bluuebunny/crossref_metadata_2025 huggingface dataset:
Release of Methyl Mercury from Sediments: Effects of Mercury Concentration, Low Temperature, and Nutrient Addition
Authors: Wright David R. , Hamilton R. D.
Published: August 2008

A flow-through system using plexiglass "microbasins" was used to study methyl mercury release from unpolluted, mercury polluted, and mercury enriched lake and river sediments. Production of methyl mercury ranged up to 3.3 μg∙m−2∙d−1, increasing with increasing mercury content as if following saturation kinetics. It leveled off when mercury content was 15–20 μg Hg/g. An equilibrium between methylating and demethylating mechanisms is suggested. Release at 4 °C was 50–70% of that at 20 °C, which suggests that in polluted Canadian lakes, production in winter may be half the total for the year. Increased methyl mercury release was observed when tryptic soy broth (TSB) was added to sediments at 0.06 or 0.25 g/dm3, and very marked increases when TSB was added to the water flow at 35 mg/L, suggesting an effect at the sediment–water interface.Key words: mercury, methyl mercury, methylation, microbasin, microorganism, sediments, biomethylation
Stock Reduction Analysis, Another Solution to the Catch Equations
Authors: Kimura Daniel K. , Tagart Jack V.
Published: August 2008

In fishery stock assessments, catch equations provide the critical link between stock size, natural mortality rate, fishing rate, and catch size. Catch equations are most powerful when age data are available, allowing cohorts to be followed through time using Virtual Population and Cohort Analysis. In this paper we propose a simple new method of linking catch equations when age data are not available. Assuming catches are given in biomass, catch equations are written for each year with a constant recruitment (R), based on a single parameter, added to the total biomass at the beginning of each year. In addition to the catch equations, a final equation is added describing the change in biomass caused by the years of fishing. If n years of catch data are available, n + 1 equations can be written. By conditioning on instantaneous natural mortality rate (M), initial stock size (B1) and the decline in stock size (P) (note P = Bn+1/B1), the n + 1 simultaneous nonlinear equations can be solved iteratively for instantaneous fishing mortality rates (F1, …, Fn) and recruitment (R). When properly plotted, the solution set to this system of equations was found to be a helpful tool to aid in the evaluation of stock condition. In particular, the plots provide a method for incorporating ancillary information from diverse sources such as hydroacoustic surveys, analysis of catch per unit effort data, and Virtual Population Analysis. This new method of stock assessment, which we call Stock Reduction Analysis, is applied to Pacific ocean perch (Sebastes alutus), Pacific herring (Clupea harengus pallasi), and Pacific hake (Merluccius productus) stocks being actively managed by the State of Washington.Key words: Stock Reduction Analysis, stock assessment, catch equations, computer modeling
Trophic Upsurge in New Reservoirs: A Model for Total Phosphorus Concentrations
Authors: Grimard Y. , Jones H. G.
Published: August 2008

A model for total phosphorus concentrations during both the trophic upsurge and depression phases in new reservoirs has been developed by a convolution of the rate of phosphorus leaching from flooded lands and the rate of reservoir filling. Model parameters for phosphorus sedimentation and leaching coefficients were estimated from data available on the Smallwood Reservoir (impoundment 1971) in Labrador. The model was subsequently applied to predict phosphorus concentrations during the trophic upsurge phase in the La Grande-2 (LG2) Reservoir (impoundment 1978) in the James Bay region of Quebec. Because the sparse data available on other new or old reservoirs during the trophic upsurge phase does not permit an analysis of the confidence limits in model output, we include discussion of the calculated values of model parameters and their relationship to the real phenomena. An evaluation of the rates of phosphorus leaching from flooded soils and vegetation and the specific leaching coefficient of phosphorus from various lands has shown indirectly that the proposed model approximates the dynamics of new reservoir phosphorus concentrations. We conclude that the model has a good potential as an empirical predictive tool in the management of large new reservoirs on the Canadian Shield.Key words: reservoir, phosphorus, model, trophic state
Descriptions and Keys for Ammocoetes of Lampreys from British Columbia, Canada
Authors: Richards J. E. , Beamish R. J. , Beamish F. W. H.
Published: August 2008

