bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Identification of Sea Lamprey (Petromyzon marinus) Populations from the Lake Superior Basin
Authors: Krueger Charles C. , Spangler George R.
Published: May 2008

Sea lamprey (Petromyzon marinus) ammocoetes collected from 18 locations within Lake Superior were electrophoretically analyzed for genetic variability at 25 enzyme loci. Analysis by F statistics and χ2 tests indicated that a significant degree of population structuring occurs among lampreys from Lake Superior. Cluster analysis of genetic distances generally grouped collections that were in close geographical proximity to each other. A weak but significant correlation was detected between genetic and geographic distances. It was concluded that multiple populations of sea lamprey occur within Lake Superior. If this is the case, then sea lamprey control emphasis might shift from individual streams to population regions to minimize the rate of reestablishment subsequent to chemical treatment. It may also be wise to avoid the planting of fish species with migratory habits so as to prevent the passive transport of adult lampreys out of their population areas.Key words: lamprey, Petromyzon, genetics, population identification, Lake Superior, electrophoresis, management
Stock Identification: Materials and Methods
Authors: Ihssen P. E. , Booke H. E. , Casselman J. M. , McGlade J. M. , Payne N. R. , Utter F. M.
Published: May 2008

Various population parameters and physiological, behavioral, morphometric, meristic, calcareous, biochemical, and cytogenetic characters have been used to identify fish stocks. We define a stock as an intraspecific group of randomly mating individuals with temporal or spatial integrity. Each character set and the associated methodology relates to specific aspects of the stock definition. Population parameters are useful primarily for the recognition of putative stocks at the practical fisheries management level. Physiological and, to some degree, behavioral characters are used primarily to study differences in the adaptation of stocks to different environments. Behavioral characters are also important for the recognition of stocks and the study of their spatial and temporal discreteness. Morphological characters, including morphometric measurements, meristic counts, and the shape, size, and type of zonation in calcareous structures provide data that are useful for the precise description of and differentiation among stocks. Although the genetic control of this type of variation is poorly understood, multivariate methods coupled with shape analyses provide techniques that describe intraspecific subdivisions that have been found to correspond to genetic stock structure as determined by other methods. Intraspecific chromosomal variation has, on occasion, been employed for stock identification. This variation has had only limited application to the study of stocks because of complications arising from intraindividual variation and artifactual variation introduced by the methodology. Electrophoresis provides an important method for measuring the genetic discreteness of stocks and for the study of genetic relationships among stocks. Electrophoretic data have recently attained a primary position among the methods used for stock identification.Key words: stock identification, genotype, phenotype, population parameters, marking, physiological, behavioral, morphometric, meristic, calcareous, cytogenetic, and biochemical characters
Perspectives and Policy Recommendations on the Relevance of the Stock Concept to Fishery Management
Authors: Spangler G. R. , Berst A. H. , Koonce J. F.
Published: May 2008

The Stock Concept International Symposium (STOCS) addressed a broad range of concerns about the relationship between intraspecific stocks and their genetic and environmental origins. STOCS produced an understanding of the stock concept that makes it possible to develop operational stock definitions reflecting the key elements of concern to fishery managers. These definitions can change as circumstances dictate because stocks represent states in a dynamic process. Extensive life history information available for Great Lakes fish provides a basis for estimating the significance of intraspecific stock structure in management of these species. Recognition of the potential for stock formation is important for evaluating the impact of management actions and for planning the restoration of individual species in fishery rehabilitation programs. Finally, we present a brief set of recommendations for research and management based on our perception of the stock concept and its relevance to fish community rehabilitation.Key words: fish stocks, fishery rehabilitation
Multistage Sampling Designs in Fisheries Research: Applications in Small Streams
Authors: Hankin David G.
Published: May 2008

A common, although generally unrecognized, use of multistage sampling designs in freshwater fisheries research is for estimation of the total number of fish in small streams. Here there are two stages of sampling. At the first stage one selects a sample of stream sections, usually of equal length, and at the second stage one estimates the total number of fish present in each selected section. This paper argues that the conventional practice of selecting stream sections of equal length is ill-advised on both biological and statistical grounds, and that errors of estimation of fish numbers within selected sections will usually be small compared with errors of estimation resulting from expansion of sampled sections to an entire stream. If stream sections are instead allowed to vary in size according to natural habitat units, then alternative two-stage sampling designs may take advantage of the probable strong correlation between habitat unit sizes and fish numbers. When stream sections of unequal sizes are selected with probabilities proportional to their size (PPS), or measures of the sizes of selected sections are incorporated into estimators, one may substantially increase precision of estimation of the total number of fish in small streams. Relative performances of four alternative two-stage designs are contrasted in terms of precision, relative cost, and overall cost-effectiveness. Choice among alternative designs depends primarily on the correlation between fish numbers and habitat unit sizes, on the total number of stream sections, and on sample size. Recommendations for choices among the designs are presented based on these criteria.
Extraction of Algal ATP and Interpretation of Measurements
Authors: Hendzel L. L. , Healey F. P.
Published: May 2008

