bluuebunny/crossref_metadata_2025 huggingface dataset:
An analysis of videotape recordings of larval feeding in the sea urchin Lytechinus pictus (Verrill)
Authors: Gilmour T. H. J.
Published: March 2009

Frame-by-frame analysis of videotapes of sea urchin larvae feeding on algal suspensions has shown that most algal cells entering the mouth are captured without reversal of the locomotory cilia. Low concentrations of the calcium blocker verapamil inhibit ciliary reversal without interfering with food capture, providing further evidence that reversals are of little significance in feeding. These observations suggest that the scan and trap theory of food capture does not apply to echinoderm larvae.
Ultrastructure of spermatogenesis and the mature spermatozoon of Haplobothrium globuliforme Cooper, 1914 (Cestoda: Haplobothrioidea)
Authors: MacKinnon Barbara M. , Burt Michael D. B.
Published: March 2009

The process of spermatogenesis and the structure of the mature spermatozoon of Haplobothrium globuliforme Cooper, 1914 were examined using transmission electron microscopy. Spermatogonia have a low cytoplasmic to nuclear volume ratio, and contain numerous free ribosomes and few mitochondria. Quaternary spermatogonia have a rosette appearance with the eight nuclei surrounding a central cytoplasmic cytophore. Spermatocytes, the largest of the developing sperm cells, contain free ribosomes and several mitochondria with pronounced cristae. No synaptonemal complexes and few endoplasmic reticulum formations were seen. Early spermatids show a regular arrangement of the nucleus, Golgi apparatus, and mitochondria. This regularity is disrupted as spermiogenesis commences, with the formation of the zone of differentiation, a conical indentation of the spermatid cytoplasm. This zone of differentiation is bordered by microtubules. Within the zone develop two interconnected basal bodies with their respective flagellar rootlets. From each basal body arises an axoneme with the 9 + "1" microtubular configuration. The axonomes elongate, eventually fusing with a cytoplasmic extension of the zone of differentiation, and the condensed nucleus migrates into the sperm body. The mature spermatozoon is elongate (30 μm long) and slender, and possesses an electron-dense nucleus, two lateral axonemes, α and β glycogen, and peripheral microtubules. The importance of sperm ultrastructure with respect to phylogeny is discussed.
Revision of the genus Ancyracanthopsis Diesing, 1861 and description of a new genus Molinacuaria n. gen. (Nematoda: Acuarioidea)
Authors: Wong P. L. , Lankester M. W.
Published: March 2009

Ancyracanthopsis Diesing, 1861 is revised and three of its species are transferred to Molinacuaria n. gen. Ancyracanthopsis belongs to the subfamily Schistorophinae and consists of the following species: Ancyracanthopsis coronata (Molin, 1860a), redescribed herein and designated as the type species because the previous one, Ancyracanthopsis bilabiata (Molin, 1860b), is regarded here as a synonym; Ancyracanthopsis petrovi Guschanskaya, 1950; and Ancyracanthopsis buckleyi Ali, 1970. One species, Ancyracanthopsis madagascariensis Kung, 1948, is transferred to Sobolevicephalus madagascariensis (Kung) n. comb. Another, Ancyracanthopsis serrata (Wang, 1966), is transferred back to Sciadiocara to which it was originally assigned, thus becoming Sciadiocara serrata Wang, 1966. Molinacuaria n. gen. is distinguished from Ancyracanthopsis by the presence of grooves at the anterior end. The new genus is regarded as a member of the subfamily Seuratinae and consists of the following species: Molinacuaria bendelli (Adams and Gibson, 1969) n. comb., designated as the type species; Molinacuaria acholonui (Schmidt and Kuntz, 1972) n. comb.; and Molinacuaria gallinulae (Wang, 1966) n. comb. Redescriptions of M. bendelli and M. acholonui are provided.
Variability in behavioural response of wintering black ducks to increased energy demands
Authors: Brodsky Lynn M. , Weatherhead Patrick J.
Published: March 2009

We observed black ducks (Anas rubripes) wintering at three sites differing substantially in food quality (energetic value) and quantity to determine what environmental factor(s) influenced changes in behaviour and whether those changes functioned to balance energy demands with supplies. All behaviours other than preening showed some variation in response to environmental factors, with temperature consistently explaining the greatest amount of that variation. However, the ducks' response to cold temperature was not consistent between sites. For example, at colder temperatures, ducks at one site increased foraging, at another site they decreased foraging, and at the third site foraging remained constant. Apparently, one can only predict the specific response of ducks to increased energetic demands, i.e., colder temperatures, by knowing the quality and quantity of food available in addition to the cost of foraging.
Habitat associations, resources, and predators of an assemblage of Brachinus (Coleoptera: Carabidae) from southeastern Arizona
Authors: Juliano Steven A.
Published: March 2009