Characters useful for the identification of ammocoetes of lampreys found in British Columbia were verified by rearing ammocoetes through metamorphosis to specifically identifiable adults. We developed a key that employs new as well as some previously published features. We showed that published descriptions previously thought to be characteristic of species are unreliable for taxonomy. Counts of trunk myomeres and body proportions were not useful for separating species.Key words: ammocoetes, taxonomy, identification criteria
Stock-Recruitment Relationship for Atlantic Salmon (Salmo salar) in Newfoundland Rivers
Authors: Chadwick E. M. P.
Published: August 2008

A stock-recruitment relationship was developed for Atlantic salmon (Salmo salar) in Western Arm Brook, a small Newfoundland river. Supportive evidence was also found on Indian and Little Codroy, two other Newfoundland rivers. On Western Arm Brook, year-class strength of smolts was correlated (P < 0.01) with egg deposition. On Little Codroy River, smolt year-class strength was correlated (P < 0.01) with potential egg deposition of adults counted as kelt. On Indian River egg to fry survival was correlated (P < 0.01) with winter temperature and discharge. On the basis of these findings, the current recommended egg deposition of 2.4 eggs∙m−2 of parr-rearing habitat was considered inadequate for Newfoundland rivers.Key words: stock-recruitment, Atlantic salmon
Immunogenic Potential of Growth Products Extracted from Cultures of Aeromonas salmonicida for Brook Trout (Salvelinus fontinalis)
Authors: Cipriano Rocco C.
Published: August 2008

Growth products from virulent (3.93 and 3.101), an avirulent (3.10), and an atypical strain (3.111) of Aeromonas salmonicida yielded four protein containing fractions (designated fractions 1, 2, 3, 4) following chromatography on DEAE Sephadex A-25 of crude material that was precipitated from broth culture supernatants with (NH4)2SO4 and ethanol. Vaccination trials, in which each of the four fractions from a virulent and an avirulent strain were injected intraperitoneally at a dose of 5 μg protein into brook trout (Salvelinus fontinalis) indicated that only fraction 4 consistently protected trout from experimental challenges. Immunizing fish with fraction 4 that was emulsified in Freund's incomplete adjuvant also protected trout from challenge but did not enhance protection. Additional brook trout that were immunized by injection with fraction 4 derived from either of two virulent, an avirulent, or an atypical strain of A. salmonicida were also protected from contact challenge with a different challenge strain. Fraction 4 was partially characterized as a glycoprotein; the protein subunit fraction had an approximate molecular weight of 66 000 daltons. Rabbit antiserum prepared against fraction 4 reacted on agar gel diffusion plates to form a single precipitin band with the homologous fraction 4 antigen but this antiserum did not cross react with either purified preparations of bacterial endotoxin or A-layer protein.Key words: Aeromonas salmonicida, Salvelinus fontinalis, growth products, fraction 4, glycoprotein, virulent, avirulent, atypical strains, contact experimental challenge
Maturation and Fecundity of Pacific Herring (Clupea harengus pallasi): An Experimental Study with Comparisons to Natural Populations
Authors: Hay D. E. , Brett J. R.
Published: August 2008

Approximately 3 mo before spawning, Pacific herring (Clupea harengus pallasi) were captured and transferred to experimental netpens varying in fish density, cover, and feeding regimes. Fecundity decreased as the fish ripened. Concurrently, ovary weight and egg weight increased and somatic weight decreased. Length-specific fecundities of fed and unfed fish were similar, but the unfed fish had higher weight-specific fecundities, corresponding to a greater loss of somatic tissue during impoundment. Feeding accelerated the rate of maturity, and fed fish spawned earlier with heavier eggs than unfed fish. Relative fecundity (eggs per gram) was highest among the unfed fish. Reduction in preovulatory egg number probably was a consequence of follicular atresia (observed but not quantified here). Age-, length-, and weight-specific fecundity of impounded herring varied within the range observed for naturally maturing populations (1974 and 1980). Fecundity in impounded fish varied no more than observed in nature: there was a greater difference in age-, length-, and weight-specific fecundity between years than there was between experimental treatments. We suggest that reduction in the number of maturing oocytes occurs naturally and reflects a mechanism that allows herring to adjust their egg size and egg number according to energetic resources and environmental conditions.
Dispersal of Homarus americanus Larvae in the Gulf of Maine from Browns Bank
Authors: Harding Gareth C. , Trites Ronald W.
Published: August 2008