We compared ATP samples collected by direct injection with those collected by filtration from exponential and P-limited algal cultures, and from summer populations of several lakes. The direct injection method yielded higher amounts of measurable ATP than did filtration on 2.5- and 4.5-cm diameter membrane filters. ATP lost to the filtrate was negligible. Variation in ATP content with increasing nutrient deficiency was measured on six cultures. ATP/C decreased with N deficiency and to a greater degree with P deficiency. Large changes of ATP/C usually occurred with little change in viability of the cells. Short-term (1 h) nutrient enrichments generally did not change the ATP/C ratio. Phosphorus deficiency tended to increase the chlorophyll/ATP ratio and N deficiency to decrease it. We found that the short- and long-term effects of alkaline phosphatase on ATP extracts from P-sufficient and P-deficient Scenedesmus quadricauda were negligible. There appeared to be little effect on frozen ATP samples stored up to 60 d. Any short-term effects were similarly negligible, since temperature and the addition of P did not affect the rate of ATP loss. The use of 0.33 mol H3PO4∙L−1as an extractant proved to be completely unreliable.
Some Causes of Variation in Estimates of Mean Weights for Hydropsyche Larvae (Trichoptera: Hydropsychidae)
Authors: Mackay Rosemary J.
Published: May 2008

I present monthly values of mean dry weight per larval instar for 1 yr for Hydropsyche betteni Ross, H. bronta Ross, H. morosa Hagen, H. slossonae Banks, and H. sparna Ross. Larvae of each species were collected from two or four sites in the Credit and Number rivers of southern Ontario. Month-to-month changes in mean weight were more irregular in spring, summer, and autumn than in winter; summer values tended to have the highest standard errors. When growth was fast in summer, any one instar was constantly receiving low-weight individuals from the previous instar while losing heavier individuals to the next instar; successive monthly collections were sampling instars at various stages in the recruitment–loss continuum. Sexual differences were additional causes of wide ranges in weight in instar V; larvae destined to produce female pupae could be twice as heavy as those developing into male pupae. Because metamorphosis into males tended to precede that into females, heavier potentially female larvae were sometimes the only individuals collected during certain prepupal periods in summer. A mixture of cohorts and generations in summer also contributed to high variance. Winter weights, in contrast, were less variable from month to month and tended to have a smaller range per instar. When a particular instar was present in winter (December–March), its mean winter weight closely approximated the overall annual mean.
Relative Importance of Anthropogenic versus Natural Sources of Acidity in Lakes and Streams of Central Ontario
Authors: LaZerte Bruce D. , Dillon Peter J.
Published: May 2008

Anthropogenic acid deposition has been implicated in the acidification of surface waters of central Ontario and elsewhere. However, alternative sources of acidity have been proposed, including (i) the release of protons and their accompanying acid anions by soils (e.g. organic acids) and (ii) the exchange of internally generated protons for the cations of atmospherically deposited neutral salts (e.g. sea salts). We show that for a typical acidified catchment in central Ontario the first hypothesis is not important during periods of high discharge or on an annual basis. As most of the neutral salts deposited on inland areas are sulphate and nitrate of anthropogenic origin, any acidity generated via the second mechanism can be reduced by reducing the emission of the salts. A third and alternative hypothesis is that deposition of strong acid alters only the balance between humic anions and sulphate in runoff waters, but not pH; we have shown this to be incorrect using catchments from the Sudbury region of Ontario where rates of acid deposition have recently declined. We conclude that in central Ontario, acidic deposition derived from anthropogenic SO2 sources is the primary causal factor in recent lake acidification, and that a reduction in the anthropogenic emissions affecting this area will result in a decrease in lake acidity.
Electrolyte and Water Balance in Plasma and Urine of Rainbow Trout (Salmo gairdneri) during Chronic Exposure to Cadmium
Authors: Giles Michael A.
Published: May 2008

Rainbow trout (Salmo gairdneri) were exposed to 3.6 and 6.4 μg Cd/L for periods up to 178 d. Transitory changes in plasma calcium and magnesium were observed in fish exposed to 3.6 μg Cd/L although the differences were not significant. Exposure to 6.4 μg Cd/L, however, resulted in significantly lowered plasma sodium, potassium, calcium, and chloride and elevated magnesium concentrations. Analyses of urine indicated that the rate of urine production, osmolality, and sodium, potassium, chloride, magnesium, calcium, and protein concentrations were unaffected by exposure to 3.6 μg Cd/L although slight changes were observed in the first week of exposure. Urine production rate and urinary concentrations of potassium and chloride were unaffected in trout exposed to 6.4 μg Cd/L but sodium, protein, and osmolality were elevated and calcium and magnesium concentrations reduced in these fish. The results demonstrate that the majority of the cadmium-induced electrolyte imbalances do not result from impairment of renal function.
Biochemical Genetic Stock Identification of Pink Salmon (Oncorhynchus gorbuscha) in Southern British Columbia and Puget Sound
Authors: Beacham Terry D. , Withler Ruth E. , Gould Allan P.
Published: May 2008

