bluuebunny/crossref_metadata_2025 huggingface dataset:
Atmosphere–Ocean Coupling and Atlantic Cod Migrations: Effect of Wind-Forced Variations in Sea Temperatures and Currents or Nearshore Distributions and Catch Rates of Gadus morhua
Authors: Rose G. A. , Leggett W. C.
Published: April 2011

Coastal upwellings and downwellings forced by alongshore winds on the north shore of the Gulf of St. Lawrence were associated with variability in onshore movements and inshore daily catches of Atlantic cod (Gadus morhua). Mean cod densities in the zone offshore from the trap sites, determined by hydroacoustic integration scaled by an in situ dual beam determined mean backscatter, ranged from 2.6 to 82.7 fish/105 m3. Cod were located where sea temperatures ranged from −0.5 to 8.5 °C. Catches were nil where temperatures were outside this range. Cod were located at depths which correlated with the strength of alongshore currents (r = −0.55). A path analysis model with predictors alongshore wind stress and current, sea temperature, and cod density accounted for 76% of the variance in catch. Cod abundance in the offshore zone accounted for the most variance independent of other factors (27%). Sea temperature and currents accounted for 15 and 13%, respectively. Peaks in catch (to 1500 kg/d) coincided with maximum rates of decline in sea temperatures and with NE upwelling currents. Low catches coincided with maximum rates of increase in temperatures and with SW currents. In a regression model, four lags of alongshore wind accounted for 83% of the variance in catch.
Immunochemical Quantification of Metallothioneins of a Marine Mollusc
Authors: Roesijadi G. , Unger M. E. , Morris J. E.
Published: April 2011

Mercury-induced, low molecular weight, metal-binding proteins were isolated from the marine mussel Mytilus edulis and used as antigen in the development of antibodies and an enzyme-linked immunosorbent assay (ELISA) for quantification of the proteins. Partial characterization of the isolated protein indicated that its properties were consistent with those of metallothionein (MT). In contrast with most MTs, this protein occurred as an apparent dimer and contained glycine at high levels. Polyclonal antibodies against this protein were produced in goats and purified to an IgG fraction by ammonium sulfate precipitation and DEAE ion-exchange chromatography. Ouchterlony analysis and ELISA showed that these antibodies were cross-reactive with two other charge variants of mercury-induced, metal-binding proteins of M. edulis, but not with rabbit MT. The ELISA was based on an indirect, competitive procedure utilizing a rabbit anti-goat IgG–horseradish peroxidase conjugate as the second antibody. Application of this assay to cytosolic extracts of mussel gills indicated 0.5 μg metal-binding proteins/g wet tissue weight in gills of control mussels and elevated levels up to 1780 μg/g following exposure to mercury, cadmium, or copper for 28 d. Zinc was not effective as an inducer of these proteins.
Sediment Record of Biogeochemical Responses to Anthropogenic Perturbations of Nutrient Cycles in Lake Ontario
Authors: Schelske Claire L. , Robbins John A. , Gardner Wayne S. , Conley Daniel J. , Bourbonniere Richard A.
Published: April 2011

Two sediment cores collected from the Rochester basin of Lake Ontario were dated with 210Pb and stratigraphic correlation and analyzed to determine whether nutrient accumulation with time was consistent with previous computer-simulated total phosphorus (TP) loadings. Relative increases in TP and nonapatite inorganic phosphorus (NAIP) accumulation were less than the fivefold increase in TP loading from 1800 to 1950 predicted independently from Chapra's simulation model. In addition, increases in TP accumulation occurred mainly after 1940 and the proportion of NAIP relative to TP increased in one core and decreased in the other. Of the nutrients studied, only increases in organic carbon (OC) paralleled the increases in modelled TP loadings. The relative increase in inorganic carbon (IC) was greatest, with accumulation increasing an order of magnitude after 1940 in one core. This large increase in IC, amounting to 20% calcite in recent sediments, was attributed to biologically induced calcite precipitation, a secondary consequence of increased planktonic photosynthetic removal of carbon dioxide that resulted from accelerated eutrophication after 1940 when modelled TP concentrations increased rapidly. Biogenic silica (BSi) accumulation, an indicator of increased diatom production, peaked between 1850 and 1870 when increases in TP and NAIP fluxes were minimal. Results provide evidence that historic biogeochemical responses inferred from OC, IC, and BSi accumulation in the sediment record provide stronger signals of phosphorus enrichment effects than can be inferred directly from changes in accumulation of different forms of phosphorus in the sediment record.
Environmental Influence on Activities and Foreign-Particle Binding by Hemocytes of American Oysters, Crassostrea virginica
Authors: Fisher William S. , Tamplin Mark
Published: April 2011

American oysters (Crassostrea virginia) from an estuarine and an oceanic habitat were held in the laboratory under various temperature and salinity regimes. After a month, their hemocytes were withdrawn from the adductor muscle and measured in vitro for time to spreading (TTS), time to spreading after an acute salinity increase (TTS + 12), rate of locomotion (ROL), and binding of fluorescent microspheres (beads). Bead binding was compared with binding of bacteria (Vibrio parahemolyticus). TTS and TTS + 12 measurements were negatively correlated with temperature whereas ROL and bead binding measurements were positively correlated with temperature. An acute rise in salinity (TTS + 12) increased the time required for hemocyte spreading. Spreading was faster, however, at higher salinities for acclimated oysters from both habitats. This finding contradicted previous results for estuarine oyster hemocytes and emphasized the role of environmental history and/or seasonality on hemocyte responses. Oceanic oysters from a less variable environment showed hemocytic responses consistent with previous studies.
Fish Growth: Investigations Based on a Size-Structured Model
Authors: Schnute Jon T. , Richards Laura J. , Cass Alan J.
Published: April 2011