Studies of larval lobster (Homarus americanus) distribution off southwestern Nova Scotia during the summers of 1977 and 1978, were used to estimate an average larval recruitment or production of 1918 and 5284 stage IV lobsters per square kilometre per year inshore and offshore, respectively. Results indicate that the offshore may contribute up to 97% of the larval recruits for the entire southwestern Nova Scotia region. Current patterns and velocities of 3–16 cm∙s−1 were estimated from surface drifter returns within the Gulf of Maine. Limits of larval dispersion are estimated from surface currents in the region and the physiological and ecological traits of the larval lobster. Offshore lobsters could make an important contribution to recruitment not only off southwestern Nova Scotia but in the entire eastern sector of the Gulf of Maine to Casco Bay. Larval dispersal provides another line of evidence that the Gulf of Maine area represents one lobster recruitment center. Our results are consistent with the idea that ontogenic seasonal migration of female lobsters has evolved to locate planktotrophic larvae in warmer shoal areas where growth and survival is optimal and from which ocean currents subsequently disperse a large portion of these larvae to settle over highly productive juvenile grounds.
Physiological Consequences of Overwintering in Streams: The Cost of Acclimitization?
Authors: Cunjak Richard A.
Published: August 2008

Proximate body composition and hematological parameters of wild brook (Salvelinus fontinalis) and brown trout (Salmo trutta) from five sites were monitored over three winters. For both species, and for immature and mature fish, lipid levels were lowest (and water content highest) in winter. Lipid levels were most rapidly depleted (to between 2 and 4% wet weight) in early winter (November–December). Brown trout and immature brook trout appeared to suffer a second period of depletion in late winter (February–March) in contrast with spent brook trout. Protein and ash components were relatively stable between dates. Serum protein levels varied greatly but generally indicated a decline in early winter from high summer (August) values prior to increasing in May. Such trends were most obvious during the winter of 1983–84, the harshest of the three winters of study. In the winter, serum glucose concentrations peaked in November. These physiological relationships corroborate earlier findings that early winter is a stressful period of acclimatization to rapidly changing environmental conditions. Even the relatively stable discharge and temperature regimens of spring-fed tributaries are insufficient to offset the effects of early winter.
Prediction of Phosphorus Release Rates from Total and Reductant-Soluble Phosphorus in Anoxic Lake Sediments
Authors: Nürnberg Gertrud K.
Published: August 2008

Release rates of phosphorus from anoxic sediment surfaces in seven North American lakes were determined from core tube incubations. These rates were compared with several P fractions within the 0–5 and 5–10 cm layers of the corresponding sediment. Regressions of release rates both on total sediment P and on reductant-soluble P were highly significant. Analysis of literature data from lakes worldwide also showed significant relationships between the release rates and total sediment P and citrate dithionite bicarbonate extractable P. Mass balance calculations for individual cores indicated that reductant-soluble P decreases in wet surficial sediments, while total P in the overlying water increases. The release rates of different P fractions in the water — total, soluble reactive, and total reactive P — were very similar, indicating the high biological availability of the released P.
Factors Affecting the Spatial Distribution of Diatoms on the Surface Sediments of Three Precambrian Shield Lakes
Authors: Earle J. C. , Duthie H. C. , Glooschenko W. A. , Hamilton P. B.
Published: August 2008

Spatial heterogeneity in species composition of surface sediment diatom assemblages was examined in three Precambrian Shield lakes of different water chemistry and basin morphometry. The study revealed that one sample cannot adequately represent the "average" diatom flora of a lake. The results of cluster analysis, multivariate analysis of variance, and analysis of covariance indicated that the lakes exhibited different patterns of spatial heterogeneity in their sedimentary diatom assemblages. In the morphometrically simple Plastic Lake the amount of variability was substantially lower than in the other lakes. In the morphometrically more complex Blue Chalk Lake and Chub Lake there was considerably more variability; however, very little of the variability could be attributed to depth or basin shape. The variability in surface diatom assemblages was markedly higher in Chub Lake, probably as a result of the influx of diatoms from the wetlands surrounding the lake. Despite a significant amount of heterogeneity in sediment diatom composition within each lake, between-lake differences were sufficiently high to suggest that comparisons between lakes based on sedimentary diatom remains are probably valid if sampling sites are selected following prescribed criteria.
Modification and Assessment of an Index of Biotic Integrity to Quantify Stream Quality in Southern Ontario
Authors: Steedman Robert J.
Published: August 2008

