bluuebunny/crossref_metadata_2025 huggingface dataset:
Breeding performance in captivity of meadow voles (Microtus pennsylvanicus) from decline- and increase-phase populations
Authors: Mihok Steve , Boonstra Rudy
Published: July 2008

A major enigma in understanding microtine cycles is the failure of decline-phase animals to increase. We compared the performance of wild-caught meadow voles and their progeny from Pinawa, Manitoba, collected from a decline year (1985) with that of animals from an increase year (1986) by breeding them in the laboratory in Pinawa (animals from both years) and in the field and laboratory in Toronto (only F1 and F2 animals from 1985). Overall only 35% of the 1985 females or their progeny bred in the laboratory in Pinawa compared with 100% of the 1986 females. The interval between pairing with a male and birth of litters was 2–7 months for the 1985 females compared with 3–4 weeks for the 1986 females. The poor breeding performance of 1985 females occurred only in the laboratory; in small field enclosures in Toronto all F1 and F2 females conceived and had litters within 3–4 weeks. In contrast, 1985 males readily sired litters either with 1986 females in the laboratory or with Toronto females in the field. We conclude that the prior experience of decline-phase females had long-term detrimental consequences for the performance of the first two generations under laboratory conditions.
Epidermal responses of chum salmon (Oncorhynchus keta) fry to the ectoparasitic flagellate Ichthyobodo necator
Authors: Urawa Shigehiko
Published: July 2008

The numbers of the ectoparasitic flagellate Ichthyobodo necator on chum salmon fry (Oncorhynchus keta) and the host's epidermal responses to infection were monitored for 15 weeks with light and scanning electron microscopy. Parasite density on the skin peaked at 3 weeks postinfection, at an average of 625 parasites/mm2, and then decreased to near zero by week 10. The staining procedure with Alcian blue (AB, pH 2.5) and periodic acid – Schiffs reagent (PAS) revealed dramatic changes in both the degree and histochemistry of epidermal mucus secretion during the course of the parasite infections. The numbers of mucous cells declined significantly during the first 4 weeks as parasite density increased, but thereafter rose to 2000 cells/mm2 by week 8, when mucous cells stained with PAS alone predominated. This increase occurred concomitantly with a reduction in parasite density. In the control fish, the concentration of epidermal mucous cells was stable at 400 – 800 cells/mm2 during the same period and acid mucopolysaccharides (PAS-negative, AB-positive) were a major constituent of the mucous cell secretion. It is suspected that the PAS-positive mucous cells may play an important role in the defence mechanism against the parasite infection.
Evaluation of an experimental wolf reduction and its impact on deer in Papineau-Labelle Reserve, Quebec
Authors: Potvin François , Jolicoeur Hélène , Breton Laurier , Lemieux Rolland
Published: July 2008

From 1984 to 1986, 56 wolves were removed by aerial shooting from two reduction blocks in Papineau-Labelle Reserve: the mean reduction rate was 71% in RB1 and 40% in RB2, compared with 17 and 9% for two untreated blocks (UB1 and UB2). Corresponding mean wolf densities in the four blocks at the end of winter were 0.6, 1.2, 1.6, and 1.7 wolves/100 km2, respectively. Each year, wolf numbers returned to their former level in the subsequent winter in RB1, mainly through immigration. Three blocks were each associated with a large deer wintering area containing 1400–1700 animals before the wolf reduction. The deer yard in RB1 reached a population of 4200 deer, a 1.32% finite rate of increase per year, compared with annual rates of 1.15–1.18% in UB1 and RB2. The harvest of bucks was not affected by the wolf reduction. The number of fawns per 100 does in the harvest was higher in RB1 than in UB1 in 1985 and 1986. We do not recommend wolf reduction as a management tool in the current context, as deer numbers increased markedly, even where no control was applied, as a consequence of mild winters.
Growth and feeding habits of grey seals (Halichoerus grypus) in the northwestern Gulf of St. Lawrence, Canada
Authors: Murie D. J. , Lavigne D. M.
Published: July 2008

Growth and feeding habits were determined for 82 grey seals (Halichoerus grypus) collected in the northwestern Gulf of St. Lawrence, Canada, between 3 July and 6 December 1983. Male grey seals reached an asymptotic standard length of 242 cm, whereas females attained a length of 201 cm. Most (96%) females 175 cm or longer and 5 years of age or older were pregnant. A larger proportion of grey seal stomachs contained food items in July than in the other months sampled, regardless of sex or maturity status. The diet consisted primarily of cod (Gadus morhua), herring (Clupea harengus harengus), and capelin (Mallotus villosus), which together contributed 72% of the wet mass and 76% of the gross energy of all the prey consumed. Invertebrates contributed negligible mass or gross energy to the diet. Grey seals primarily consumed fish ≤30 cm in length and ate only one or two different fish species during any one feeding bout. Based on our stomach content analyses, the food consumed daily by adult male and female grey seals provided an average gross energy of 3628 and 2925 kcal (1 kcal = 4.18 kJ), respectively, which is consistent with daily energy requirements estimated using bioenergetic models. However, the large percentage of empty stomachs (50%), together with differential digestion of fish species, suggests that grey seals may not feed every day.
Les parasites de l'alose d'été (Alosa aestivalis) et du gaspareau (Alosa pseudoharengus) de la rivière Miramichi, Nouveau-Brunswick
Authors: Landry T. , Boghen A. D. , Hare G. M.
Published: July 2008