Bombardier beetles (Brachinus) at margins of ponds across gradients of elevation and pond permanence were studied to describe habitat associations and resource use and to form hypotheses concerning the ecological factors affecting these beetles. Assemblage composition differed significantly among pond types, with more permanent ponds dominated by Brachinus lateralis, high-elevation temporary ponds dominated by Brachinus mexicanus, and Brachinus javalinopsis and Brachinus lateralis codominant at a low-elevation temporary pond. Brachinus mexicanus was sometimes found at dry temporary pond sites, but none of the other species was ever found at dry sites. These species shared at least two potentially limiting resources: food for adults (carrion and arthropods) and hosts for ectoparasitoid larvae (water beetle pupae). Reproductive phenology, host use, and diets overlapped extensively. Host abundances and host-assemblage composition varied among sites and most hosts went unparasitized. Predation on adults by vertebrates appeared to be very rare. Although some predatory arthropods ate Brachinus in the laboratory, these predators were either rare or ineffective in natural situations.
Digenean (Trematoda) populations in winter flounder (Pseudopleuronectes americanus) from Passamaquoddy Bay, New Brunswick, Canada
Authors: Scott J. S.
Published: March 2009

Examination of monthly samples of winter flounder (Pseudopleuronectes americanus) from Passamaquoddy Bay revealed seven digenean parasites (Genolinea laticauda, Podocotyle atomon, Stenakron vetustum, Fellodistomum furcigerum, Derogenes varicus, Lecithaster gibbosus, and Steganoderma formosum) in the alimentary tract and two metacercariae (Stephanostomum baccatum and Cryptocotyle lingua) in the body surface tissues and gills. Prevalence of alimentary tract parasites ranged from 0.2 in S. formosum to 39.8 in P. atomon and intensity ranged from 1.5 for D. varicus to 7.0 for S. formosum (one fish). Monthly and seasonal levels of prevalence varied: high in spring and autumn and low in summer and winter for most species. Prevalence and length-frequency distributions of the parasites did not support differential migration by size group or diminishing feeding activity from spring to winter in winter flounder, as proposed in other studies.
Ceratomyxa shasta (Myxozoa: Myxosporea) in juvenile chinook salmon (Oncorhynchus tshawytscha): experimental transmission and natural infections in the Fraser River, British Columbia
Authors: Bower Susan M.
Published: March 2009

Ceratomyxa shasta (mainly trophozoites) from the intestinal tract of a naturally infected juvenile chinook salmon (Oncorhynchus tshawytscha) developed in the coelom of laboratory-reared chinook salmon when inoculated intraperitoneally. All developmental stages were observed. Successful subpassages were accomplished by intraperitoneal inoculation of trophozoites and sporoblasts, but an infection did not develop when these stages were pipetted into the esophagus of susceptible fish. Heavy infections, including the presence of C. shasta sporoblasts or spores, were observed in 2 of 28 feral juvenile chinook salmon seined from the Fraser River estuary in late July and early August. Trophozoite-like cells were observed in six other chinook salmon from this group. No C. shasta were observed in 15 juvenile sockeye salmon (Oncorhynchus nerka) caught in the estuary along with the chinook salmon.
Histopathological and electron microscopic studies of gills of brook trout, Salvelinus fontinalis, from acidified lakes
Authors: Chevalier Gaston , Gauthier Laurent , Moreau Guy
Published: March 2009

Histopathological and electron microscopic studies of gill tissue were carried out in brook trout, Salvelinus fontinalis, from wild populations inhabiting three acidified lakes and in others from three nonacidified lakes located in the Canadian Shield (Québec). The acidified lakes were characterized by low pH (5.5), poor buffering capacity, and low conductivity. By comparison with trout from nonacidified lakes, gills of trout from acidified lakes showed extensive epithelial damage, mainly separation of the epithelial layer from underlying tissue, deformation of secondary lamellae, and degeneration of chloride cells, which was accompanied by pronounced hyperplasia of undifferentiated epithelial cells in the primary lamellae. Histopathological changes were quantified by morphometry. Most damaged gills were also shown to contain a higher concentration of aluminum. The observed changes in gill cells and tissues are interpreted as reactions to sublethal environmental conditions adverse to the osmoregulatory balance of the fish, specifically chronic exposure to low pH and low calcium concentrations, possibly combined with a high level of aluminum.
Homing by released captive California sea lions, Zalophus californianus, following release on distant islands
Authors: Ridgway S. H. , Robison C. C.
Published: March 2009

Captive male California sea lions were twice flown to offshore breeding islands and released. Three animals returned to their pen in San Diego Bay after discharge on San Clemente Island, about 115 km away. Two of four returned to the same facility from San Nicolas Island, about 240 km away. The fastest sea lion returned in 2 days from San Clemente and in 4 days from San Nicolas. This is the first evidence for such specific east–west navigation by sea lions and suggests that these animals are good navigators.
Les conséquences de la reconnaissance des contraintes phylogénétiques lors de l'étude évolutive de l'origine des traits
Authors: Chapleau François
Published: March 2009

This study examines the origin and consequences of the disregard of evolutionary biologists towards the historical constraints emerging from phylogenetic studies. An attempt is made to establish the theoretical basis that would allow the integration of these constraints in studies related to the understanding of evolutionary processes responsible for the origin of traits. First, the historical context is defined following the concepts of cladistic methodology. Then the empirical limits intrinsic to the structure of the theory of natural selection are outlined. Extrapolations of this evolutionary process at a historical level are not justifiable because of the impossibility of empirical verification. As a prerequisite for the study of species, it becomes essential to distinguish the autapomorphies (evolutionary novelties) from the plesiomorphies (primitive characters). Only the autapomorphies are potentially open to studies concerned with the ultimate causes related to their origin, since it is possible to gather the relevant data. On the other hand, since the selective pressures now affecting the plesiomorphies are not necessarily the same as those responsible for their origin, and since it is impossible to recreate the historical context in which they have originated, it is preferable that evolutionary biologists refrain from elaborating scenarios pertaining to the origin of those traits. A parallel is made between these two types of features and previous concepts of adaptation and exaptation. An example related to the origin of the "reversed" size dimorphism of the Falconiformes is used to illustrate these theoretical concepts.
Summer–autumn habitat utilization of subyearling steelhead trout in tributaries of the Clearwater River, Idaho
Authors: Johnson James H. , Kucera Paul A.
Published: March 2009