In this paper and its companion (Schnute et al. 1989, Can. J. Fish. Aquat. Sci. 46: 743–769), we present a statistical analysis of Schnute's size-structured model for exploited fish populations. Here we emphasize model parameters associated with fish growth. The model projects the growth of population biomass from the growth of individual fish. We show that this relationship between individual and global behavior is formally analogous with the kinetic theory of gases, where properties of a gas follow from the motions of individual particles. Our statistical analysis allows for error in all observed variables, and we support all analytical arguments with simple graphical techniques. We illustrate the model with tag–recapture and fishery data from an exploited lingcod (Ophiodon elongatus) stock. Growth parameter estimates from the population are based on weight means and variances within the catch over the period 1956–86. These estimates agree well with estimates based on weights of individual fish released in 1982 and recaptured in 1983.
Fixation Artifacts in Rainbow Trout (Salmo gairdneri) Gills: A Morphometric Evaluation
Authors: Speare D. J. , Ferguson H. W.
Published: April 2011

Epithelial capillary separation (E.C.S.) and epithelial cell hypertrophy (E.H.) of the gill lamellae of fish are two histopathological changes frequently described in association with toxic insults. Both of these gill changes increased in a significant linear manner over delay periods of 20–900 s from death to first entering either Bouin's or 10% formalin fixative. E.C.S. also occurred rapidly when gills were examined as whole mount preparations. The presence of occasional necrotic epithelial and chloride cells resembled apoptosis and is not in itself abnormal, nor did the type of fixative used or fixation delay have an effect on their extent. Gills from fish killed by either MS-222 or cervical spinal severance were similar, except that the latter also had multifocal lamellar telangiectasis. We conclude that E.C.S. and E.H. are readily mimicked by preparation and postmortem artifacts that occur rapidly after death when this is caused by either MS-222 or spinal severance. Bouin's fixative should be used to minimize these changes.
Temperature Requirements in Atlantic Salmon (Salmo salar), Brown Trout (Salmo trutta), and Arctic Char (Salvelinus alpinus) from Hatching to Initial Feeding Compared with Geographic Distribution
Authors: Jensen Arne J. , Johnsen Bjørn O. , Saksgård Laila
Published: April 2011

Development time at different temperatures from hatching to 50% feeding was studied in Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) alevins. Live animals were used as food. In both species the development time decreased with increasing temperature, and these relationships were described by power curves. The results were compared with similar data for Arctic char (Salvelinus alpinus). At temperatures above about 8 °C, the development time to 50% feeding was the same for all three species. However, at lower temperatures Atlantic salmon alevins needed more time to reach the stage of initial feeding than did Arctic char. Brown trout were intermediate. These results are in accordance with the known optimum temperature ranges for the three species and their geographic distribution.
Golden Shiner (Notemigonus crysoleucas) Population Abundance Correlations with Food and Predators
Authors: Johannes Mark R. S. , McQueen Donald J. , Stewart Tom J. , Post John R.
Published: April 2011

A winterkill at Lake St. George, Ontario eliminated most of the piscivorous fish and some of the planktivores and also influenced zooplankton community structure. This disturbance and the subsequent recovery of the populations provided the opportunity to evaluate potential impacts of food and predators on the population structure and abundance of the dominant planktivore; the golden shiner (Notemigonus crysoleucas). interpretation of the 8-yr data set suggested that there was a positive relationship between adult golden shiner condition and zooplankton abundance, but that this did not translate into a significant stock–recruitment relationship between female numbers and young-of-the-year (YOY) recruitment. Also, there was no significant relationship between golden shiner survival and zooplankton abundance. However, there were significant negative correlations between YOY and adult golden shiner survival estimates and predator abundances. We conclude that at Lake St. George, golden shiner recruitment and population density is strongly influenced by predator density and is not influenced by food abundance.
River Spawning of Artificially Reconditioned Atlantic Salmon (Salmo salar)
Authors: Gauthier D. , Desjardins L. , Robitaille J. A. , Vigneault Y.
Published: April 2011

We present information on the reproduction of artificially reconditioned Atlantic salmon (Salmo salar) in an enclosed spawning area and report evidence that some of these fish are fit for natural spawning 1 yr after their previous reproduction as wild fish, in spite of numerous treatments and manipulations.
Mechanisms of Tri-N-Butyltin Bioaccumulation by Marine Phytoplankton
Authors: Chiles Thomas C. , Pendoley Peter D. , Laughlin Jr. Roy B.
Published: April 2011