The parasite fauna of blueback herring (Alosa aestivalis) and alewife (Alosa pseudoharengus) were examined to determine their usefulness as biological indicators in the differentiation of these two sympatric species. Thirteen parasite species were identified from 100 specimens each of blueback herring and alewife from the main estuary of the Miramichi River, New Brunswick, of which 11 and 8, respectively, represent new host records. Significant differences (p < 0.05) in the counts of Mazocraeoides sp., Diplostomum spathaceum (metacercaria), Derogenes varicus, Anisakis simplex (larvae), and Echinorhynchus gadi between alewives and blueback herring reflect differences of physiological and ecological order between these two host species.
From individual to collective vigilance in wild boar (Sus scrofa)
Authors: Quenette Pierre-Yves , Gerard Jean-François
Published: July 2008

Vigilance behaviour of captive wild boars at feeding points was investigated using films. Results show that individual vigilance decreased with increasing group size, especially between solitary individuals and groups of 2. Moreover, the collective vigilance was, whatever the group size, below the individual vigilance in solitary animals. The study of the motor variability of vigilance behaviour allows three types of movement to be distinguished. The mean durations of each type vary largely, but are almost constant whatever the group size. On the other hand, the relative proportions of the vigilance acts change according to group size. Although previous studies of vigilance are in keeping with the functional approach of behaviour, these data are interpreted in terms of proximate causation. A mechanism based on allelomimesis is proposed to explain the results.
Do rainbow trout and Atlantic salmon discriminate kin?
Authors: Brown Grant E. , Brown Joseph A.
Published: July 2008

The purpose of this study was to determine if juvenile Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) can discriminate kin from non-kin, since other salmonid species (coho salmon (Oncorhynchus kisutch) and Arctic charr (Salvelinus alpinus)) have been shown to possess this ability. When tested in water conditioned by conspecifics (kin and non-kin) and heterospecifics in a two-choice tank, both rainbow trout and Atlantic salmon demonstrated a significant preference for kin over non-kin and heterospecifics, indicating that these species possess kin-discrimination abilities. This ability appears to be widespread among salmonid fishes.
Influence of storms and maternal size on mother–pup separations and fostering in the harbor seal, Phoca vitulina
Authors: Boness Daryl J. , Bowen Don , Iverson Sara J. , Oftedal Olav T.
Published: July 2008

Fostering behavior has been documented in a large number of mammals and birds, but its frequency of occurrence and proximate causes are poorly understood in most species. Ten percent of a sample of 76 paint-marked female harbor seals (Phoca vitulina) fostered pups for some portion of the lactation period. Fostering appears to be associated with females having lost their own pup. In a subsample of 30 pairs that were followed closely, 3 of 16 females that lost their pups fostered, but none of 14 females that maintained continuous association with their pups throughout lactation did so. Smaller, and presumably younger, females were significantly more likely to become separated from their pups than were larger, and presumably older, females (73 vs. 33%). A high proportion (68%) of 35 separations observed occurred during the same day as, or within 1 day following, a storm. In 7 of 8 instances where we relocated pups after they were separated from their mothers during a storm, we found them in the direction of the surface current, 4.9 km from their previous location, on average. These data suggest that storms were the primary cause of separation of harbor seal mothers from their pups, and that younger mothers may be more likely to become separated from their pups. As fostering only occurs after a mother has lost her pup, we suggest that fostering, too, may be more likely among younger females.
Comportement de chasse des orques (Orcinus orca) autour des îles Crozet
Authors: Guinet Christophe
Published: July 2008

Killer whales around Crozet Islands consume a great variety of preys, including fish, penguins (Eudyptes sp.), elephant seals (Mirounga leonina), and, occasionally, large cetacea. Prédation techniques used on elephant seals and penguins, which are easily observed from the shore, are described. Hydrophones were used to record the acoustic behaviour of the whales during their hunts for both types of prey. The successful predation of 29 elephant seals was observed, 24 of which were weaned pups. Seals were captured along the banks (n = 3), near river outlets (n = 14), by voluntary stranding of the whales on the beaches (n = 7), or by attack of seals swimming in bays (n = 5). Hunting techniques were routinely used in "strategic" points apparently chosen specifically according to the location and climatic factors. King penguins were hunted along the banks (n = 13), particularly where algae prevailed, or offshore (n = 32). While hunting, whales tended to be very quiet and used acoustic signals sparingly, emitting a few isolated clicks and short distance contact calls. Reactions of whales exposed to artificial sounds tended to show that they localize their prey by passive listening. When an elephant seal was captured, long distance contact calls characterized by excitement were emitted 72% of the time and resulted in the arrival, by "porpoising," of the most distant members of the group, along with whales of other groups coming from several kilometers away. The author hypothesizes that the adaptive value of this behaviour is to allow the size of the hunting unit to adjust itself to the size of the prey by permitting not only members of the same groupu to associate, but also members of other groups to associate temporarily.[Journal translation]
Seasonal patterns of body temperature and activity in free-ranging beaver (Castor canadensis)
Authors: Dyck Alvin P. , MacArthur Robert A.
Published: July 2008