The summer–autumn habitat utilization of 801 subyearling steelhead trout was examined in three tributaries of the Clearwater River, Idaho. During both summer and autumn most subyearling steelhead occupied water depths < 20 cm and mean water velocities < 20 cm/s. Trout were generally associated with gravel and cobble substrates in summer and cobble and boulder substrates in autumn. The transition to larger size substrate materials in autumn from smaller size substrate during summer was significant (p < 0.05) in each stream. Subyearling steelhead generally did not occupy depths, water velocities, or substrate types in proportion to availability and consequently trout were selecting certain habitats. Habitat selection was most pronounced in autumn when no significant differences were observed among streams for the three habitat parameters utilized by steelhead even though available habitat among streams differed significantly in most cases. Substrate size appears to be the most important habitat parameter affecting the autumn habitat utilization of subyearling steelhead trout in Clearwater River tributaries.
A comparison of eastern kingbird breeding biology in lakeshore and upland habitats
Authors: Blancher Peter J. , Robertson Raleigh J.
Published: March 2009

We compared aspects of eastern kingbird (Tyrannus tyrannus) breeding biology between lakeshore and upland habitats in eastern Ontario. Nests were more closely spaced and eggs were laid earlier at the lakeshore than in the uplands. Within the lakeshore habitat, nests were more likely to be placed on small islands (< 0.2 ha) and eggs were laid earlier there than on large islands or the mainland shore. Kingbirds nesting in lakeshore habitat had some advantages: (i) moderated temperatures for nests placed low over water, (ii) more efficient foraging when feeding nestlings, and (iii) faster growing nestlings, relative to upland nestlings. However, upland nests fledged more young than lakeshore nests. Within lakeshore habitat, small island sites had the highest breeding success. With the exception of nest site location, which differed markedly between habitats, differences in breeding biology and behaviour between the two habitats were small. A lack of substrate specificity in foraging, together with an ability to use a range of nest sites, apparently allow kingbirds to nest successfully in a wide variety of habitats.
Morphological relationships among subspecies of the Rufous-collared Sparrow, Zonotrichia capensis
Authors: Handford Paul
Published: March 2009

The phenetic relationships among 22 described subspecies of Zonotrichia capensis, the Rufous-collared Sparrow, are investigated by analyses of variation in six external metric variables taken from over 1500 museum specimens. Both sexes show the same marked dichotomy between two groups of subspecies: pulacayensis, sanborni, antofagastae, chilensis, choraules, and australis versus all others. These six subspecies are from temperate high altitudes and high latitudes and occupy a geographically contiguous region in the southern Andes mountains and Patagonia. Within these two subgroups there is extensive overlap among individuals; finer division of the subspecies is difficult, and involves the association of subspecies from geographically disjunct regions. Thus the taxonomic hierarchy appears to be a poor representation of variation of the characters considered here. The association of geographically disjunct forms suggests that intraspecific variation in these characters reflects the local environment (via selection and (or) environmental effects) rather than historical (genealogical) relationships.
Cyclical growth in juvenile rainbow trout, Salmo gairdneri
Authors: Wagner G. F. , McKeown B. A.
Published: March 2009

The growth rate (weight) of 70 juvenile rainbow trout, monitored on a weekly basis for a period of 4 months, was observed to cycle, with alternating phases of accelerated and reduced growth every 3 to 4 weeks. The significance of this phenomenon is discussed in relation to recent studies on growth physiology in rats.
Rearing of eight species of terrestrial gastropods (order Stylommatophora) under laboratory conditions
Authors: Gray J. B. , Kralka R. A. , Samuel W. M.
Published: March 2009

The snail Triodopsis multilineata (Say) and the slugs Deroceras laeve (Müller) and Deroceras reticulatum (Müller) were successfully reared using inorganic vermiculite as a substrate and carrots and lettuce as food. Discus cronkhitei (Newcomb), Vallonia gracilicosta Reinhardt, Vallonia pulchella (Müller), Vertigo gouldii (Binney), and Zonitoides arboreus (Say) were reared on various types of organic leaf-litter substrates that simulated their natural environments. Triodopsis multilineata was the gastropod most easily reared and maintained.
Modes of entry of first stage larvae of Protostrongylus stilesi and P. rushi (Nematoda: Metastrongyloidea) in the snail intermediate host Vallonia pulchella
Authors: Samson J. , Holmes J. C.
Published: March 2009

First-stage larvae of Protostrongylus stilesi and P. rushi were able to infect the snail Vallonia pulchella both by penetrating the epithelium of the foot, the mantle, and probably the proboscis, and by penetrating the gut mucosa after being ingested by the snail.
Variation in tolerance to low environmental pH by the crayfish Orconectes rusticus, O. propinquus, and Cambarus robustus
Authors: Berrill Michael , Hollett Lois , Margosian Arlene , Hudson Jeff
Published: March 2009