A multivariate measure of stream quality, the Index of Biotic Integrity (IBI), was adapted to southern Ontario and calibrated to watershed land use on a variety of spatial scales. The fish fauna at 209 stream locations on 10 watersheds near Toronto, Ontario, was sampled with a backpack electrofisher in the summers of 1984 and 1985 to provide biological information for the IBI. Watershed urbanization, forest cover, and riparian forest were measured from 1:50,000 scale topographic maps and related to IBI estimates by linear regression. Of the biological measures tested, species richness, local indicator species (brook trout (Salvelinus fontinalis) and Rhinichthys spp.), abundance of large piscivores, fish abundance, and incidence of blackspot disease were found to contribute significantly to IBI estimates. Variation in IBI estimates at the same location ranged from 0 to 8% within the sample season and from 0 to 24% between years. Linear models based on measures of watershed urbanization and forest cover accounted for 11–78% of the variation in IBI scores, depending on the spatial scale of the analysis. Significant IBI/land use relationships were found with whole-basin IBI estimates and for IBI estimates from individual stream reaches. Land use immediately upstream of sample stations was most strongly associated with stream quality as measured by the IBI.
Experimental Designs for Estimating Transient Responses to Management Disturbances
Authors: Walters Carl J. , Collie Jeremy S. , Webb Timothy
Published: August 2008

Simple experimental designs invoking treated and control areas, with all treatments initiated at the same time, should not be used to assess transient responses to management actions or environmental disturbances. Such designs will not properly control for "time–treatment" interactions, involving differential responses of treated areas to nonrandom trends in the experimental environment. For example, survival trends for hatchery salmon stocks cannot be simply compared with survival trends in wild stocks, since the hatchery stocks may be more susceptible to changes in environmental factors such as ocean temperature. To control for such time–treatment interactions, it is suggested to use a "staircase" experimental design in which treatment is initiated at different times on the treated areas. Computation of the average transient and interaction response parameters for such designs, while correcting for temporal trends and inherent differences among areas, can be done using general linear models. The optimum design configuration (number of treated versus control areas, number of pretreatment control times, etc.) involves spreading the treatment starts widely over time and using relatively few control areas.
Bias in Estimation of Stock-Recruit Function Parameters Caused by Nonrandom Environmental Variability
Authors: Armstrong Michael J. , Shelton Peter A.
Published: August 2008

Parameter estimation for stock–recruit models normally assumes a random distribution of residuals around the underlying function. Monte Carlo simulations, in which departures from the mean stock-recruit function were determined by periodic forcing with a random component, showed that bias may occur in the estimation of average parameter values if randomness is assumed. The bias occurred when the spawning stock size varied in-phase or out-of-phase with the periodic forcing and was greatest when the period was approximately twice the mean age of the spawning stock. In addition to bias, patterning of spawner stock size and recruitment data caused by the periodic variability gave misleading impressions of parameter precision.
A Subice Suction Corer for Sampling Epontic Ice Algae
Authors: Welch Harold E. , Bergmann Martin A. , Jorgenson John K. , Burton William
Published: August 2008

Standard SIPRE coring was compared with a new Subice Suction Corer and cores taken by diver for the quantitative assessment of epontic (subice) algae on first-year congelation sea ice at Resolute, N.W.T., Canada (≈75°N). The diver cores were probably most accurate but were slow and costly. SIPRE coring was as good as other techniques in late winter and early spring but gave progressively poorer (under) estimates as the season progressed, with up to 90% of the ice algae being lost from SIPRE cores by June. The Subice Suction Corer was fast, easy to operate, cheap, and gave results comparable with samples obtained by diving. Sources of error are discussed.
Dependence of Lake Oxygen Depletion Rates on Maximum Oxygen Storage in a Partially Meromictic Lake in Alberta
Authors: Trimbee Annette M. , Prepas E. E.
Published: August 2008

Areal rates of hypolimnetic oxygen depletion (AHOD) and winter oxygen depletion (AWOD) varied considerably from year to year in a partially meromictic lake (Narrow Lake) in central Alberta. AHOD ranged from 0.222 to 0.522 g O2∙m−2∙d−1 over four summers and AWOD ranged from 0.354 to 0.614 g O2∙m−2∙d−1 over three winters. AHOD was positively correlated with maximum storage of dissolved oxygen (O2) at the onset of summer thermal stratification (P < 0.05). Similarly, AWOD was higher in years when mixing was more complete and maximum O2 storage at freeze-up was higher. These results suggest that the prediction of O2 depletion rates for lakes with year-to-year variation in maximum O2 storage can be improved if maximum O2 storage after lake mixing is considered in addition to other factors known to influence O2 depletion rates such as lake productivity and morphometry.
Differences in Brown Trout (Salmo trutta) Production among Contiguous Sections of an Entire Stream
Authors: Newman Raymond M. , Waters Thomas F.
Published: August 2008

