulation. However, the compensatory mechanisms are only partially successful, and substantial alterations in acid–base status and related strong ion changes are common. Changes in intracellular pH have wide metabolic effects but the acid–base and ionic status of the cell is dependent on its energy expenditure. The most vulnerable tissue to reduced metabolism is the brain. The turtle brain can greatly lessen its energy requirements by reducing activity; this is achieved by (i) depression of synaptic transmission, (ii) membrane hyperpolarisation through opening of Cl− channels resulting from release of γ-aminobutyric acid, and (iii) slowing transmembrane ion flux by the selective closure of ion channels. CO2 retention is common in hypometabolic animals. Increased levels of CO2 and H+ and decreased [Formula: see text] can directly cause metabolic depression via a variety of mechanisms, as well as a reduction in neural tissue activity. It is concluded that the hypometabolic state represents a very general condition of temporarily reduced energy expenditure which embraces aestivation, hibernation, torpor, and sleep, and that the common phenomena of CO2 accumulation and consequent changes in acid–base balance play a role in the coordinated reductions in energy expenditure and energy cost.
Regulation of acid and ion transfer across the membrane of nucleated erythrocytes
Authors: Nikinmaa Mikko , Tufts Bruce L.
Published: March 2009

The major pathways for proton transport across the membrane of nucleated erythrocytes are the passive Jacobs–Stewart cycle and the secondarily active sodium–proton exchange. The relative importance of these two pathways in the control of red cell pH depends on the sodium–proton exchange rate and the rate of the slowest step of passive proton equilibration. In cyclostome red cells, which lack anion exchange, intracellular pH is controlled by the sodium-dependent acid–extrusion mechanism. In unstimulated teleost red cells, the Jacobs–Stewart cycle appears to be the most important pathway for the transport of protons across the membrane. Adrenergic stimulation activates sodium–proton exchange. Sodium–proton exchange is able to increase intracellular pH and decrease extracellular pH because the rate of proton transport via the Jacobs–Stewart cycle is limited by the uncatalysed extracellular dehydration of carbonic acid to carbon dioxide. The turnover rate of the adrenergically activated sodium–proton exchange is influenced by pH and oxygen tension. In amphibian red cells, acidification activates sodium–proton exchange. The exchange may limit the changes in intracellular pH after acid–base disturbances.
Acid and ion transfer across the gills of fish: mechanisms and regulation
Authors: McDonald D. G. , Tang Y. , Boutilier R. G.
Published: March 2009

This review examines the mechanisms and regulation of ion and acid transfers across the gills, focussing on freshwater fish. Apical ion-exchange mechanisms (i.e., [Formula: see text] and [Formula: see text] exchange) are shown to play an important though not exclusive role in acid–base transfers. Under some circumstances, for example when either [Formula: see text] or [Formula: see text] but not H+ levels in plasma are elevated, a second mechanism of acid–base transfer then becomes apparent. This mechanism is thought to involve diffusion of acid–base relevant and "strong" ions through paracellular channels. Factors that affect acid–base transfers across the gills include the external [NaCl] and the nature of the acid–base disturbance, the latter being at least as important as the magnitude of the disturbance. Catecholamines are shown to play an important role in the regulation of acid–base transfers across the gills, acting largely through activation of β-adrenergic receptors. Current evidence, nonetheless, suggests that other elements (e.g., α-receptors, adrenergic and cholinergic neurons) may also be involved.
TEMPERATURE DEPENDENT FRACTURE MODEL AND ITS APPLICATION TO ULTRA HEAVY THICK STEEL PLATE USED FOR SHIPBUILDING
Authors: JANG YUN CHAN , LEE YOUNGSEOG , AN GYU BAEK , PARK JOON SIK , LEE JONG BONG , KIM SUNG IL
Published: March 2009

In this study, experimental and numerical studies were performed to examine the effects of thickness of steel plate on the arrest fracture toughness. The ESSO tests were performed with the steel plates having temperature gradient along the crack propagation direction. A temperature dependent crack initiation criterion was proposed as well. A series of three-dimensional FEA was then carried out to simulate the ESSO test while the thickness of the steel plate varies. Results reveal that a temperature dependent brittle criterion proposed in this study can describe the fracture behavior properly.
INVESTIGATION OF FRETTING FATIGUE BEHAVIOR OF TI811 ALLOY AT ELEVATED TEMPERATURE
Authors: ZHANG XIAO-HUA , LIU DAO-XIN
Published: March 2009

The fretting fatigue behavior of the Ti 811titanium alloy, as influenced by temperature, slip amplitude, and contact pressure, was investigated using a high-frequency fatigue machine and a home-made high-temperature apparatus. The fretting fatigue failure mechanisms were studied by observing the fretting surface morphology features. The results show that the sensitivity to fretting fatigue is high at both 350°C and 500°C. The higher the temperature is, the more sensitive the alloy is to fretting fatigue failure. Creep is an important factor that influences the fretting fatigue failure process at elevated temperature. The fretting fatigue life of the Ti 811 alloy does not change in a monotonic way as the slip amplitude and contact pressure increase. This is due to the fact that the slip amplitude affects the action of fatigue and wear in the fretting process, and the nominal contact pressure affects the distribution and concentration of the stress and the amplitude of fretting slip at the contact surface, and thus further influences the crack initiation probability and the driving force for propagation.
PLASTIC DEFORMATION OF POLYMER INTERLAYERS DURING POST-BREAKAGE BEHAVIOR OF LAMINATED GLASS - PARTIM 1: ANALYTICAL APPROACH
Authors: BELIS J. , DELINCÉ D. , CALLEWAERT D. , VAN IMPE R. , DEPAUW J.
Published: March 2009

Transparent polymer interlayer foils are widely used to increase the safety of glass applications, mainly in construction and automotive industry. In case one or more glass sheets in a laminate fracture, the remaining structural capacity (i.e. stiffness and strength) highly depends on the solicitation and mechanical properties of the interlayer. In such a post-breakage state, the interlayer is subjected to a complex combination of phenomena such as partial delamination, large strain deformation, strain hardening, rupture, etc. In partim 1, an analytical model is presented in order to describe the mechanical behavior of glass laminates in post-breakage state for a simple configuration. In addition, the theoretical model is compared to experimental results in part 2, which is published together with part 1.
EFFECTS OF IMPACT VELOCITY AND SLENDERNESS RATIO ON DYNAMIC BUCKLING LOAD FOR LONG COLUMNS
Authors: MIMURA K. , UMEDA T. , YU M. , UCHIDA Y. , YAKA H.
Published: March 2009

In this research, the buckling behavior of long columns under dynamic load was investigated both experimentally and numerically, and an effective buckling criterion for dynamic load was derived from the results in terms of the impact velocity and the slenderness ratio. In the experiments, a free fall drop-weight type impact testing machine was employed. The dynamic buckling loads were measured by the load sensing block, and the displacements were measured by a high speed magnetic-resistance device. In the numerical analyses, dynamic FEM code 'MSC-Dytran' was used to simulate the typical experimental results, and the validity and the accuracy of the simulations were checked. The dynamic buckling loads at various impact velocities were then systematically investigated. From both experimental and simulated results, it was found that the dynamic to static buckling load ratios can be successfully described as a square function of the slenderness ratio of the columns, while they can be also described by a power law of the applied impact velocity.