We examined uptake of tri-n-butyltin (TBT) by three genera of marine microalgae and one genus of cyanobacterium. There was a linear relationship between external concentrations of TBT and cell burdens in the microalgae Nannochloris sp., Chaetoceros gracilis, and the cyanobacterium Synechococcus sp. (PR-6). The relationship between external TBT concentrations and cell TBT burdens was distinctly nonlinear for Isochrysis galbana. Competitive binding experiments showed a decrease of approximately 88% of the total bound radiolabeled TBT to I. galbana in the presence of a 200-fold excess of unlabeled TBT. No significant decrease of bound TBT was observed for Nannochloris sp. These studies demonstrate that either partitioning or binding may control bioaccumulation of TBT by marine phytoplankton.
Gear Bias in Field Estimation of the Amount of Food Consumed by Fish
Authors: Hayward Robert S. , Margraf F. Joseph , Knight Carey T. , Glomski Daniel J.
Published: April 2011

We made concurrent collections of small (85–100 mm total length) yellow perch (Perca flavescens) at the bottom of Lake Erie with an active gear (otter trawl) and a passive gear (gillnet) within a 24-h sampling period. During daylight periods when yellow perch feeding activity was most prominent, gillnetted fish possessed significantly higher median food amounts in stomachs than did trawled fish. Estimated daily food consumption for small yellow perch was 5.86% of body weight by gillnet sampling and 3.98% by trawl sampling. Passive gears tend to sample the most active fish (more likely to be feeding) and may, therefore, yield upwardly biased estimates of food consumption for individuals within a population. Active gears are considered to give more accurate estimates because quiescent and low activity, as well as the more active members of a population, are sampled.
Significance of Mature Male Parr in a Small Population of Atlantic Salmon (Salmo salar)
Authors: L'abée-Lund Jan Hennsng
Published: April 2011

The spawning population of Atlantic salmon, Salmo salar, (mature male parr and adults (anadromous salmon)) were assessed in the River Baevra, central Norway, when the river was treated with rotenone in November 1986. The spawning population of adults consisted of 15 males and 19 females. The spawning population of males consisted of 167 mature male parr per adult male. The effective population size of adults was small; Na = 33.5 individuals. The presence of mature male parr theoretically increased the effective population size to Na = 71.7 individuals. This increase indicated that mature male parr brought the effective population size above a recommended minimum (Na = 50) to ensure long term viability.
Evaluating Fisheries Management Models by Simulated Adaptive Control — Introducing the Composite Model
Authors: Fournier David A. , Warburton A. R.
Published: April 2011

This paper uses the technique of simulated adaptive control to provide a method for comparing the performance of different fisheries management models. The management model is evaluated not in isolation, but rather as part of an integrated fisheries management system which includes the simulated population dynamics of the exploited fish, the simulated fishery, the fishery management policy formulation process, and the analysis of the simulated fisheries data. The technique is used to compare a simple biomass dynamic based model introduced by Ludwig and Hilborn with a more complicated length-based model developed by Fournier and Doonan. A composite model which combines the biomass dynamic based model with the length-based model was also evaluated. The composite model performed better than either of its component models.
Random Movement and Orientation in Pink Salmon (Oncothynchus gorbuscha) Migrations
Authors: Hiramatsu Kazuhiko , Ishida Yukimasa
Published: April 2011

The homing migration of pink salmon (Oncorhynchus gorbuscha) from the open ocean towards their natal rivers was studied by a mathematical model using data from tagging experiments. In this model fish migration was considered to be the resultant of fish orientation and random movement. The mean migration speed and dispersion coefficient (an index of random movement) evaluated from regression analysis were 19.6 km∙d−1 and 739 km2∙d−1 for the North American group and 47.1 km∙d−1 and 863 km2∙d−1 for the East Kamchatkan group, respectively. The results indicated that pink salmon migration has more oriented movement than had been suggested by a previous computer simulation by other workers. The results also indicated that there is a distinct difference in the migratory behavior of North American and East Kamchatkan pink salmon.
Physiological and Histological Aspects of Late Oocyte Provisioning, Ovulation, and Fertilization in Pacific Herring (Clupea harengus pallasi)
Authors: Gillis D. J. , McKeown B. A. , Hay D. E.
Published: April 2011

Late vitellogenic, ovulating, and ovulated Pacific herring oocytes were examined histologically and histochemically in order to understand these fine-scale processes and to evaluate egg maturation timing test criteria for use in resource management. Late vitellogenic events were investigated using an alkali-labile protein phosphorus (ALPP) assay of serum, liver, and gonad tissue. Serum levels were constant in males but declined in females. Ovarian levels declined (110 to 15 mg/L) during ovulation. Hepato-somatic indices were constant in males but declined in females (1.6 to 0.9%) during ovulation. The abundance of electron-lucent hepatocytes in female livers compared with males, their synthetic and secretory structures, and their reversion during ovulation suggest these cells as vitellogenin synthetic locations. During population ovulation, the gonosomatic index for females and males increased from 15–27%, and 15–23% respectively. Eggs hydrated from 67–76% during ovulation, and secondarily to 83% after fertilization. Unfertilized eggs dehydrated to 74% water. Alkaline phosphatase was localized in follicular granulosa and thecal cells suggesting these as locations of vitellogenin dephosphorylation. The test criteria; hepato-somatic index, lucent hepatocyte ratios, gonadosomatic index, and egg moisture are problematic but ovarian ALPP determination appears promising.
Distribution and Growth of Pre-Recruit Cohorts of the Northern Shrimp (Pandalus borealis) in the Western Gulf of St. Lawrence as Related to Hydrographic Conditions
Authors: Simard Yvan , Brunel Pierre , Lacelle Johanne
Published: April 2011