We compared the tolerance of three common Ontario crayfish species to low pH under natural and laboratory conditions in water varying in aluminum concentration and hardness. Both transplant and laboratory experiments indicated that exposure to a pH range of 5.4–6.1 in soft water was toxic to attached juvenile stages of Orconectes rusticus and O. propinquus but not to females carrying the broods. In contrast, stage III juveniles of Cambarus robustus molted and survived in soft water at pH 4. Cambarus robustus is clearly far less sensitive to low pH stress than the two Orconectes species. No increased mortality due to the presence of elevated aluminum occurred among stage III juveniles of the three species exposed to pH 4.5–5.0 in soft water. Physiological differences, augmented by differences in life cycle, may account for the continued presence of C. robustus in acid-stressed lakes and streams.
The evolution of freshwater diversity in the threespine stickleback (Gasterosteus aculeatus): site-specific differentiation of trophic morphology
Authors: Lavin P. A. , Mcphail J. D.
Published: March 2009

To assess interpopulation levels of morphological variability populations of Gasterosteus aculeatus were sampled from lakes within the upper Cowichan River system (Vancouver Island, British Columbia). Phenotypic divergence between populations is assumed to be a postglacial event. Nine characters were scored; eight were related to feeding and the ninth character was lateral plate number. All populations were the low plate morph; however, populations of Gasterosteus in lakes lacking piscivorous fish had significantly fewer lateral plates than populations in lakes with predatory fish species. Two distinct trophic "morphotypes" were identified, each one associated with a specific lake environment. Populations inhabiting benthic-dominated environments were found to possess reduced gill raker number and reduced gill raker length but increased upper jaw length relative to populations from limnetic environments. We propose that the interpopulation variability in trophic morphology is a response to trophic resource differences between lakes.
The influence of external cation concentration on the hatching of amphibian embryos in water of low pH
Authors: Freda Joseph , Dunson William A.
Published: March 2009

Amphibian embryos exposed to water of low pH were killed by two distinct mechanisms. At very low pH levels, embryos stopped development soon after exposure to test solutions. At higher but still lethal pH levels, embryos became curled within a shrunken perivitelline space and failed to hatch (curling defect). The addition of Ca, Mg, and to a lesser extent Na (> 10 mg/L), prevented the early mortality of embryos in acidic water. However, increasing concentrations of these ions also caused the curling defect. Embryos of Ambystoma maculatum and Ambystoma jeffersonianum were generally able to hatch even though they became curled, but Rana sylvatica remained trapped and died. Consequently, as the concentration of Ca, Mg, or Na was increased at low pH, greater numbers of embryos of A. maculatum and A. jeffersonianum hatched, while survival of embryos of R. sylvatica was drastically reduced.
Ultrastructure of the cysts of Sarcocystis hardangeri from skeletal muscle of reindeer (Rangifer tarandus tarandus)
Authors: Gjerde Bjørn
Published: March 2009

Cysts of Sarcocystis hardangeri from reindeer (Rangifer tarandus tarandus) were examined by transmission electron microscopy. The large ovoid cysts were located within distended skeletal muscle cells, which were encapsulated by the thickened external lamina of the muscle cell and an exterior thick layer of collagen-rich connective tissue. The cysts were limited by a unit membrane (the cyst membrane) that was raised into closely spaced anastomosing microplicae, forming a honeycomb pattern. Between the microplicae the cyst membrane formed vesiclelike invaginations. The cyst surface was provided with numerous slanting linguiform processes, measuring 25–35 μm in length. The entire cyst surface, including the surface of the projections, had a highly irregular, folded outline. The projections contained a central bundle of longitudinally orientated microtubules. The interior of the cyst was rich in cyst ground substance that formed conspicuous septa. The metrocytes showed an extensive vacuolation of their cytoplasm, eventually leading to a disintegration of the cell. The cysts of S. hardangeri were structurally very similar to one type of sarcocysts previously reported from moose (Alces alces).
Neutron activation analysis of bald eagle feathers: analytical precision and sources of sampling variation
Authors: Bortolotti Gary R. , Barlow Jon C.
Published: March 2009

Instrumental neutron activation analysis was used to investigate the feather chemistry of wild and captive bald eagles (Haliaeetus leucocephalus). This paper documents variation that may be attributable to method of feather collection, laundering of samples, and precision of the analysis, as well as the variability within and among feathers from different locations on the body of individual birds. For most samples, reliable estimates could be made of the concentrations of bromine, magnesium. manganese, sodium, vanadium, aluminum, chlorine, calcium, and sulphur. Iodine and copper were detected but could not be measured precisely. There were highly significant patterns of variation along the length of a single feather for most chemical elements. The vane and calamus portions of feathers differed in chemical composition and the concentrations of the elements in the two parts were not correlated. Feathers belonging to the same molt but collected several months apart had similar chemical profiles. Variation within an individual feather and among feathers from different parts of the body necessitates rigorous consistency in the method of sampling feathers. Possible explanations for the observed patterns of elemental composition are discussed.
Biogeography of scavenging scarab beetles in the Florida Keys: post-Pleistocene land-bridge islands
Authors: Peck Stewart B. , Howden Henry F.
Published: March 2009