We used electrophoresis to examine genetic variability at 12 loci for 4 even-year broodline stocks and at 14 loci for 21 odd-year broodline stocks of pink salmon (Oncorhynchus gorbuscha) in southern British Columbia and Puget Sound. Allelic frequencies were most heterogeneous between the two pink salmon broodlines, but within the odd-year broodline, Fraser River, Canadian non-Fraser, and Puget Sound pink salmon had significantly different allelic frequencies at some loci. Canadian non-Fraser River stocks had the greatest heterogeneity of allelic frequencies within a region, whereas the Fraser River stocks had the least amount of heterogeneity. There was no significant two-locus linkage disequilibrium for the pink salmon stocks surveyed. Cluster analyses by allelic frequencies indicated that Fraser River, Canadian non-Fraser, and Puget Sound stocks were reasonably distinctive. We used differences in genotypic frequencies at 11 loci (3 were duplicated loci) to estimate stock composition of these three groups of pink salmon in mixtures in which the true compositions were known, and we were able to compare the accuracy and precision of our estimates with respect to mixture size and stock composition. We estimated that 100% of pink salmon sampled in a test fishery in Thompson Sound were of Canadian non-Fraser origin.
Micro- and Macrozooplankton on the Nova Scotian Shelf in the Prespring Bloom Period: A Comparison of Their Potential Resource Utilization
Authors: Paranjape M. A. , Conover R. J. , Harding G. C. , Prouse N. J.
Published: May 2008

Mean abundance and organic carbon content of the microzooplankton community in the euphotic zone across the Nova Scotian Shelf in late winter ranged from 1.22 × 102 to 1.63 × 103∙L−1 and 1.61 to 7.0 μg C∙L−1, respectively. Microzooplankton carbon was 4–13% of the phytoplankton carbon and 55–456% of the macrozooplankton carbon. There was no evidence of onshore–offshore gradients in microzooplankton distribution, primary productivity, standing stock of phytoplankton, or macrozooplankton biomass. Estimated ingestion and respiration rates of microzooplankton and measured ingestion and respiration rates of macrozooplankton suggest that phytoplankton carbon or daily primary production probably would be sufficient to satisfy respiratory carbon requirements of both groups of herbivores but growth and reproduction could not have been sustained without ingestion of nonplant carbon.
Patterns of Epipelic Algal Abundance with Depth, Trophic Status, and Acidity in Poorly Buffered New Hampshire Lakes
Authors: Stevenson R. J. , Singer R. , Roberts D. A. , Boylen C. W.
Published: May 2008

The biovolume and species composition of algae on sediments in 20 poorly buffered New Hampshire lakes were surveyed in autumn to delineate patterns of community structure and composition with acidity and trophic status of lakes, and along depth gradients within lakes. Patterns of total algal biovolume on sediments were not strongly related to these habitat conditions because of masking by algae that probably settled from the plankton onto sediments. Biovolumes of "benthic" algae generally decreased with depth; however, weak and positive correlations between biovolumes of some benthic algal taxa and depth indicated that benthic algae had adapted to low light conditions and were perhaps facultatively heterotrophic. Decreases in diatom and increases in blue-green algal biovolumes with total phosphorus and chlorophyll a concentrations in lake water indicated that blue-green algae were better adapted for sequestering nutrients in low light environments. The variability in patterns of algal biovolume with acid neutralizing capacity (ANC) and pH indicated that algae had adapted well to different levels of ANC and pH. Biovolumes of blue-greens were negatively correlated with ANC, primarily because of the high biovolumes of various blue-green algae that occurred sporadically in lakes with ANC between 0 and 20 μeg/L and pH between 5.8 and 6.0. Diatom biovolumes generally increased with ANC and pH; however, biovolumes of several species of diatoms, including a Pinnularia, were greatest in low ANC and pH lakes. In general, Eunotia biovolumes decreased and Navicula and Pinnularia biovolumes increased with ANC and pH.
Organic Matter in the Gulf of St. Lawrence in Winter
Authors: Pocklington Roger
Published: May 2008

Concentrations of organic matter in particulate and dissolved form are low in the Gulf of St. Lawrence in winter, comparable with levels in waters outside the Gulf. There is no substantial export of organic matter from the Gulf through Cabot Strait at this time. Within the Gulf, particulate transports into and out of the Estuary are lower than at other seasons.
Chromosome Polymorphism Patterns Indicate Failure of a Scottish Stock of Salmo salar Transplanted into a Spanish River
Authors: García-Vázquez E. , Morán P. , Pendás A. M.
Published: May 2008

A river in the Asturias region of northern Spain was repopulated with fry originating from two different stocks of Salmo salar: native adults and a Scottish stock. A sample of parr captured in the river in 1989 showed the same pattern of chromosome polymorphism as the autochthonous stock released 6 mo before. We conclude that repopulation with the foreign stock was unsuccessful and that chromosome polymorphism patterns yield a useful method of stock discrimination in certain situations.
Growth and Reproductive Energetics of three Scallop Species from British Columbia (Chlamys hastata, Chlamys rubida, and Crassadoma gigantea)
Authors: MacDonald B. A. , Thompson R. J. , Bourne N. F.
Published: May 2008

Three scallop species from British Columbia display different strategies for partitioning available energy between somatic tissue growth and gamete production as they increase in age. The spiny scallop Chlamys hastata and the pink scallop Chlamys rubida only live about 6 yr and rarely exceed 80 mm in shell height whereas the rock scallop Crassadoma gigantea may reach 170 mm in height and live for 20 yr or more. Growth, reproductive output, and reproductive effort at any given age are higher in Chlamys hastata than in the smaller Chlamys rubida. Somatic growth in Crassadoma gigantea ceases completely in the final years, but in the short-lived species Chlamys hastata and Chlamys rubida, individuals continue to grow until they die. In long-lived pectinids the emphasis often shifts from somatic growth to gamete production before the midpoint of the life cycle, and our observations on Crassadoma gigantea are consistent with this trend. Short-lived species, however, invest relatively less in reproduction; in our study, reproductive output in Chlamys rubida did not exceed 40% of nonrespired assimilation (net production), and reproductive effort in Chlamys hastata did not reach 50% until the final year of life.
Interbreeding with Domestic Strain Increases Foraging under Threat of Predation in Juvenile Steelhead Trout (Oncorhynchus mykiss): An Experimental Study
Authors: Johnsson Jörgen I. , Abrahams Mark V.
Published: May 2008