Daily activity and body temperature patterns of beavers (Castor canadensis) were monitored in the field with an automated radiotelemetry system from June 1988 through March 1989. Body temperatures of kits and adults averaged close to 37 °C throughout the year, with no evidence of seasonal hypothermia. The greatest temperature changes accompanied episodes of aquatic activity. Body temperature typically dropped 1.0–1.5 °C during periods when beavers were absent from the lodge, then recovered when animals returned to the house. Throughout the open-water season (20 June – 1 November), both age groups demonstrated a daily rhythm in body temperature characterized by a gradual rise between 06:00 and 18:00 followed by a general decline during the nocturnal active period. During the ice-bound season (2 November – 15 March), there was little evidence of a distinct daily rhythm in activity or body temperature, especially in adults. Both age groups exhibited a 0.22–0.64 °C increase in mean body temperature during the 3-h period preceding the first trip in each sequence of excursions away from the lodge. We propose that this predeparture rise in temperature may contribute to the avoidance of immersion hypothermia in foraging beavers.
Genetic variation in the longear sunfish (Lepomis megalotis)
Authors: Jennings Martin J. , Philipp David P.
Published: July 2008

The systematics and zoogeography of the longear sunfish (Lepomis megalotis) are poorly understood. Relationships among geographic variants throughout the range of the species are unclear, and it is uncertain whether the northern longear sunfish, L. m. peltastes, should be classified as a separate species. We used protein electrophoresis to examine genetic variation among 22 longear sunfish populations and one dollar sunfish (Lepomis marginatus) population. Principal component analysis of allele frequency data could not separate the most morphologically distinct form, the northern longear sunfish, from the central long-ear sunfish, L. m. megalotis. Populations distributed from the Missouri River basin to the Colorado River in Texas, for which the subspecific names L. m. breviceps and L. m. aquilensis are available, clustered as a distinct group. No evidence was found to suggest that a distinct form exists in the Ozark Highlands. Lepomis marginatus was genetically distinct from all L. megalotis populations, but most distinct from L. m. megalotis and L. m. peltastes. Protein electrophoresis should allow diagnosis of distribution limits and intergrade zones of southwestern forms, but a more sensitive technique is required to separate L. m. megalotis and L. m. peltastes.
Reproduction, early life history, and characteristics of the spawning grounds of the lake sturgeon (Acipenser fulvescens) in Des Prairies and L'Assomption rivers, near Montréal, Quebec
Authors: LaHaye Michel , Branchaud Alain , Gendron Marc , Verdon Richard , Fortin Réjean
Published: July 2008

Spawning, early life history, and physical characteristics of lake sturgeon (Acipenser fulvescens) spawning grounds were compared between two rivers located in the Montréal region. The spawning grounds in Des Prairies River were enlarged in 1985, during the reconstruction of the Des Prairies power plant spillway. The L'Assomption River spawning ground has not been physically altered by human activities. In 1989, spawning occurred between May 14 and 27 in Des Prairies River (water temperature 11.6–15.4 °C) and between May 15 and 22 in L'Assomption River (water temperature 11–21.5 °C). On a given date, embryos were slightly more developed in L'Assomption River, where hatching began 3 days earlier than in Des Prairies River (26 vs. 29 May). The great similarity in the spawning and early development sequence suggests that spawners utilizing these two rivers cannot be differentiated on the basis of these biological characters. In 1990, larval emigration from the Des Prairies River spawning ground began on May 29, 11 days after peak spawning. The larvae drifted to the St. Lawrence River in June (peak on 16 June), at a mean length of approximately 20 mm. In both rivers the proportion of stations with eggs present tends to decrease as depth and current velocity increase. Egg deposition occurs on a wide variety of substrate types, ranging from fine- to medium-sized gravel to boulders. Although utilization varies with prevailing hydrological conditions, in 1990 the artificial spawning bed in Des Prairies River showed a high proportion of stations with eggs present.
Observations of body size, growth, and reproduction in Blanding's turtle (Emydoidea blandingii) from western Nebraska
Authors: Rowe John W.
Published: July 2008

Body size, growth, and reproduction of Emydoidea blandingii from several localities in western Nebraska were investigated. Female carapace length averaged 209.2 mm (214.8 mm for those known to be sexually mature). Adult male carapace length averaged 200.8 mm and was not significantly different from that of females, but males had pigmented tomia. Covariance analysis using carapace length as a covariate revealed that females had a significantly longer plastron and higher shell than males. Turtles showed a 70.1% increase in length of the left abdominal scute during the 1st year. Growth declined rapidly and became more constant about the 4th year (about 4–9% per year). Clutch size averaged 14.9, clutch wet mass averaged 168.5 g, and egg wet mass averaged 11.82 g. No measure of reproductive output (i.e., clutch size, clutch wet mass, relative clutch mass) or egg size (relative egg mass, egg wet mass, egg length, or egg width) was significantly correlated with maternal carapace length. Comparisons with other populations of E. blandingii are made.
Diel variations in the effect of spates on mayflies (Ephemeroptera: Baetis)
Authors: Lancaster Jill
Published: July 2008