Samples collected with a suprabenthic sled from May to October were analysed to determine the number of pre-recruit cohorts in the northern shrimp population of the Gulf of St. Lawrence and to estimate their growth and distribution. An unexpected cohort was found with carapace lengths of 4.5–9.5 mm. This appeared to be cohort I, thus indicating three pre-recruit cohorts: cohorts 0 (2.5–4.5 mm), I (4.5–9.5 mm), and II (9.5–14.5 mm). The comparatively slow growth rate of 4–5 mm per year was attributed to the low temperatures (0.5–2.0 °C) in the bottom water inhabited by the pre-recruits, immediately below the intermediate cold water mass of the Gulf of St. Lawrence. Growth rates peaked in August–September, reaching 1 mm per month. Benthic settlement of the postlarvae also appeared to occur in August–September, at an age of 4–5 mo. Sexual differentiation in males started at an age of 16 mo and maturity was reached by 30–37 mo. Two strata were sampled, 0.3–0.7 m and 1.0–1.4 m above the bottom. More than 70% of the shrimps were concentrated in the first 0.3–0.7 m stratum. Maximum density observed for one single cohort was 67 individuals per 100 m2. Large spatial and temporal variations of densities occured daily, semimonthly, and seasonally, and are thought to be partially related to horizontal transport of water masses. Densities in the strata sampled were significantly lower at night, as a result of vertical migrations in the water column.
Is Precipitation of Aluminum Fast Enough to Explain Aluminum Deposition on Fish Gills?
Authors: Playle Richard C. , Wood Chris M.
Published: April 2011

A peristaltic pump was used to mix environmentally realistic concentrations of Al in soft water (14–15 °C) with 30 μM base (NH4OH) to simulate the alkalinization which occurs when acidic soft water passes over fish gills. Solutions were filtered under vacuum through 0.2 μm prerinsed filters using a polycarbonate filter apparatus. If final solution pH was [Formula: see text], only about 10% of total Al (159 μg∙L−1) was filtered from solution. If solution pH was raised from pH 5.3 to pH 5.7 with base, about 35% of Al was removed from solution, 1–4 s after the pH was raised. Similar results were obtained for 335 μg∙L−1 Al solutions. Production of additional Al retained by filters was fast enough to show that Al accumulation on fish gills may be partly due to polymerisation and precipitation of Al, as Al solubility is reduced in the more alkaline gill micro-environment.
An Assessment of Chironomidae as Quantitative Indicators of Past Climatic Change
Authors: Walker Ian R. , Smol John P. , Engstrom Daniel R. , Birks H. J. B.
Published: April 2011

The distribution among Labrador (Canada) lakes of remains from 21 chironomid taxa was analysed by means of canonical correspondence analysis (CCA). Tests with partial CCA of three hypotheses revealed that the distributions of chironomid taxa were significantly correlated with summer surface-water temperature and maximum lake depth, but not sediment organic content. In addition, an exploratory CCA revealed possible relationships of chironomid fauna with residual longitude and Fe concentration. A weighted-averaging-regression/calibration model of the chironomid–temperature relationship (derived from a temperature-constrained CCA) allowed the summer surface-water temperature of lakes to be inferred from chironomid remains. Accurate quantitative reconstructions of late glacial and Holocene temperature variations should be possible from fossil Chironomidae.
Effect of Smolt Size on Smolt-to-Adult Survival for Chilko Lake Sockeye Salmon (Oncorhynchus nerka)
Authors: Henderson M. A. , Cass A. J.
Published: April 2011

Three approaches were used to test the hypothesis that smolt-to-adult survival is independent of smolt size for Chilko Lake sockeye salmon (Oncorhynchus nerka). The mean distance between the focus of the scale and the first annulus, a reliable indicator of smolt size, was greater for adult scales than for smolt scales from the same brood year in two of the three years we examined. This indicated a higher smolt-to-adult survival for larger smolts in these brood years. The abundance of smolts of different fork lengths, based on back-calculation procedures from adult scales, was compared with the abundance of smolts of different fork lengths at the time of outmigration within brood years. In all three years studied, there was a two- to threefold increase in smolt-to-adult survival as smolt length increased. However, there was no significant relationship between smolt-to-adult survival and mean annual smolt fork length based on a 34-yr time series; this lack of relationship was probably caused by limited variation in mean annual smolt fork length over the 34-yr period and other variables, independent of smolt size, that affect survival and exhibit considerable interannual variation.
Precision of Ages Estimated from Five Bony Structures of Arctic Char (Salvelinus alpinus) from the Wood River System, Alaska
Authors: Baker Timothy T. , Timmons L. Saree
Published: April 2011

Ages of 32 Arctic char (Salvelinus alpinus) were estimated from otoliths (surface-examined and broken-and-burned), vertebrae, cleithra, opercula, and subopercula. Six readers examined each structure three times, and the precision of these estimates among structures and readers was compared with means, aging differences, and analyses of variance. Surface-examined otoliths provided the most precise age estimates and were one of the easiest structures to prepare and read. Broken-and-burned otoliths produced less precise estimates for larger, older Arctic char than for smaller, younger Arctic char. Based on lack of precision, cleithra should probably not be used to age Arctic char. Although mean estimates for the five structures were not significantly different, surface-examined otoliths produced older age estimates than break and burn otoliths. We feel that surface-examined otoliths are best for precise estimation of age of Arctic char but recommend that both otolith methods be compared when aging Arctic char older than 8 yr. Scales were also examined from 30 Arctic char but were not included in the analyses after preliminary examination because age was difficult to interpret (circuli were clear on all scales, but only two or three annuli of uncertain significance could be distinguished).
Metal Binding Activity of the Gills of Rainbow Trout (Oncorhynchus mykiss)
Authors: Reid Scott D. , McDonald D. G.
Published: April 2011