Fieldwork on 15 islands of the Florida Keys produced 13 species of scavenging scarab beetles (Laparosticti and Trox). Six of these species represent new records for the Keys. Twenty-three additional species (many of which are synanthropic or tramps), previously recorded from the Keys, were not found. Species–area relationships for the islands form a significant regression line as predicted by equilibrium island biogeography theory. It is concluded that many of the islands have low species numbers either because (i) human habitat disturbance has caused many local species extinctions or (ii) species turnover rates (extinction over immigration) are high because of scarcity of suitable hosts or adverse soil conditions. Data from highly disturbed Key West and Stock Island suggest that as species turnover continues, higher species saturation levels may be regained through the immigration of synanthropic and tramp species. This work generally points to the lack of much basic information on scarab beetle bionomics.
A study of the neurosecretory centres of the eyestalk in Siriella armata M. Edw. (Crustacea: Mysidacea): their involvement in molting and reproduction
Authors: Cuzin-Roudy Janine , Saleuddin A. S. M.
Published: March 2009

Neurosecretory cells and centres arc described in the eyestalk of the mysid Siriela armata. The sinus gland is situated on the neuropilar regions along the main blood sinus. The medulla interna and medulla externa X organ is formed of G1 cells; the medulla terminalis X organ consists of G3 and G4 cells. Other neurons, the G2 cells, and a "giant cell" may also be neurosecretory. Destruction of the medulla interna – medulla externa X organ results in an inhibition of the preparation for molt and ecdysis in both sexes. Reproducing females also show inhibition of secondary vitellogenesis and of marsupial development. The role of the medulla interna – medulla externa X organ in the control of premolt, secondary vitellogenesis, and marsupial development is discussed.
Dynamique de la population d'Orchestia mediterranea L. (Crustacé, Amphipode) dans l'estuaire du Bou Regreg (Maroc)
Authors: Elkaïm B. , Irlinger J. P. , Pichard S.
Published: March 2009

Some aspects of the population ecology of Orchestia mediterranea, found in the estuary of Bou Regreg (Morocco), were studied over the course of 1 year. Histograms of cohort frequency and observations on reproductive activity showed seasonal variations all year long: O. mediterranea can be characterized as a multivoltine, semiannual species. By statistical analysis, associated with a procedure near successive maxima, the population structure was determined by identifying cohorts that are associated in a complex manner. All these characteristics are similar to those of O. mediterranea and Talorchestia deshayesei found in the Mediterranean Sea. The exceptionally high annual reproductive potential estimated from the fecundity (which varies with the age of females and with the seasons), the sex ratio, and the brood number of the successive cohorts from the same filiation, all in a nutrient-rich environment, suggests an r type of adaptative strategy.
The duration of the period of hibernation of three species of vespertilionid bats. I. Field studies
Authors: Brack Jr. Virgil , Twente John W.
Published: March 2009

The durations of the periods of hibernation of the big brown bat (Eptesicus fuscus), little brown bat (Myotis lucifugus), and eastern pipistrelle (Pipistrellus subflavus) under natural conditions were determined by following intracave movements through two winter seasons in two Missouri caves. Average durations of periods of hibernation were similar for all three species (10–20 days) over a range of temperatures. Maximum durations of periods of hibernation determined were as follows: E. fuscus, 72 days; P. subflavus, 111 days (?); M. lucifugus, 83 days. Variability in the durations of the period of hibernation was much greater for P. subflavus and may be attributable to a lack of movement after arousal or the inability of the observer to discern movement between periods of hibernation. The frequency of arousal was determined to be statistically temperature dependent for M. lucifugus, but not for E. fuscus or P. subflavus, probably because of insufficient data.
Emergence patterns and an assessment of collecting methods for adult stoneflies (Plecoptera) in an Ozark foothills stream
Authors: Ernst Mark R. , Stewart Kenneth W.
Published: March 2009

Emergence periods and patterns for adult stoneflies were assessed using five collecting methods on a second-order stream in northeastern Oklahoma. Twenty-two species, representing six families, displayed successional emergence periods with at least one species being present every month of the year. Searching emergent leaf packs, logs, and rocks with an aspirator and forceps resulted in the collection of 21 of 23 species (91%) and was particularly suited to cryptic species such as Amphinemura delosa, Allocapnia rickeri, Prostoia completa, and Isoperla namata. Sweeping resulted in the collection of fewer species (13 species, 57%), and was most applicable to actively flying, late spring emerging Haploperla brevis and Alloperla caudata. Light-trapping (12 species, 52%) was successful only during late spring and summer for crepuscular Perlids such as Neoperla spp., Acroneuria evoluta, and Perlesta placida. Significantly greater numbers of females were found in light trap collections. Sticky traps (8 species, 35%) and pit traps (6 species, 26%) collected relatively few species. Significant correlations existed between benthic density and numbers of adults collected by searching and all methods combined. Collections of Paracapnia angulata, Leuctra tenuis, Isoperla signata, Perlinella ephyre, Neoperla stewarti, and Neoperla catharae represent extensions of the reported ranges of these species.
Duncan's critique of Matsuda
Authors: Pearson Roy Douglas
Published: March 2009