Field experiments were carried out to determine whether there are diel variations in the effect of spates on baetid mayflies. Short-term spates were created in experimental streamside channels by pumping filtered creek water into selected channels at various times of day, resulting in three- or four-fold increases in discharge. Drift samples were collected before, during, and after spates; benthic samples were collected before and after. Drift rates of Baetis from channels in spate were higher than controls at all times of day. Natural increases in drift were observed in all channels after sunset, and drift rates from channels in spate were highest at this time. The susceptibility of nymphs to drift from channels was calculated as the ratio of drift densities in spate and control channels. Baetis appeared to be more vulnerable to spates after sunset than at dawn or midday. In unmanipulataed flow, large nymphs occurred most frequently in the drift after sunset. Spates had no apparent effect on the size distribution of nymphs in the drift compared with unmanipulated flows at the same time. These spates were not large enough and (or) long enough to greatly decrease mayfly densities in the benthos. It is notable, however, that benthic densities of Baetis were reduced significantly only by one spate at dusk.
Développement morphologique et croissance des juvéniles de l'Owenia fusiformis Delle Chiaje (Polychaeta, Oweniidae)
Authors: Thiébaut Éric , Dauvin Jean-Claude
Published: July 2008

The morphological development of the branchial crown and uncinigerous tori, growth, and demographic structure were observed in juveniles of Owenia fusiformis Delle Chiaje, 1841 from the Bay of Seine (eastern English Channel). Growth becomes significant only after one and a half months of benthic life; individual growth is highly variable and results in a progressive widening of the size distribution of the population over time. From six initial branches present at the post-larval stage, seven stages of branchial development can be distinguished. The branchial crown develops by successive dichotomous divisions and growth of the new branches. The number of dichotomous divisions (D) increases with total length (LT) and age (A): D = 1.718 ln(LT) − 0.291; D = 0.987 ln(A) − 1.471. The number of uncinigerous tori (T) increases with total length (LT) and age (A): T = 4.272 ln(LT) + 7.272; T = 4.477 ln(A) − 2.479. The acquisition of fully grown characters after metamorphosis was progressive and depended more on total length of the juvenile than on age. At any given age, there was an important variability in investigated characters because of differential growth of juveniles. Ecological consequences resulting from interactions between morphological development and growth with respect to recruitment are discussed.
Under-ice movements and the sensory basis of hole finding by ringed and Weddell seals
Authors: Wartzok Douglas , Elsner Robert , Stone Henry , Kelly Brendan P. , Davis Randall W.
Published: July 2008

Arctic ringed seals (Phoca hispida) and antarctic Weddell seals (Leptonychotes weddelli) were tracked using an attached acoustic tag during their under-ice movements at isolated experimental sites with varying numbers of novel breathing holes. Both natural and artificial visual landmarks were used by the seals during their dives. Seals deprived of vision through blindfolding greatly restricted their diving. Blindfolded seals responded to supplied acoustic cues and moved toward them. Prior to swimming toward an acoustic cue, the animals often swam at an angle to the direct line to the source of the acoustic cue. This movement could have provided information on the distance to the source of the sound. After executing this presumed ranging behavior, the seals swam directly toward the acoustic cue up to 4 km away. The contribution of vibrissal sensation to location of an open hole was investigated in blindfolded ringed seals. Seals farther than 1 m from an open hole were unable to find the hole without an acoustic cue. Vibrissal sensation apparently contributed to centering the blindfolded ringed seal within a breathing hole, but not to locating the hole. Weddell seals were able to maintain straight-line tracks for several hundred metres out from and back to a hole, were able to follow the same path on subsequent trips separated by up to 64 h, and continued using established routes between holes even though shorter, direct routes were available. The spatial memory implied by these observations is postulated to be a mechanism by which seals are able to move from one breathing hole to another under ice during dark polar winters.
Genetic structure and mode of reproduction in five species of sea stars (Echinodermata: Asteroidea) from the Alaskan coast
Authors: Stickle William B. , Foltz David W. , Katoh Masaya , Nguyen Hong L.
Published: July 2008

Genetic structure was studied in five sea star species with diverse patterns of reproduction. Eleven sea star samples from six locations in Alaska, representing five species and three genera in the family Asteriidae, were analyzed for allozyme variation at 16–25 loci. Levels of intra- and inter-population variation were determined for three brooding species (Leptasterias hexactis, Leptasterias epichlora, and Leptasterias polaris) and two free-spawning species with long planktonic larval periods (Evasterias troschelii and Pisaster ochraceus). Population divergence of L. epichlora (FST = 0.156) was much higher than that off. ochraceus (FST = 0.006) or E. troschelii (FST = 0.023). Earlier work in our laboratory found that L. hexactis also showed significant interpopulation differences in allele frequencies. Expected heterozygosity was 0.050 in E. troschelii, 0.083 in L. polaris, 0.092 in P. ochraceus, 0.135 in L. epichlora, and 0.151 in L. hexactis, and was unrelated to mode of reproduction.
Effects of thermal acclimation on seasonal accumulation of an apolipoprotein A-I-like molecule in a cold-adapted lizard
Authors: Laurent-Winter Christine , Gavaud Jacqueline
Published: July 2008