The foraging behaviour of laboratory-reared juvenile steelhead trout (Oncorhynchus mykiss) and steelhead/domesticated rainbow trout hybrids were compared. In 10 replicate experiments, 10 fish from each strain were allowed to choose between foraging in a safe area or an area containing a predator. The hybrid trout were significantly more willing to risk exposure to the predator than were the steelhead. It was possible that differences in the relative willingness to risk exposure may have reflected differences in their susceptibility to predation. A second experiment measured the susceptibility of these two strains to the predator by simulating standardized encounters between predator and prey. Both strains suffered identical mortality rates and therefore were considered to be equally susceptible to the predator. This experiment confirmed that the hybrid trout were significantly more willing to take risks than the wild steelhead. These results indicate that interbreeding between escaped hatchery and wild fish may have a potentially damaging effect on the wild population.
Evaluation of a Mark–Recapture Method for Estimating Mortality and Migration Rates of Stratified Populations
Authors: Dorazio Robert M. , Rago Paul J.
Published: May 2008

We simulated mark–recapture experiments to evaluate a method for estimating fishing mortality and migration rates of populations stratified at release and recovery. When fish released in two or more strata were recovered from different recapture strata in nearly the same proportions, conditional recapture probabilities were estimated outside the [0, 1] interval. The maximum likelihood estimates tended to be biased and imprecise when the patterns of recaptures produced extremely "flat" likelihood surfaces. Absence of bias was not guaranteed, however, in experiments where recapture rates could be estimated within the [0, 1] interval. Inadequate numbers of tag releases and recoveries also produced biased estimates, although the bias was easily detected by the high sampling variability of the estimates. A stratified tag–recapture experiment with sockeye salmon (Oncorhynchus nerka) was used to demonstrate procedures for analyzing data that produce biased estimates of recapture probabilities. An estimator was derived to examine the sensitivity of recapture rate estimates to assumed differences in natural and tagging mortality, tag loss, and incomplete reporting of tag recoveries.
Mysis relicta Assimilation of Hexachlorobiphenyl from Sediments
Authors: Klump J. Val , Kaster Jerry L. , Sierszen Michael E.
Published: May 2008

Assimilation and retention of a PCB congener, 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP), by the oppossum shrimp, Mysis relicta, was followed during sediment ingestion and defecation using a 14C label. Uptake was rapid and essentially linear, with mysids reaching a [14C]HCBP specific activity equivalent to that in the labeled sediment within 2 wk. Assimilation efficiencies calculated from the relative depletion of the label in the fecal material averaged 53% (±7%). Sediment ingestion rates calculated from the activity required to supply the label retained were approximately 1 mg∙mysid−1∙d−1, in agreement with published estimates. The distribution of HCBP as a function of particle size indicates that particle-size selective feeding by detritivores can have a significant effect on calculated assimilation efficiencies. Given the vertical migration behavior of M. relicta, sediment ingestion is a potentially important pathway for the reintroduction of sediment-associated contaminants into the pelagic environment of deep lakes.
Identification of Thunnus Tuna Species by the Polymerase Chain Reaction and Direct Sequence Analysis of their Mitochondrial Cytochrome b Genes
Authors: Bartlett Sylvia E. , Davidson William S.
Published: May 2008

Four commercially important tuna species in the genus Thunnus are caught off the east coast of Canada. The harvest of bluefin tuna (T. thynnus) is regulated, but that of bigeye (T. obesus), yellowfin (T. albacares), or albacore (T. alalunga) is not. Enforcement of the regulations governing the biuefin fishery has been difficult because of the close genetic relationships among these species and the ease with which morphological characters may be removed once a fish has been landed. Isoelectric-focusing of water-soluble muscle proteins does not resolve these four tuna species beyond two groups: one consisting of bluefin and yellowfin and the other comprising bigeye and albacore. The polymerase chain reaction was used to amplify a 307 base pair segment of the mitochondrial cytochrome b gene from members of these species. There is intraspecific variation at this locus in each of the species. More importantly, there are differences between the four species and these genetic markers can be used to determine the species identity of an individual tuna with a high degree of confidence. This methodology should prove very useful for enforcing the regulations governing Canada's bluefin tuna fishing industry.
Determining Fish Age from Temporal Signatures in Growth Increments
Authors: Ogle D. H. , Spangler G. R. , Shroyer S. M.
Published: May 2008