Although Duncan (K. W. Duncan. 1985. Can. J. Zool. 63: 2230–2232) holds, "there can be little point in taking Matsuda's thesis seriously," this author argues that some of the ideas found in Matsuda's paper (R. Matsuda. 1982. Can. J. Zool. 60: 733–749) are actually a refinement of Waddington's notion of "genetic assimilation" by means of "canalization." The latter term implies not only the rigidity of the genotype but also its flexibility; it was this quality, plasticity, that Matsuda laboured to examine but that Duncan failed to appreciate.
Choix de l'emplacement des nids de Cormorans à aigrettes (Phalacrocorax auritus) aux îles de la Madeleine, Québec
Authors: Léger Claire , McNeil Raymond
Published: March 2009

The periods during which cormorants build their nests in relation to various parameters describing the coniferous tree on which the nest is located (height, trunk diameter, health, supporting capacity of branches), its location with regard to the center of the colony and to areas occupied by gulls (Larus argentatus and Larus marinus), and its utilization as a nest site during previous years, were investigated using a bidimensional contingency analysis. The results reveal that the first cormorants to come back to the island in the spring choose first the coniferous trees that are located in the center of the area occupied by the colony, even if most of those trees, injured during previous years, are dead or have lost their needles. The stability of the trees (strength and diameter of trunks), the supporting capacity of branches, as well as the height and position of nests do not seem to play an important role in the choice of nest sites.
The effects of acidification on life-history traits of the freshwater clam Musculium partumeium (Say, 1822) (Bivalvia: Pisidiidae)
Authors: Hornbach Daniel J. , Childers Daniel L.
Published: March 2009

This study examines the effects of acidification on growth, survivorship, and natality of the fingernail clam, Musculium partumeium. Six groups of newborn clams (parents), collected in either October (replicate 1) or January (replicate 2), and their offspring (F1) were maintained in river water kept at a pH of 3, 4, 5, or 6 with the addition of H2SO4. A control (no acid added) had an average pH near 7. Generally, growth and survivorship were poor in treatments of pH 3 and 4. Maximal growth occurred at a pH of 5, which approximates that of the stream from which these clams were collected. Also, clams maintained at a pH of 5 generally had the highest gross and net reproductive rates and the youngest age at first reproduction, leading to maximum values of r (intrinsic rate of increase) for clams maintained at pH 5. Usually the F1 generations had greater survivorship than their parents and under adverse conditions could attain greater shell lengths. Life-history traits in M. partumeium appear to be sensitive to changes in environmental pH and populations of these clams may be able to acclimate to changing pH regimes over time, i.e, from one generation to the next.
Fine structure of ocelli of the larval black fly Simulium vittatum (Diptera: Simuliidae)
Authors: Nyhof Joyce M. , McIver Susan B.
Published: March 2009

The fine structure of light- and dark-adapted ocelli of last instar larval Simulium vittatum Zetterstedt was described using scanning and transmission electron microscopy. Larvae have six ocelli arranged in groups of three on each side of the head. The larger two ocelli of each group are externally visible as two darkly pigmented eyespots. The third, smaller ocellus lacks pigmentation and, therefore, is not externally visible. Each ocellus has its long axis oriented dorso-ventrally, has 13 retinular cells, and lacks an expanded cuticular lens. Conspicuous rhabdoms occur in the three ocelli. The rhabdoms of the pigmented ocelli are centrally located and enveloped by pigment granules. The microvilli of the rhabdoms are oriented primarily in one plane, an indication of a possible sensitivity to polarized light. The rhabdom of the unpigmented ocellus is eccentrically located and its microvilli are not uniplanar. Each ocellus has numerous cell organelles, including mitochondria, ribosomes, endoplasmic reticulum, and Golgi bodies. Especially conspicuous are membranous figures, which are associated with the nuclei and vary in size and complexity from simple stacks to lamellar whorls. These latter organelles are probably involved in the turnover processes of the rhabdomeric membranes. In light- and dark-adapted ocelli the only structural differences were associated with the microvilli and multivesicular bodies. Differences in location of pigment granules and in size of rhabdomeres and membranous figures were not observed.
A note on Alona macronyx Daday, 1898 (Crustacea, Cladocera), a rare species from the Oriental Region
Authors: Rajapaksa R. , Fernando C. H.
Published: March 2009

The species described as Kurzia yunnanensis Shen et al., 1966 from southern China and Indialona jabalpurensis Rane, 1983 from India are synonymized with Alona macronyx Daday, 1898. The known distribution of this species is now extended to central India and southern China.
Observations on demography, reproduction, and morphology of muskoxen (Ovibos moschatus) on Banks Island, Northwest Territories
Authors: Latour P. B.
Published: March 2009

Muskoxen were harvested from three locations on Banks Island in 1981, 1982, and 1983 in the following numbers: 1981, 224; 1982, 87; 1983, 82. Only the 1981 harvest was nonselective for specific age-classes. There was a maximum of 0.83 calves per female ≥ 3 years old in mid-May, as determined by calf and fetus counts; these calves represented 24% of the total sample. Over 90% of all calving was completed by 8 May. Calving may start as early as 8 April and likely no later than 19 April. Body weight increased until at least 5 years of age for both males and females; males were significantly heavier than females at 2 years of age and older. Length and girth increased for both sexes until 5 years of age with significant differences between the sexes occurring at approximately 4 years for girth and 5 years for length.
Adult habits, larval morphology, and phylogenetic placement of Taurocerastes patagonicus Philippi (Scarabaeidae: Geotrupinae)
Authors: Howden H. F. , Peck S. B.
Published: March 2009