Using two-dimensional electrophoresis on total extracts of ovary, liver, and muscle of a cold-adapted lizard, Lacerta vivipara, we investigated the effects of cold at the protein level during autumn and winter. The major phenomenon observed was an accumulation in tissue of an apolipoprotein A-I-like molecule which displayed the same electrophoretic pattern as that previously described in human serum and peripheral tissues (isoform number, charge, apparent molecular mass). However, we detected the isoforms I4, I5, and I6 in all the lizard tissues examined, and two additional more acidic forms (I7, I8), which might come from proteolysis of the basic components. In this study, we report that the accumulation and distribution of the apolipoprotein A-I-like isoforms differ according to thermal acclimation, season, and the particular organ. These findings strongly suggest that significant movements of lipids are involved in the ectothermic hibernation process.
Differences in body size and lipid reserves between maturing and nonmaturing Atlantic salmon parr, Salmo salar L.
Authors: Simpson A. L.
Published: July 2008

Body size and lipid reserves of a group of sibling 0 + salmon parr were monitored monthly from January 1990 until the start of the breeding season in October. Those males that subsequently matured as parr were larger and had a higher fat content than the nonmaturing fish. The size differences were apparent in January and continued throughout the study period. The differences in fat content were apparent in February and continued until October, when the fat content of maturing fish dropped to that of the nonmaturing fish. By the use of logistic regressions basesd on fat reserves and body size it was possible to predict, in late winter, the probability that a male parr would mature in the following autumn. The relative importance of body size and fat content in the maturation process was masked by the strong positive correlation between these two variables.
Suckling, weaning, and growth in captive woodland caribou
Authors: Lavigueur Lucie , Barrette Cyrille
Published: July 2008

To delimit the different stages of the weaning process and to understand the relationship between suckling and growth, the evolution of suckling performance and mother–young interactions associated with milk transfer was closely monitored in a group of woodland caribou (Rangifer tarandus caribou) from birth up to 160 days. Suckling rate and total suckling time dropped rapidly during the first 20 days and slowly thereafter, while suckle duration remained stable during the first 20 days and decreased gradually thereafter. In the first 20 days of life, suckling success declined from 90 to 50%, the proportion of suckles terminated by the mother increased from 30 to 90%, and the proportion of suckles with bunting increased from 40 to almost 100%. The mother licked the calf in 70% of the suckles from birth to 20 days, 40% from 20 to 40 days, and less than 20% subsequently. Suckles with licking were longer than suckles without licking during the first 30 days of life. Suckling was initiated by the calf in more than 80% of the suckles, even in the first days of life. No sex differences were found at any age for any of the behavioral variables measured. Birth weights and growth rates of males from 0 to 45 days, however, were higher than those of females. Growth rates from birth to 45 days were positively correlated with suckling rate during the first 35 days. From 46 to 100 days, growth rates were positively correlated with time spent feeding on pelleted ration and on hay. We suggest that metabolic weaning could begin at around 15–20 days, when suckling success and the mother's contribution to establishing and maintaining suckling interactions decreased most steeply. The end of metabolic weaning could occur at 40–45 days, when suckling rate, suckling success, and the mother's contribution to suckling reached low values from which they declined very slowly to the end of behavioral weaning. Behavioral weaning was not yet completed at the age of 160 days.
The social organisation of Lasioglossum (Dialictus) laevissimum (Smith) in southern Alberta
Authors: Packer Laurence
Published: July 2008

An aggregation of Lasioglossum (Dialictus) laevissimum was studied in Calgary, Alberta, in the summer of 1988. This species was weakly eusocial, with an average of less than 2.5 workers per nest, 43% males in the worker brood, 63% of workers with well-developed ovaries, 35% of them mated, and a mean queen–worker size dimorphism of 7%. Based upon its average rank for these variables, in comparison with eight other species, L. laevissimum is the most weakly eusocial member of the subgenus Dialictus. Nonetheless, reproductive-brood production averaged around 25 per nest, and this species is clearly well adapted to short-summer environments. There was little evidence that any worker-brood females entered early diapause rather than functioning as workers. A few spring nests were initiated by more than one overwintered foundress. These pleometrotic nests often had worker-brood productivities that exceeded average reproductive-brood size. Brood mortality was low, infection of provision masses after rainfall being the major factor.
The interrelationships between gill chloride cell morphology and ionic uptake in four freshwater teleosts
Authors: Perry S. F. , Goss G. G. , Laurent P.
Published: July 2008