The objective of this study was to characterize the metal binding of the external gill surface in an attempt to interrelate metal chemistry, gill surface binding activity, and possibly metal toxicity. Individual gill arches from adult rainbow trout (Oncorhynchus mykiss) were exposed to various concentrations of either 140La, 45Ca, 109Cd, or 64Cu. The apparent dissociation constant (KD) and capacity (Bmax) of the external gill surface for the metals was calculated using Scatchard plot analysis. Half-saturation time (t1/2) and binding cooperativity (Hn) were also determined. The KD for gill metal binding ranged from 0.31 ± 0.02 mM for La3+ (high affinity) to 4.3 ± 0.04 mM for Cu2+ (low affinity). The gill binding affinity for Ca2+ was threefold lower than for La3+, but was similar to that for Cd2+. The gills had the lowest affinity for Cu2+, almost 14 times lower than that for La3+. Bmax for La3+ was found to be significantly lower than for any other metal (0.14 ± 0.001 μmol∙g−1), while nearly seven times as much Cu2+ was accumulated by the gills compared with La3+, The Ca2+ and Cd2+Bmax estimates were intermediate.
Picoplankton Associations in an Ultra-Oligotrophic Lake on Vancouver Island, British Columbia
Authors: Klut M. E. , Stockner J. G.
Published: April 2011

Epiphytic associations or "microaggregates" of picoplankton with larger phytoplankton in Sproat Lake, British Columbia, occurred in the epilimnion throughout the 1-yr study, but were most frequently seen at times of severe nutrient limitation in summer and autumn. Both bacterial and algal picoplankton epiphytes were attached to the cell surface of algal hosts by either fine protrusions or by their fibrillar extracellular matrix (glycocalyx). This surface coat increased in thickness as ambient nutrient concentrations became limiting, and harboured a range of heterogeneous organic and inorganic particles and phytoplankters. The phytoplanktonic host cells for these picoplankton associations included filamentous cyanobacteria, dinoflagellates, chlorophytes, coccolithophores, and diatoms. Under controlled nutrient-depleted conditions, the filamentous nitrogen-fixing cyanobacterium Anabaena flos-aquae became a common host of chroococcoid cyanobacterium. Some picoplankters were endophytic within the cytoplasm and vacuoles of protozoa and microflagellates, serving either as prey or as symbionts. These associations are thought to facilitate rapid carbon and nutrient recycling in pelagic ecosystems.
Enzyme Activities of Gill, Hepatopancreas, Mantle, and Adductor Muscle of the Oyster (Crassostrea virginica) after Changes in Diet and Salinity
Authors: Ballantyne J. S. , Berges J. A.
Published: April 2011

We examined the effects of exposure to low salinity (1/3 seawater) on the maximal activities of enzymes of lipid oxidation, amino acid and ketone body metabolism, gluconeogenesis, and glycolysis in gill, mantle, hepatopancreas, and adductor muscle of the oyster (Crassostrea virginica). No significant metabolic reorganization occurred after 4–6 wk in low salinity. The few significant differences which were found between enzyme activities of high- and low-salinity treatment groups were always due to lower activities in the low-salinity group. In particular, hexokinase, fructose bisphosphatase, and 3-hydroxyacyl CoA dehydrogenase declined in gill, hepatopancreas, and adductor muscle. Since high ionic strength depresses the activity of many enzymes, the reduced ionic strength in the cells of the low-salinity group may perturb metabolism by elevating rates of enzyme activity. As indicated by the present study, part of the response to low salinity by euryhaline molluscs may involve reducing the activity of certain enzymes to achieve a homeostasis of metabolic function.
Influence of Daily Variations of Light and Temperature on the Emergence Rhythm of Grayling Fry (Thymallus thymallus)
Authors: Bardonnet Agnès , Gaudin Philippe
Published: April 2011

The emergence rhythm of grayling fry (Thymallus thymallus) was studied in four aquaria fitted with traps under four different conditions of light and temperature. Both light and temperature induced an emergence rhythm characterized by a 24-h period. Under ambient Sight and constant temperature, emergence peaked at the end of the night before the onset of dawn. Under constant dim light and varying temperature, emergence peaked in early morning during the coldest hours. When both light and temperature fluctuated daily the emergence pattern was equivalent to the "sum" of these previous two regimes and was similar to that described in the field in a previous report. In the absence of light and temperature variations, no emergence rhythm was observed.
Effects of Selenite and Selenate on the Growth and Motility of Seven Species of Marine Microalgae
Authors: Wong Donald , Olivesra Luis
Published: April 2011