The temporal signature technique can be used to assign age to fish that show an incomplete or indistinct growth history at the margins of their scales. The temporal signature technique matches part of an individual's "environmental" growth history to characteristic patterns found in a master chronology that was developed from reliably aged specimens of a species in a particular environment. An error sum of squares measures the concordance between an individual's environmental growth history and the master chronology. Ages assigned to walleye (Stizostedion vitreum) by the temporal signature technique and by examination of scales were compared to assess the performance of the new technique. Scale-age agreed with one of the three most likely signature-ages in 67–77% of the comparisons using ail observed increments. These results are purposely conservative because of the methods employed and the nature of the example. All observed growth increments should be used in applying the temporal signature technique, but age may still be accurately assigned if as few as three increments are available. The temporal signature technique will perform best for species that exhibit high interannual variation in growth.
Consequences of Pulsed DC Electrofishing and Air Exposure to Rainbow Trout (Oncorhynchus mykiss)
Authors: Mitton C. J. A. , McDonald D. G.
Published: May 2008

Electrofishing, a technique widely used for fish collection, is a procedure that is often followed by handling and air exposure before fish are released. In this study the pathological and physiological consequences of capture with pulsed DC (pDC) electroshock with and without the additional disturbance of air exposure were examined on rainbow trout (Oncorhynchus mykiss). Electroshocked fish showed no evidence of direct mortality, and skeletal damage was only induced under the most severe conditions (~600-g fish, 600 V, 20 or 40 s). Physiological disturbances induced by pDC, in the absence of physical damage, consisted of lactacidosis and stimulation of the interrenal stress response. The acidosis was likely induced by tetany during immobilization and apnea during immobilization and early recovery. In fact, the physiological disturbances induced by pDC were similar in magnitude and duration to 2–3 min of exhaustive exercise and generally more severe than responses previously reported for nonpulsed (i.e., continous) DC gear. In addition, following pDC, fish appeared to experience a mild narcosis, as was evident by a reduced response to the additional stress of air exposure.
Effects of Electroshock, Air Exposure, and Forced Exercise on Swim Performance in Rainbow Trout (Oncorhynchus mykiss)
Authors: Mitton C. J. A. , McDonald D. G.
Published: May 2008

Swim performance of rainbow trout (Oncorhynchus mykiss) following forced exercise and pulsed DC electroshock both with and without subsequent air exposure was examined. Swim stamina was assessed by exercising fish at 39 cm/s until exhausted. Swim performance was impaired following all treatments. Increasing durations of air exposure (0–4 min) after electroshock resulted in progressively prolonged durations of swimming impairment (from 1 to 6 h). Electroshock reduced swimming stamina in a virtually identical fashion to that of 5 min of forced exercise. By comparison with the existing literature on the physiological effects of forced exercise, the impairment of swim performance most likely resulted from a reduction in intracellular pH.
Sedimented Diatoms in Northern New England Lakes and Their Use as pH and Alkalinity Indicators
Authors: Davis Ronald B. , Anderson Dennis S. , Norton Stephen A. , Ford Jesse , Sweets P. Roger , Kahl Jeffrey S.
Published: May 2008

Gradient analyses of 29 chemical and physical (C–P) variables and diatom remains in surface sediments of 63 New England lakes (pH 4.4–7.9) indicate a primary C–P gradient of pH, alkalinity, Ca, Mg, conductance, and Al; diatom distributions are most strongly related to that gradient (especially to pH and alkalinity) and also reflect secondary gradients (oceanic–inland, lake morphology, and regional chemistry). The primary relationship supports the calibration of regression models for paleolimnological inference of pH and alkalinity based on diatoms. To optimize inference models for the region's most acidic lakes, a second set of calibrations was run after culling the seven least acidic lakes. Diatom distributions on the restricted pH and alkalinity gradients are of two types: roughly uniclinal and variously unimodal. Models assuming each type were calibrated: CLUSTER (linear), DCA (unimodal), and CCA (unimodal). Log-transformation of alkalinity improved the 63-lake DCA and CLUSTER regressions, but worsened or left the others unchanged. Postulated causes of incongruous diatom assemblages and outlier pH and alkalinity inferences are sediment mixing, focusing time lag, growth of epipelic diatoms at the core site, and atypical lake morphology. Careful selection of calibration lakes is at least as important as the choice of regression models.
Immunohistochemical localization of vitellogenin and associated morphologic changes in hepatocytes of channel catfish, Ictalurus punctatus
Authors: Pacoli Cecily Q. , Grizzle John M. , Bradley James T.
Published: May 2008

Vitellogenin (VG) was localized in the cytoplasm of hepatocytes in freeze-dried, plastic-embedded and Bouin's-fixed, paraffin-embedded sections of channel catfish liver. The location of VG was demonstrated by using a peroxidase–antiperoxidase immunohistochemical method. Positive immunostaining was obtained only in naturally vitellogenic females and in fish that had been injected with 2 mg/100 g body weight 17β-estradiol. Vitellogenin reaction product was observed in most but not all of the hepatocytes from estradiol-induced and naturally vitellogenic fish. Glycogen content was reduced in hepatocytes that showed positive VG immunostaining. Nuclear size was larger in hepatocytes from vitellogenic fish compared with nonvitellogenic fish.
Detecting stress responses in Rocky Mountain bighorn sheep (Ovis canadensis canadensis): reliability of cortisol concentrations in urine and feces
Authors: Miller Michael W. , Hobbs N. Thompson , Sousa Marsha C.
Published: May 2008