We have investigated the role of the gill chloride cell in transbranchial Na+ and Cl− uptake in four species of freshwater teleost maintained in water of identical ionic composition. The basic experimental protocol was to determine whether interspecific variability in the rates of whole body Na+ or Cl− uptake could be accounted for by similar interspecific variability in the fractional area of branchial chloride cells exposed to the external environment. To investigate the underlying cause(s) of intraspecific variability, chronic (10 day) treatment with cortisol in each species was used as a tool to evoke variations in both the rates of ionic uptake and chloride cell morphology. Examination of transmission and scanning electron micrographs revealed distinctive chloride cell and pavement cell morphology in each species. The results of quantitative morphometry, based on analysis of scanning electron micrographs, demonstrated that European eel (Anguilla anguilla) possessed the lowest chloride cell fractional area on the filament epithelium (11 288 ± 2133 μm2/mm2) followed, in increasing order, by brown bullhead catfish (Ictalurus nebulosus; 48 341 ± 7694 μm2/mm2), tilapia (Oreochromis mossambicus; 85 194 ± 10 326 μm2/mm2), and rainbow trout (Oncorhynchus mykiss; 146 333 ± 31 356 μm2/mm2). With the exception of rainbow trout, chronic treatment with cortisol caused significant increases in the chloride cell fractional area of filament epithelium owing to enlargement of the surface area of individual chloride cells and (or) proliferation of chloride cells. Both the inter- and intra-specific differences in chloride cell fractional area were reflected by similar differences in whole body Cl− and Na+ uptake. The results of correlation analysis revealed (with the exception of whole body Na+ uptake in A. anguilla) significant correlations between chloride cell fractional area and the rates of ionic uptake within and among the four species that were examined. These data suggest that the chloride cell is a significant site of ionic uptake in freshwater teleosts and that both inter- and intra-specific differences in the rates of ionic uptake can be explained by variability in the surface area of chloride cells on the gill epithelia.
Hydrothermal vents in turbidite sediments on a Northeast Pacific spreading centre: organisms and substratum at an ocean drilling site
Authors: Juniper S. Kim , Tunnicliffe Verena , Southward Eve C.
Published: July 2008

The interaction of substratum, organisms, and hydrothermal venting was studied at Middle Valley on the northern Juan de Fuca Ridge, where venting occurs through turbidite sediments. Presently, hydrothermal activity in Middle Valley is concentrated within the 300 × 800 m High Heat Flow Area vent field, where it is associated with 10–15 m high sulphide mounds topped by active chimneys. Information on the biological nature of the area was derived from video and photographic records of four 1990 dives by the submersible Alvin, samples collected by Alvin, and bottom photographs by a towed camera. Fieldwork was carried out prior to commencement of 1991 Ocean Drilling Program activities at this site. Despite the limited nature of the collections, the Middle Valley fauna is remarkably specious. We documented 18 vent species new to the Juan de Fuca Ridge. Most interesting were the bivalves, which are rare elsewhere on the ridge. Two new species of vesicomyid clams and a new mussel species were present in the collections, as were a previously known mussel (Idasola washingtonia) and the gutless bivalve Solemya johnsoni. Other notable features are the close proximity of vent and non-vent organisms and the evident influence of surficial and subsurface geological features on venting and organism distribution. The number of new species and the small area occupied by vent sites led us to recommend several precautionary measures to the 1991 drilling program to prevent adverse effects on the vent fauna.
Phylogeny of the Rhyparini and the new tribe Stereomerini, with descriptions of new genera and species (Coleoptera; Scarabaeidae; Aphodiinae)
Authors: Howden Henry F. , Storey Ross I.
Published: July 2008

A new tribe, the Stereomerini, is established for four unusual genera: Stereomera Arrow, Termitaxis Krikken, Australoxenella n.gen., and Bruneixenus n.gen. The previously described genera are monotypic, as is Bruneixenus, the type species being B. squamosus n.sp. from Brunei. Australoxenella contains two new species, A. humptydooensis, type species, and A. bathurstensis, both from the Northern Territory, Australia. The relationships of the new tribe are analyzed and compared with the most closely related tribe, the Rhyparini, in the Aphodiinae. The tribe Rhyparini is redefined, and the genus Notocaulus Quedenfeldt is transferred to the Eupariini. A key to genera in both the Stereomerini and the Rhyparini is presented, important characters are illustrated, a cladogram is given, and convergence is discussed.
Effects of density and food limitation on size variation and mortality of larval Hexagenia rigida (Ephemeroptera: Ephemeridae)
Authors: Hanes Elizabeth C. , Ciborowski Jan J. H.
Published: July 2008