Seven species of marine phytoplankters from different taxonomic divisions were tested for toxic responses to two different molecular species of selenium known to be prevalent in seawater, selenite and selenate. Selenate was slightly more toxic, although severe toxicity was only observed at high concentrations (selenate, 10−2 M; selenite, 10−3 M). At these concentrations, growth was completely or severely inhibited in most species tested. ln some species that remained viable, both the percentage of motile cells and their swimming speed were drastically reduced. These cells possessed much shorter flagella compared with controls, while nonmotile cells lacked flagella altogether. Despite such striking alterations, cells of Amphidinium carterae, Dunaliella tertiolecta, and Pavlova lutheri showed signs of adaptation to high selenium concentrations. Lower concentrations of selenium were generally nontoxic and frequently stimulated growth. These observations suggest that both the concentration range and the length of the exposure must be considered if meaningful inferences on selenium toxicity are to be made.
Are Chloride Cells Involved in Low pH Tolerance and Sensitivity? The Mayfly Possibility
Authors: Berrill Michael , Taylor Graeme , Savard Helene
Published: April 2011

Sensitivity to low pH in freshwater fish appears to be correlated with density and replacement rates of gill chloride cells, but these cells are difficult to examine. Mayfly nymphs possess cells of similar appearance and probable function and are easily observed in dense accumulations on gill surfaces. We examined chloride cell density on the gills of nymphs of seven species of mayflies (two Heptageniidae, two Leptophlebidae, one Siphlonuridae, and two Baetidae). Although tolerance of low pH exposure varied considerably among the seven species, it was not correlated with gill area or chloride cell density. Gills of nymphs from soft water also had no greater chloride cell density than gills of nymphs of the same species from hard water. Finally, nymphs of the two species able to withstand 2 wk exposure to low pH did not show an increase in chloride cell density. It remains possible that the prolonged ionoregulatory stress of low pH results in cell damage rather than cell proliferation in sensitive species.
Adaptive Management of Spatially Replicated Groundfish Populations
Authors: Collie Jeremy S. , Walters Carl J.
Published: April 2011

Assessment techniques that recognize information shared among substocks can help reduce uncertainty about stock size and productivity, compared with methods that treat each subpopulation independently. We develop this methodology using time series of catch and relative abundance data for six subpopulations of yellowtail flounder, Limanda ferruginea, from the Northwest Atlantic. The Deriso/Schnute delay-difference production model was fit to the data, but the model parameters associated with population productivity and absolute population size were very uncertain. Estimates of parameter uncertainty were used to identify a set of models that are consistent with the observed data and imply different management policies. The value of these different policies was estimated with a stochastic simulation program that uses a Kalman filter to predict stock size for each model and Bayesian updating to assign a probability of each model being correct. With parameters shared among stocks and a shared response to external influences, in the order of 10–20 yr was needed to distinguish the correct model. Adaptive management simulations indicated that long-term yield was greater in simulations with adaptive learning and that a lower initial exploitation rate should be applied than would be the case if adaptive learning were ignored.
Phosphorus Pool Sizes and Fluxes in the Epilinnnion of a Mesotrophic Lake
Authors: Taylor William D. , Lean David R. S.
Published: April 2011

A plausible budget for phosphorus fluxes between different size/functional groups was constructed for the early summer epilimnetic plankton of Jacks Lake, Ontario. Consideration of the complex interactions at the base of the food web, particularly the ability of nanoplankton to graze on picoplankton, helped to resolve the question of phosphate uptake by bacteria versus algae. While the concentration of phosphate we estimated with column chromatography was lower than chemical detection limits, it was still too high to reconcile with our other measurements and we conclude that actual phosphate concentrations may be less than 1 nM. Some microplankton were shown to liberate dissolved phosphate and organic phosphorus when lake water is filtered. The phosphorus content and turnover of major ciliate, rotifer, and crustacean zooplankton were determined and the importance of these compartments as phosphorus sources and sinks was included in the epilimnetic model.
Fish Introductions in Europe with Particular Reference to its Central and Eastern Part
Authors: Holčík Juraj
Published: April 2011

At least 134 exotic and/or translocated fish species belonging to 34 families which were introduced to 29 of 33 European countries are documented. These include 35 species of Cyprinidae (introduced to 28 countries), 17 Salmonidae (28), 11 Coregonidae (12), 10 Cichlidae (8), six Centrarchidae (23), five Acipenseridae (8), four Ictaluridae (18), four Poeciliidae (11), four Percidae (9), four Mugilidae (1), three Catostomidae (6), three Gasterosteidae (5), two Anguillidae (3), two Atherinidae (2), two Clariidae (4), two Gobiidae (2), two Umbridae (6), two Pleuronectidae (1), two Thymallidae (3) and one species each of Anabantidae (1), Channidae (2), Clupeidae (1), Cobitidae 91), Eleotridae (1), Engraulidae (1), Esocidae (3), Mullidae (1), Osmeridae (1), Percichthyidae (1), Petromyzontidae (1), Polyodontidae (2), Siluridae (5), and Syngnathidae (1). True exotic species amount to 74 species/forms belonging to 21 families, of which 11 families are exotic for Europe. The remaining 60 species (21 families), are native in Europe and were translocated among various watersheds and/or countries. Most species were intentionally released since 1945 to enhance sport, commercial and subsistence fisheries, for fish farming and aquaculture, and for purposes such as mosquito, macrophytes and algal bloom control. Poor success was registered in most cases, along with adverse or unexpected effects on native fishes and their habitat.
Genetic Implications of Introducing Florida Largemouth Bass, Micropterus salmoides floridanus
Authors: Philipp David P.
Published: April 2011