We evaluated the reliability of using cortisol concentrations in urine and feces to indicate stress responses in captive Rocky Mountain bighorn sheep (Ovis canadensis canadensis). Tests for parallelism and quantitative recovery of cortisol in bighorn plasma, urine, and fecal supernatant revealed that radioimmunoassay reliably measures cortisol in these media. High performance liquid chromatography confirmed the presence of cortisol in fecal extracts. In a randomized complete block experiment, we observed cortisol responses of eight bighorn sheep injected with either 0.0 or 0.50 U/kg of adrenocorticotrophic hormone (ACTH) gel delivered at 48 h intervals over a 29-day period. Treatment elevated (P < 0.01) cortisol in urine and fecal supernatant during 0–24 h following ACTH injections but levels dropped below those of controls during 24–48 h posttreatment. Magnitude of cortisol responses did not change with time during the experiment (time × treatment, P > 0.05). In a separate experiment, we observed short-term (0, 2, 4, 8, 12, 24 h) cortisol responses in plasma, urine, and feces from eight bighorns following a single challenge with 0.0, 0.25, 0.5, or 1.0 U/kg of repository corticotropin. Plasma cortisol concentrations rose within 2 h of treatment (P < 0.025) and remained elevated for at least 8 h. Urine cortisol excretion showed a similar trend with peak response delayed 2–6 h. Fecal cortisol trends resembled those of plasma and urine but were more variable. We failed to observe a dose response above the 0.5 U/kg level in any media. Concentrations of cortisol (ng/mL) in plasma correlated (r2 = 0.76) with cortisol:creatinine ratios (ng/mg) in urine. We conclude that measuring cortisol in excreta of bighorn sheep offers promise as a noninvasive means of sampling their responses to environmental stressors.
Decline in doe fawn fertility in southern Michigan deer
Authors: Verme Louis J.
Published: May 2008

Odocoileus virginianus declined from a 60% pregnancy rate to <47% between 1952 and 1982. This change was inversely correlated (P = 0.010) with annual deer kill, which increased more than 18-fold over that period owing to herd eruption. Sustained high fecundity among doe fawns that bred suggests that nutritional resources on this prime agricultural land had not diminished during the interim. I hypothesize that the declining pregnancy rates were related to biosocial factors, namely the effect of orphaning in accelerating doe fawn sexual maturity (due to lack of maternal domination), associated with a reduction in the proportion of antlerless deer harvested as the population continued to rise over the three decades studied.
Évolution spatio-temporelle du réseau de galeries chez le polychète Nereis virens (Sars) en relation avec la densité
Authors: Miron G. , Desrosiers G. , Retière C. , Lambert R.
Published: May 2008

In burrowing species, burrowing behaviour sometimes gives rise to the establishment of a territory. The spatio–temporal evolution of tunnels in the Polychaete Nereis virens (Sars) allowed us to study space allocation between individuals under two conditions of population density. During the first 3 days, a behaviour of exploration–construction within the substrate is observed. At that point, the tunnel has many branches and is a complex system of ramifications. On the 7th day, the system is simplified. The fluctuations of the various structural parameters of the burrow indicate alternating phases of activity in the animal. The shape and size of the burrow are density dependent. When the density is low, the burrow is U-shaped, whereas it is I-, L-, or Y-shaped at high density. The structure of the burrows, as observed in resin casts in the laboratory, and the absence of connections between the burrows indicate the onset of a territorial behaviour within the sediment right at the beginning of construction.[Journal translation]
Organ-specific regulation of phosphofructokinase during facultative anaerobiosis in the marine whelk Busycotypus canaliculatum
Authors: Whitwam Ross E. , Storey Kenneth B.
Published: May 2008

The kinetic properties of 6-phosphofructo-1-kinase (PFK) were assessed in five organs (ventricle, radular retractor muscle, gill, hepatopancreas, and kidney) of aerobic and anoxic (21 h in N2-bubbled seawater) whelks, Busycotypus canaliculatum. The enzyme in all organs showed a stable modification of kinetic parameters as a result of exposure of the animal to anoxic conditions. In most cases these changes were consistent with the conversion of the enzyme to a less active form in the anoxic organ. In ventricle, for example, the anoxic enzyme form showed significant changes, including a 36% increase in the value of the substrate affinity constant (S0.5) for Mg∙ATP, a 19% increase in S0.5 fructose-6-phosphate, a 57% increase in the 50% inhibition value (I50) for phosphoenolpyruvate, a 30% increase in I50 citrate, and a fivefold increase in the activator constant (Ka) for fructose-2, 6-bisphosphate, as compared with the aerobic enzyme. Analysis of the time course of anoxia-induced modification of PFK showed that changes to the properties of gill PFK were accomplished within 2 h of the exposure to N2-bubbled seawater, whereas changes to ventricle PFK required up to 8 h. In vitro incubation of ventricle homogenates with Mg∙ATP plus protein kinase second messengers or with Mg2+ plus added protein phosphatases showed that the aerobic enzyme form was modified by protein kinase action with an increase in Ka fructose-2,6-bisphosphate that mimicked the effect of the aerobic to anoxic transition on the enzyme. Phosphatase action on the anoxic enzyme form had the opposite effect. The data suggest that the modification of PFK properties under anoxia in whelk organs is due to protein phosphorylation of the enzyme. Such covalent modification of PFK and other enzymes, notably pyruvate kinase, coordinates the anoxia-induced glycolytic rate depression and overall metabolic arrest that is a prominent feature of facultative anaerobiosis in marine molluscs.
Partial characterisation of a spawning pheromone in the herring Clupea harengus pallasi
Authors: Sherwood Nancy M. , Kyle Ann L. , Kreiberg Henrik , Warby Carol M. , Magnus Timothy H. , Carolsfeld Joachim , Price W. Stephen
Published: May 2008