Natural populations of the burrowing mayfly belonging to the genus Hexagenia are characterized by unusually broad size-frequency distributions. Environmental features are often invoked to explain among-populations growth differences. We used a 4 × 4 factorial design to investigate differences in mean larval size and mortality of Hexagenia reared at different densities and food levels over four time intervals (30, 60, 90, and 120 d) in the laboratory. Larvae were hatched from eggs collected from imagoes at the Detroit River near Windsor, Ontario. Although neither density nor food limitation influenced larval growth at either 30 or 60 d growth, the number of days required for eggs to hatch did significantly influence larval growth at this time. At 30 d growth, larvae that hatched after 6 d incubation were significantly smaller than larvae that required an additional day to hatch (7 d). At both 30 and 60 d, larvae that hatched after 6 d incubation had lower mortality than larvae that hatched after 7 d. At 90 and 120 d growth, density and food significantly influenced larval size and mortality. Larvae reared at low density and with a high food level attained the largest size. Mortality increased under stressed conditions (high density and (or) low food level). Since endogenous features (day of hatch) can be important early in larval development (at 30 or 60 d), such features may contribute to the outcome of competitive events that occur later in development (at 90 or 120 d), when exogenous factors (density and food) become significant.
The ultrastructure of a gutless annelid, Parenterodrilus gen. no v. taenioides (= Astomus taenioides) (Polychaeta, Protodrilidae)
Authors: Jouin Claude
Published: July 2008

An ultrastructural investigation of the mouthless protodrilid Parenterodrilus taenioides shows that the residual gut, with its very narrow ciliated lumen, has lost any digestive function. Salivary glands are retained in some anterior segments and their canals converge in a ventral area of the prostomium and open at the epidermal surface. The epidermal ciliation is much more developed than in any other protodrilid species. In the middle and posterior body segments the enlarged epidermal surface area is covered by a cuticle bearing an array of epidermal microvilli which are probably the site of active transport of dissolved organic compounds. The presence of numerous subcuticular coated vesicles and lysyosomes in the support cells suggests that particulate material from the ambient milieu is taken up by endocytosis and finally digested in the epidermis. The origin and nature of the organic substances that constitute the food of P. taenioides are still unknown. There are no symbiotic bacteria in the cuticle, epidermis, or residual gut. Abundant intracellular crystals in the nonfunctional gut indicate that this residual organ plays a role in the bioaccumulation of environmental substances which enter the body through the epidermis. The epidermis is the only absorptive surface of this unique polychaete, which is devoid of both a functional gut and symbiotic bacteria.
Sexually differentiated effects of radio transmitters on predation risk and behaviour in kangaroo rats Dipodomys merriami
Authors: Daly Martin , Wilson Margo I. , Behrends Philip R. , Jacobs Lucia F.
Published: July 2008

In a 12-year study involving 191 radio-tracked Merriam's kangaroo rats and 337 subcutaneous radio implantations, females were killed by predators at a rate of 0.0054 per radio-bearing night and males at a rate of 0.0116. Both the mortality rate and the sex difference therein declined over the course of several nights after radio implantation. Females reduced their excursions from the day burrow for the first few nights after radio implantation, whereas males exhibited little if any such inhibition of movement. This sexually differentiated behavioural response to the transmitters is a likely source of the sexually differentiated mortality patterns.
Comment: Why is conspecific nest parasitism more frequent in waterfowl than in other birds?
Authors: Sorenson Michael D.
Published: July 2008

Rohwer and Freeman (F. C. Rohwer and S. Freeman. 1989. Can. J. Zool. 67: 239–253) have suggested that conspecific nest parasitism is rare in species with parentally fed young because high costs to hosts result in strong selection for defenses against parasitism. In contrast, conspecific nest parasitism is frequent in waterfowl and other species with self-feeding young because the costs of parasitism to hosts are minimal and produce little selection for host defenses. I offer several criticisms of this hypothesis and suggest that variation in the rate of conspecific nest parasitism among birds is better understood by focusing on the costs and benefits of parasitism for the parasitic female. I suggest that conspecific nest parasitism is more successful and therefore more frequent in waterfowl species because parasitic eggs and young require no more parental care from the host than it is already providing to its own offspring. In contrast, parasitism is less successful and less frequent in species with parentally fed young because parasitic young require additional care that hosts may not be capable of providing.
Acute olfactory sensitivity to prostaglandins but not to gonadal steroids in two sympatric species of Catostomus (Pisces: Cypriniformes)
Authors: Cardwell J. R. , Dulka J. G. , Stacey N. E.
Published: July 2008

The discovery that released hormones (steroids and prostaglandins) and their metabolites function as potent pheromones in some fishes provides an opportunity to determine whether these chemically identified pheromones are species specific. As a first step in studying this complex issue, we used an extracellular electrophysiological recording technique (electro-olfactogram) to investigate the olfactory sensitivity of two sympatrically spawning catostomid species (white sucker, Catostomus commersoni, and longnose sucker, Catostomus catostomus; Cypriniformes: Catostomidae) to steroids and prostaglandins that might function as sex pheromones. Both species were acutely sensitive to F-series prostaglandins, particularly prostaglandin-F2α and its metabolite 15-ketoprostaglandin-F2α, but exhibited no olfactory responses to free or conjugated gonadal steroids. The data from tests of olfactory sensitivity to a range of gonadal steroids, though negative, provide preliminary evidence that maturational steroid hormones do not function as pheromones in catostomids as they do in other cypriniform fishes. We were unable to detect species differences in receptor-level olfactory sensitivity to hormones or hormone metabolites, although we cannot discount possible differences at other levels of the olfactory system.
Hematozoa of deep-sea demersal fish of the Northwest Atlantic Ocean
Authors: Khan R. A. , Threlfall W. , Whitty W. S.
Published: July 2008