Stocks of northern largemouth bass (NLMB), Micropterus salmoides salmoides, Florida largemouth bass (FLMB), M. s. floridanus, and both reciprocal F1 hybrids were produced through natural spawning; the genetic composition of each stock was confirmed electrophoreticaliy, and experimental populations established. One set of experimental populations (P1 and P2) contained as broodstock equal numbers of adult NLMB and FLMB, whereas the other set (H1 and H2) initially contained equal numbers of adults of both reciprocal F1 hybrids and both pure subspecies. Each year-class produced experimentally were sampled and individuals analyzed genetically to determine their parentage. Initially, much of the YOY production in P1 and P2 was composed of small FLMB that did not survive winter well; once naturally produced F1 hybrids entered the breeding pool, most offspring were Fx hybrids, and the population became heavily introgressed. In H1 and H2 introgression began with the production of the first year-class. Within each year-class NLMB produced in all ponds were significantly larger than all other genotypes, but it appears likely that after only a few generations, production of pure NLMB ceases, all individuals being Fx hybrids. Results illustrate the potential negative impacts of introducing FLMB or hybrids between it and NLMB into waters within or contiguous to the native range of the northern subspecies.
Implications of Introduction of Transgenic Fish into Natural Ecosystems
Authors: Kapuscinski Anne R. , Hallerman Eric. M.
Published: April 2011

Production of transgenic fish has increased in scope, aimed at improving performance traits in economically important species or at creating model systems for basic biological problems. A variety of transgenic phenotypes will become possible as more genes are cloned and characterized. Categories of altered phenotypes include modified: metabolic rates; tolerance of physical factors; behavior; resource or substrate use; and resistance to disease, parasitism, or predation. Ecological impacts of transgenic fishes are uncertain but will depend primarily on their altered phenotypes and secondarily on the scale and frequency of their introduction into ecosystems. Production of ecologically noxious transgenic types is possible, because many fish varieties readily disperse and persist in aquatic ecosystems, are fit in natural settings, interact substantially with other organisms, and play a role in ecosystem processes. Releases of transgenic fishes may impact aspects of fisheries management. Because future uses of transgenic fish in commercial aquaculture or in stocking of natural waters are contemplated, interdisciplinary teams of fisheries biologists, ecologists, and resource managers must develop integrated approaches to assessing risks of ecological impacts. The current situation of uncertainty demands caution in expecting "safe" uses of transgenic fishes.
U.S. Federal Policies, Legislation, and Responsibilities Related t Importation of Exotic Fishes and Other Aquatic Organisms
Authors: Stanley Jon G. , Peoples Jr. Robert A. , McCann James A.
Published: April 2011

Within the Federal government, the U.S. Fish and Wildlife Service (Service) has primary responsibility for legal and policy responsibility for introduced exotic species. The Lacey Act of 1900 authorizes the Service to prohibit the importation of species that are potentially injurious to native fish and wildlife. However, regulations under authority of the Lacey Act cover only a few species. The Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 established a Task Force co-chaired by the Director of the Service and Under Secretary of Commerce for Oceans and Atmosphere. The Task Force consults with the Secretary of Transportation to develop regulations to prevent the importation and spread of aquatic nuisance species into the Great Lakes through exchange of ballast water. Federal agencies must comply with Presidential Executive Order 1198, Exotic Organisms, that prohibits Federal agencies or activities they fund or authorize from introducing exotic species. The Service conducts research and evaluation of exotic species to support Federal, State, and local efforts to prevent further importation of harmful species. Effective regulation will also depend on the full cooperation with Canada.
Prey field and diet of larval cod on Western Bank, Scotian Shelf
Authors: McLaren Ian A. , Avendaño Patricia
Published: April 2011

In vertically integrated samples (from ≤ 75 m) taken around and over Western Bank in November and December 1991, and January 1992, densities of larval cod (Gadus morhua) correlated with those of copepods, notably with relative densities of copepodids plus adults of predominant prey, Pseudocalanus spp. and Paracalanus parvus. Pseudocalanus showed a large increase from time of cod spawning but was concentrated over the bank through gyral circulation rather than enhanced productivity. Numbers of both copepods in stomachs of larvae < 10 mm were significantly related to their field densities, when controlled for sample month, larva size, and time of day. Stomach fullness was related to sample month, time of day, size of larva, and density of Pseudocalanus, but not P. parvus. Smaller larvae from four depths at four stations over the bank in late 1992, ate mostly nauplii of Pseudocalanus and Centropages typicus. Numbers eaten were strongly related to their field densities, weakly to sample depth, and not to larva size. Stomach fullness was positively related only to densities of Pseudocalanus nauplii. Larvae > 5–6 mm switched to larger prey, mostly Pseudocalanus copepodids. More research is needed on interactions between copepod behaviour and the physical mechanisms that concentrate or disperse them on offshore banks.
Redescription of Benedenia epinepheli (Yamaguti, 1937) Meserve, 1938 (Monogenea: Capsalidae) from cultured and aquarium marine fishes of Japan
Authors: Ogawa Kazuo , Bondad-Reantaso Melba G. , Wakabayashi Hisatsugu
Published: April 2011