The production of a pheromone-like spawning substance by male herring is confirmed and biochemical properties of the substance are characterised. A behavioural bioassay is described in which 0.25–0.5 mL of test solution was added to 46 L of water containing a single male herring. The effect of the solution was judged by the degree of extension of the herring gonadal papilla and release of milt. Treatment with fresh milt, extracts of milt, or extracts of mature testes resulted in papilla extension, often with milt release; extracts of ovaries or immature testes were not effective. The milt and testicular extracts retained their bioactivity during purification, including removal of substances soluble in petroleum ether, elution from C-18 Sep-Pak cartridges, and elution from C-18 high-performance liquid chromatography (HPLC) columns. The bioactive substances do not appear to be proteins or peptides, because (i) bioactivity was retained in milt and testicular extracts after the large proteins were precipitated by acetone−HCl solution and discarded, and (ii) bioactivity was present after the remaining soluble peptides were degraded by incubation with pronase E, proteinase K, or protease type VI enzymes. The pheromone is also not a neutral lipid or nonpolar fatty acid, as bioactivity remained in the aqueous phase after extraction with petroleum ether. Rather, the proposed pheromone(s) eluted from Sep-Pak C-18 cartridges with 30% acetonitrile and subsequently from the reverse-phase HPLC column in fractions 33–48 with a gradient of acetonitrile. Several polar steroids, conjugated steroids, and prostaglandin F2α were also shown to elute in this region, whereas a variety of other less polar compounds eluted later. Finally, after the post-Sep-Pak material was extracted with dichloromethane, bioactivity was shown to be present to a lesser extent in the dichloromethane fraction (containing free steroids) and to a greater extent in the water phase (containing conjugated steroids). The bioactivity of the water phase was reduced by incubation with glucuronidase but was eliminated by a combination of glucuronidase and sulfatase treatment. Various synthetic free steroids, conjugated steroids, prostaglandins, and amino acids were tested in the bioassay, but none mimicked the effect of the crude or semipurified testicular and milt extracts. We conclude that at least one substance is active as a pheromone-like spawning substance in males. These substances show hydrophobic properties similar to those of polar steroids, prostaglandins, or their conjugated forms, and at least one form likely contains a sulfate or glucuronide group. The role of a male pheromone may be synchronisation of spawning in schools of herring.
Identification of free and conjugated steroids, including cortisol and 17α,20β-dihydroxy-4-pregnen-3-one, in the milt of Pacific herring, Clupea harengus pallasi
Authors: Scott A. P. , Sherwood Nancy M. , Canario A. V. M. , Warby Carol M.
Published: May 2008

Milt from Pacific herring (Clupea harengus pallasi) was extracted and purified on reversed-phase high-performance liquid chromatography. The fractions were radioimmunoassayed for the following free and conjugated steroids: cortisol; 17α,20β-dihydroxy-4-pregnen-3-one; 17α,20α-dihydroxy-4-pregnen-3-one; 17α,21-dihydroxy-4-pregnene-3,20-dione; 17α,20β,21-trihydroxy-4-pregnen-3-one; 17α-hydroxy-4-pregnene-3,20-dione; 3α,17α,21-trihydroxy-5β-pregnan-20-one; testosterone; 11-ketotestosterone. Fractions containing significant amounts of immunoreactive material were subjected to further purification on thin-layer chromatography. Substantial amounts of cortisol (271 ng∙g−1 of milt) and 17α,20β-dihydroxy-4-pregnen- 3-one (ca. 38 ng∙g−1 of milt) were found in the free fractions of one of the extracts. Substantial amounts of cortisol (229 ng∙g−1 of milt), 17α,20β-dihydroxy-4-pregnen-3-one (25.7 ng∙g−1 of milt), and 3a, 17α,21-trihydroxy-5β-pregnan- 20-one (13 ng∙g−1 of milt) were found in the conjugated fractions of both extracts. Levels of the other steroids (free and conjugated) ranged from undetectable (<0.1) to 5.9 ng∙g−1 of milt. The possible reasons for the differences in free steroid levels between the extracts, and the potential role of the steroids as pheromones, are discussed.
Ecological distribution of moss-dwelling tardigrades on Vancouver Island, British Columbia, Canada
Authors: Kathman R. Deedee , Cross Stephen F.
Published: May 2008

Replicate samples of tardigrades were collected at six altitudes from five mountains on Vancouver Island, British Columbia, Canada, to determine the relationship between species of tardigrades and altitude, and between species of tardigrades and species of mosses in which they were collected. A total of 13 696 tardigrades representing 39 species were collected and identified. Thirty-seven species of mosses were identified. Data were analyzed using principal components analysis and cluster analysis. The results from both multivariate statistical methods indicated that the distribution and abundance of tardigrades were not dependent upon the altitude or moss species.
Redescription ofDiclidophoroides maccallumi(Monogenea: Diclidophoridae) from the gills of longfin hake,Phycis chesteri, from the Gulf of St. Lawrence
Authors: Rubec Louise A.
Published: May 2008