Adults of Taurocerastes patagonicus Philippi were observed in Patagonian Chile. They pulled sheep dung with their forelegs to their inclined, 10–35 cm deep burrows. The third-stage larva was collected and is described and illustrated, and its relationship with some genera in the tribe Geotrupini is discussed. Within the Geotrupini the morphology of Taurocerastes indicates a distant, relict relationship to the other genera.
The next 25 years: introduction/Les 25 prochaines années: introduction
Authors: Weisbart Melvin
Published: March 2009

The papers in this collection were part of a symposium organized by the Canadian Society of Zoologists on the occasion of its Silver Anniversary. The goal was to have a symposium that would attempt to look forward and predict new directions that zoology will take in the next 25 years. The symposium was held on the campus of the University of Saskatchewan during the annual meetings of the Society, May 11 to 14, 1986.It was my privilege to seek out some of the best zoologists in Canada and organize this symposium to cover the disparate fields of our discipline. The choice of speakers was not solely my doing, but evolved from discussions with the Silver Anniversary Planning Committee, which consisted of Ed Bousfield, Sal Saleuddin, Ed Crossman, Nancy Henderson, Dave Mettrick, Roly Brett, Gaetan Faubert, Tom Moon, and myself. Sections of the Society as well as Jean-Guy Godin, Max Blouw, George Mackie, Charles Krebs, and Bev Scott also provided advice on the choice of speakers. One area that was covered by the symposium but is not represented in manuscript form here is that of "Terrestrial ecology and behaviour." Gail Michener agreed at a late date to participate in the symposium at Saskatoon. However, because of prior research commitments, she was unable to prepare a manuscript for inclusion in this publication.Early in the planning, the decision was made that the symposium would not be retrospective but rather forward-looking and, hopefully, provocative. I believe that we have been successful in both regards. It will be interesting to read these papers on the Golden Anniversary and determine their accuracy. The Society is grateful to all of the speakers for their participation.
Effect of pinealectomy on photoperiodic gonadal response of Indian palm squirrel, Funambulus pennanti
Authors: Haldar-Misra C. , Srivastava M.
Published: March 2009

The role of the pineal gland in mediating the effects of photoperiod on the reproductive axis is not well established in tropical mammals. Indian palm squirrels (Funambulus pennanti) were exposed to experimental long (16L:8D) and short (6L:18D) photoperiods. It was observed that the testes regressed in response to short photoperiod, while during the long photoperiod the gonads were active. When squirrels were maintained for a long experimental period (130 days) under the short photoperiodic schedule (6L:18D), gonadal regrowth eventually occurred even though the photoperiod was the same one that initially induced testicular regression. Pinealectomized animals maintained the gonadal activity even in short photoperiod, suggesting that the effect of photoperiod is mediated through the pineal gland.
Cannibals of Oxytricha bifaria (Ciliata, Hypotrichida). Macro- and micro-nuclear DNA content
Authors: Riggio Daniela C. , Ricci Nicola , Banchetti Rosalba , Seyfert Hans Martin
Published: March 2009

Investigation of cell differentiation led us to study the giants of Oxytricha bifaria. Here we report systematic variations in nuclear DNA content. Comparing giants, controls starved for 10–14 days, and controls we conclude that (i) the amount of DNA is indicative of the occurrence of cell differentiation, while cell size or nuclear size is not; (ii) the macronuclear DNA content of a giant is about 3.7 times that of the controls; and (iii) the micronuclear DNA content of a giant is about 1.8 times that of the controls. The macronuclear DNA content declines throughout the four successive divisions which typically lead a giant cell back to the normal morpho-physiological state: the amount decreases steadily from a level of about 3.7 times the macronuclear DNA content of the controls to 2.57 and to 1.77 before dropping to 1.08, the normal value.
Habitat use of the central mudminnow (Umbra limi) and yellow perch (Perca flavescens) in Umbra-Perca assemblages: the roles of competition, predation, and the abiotic environment
Authors: Tonn William M. , Paszkowski Cynthia A.
Published: March 2009

We compared spatial distributions and diel activity patterns of three fish populations (co-occurring central mudminnows and yellow perch, and a mudminnow population in a single-species assemblage) throughout the year in two small, northern Wisconsin dystrophic lakes. In winter, all three populations were more active offshore and during the day. During spring and summer–fall all were concentrated inshore, near the bottom, and were more active around dawn and dusk. Winter distributions appeared to be responses to abiotic conditions (ice cover and low oxygen availability); overall patterns during open-water periods appeared to be linked to prey availability (e.g., chironomid emergences). Although the three populations were generally similar, some aspects of habitat use differed between species, between lakes, or between dominant and subdominant populations, with the direction of differences varying seasonally. The yellow perch population was recovering from a size-selective winterkill and between spring and summer underwent an ontogenetic niche shift, first being competitors with mudminnows, then becoming predators on mudminnows. Mudminnows did not alter their vertical or diel activity patterns in the presence of these predatory perch. They did become more concentrated inshore in summer–fall, near structural refuge provided by the bog mat, and, unlike the other two populations, failed to shift their activities offshore at twilight. Our study suggested that a simple habitat in the study lakes contributed both to overall similarities in habitat use and strong interactions between co-occurring populations. However, the ecological flexibility demonstrated by mudminnows may prevent their total exclusion from lakes inhabited by perch and allow them to respond to changing biotic environments.
Hypercapnic acidosis in the rainbow trout (Salmo gairdneri). II. Renal ionic fluxes
Authors: Perry S. F. , Malone S. , Ewing D.
Published: March 2009