The monogenean Benedenia epinepheli (Yamaguti, 1937) Meserve, 1938 is redescribed and reported for the first time from the fins, eyes, and body surface of cultured marine fishes of Japan. Because of close similarity in the general morphology of the reproductive system and median sclerites, comparable morphometrics, and the presence of a flap slightly left of the common genital aperture, Benedeniella congeri Yamaguti, 1958 (= Neobenedeniella congeri (Yamaguti, 1958); Benedenia congeri (Yamaguti, 1958)) and Benedenia sp. of Tsutsumi and Ito, 1965 are synonimized with this species. Twelve new hosts are presented, bringing the total number of known hosts to 25 (11 Tetraodontiformes, 9 Perciformes, 3 Scorpaeniformes, 1 Pleuronectiformes, and 1 Anguilliformes). The ability of B. epinepheli to cause death of cultured fishes during heavy infection, and its low host specificity, ubiquitous distribution in western Japan, and the high susceptibility of marine aquarium fishes are indicative of the parasite's great potential to become a disease problem.
Development to third-stage larvae occurs in the eggs of Anisakis simplex and Pseudotetranova decipiens (Nematoda, Ascaridoidea, Anisakidae)
Authors: Køie Marianne , Berland Bjørn , Burt Michäel D.B.
Published: April 2011

Two moults occur during larval development in the eggs of Anisakis simplex (Rudolphi, 1809) and Pseudoterranova decipiens (Krabbe, 1878) from the North Atlantic. Live larvae forced out of eggs in sea water by coverslip pressure shortly before spontaneous hatching were surrounded by the thin cuticle of the first-stage larva. Infective larvae from naturally hatched eggs are loosely ensheathed in the thick cuticle of the second-stage larva. Thus, it is the third-stage larva that emerges from the egg of both species and not the second-stage larva as previously believed. The thin, smooth, fragile cuticle of the first-stage larva remains in the egg. The striated, cocoon-like cuticle of the second-stage larva of A. simplex may increase the buoyancy of the third-stage larva. The tail tip of the cuticle of the second-stage larva of P. decipiens is sticky and adheres the sheathed third-stage larva to the substrate.
The poor potential of cunner, Tautogolabrus adspersus, to act as cleaner fish in removing sea lice (Caligus elongatus) from farmed salmon in eastern Canada
Authors: MacKinnon B.M.
Published: April 2011

Cunner, Tautogolabrus adspersus, were found not to be good candidates for removal of sea lice, Caligus elongatus, from farmed Atlantic salmon (Salmo salar) during seapen trials conducted in Passamoquoddy Bay, N.B. In laboratory trials conducted in 30-gal (~136 L) glass tanks, using one cunner per infected salmon, a significant reduction in sea lice numbers was evident. In seapen trials using 30 cunner to 2000 Atlantic salmon, no significant reduction in sea lice numbers was evident after 12 weeks. Availability of fouling organisms on the seapen net may account, in part, for the lack of cleaning behaviour in these fish.
Parasitological evidence for specialized foraging behavior in lake-resident Arctic char (Salvelinus alpinus)
Authors: Curtis Mark A. , Bérubé Michel , Stenzel Andreas
Published: April 2011

Analyses of statistical associations between the stomach contents and endoparasites of Arctic char, Salvelinus alpinus, from a small (9 ha) lake in northern Quebec revealed that food items found in fish stomachs at the time of capture frequently consisted of intermediate hosts for the parasites infecting the fish. Thus the stomach contents of Arctic char infected by Diphyllobothrium ditremum, D. dendriticum, and Eubothrium salvelini tended to include copepods, while fish infected by the digenean Crepidostomum farionis more frequently contained insect larvae (ephemeropterans) and fish infected by the acanthocephalan Echinorhynchus lateralis most often had amphipods in their stomachs. Moreover, strong quantitative associations were evident between parasites utilizing intermediate hosts from either the benthic or the limnetic zone of the lake. This suggests that some degree of persistent feeding specialization was present among members of the Arctic char population over an extended period of time, with individual fish predominantly feeding upon prey organisms in either limnetic or benthic habitats. In this manner an allopatric Arctic char population may function analogously to more diverse fish communities, where specialist foraging behavior is developed to most efficiently exploit the food web.
Growth rates of four Hawaiian deep slope fishes: a comparison of methods for estimating age and growth from otolith microincrement widths
Authors: Williams H A , Lowe M K
Published: April 2011

Two methods were used to estimate the age and growth of four Hawaiian deep slope fishes. Otolith daily increment width estimates from radial sections of sagittal otoliths were integrated over the otolith radius to approximate age by (i) dividing interval length (micrometres) by mean increment width (micrometres per day) and summing this quotient for consecutive 500- µm radial intervals (S. Ralston and H.A. Williams. 1989. Fish. Bull. 87: 1-16) and (ii) fitting increment width (y) versus otolith radius (x) to a Gompertz rate curve and calculating the inverse integral of this curve (M.K. Smith and E. Kostlan. 1991. Fish. Bull. 89: 461-472). The methods also differ in the way the age-length key is generated. Ralston and Williams' method uses integrated age versus a regression-based estimate of fish length at 500- µm otolith radial intervals; Smith and Kostlan's method uses estimated age versus actual fish length. Neither method of integration produced significantly different age estimates; however, the use of regression-based fish length estimates instead of sampled fish lengths resulted in significant differences between estimated growth curves. The minimum number of daily increment width estimates required as a function of otolith radius was calculated, on the basis of observed microincrement width variation.