A total of 410 deep-sea demersal fish comprising 54 species was taken at depths of 1000–3200 m from two locations in the Northwest Atlantic Ocean and examined for hematozoans. Prevalences of 29% of the total fish and 61% of the species examined were observed. Piroplasms (Haemohormidium spp.) were the most common parasites (26% infection), with hemogregarine, trypanosome, and cryptobia infections being considerably lower. Haemogregarina marshalllairdi sp.nov. is described from Nezumia bairdi and Macrourus berglax. An enigmatic intraerythrocytic parasite was observed in one fish. A comparison of prevalences of the infections in fish living in the deep sea, on the continental shelf, and in inshore areas indicates that the percentages of fish species infected are comparable in the three areas and that the prevalence of piroplasm infections is greater in the deep-sea locations. It is likely that transmission of hematozoans, probably by hematophagous leeches, in the deep-sea demersal zone is similar to that on the continental shelf, despite the dramatic changes in biological and physico-chemical factors with increasing depth.
Revision of Egglestonichthys and of Priolepis species possessing a transverse pattern of cheek papillae (Teleostei; Gobiidae), with a discussion of relationships
Authors: Winterbottom Richard , Burridge Mary
Published: July 2008

We recognize seven species in this group, five of which are described here. Priolepis profunda (Weber) occurs in central Indonesia and western Australia; P. anthioides (Smith) is known only from Zanzibar; P. aithiops n.sp. and P. sticta n.sp. are known only from Flores, Indonesia; P. fallacincta n.sp. occurs fairly widely in the western Pacific from Taiwan to Fiji and the Great Barrier Reef; P. randalli n.sp. is present in the Persian Gulf (and probably the Red Sea); and Priolepis RW sp. 8, to be described by other workers, is known from Japan through to western Australia, the Great Barrier Reef, and New Caledonia. The monotypic Egglestonichthys (known from a single specimen from the South China Sea) exhibits all the defining characteristics of Priolepis, and represents the plesiomorphic sister-group of either Priolepis, if the latter proves to be monophyletic, or of a monophyletic group composed of Priolepis, Trimma, Trimmatom, Paratrimma, and possibly some other genera. The entire clade is defined by two autapomorphies: loss of the cephalic sensory canals and associated pores, and a broad gill opening extending anteroventrally to below at least the vertical limb of the preopercle.
Maternal investment in otariid seals and walruses
Authors: Kovacs Kit M. , Lavigne D. M.
Published: July 2008

We examined neonatal size, growth rate during lactation, weaning mass, adult body mass, and the degree of polygyny among fur seals and sea lions (Otariidae) and walruses (Odobenidae). Observed patterns of maternal and sexual investment were compared with those reported for true seals (Phocidae) and for other mammals. There was a strong positive interspecific allometric relationship between mass at birth and maternal mass for otariid species (p < 0.001). The slope of this relationship was significantly different from that for phocid species (p < 0.001). All pinniped data were above the regression line for terrestrial mammals. Lactation was longer and growth rates were slower for otariid and odobenid species than for phocid species. The cyclic foraging pattern of lactating otariids allows for more flexibility in the duration of lactation than is possible in phocids. Such flexibility may serve as a buffer when food is scarce. The longer lactation period of otariids and walruses also permits offspring to develop swimming and foraging skills while still depending on their mothers for energy. The relationship of mass at weaning to maternal mass suggests a greater investment in each neonate in otariids and walruses than in phocids. The large body size and advanced state of development at weaning may be an adaptive response to predation pressure on otariids. Adult male otariids and walruses are larger than females and, in both families, the average birth mass, mass at weaning, and growth rate of male pups are greater than those of females. The ratio of body masses of male pups to female pups at birth and at weaning was not correlated with the degree of adult sexual dimorphism within species, despite a positive correlation between the ratio of body masses of adult males to adult females and the degree of polygyny across otariid species.
Immunohistochemical detection of biogenic amines in the photophores of the midshipman fish Porichthys notatus
Authors: Mallefet Jérôme , Anctil Michel
Published: July 2008

Biogenic amines are known to be present in the luminescence organs (photophores) of the teleost midshipman fish Porichthys notatus, but their distribution within the photophores was unknown until now. The cellular localization of endogenous monoamines was therefore investigated in the photophores of this fish by peroxidase–antiperoxidase immunohistochemistry with antibodies against serotonin, noradrenaline, and adrenaline. Strong serotonin-like immunoreactivity was detected exclusively within the light-emitting cells (photocytes). By contrast, strong noradrenaline immunostaining was present in axonal processes surrounding the photocytes and the lens border cells, and light staining was also observed within the photocytes. Adrenaline immunostaining was strongest in lens border cells, weak in photocytes, and absent in axonal processes. These observations support previous experimental results which suggest that noradrenaline is the excitatory neurotransmitter for light emission in this fish. The non-neuronal distribution of serotonin and adrenaline in the photophore suggests that these amines, or mere metabolites of adrenaline, play a neuromodualtory or paracrine role related to regulation of luminescence.