Diclidophoroides maccallumi is redescribed from the gills of longfin hake, Phycis chesteri, caught off the coast of Newfoundland in the Gulf of St. Lawrence. Specific characteristics such as the number of genital corona spines and morphometric measurements are within the range limits given in previous descriptions of this species from red hake, Urophycis chuss. The detailed morphology of the clamp, the male genital terminalia, and the female reproductive system is presented. This redescription confirms the restoration of Diclidophoroides Price, 1943 (sensu Mamaëv, 1976) as a primitive genus in the subfamily Diclidophorinae. The generic diagnosis of Diclidophoroides should be emended to include the following: in the male genital terminalia, the presence of a prostatic vesicle, and in the clamp, the presence of a partially developed lamellate extension, b, originating from median sclerite a1, with distal attachment to the terminal half of peripheral sclerite c1, with no proximal border between sclerites a2and c2, and the presence of a sucker in the inner side. Major generic characteristics that differentiate the genera Diclidophoroides and Diclidophora are briefly discussed. The occurrence of Diclidophoroides maccallumi on Phycis chesteri in the Gulf of St. Lawrence represents a northern range extension of the parasite and a new host record, and provides further evidence for the close phylogenetic affinity between Phycis chesteri and the genus Urophycis.
Effects of gender, age, and castration on porphyrin concentration and melatonin synthesis in the Harderian glands of the Mongolian gerbil, Meriones unguiculatus
Authors: Buzzell Gerald R. , Menendez-Pelaez Armando , Blank James L. , Nonaka Keico O. , Reiter Russel J.
Published: May 2008

In this study, we investigated porphyrin and indole metabolism in the Harderian glands of the Mongolian gerbil, Meriones unguiculatus. Total porphyrin concentrations were similar in male and female glands and were not affected by castration in either sex. In females, there was a slow increase in porphyrin concentrations up to 45 days of age, followed by a drop at 60 days, and a subsequent increase at 75 days. Indole metabolism was studied by measuring immunoreactive melatonin concentrations and the activities of the two enzymes that convert serotonin to melatonin: N-acetyltransferase and hydroxyindole-O-methyltransferase. These measurements were similar in intact and castrated males and in intact females. However, whereas 4 weeks of ovariectomy had no effect on N-acetyltransferase activity, 8 weeks after the ovaries were removed a significant rise in Harderian N-acetyltransferase activity occurred. This enzyme exhibited a biphasic curve with age; an initial sharp increase in N-acetyltransferase activity after 15 days was followed by a decrease at 60 days and a significant increase at 75 days. Hydroxyindole-O-methyltransferase activity and melatonin concentration were not affected by sex or reproductive status. Melatonin concentration remained relatively constant until 60 days of age; it then increased sharply at 75 days.
Egg and clutch size in the mallard as related to food quality
Authors: Pehrsson Olof
Published: May 2008

The effect of food quality on egg and clutch size was studied in captive wild-strain and game-farm mallards, Anas platyrhynchos, and comparisons were made with various wild Swedish populations from different habitat types. Captive mallards laid larger eggs than wild birds. In captivity, game-farm ducks laid larger eggs than wild-strain birds, but when they were exposed to wild conditions the size was reduced. Captive ducks supplied with high-protein food laid larger eggs than ducks fed low-protein food. In the wild, there was a negative correlation between egg size and population density. Various wild Swedish populations showed similar egg-size variations among years, indicating some common factor operating outside the breeding season. In the food quality experiments, clutch size was positively correlated with egg size, but no correlation was found in wild populations. A negative correlation between clutch size and laying date, obtained in the wild, was not found in captivity. Egg and clutch sizes were both significantly smaller in a lake with food competition from fish than in an area rich in lakes empty of fish. When comparing egg characteristics of mallard populations it is important to distinguish between wild, captive wild-strain, and captive game-farm birds.
Breeding biology of American crows in Saskatchewan parkland habitat
Authors: Ignatiuk Jordan B. , Clark Robert G.
Published: May 2008

The breeding biology of American crows (Corvus brachyrhynchos) was studied in two areas (St. Denis and Elstow) of aspen parkland habitat in Saskatchewan, Canada, in 1987 and 1988. The St. Denis area had relatively more diverse land use and contained more wetlands than the Elstow area. Crows returned from winter ranges in early April and were frequently observed at breeding sites in late April, when nest building began. Overall, mean (± SD) clutch initiation dates were 6 May (± 6 days) at St. Denis and 10 May (± 6) at Elstow, but, in 1988, clutches were initiated about 6 days earlier at St. Denis than at Elstow (P < 0.05). Density of nests at St. Denis averaged twice that found at Elstow (0.70 and 0.35/km2, respectively; P < 0.05). Size of incubated clutches did not differ between years or areas, and averaged 4.8 ± 0.6 eggs (n = 104). Hatching success did not differ by year or area, but in 1987, nests at St. Denis produced nearly twice as many young as at Elstow. Brood losses resulted from predation, starvation, and possibly other factors. Chicks in smaller broods gained mass faster and fledged at a lighter mass than chicks in larger broods. There were no consistent differences between areas in the mass, bill length, and head–bill lengths of 22-day-old chicks. Young fledged when they were between 30 and 34 days old. Crows at St. Denis had higher reproductive success (1987), nested at greater densities (1988 and both years combined), and began egg laying earlier (1988) than at Elstow, suggesting that St. Denis was a more productive breeding habitat.