The involvement of the rainbow trout kidney in acid–base regulation was assessed before, during, and after 72 h of exposure to external hypercapnia (1% CO2). Hypercapnia caused a significant elevation of renal acid excretion throughout most of the hypercapnic period, which could account for 16% of the overall compensatory increase in plasma bicarbonate concentration. The two predominant urine buffers, phosphate and ammonia, both increased markedly during hypercapnia, thereby preventing reductions in urine pH during the period of enhanced urinary acidification. Stimulation of tubular H+ secretion was the mechanism responsible for the elevation of acid excretion and, more importantly, ensured tubular reabsorption of the additional [Formula: see text] that must have appeared in the glomerular filtrate. Such a mechanism is considered essential for the ultimate compensation of hypercapnic acidosis. The results are discussed with respect to the possible involvement of increased plasma epinephrine levels in mediating the various renal responses of hypercapnic acidosis.
Influence of habitat structure on demography of two rodent species in eastern Massachusetts
Authors: Adler Gregory H.
Published: March 2009

Populations of two rodent species (Peromyscus leucopus and Microtus pennsylvanicus) were livetrapped monthly for over 3 years at three study sites in eastern Massachusetts (U.S.A.) to examine relationships between microhabitat structure and demography. Measures of microhabitat structure–diversity gradients and an index of microhabitat heterogeneity were developed separately for each study site using principal components analysis. Relative densities of both species were ordered linearly along microhabitat gradients. Peromyscus densities increased along a woody habitat gradient, and Microtus densities generally decreased along woody gradients or increased along herbaceous gradients. Microhabitat structure appeared to influence population density more than it did other demographic characteristics. Where relationships between density and demographic variability existed, the most variable segments of a population were in the lowest density areas. It is suggested that this variability may be partitioned into biological effects (dispersal and response to environmental fluctuations) and density dependence of variability. Microhabitat heterogeneity, in contrast to gradients of microhabitat structure and diversity, was apparently unimportant in affecting demography of these rodent populations.
The meningeal arrangement of the avian lumbosacral spinal cord
Authors: Azcoitia Iñigo , Fernández Benjamin , Fernandez Agustín
Published: March 2009

The meningeal arrangement of the lumbosacral cord of Gallus is comparable to that of mammals. The meninges are formed by three lamellae: inner, intermediate, and outer. The arachnoid space, between the outer and intermediate lamellae, is wide and filled with a trabecular network, except in the region of the glycogen body and lobes of Lachi. This region is invaded by the glycogen body cells which also disrupt the inner and intermediate lamellae. A similarity between this region and the cerebellomedullary cistern of mammals is postulated, and the meaning of the presence of glycogen in the outer cerebrospinal fluid compartment is also discussed.
Innervation of muscle in the cestode Hymenolepis microstoma
Authors: Webb Rodney A.
Published: March 2009

The innervation of muscle in the cestode Hymenolepis microstoma was investigated by analysis of serial thin sections in the electron microscope. The myocytons, containing the nucleus and cell organelles, formed sarcoplasmic processes that contained the myofibers. Junctional complexes resembling gap junctions were found between sarcoplasmic processes. Sarcoplasmic extensions from the myofibers passed to the segmental ring commissures and formed sarconeural junctions. The presynaptic component of the sarconeural junctions was characterized by an axon terminal, or axon en passant, containing electron-lucent and occasional electron-dense synaptic vesicles, occasional mitochondria, and presynaptic dense projections. The presynaptic terminal was isolated from the postsynaptic terminal by a synaptic cleft of ~20 nm. The postsynaptic sarcoplasmic process, which often was wrapped around the nerve terminal, displayed a postsynaptic thickening. Single axon terminals were observed to form sarconeural junctions with up to four sarcoplasmic processes. Sarcoplasmic processes formed synaptic contacts with more than one axon, and sarcoplasmic processes formed more than one synaptic contact with a single axon, suggesting a polyneuronal multiterminal pattern of innervation. Serial synapses were found in conjunction with sarconeural junctions in the suckers. The functional significance of this type and pattern of innervation of muscle in H. microstoma is discussed.
Early infection of Merluccius productus (Ayres) (Pisces: Teleostei) with Kudoa thyrsites (Gilchrist) (Myxozoa)
Authors: Whitaker D. J. , Kabata Z.
Published: March 2009

Within 5 months of metamorphosis, age 0+ Pacific hake (Merluccius productus) became infected with the myxozoan muscle parasite Kudoa thyrsites. Prevalence and intensity of infection increased with time. Approximately 4 months after the parasite had become established in a muscle fibre, a host response was initiated, which rapidly destroyed it. Three stages of host response were recognized depending on the extent of the host reaction. The prevalence and intensity of infections showing a host response also increased with time. The possibility of a fish developing high intensity infections by ingesting spores from the water column is discussed.