Production dynamics of a wild brown trout (Salmo trutta) population were examined for 3 yr in each of eight contiguous 305-m-long sections that constituted the entire length of South Branch Creek, a limestone stream in southeastern Minnesota. Total trout densities increased from about 1600/ha in 1980 to 2300/ha in 1982. There were large and significant differences in density among sections; relative differences among sections, however, were nearly constant over the 3 yr. Mean annual standing stock and production increased over the 3 yr from about 90 and 100 kg/ha, respectively, in 1980 to 150 and 174 kg/ha, respectively, in 1982. Standing stock and production also differed significantly among sections, but relative differences among sections were fairly constant over the 3 yr. The most productive sections had standing stocks and production rates that were 1.5–2 times higher than the least productive sections. Year strongly influenced growth rate, with growth in 1982 almost double that in 1981, but growth rates did not differ significantly among sections. Habitat differences among sections appeared to regulate density, size, standing stock, and production. Factors that affected the entire stream influenced recruitment and growth.
Comparative Mortality of Three Esocids due to Stocking Stressors
Authors: Mather Martha E. , Wahl David H.
Published: August 2008

For stocked sportfish, stocking stress can cause substantial mortality. We evaluated mortality of three young-of-year esocids, northern pike (Esox lucius), muskellunge (E. masquinongy), and their F1 hybrid, the tiger muskellunge, in response to simulated handling, transport, and thermal stressors in the laboratory. In 15 °C acclimated esocids, a 10° rapid temperature increase caused little mortality. A 12° increase killed some fish in all taxa; however, mean mortality did not differ significantly among northern pike [Formula: see text], tiger muskellunge [Formula: see text], and muskellunge [Formula: see text]. Nearly all 15 °C acclimated fish (98%) died in response to a 15° increase. Tempering (0.15°∙min−1) did not reduce this near complete mortality. Handling (30 s dipnet) and transport confinement (60 g∙L−1 for 120 min) also did not alter mortality when compared with a 12° temperature increase alone. Field experiments, completed concurrently, confirmed our laboratory finding that healthy esocids, acclimated to 15 °C, stocked at lake temperatures corresponding to a temperature increase [Formula: see text], suffered little mortality. Because mortality did not differ among these two species and their hybrid, differential vulnerability to these stocking stressors need not be considered when deciding which esocid to stock.
Chemical Response of Lakes Treated with CaCO3 to Reacidification
Authors: Driscoll Charles T. , Ayling William A. , Fordham G. F. , Oliver Leah M.
Published: August 2008

The reacidification of two lakes in the Adirondack region of New York treated by CaCO3 application was evaluated. Base treatment resulted in a very high immediate dissolution efficiency in both lakes (78–82%), increasing acid neutralizing capacity (ANC) to values of 450–550 μeq∙L−1. During the fall following manipulation, completely mixed water columns and elevated hydrologic inputs greatly facilitated reacidification, decreasing pH and diluting Ca2+ concentrations. Cranberry Pond effectively reacidified within 7 mo of treatment, while the ANC of Woods Lake decreased to near 0 μeq∙L−1 15 mo after application. In Cranberry Pond, pH values decreased below 5.5 resulting in transport of elevated concentrations of inorganic Al through the lake. Annual ANC budgets suggest that little CaCO3 penetrated to the sediments, limiting long-term release of ANC from sediment dissolution. Hydrolysis of Al, due to the elevated lake pH, served to consume ANC and there is evidence to indicate limited exchange of water column Ca2+ with sediments shortly after treatment followed by release of this Ca2+ during reacidification. However these processes did not significantly accelerate or attenuate the rate of reacidification. The rate of acidification could largely be explained by the flushing of ANC from the lakes by hydrologic inputs.
Hydrology of Two Headwater Lakes in the Adirondack Mountains of New York
Authors: Staubitz Ward W. , Zarriello Phillip J.
Published: August 2008

Cranberry Pond and Woods Lake are small, acidic headwater lakes in the west-central Adirondack region of New York State. The lakes differ in size and depth but have similar watershed characteristics. Both watersheds contain thin eolian and sandy till deposits overlying granitic gneiss and have limited capacity to store and transmit groundwater. Total lake inflow was calculated as a residual of a monthly hydrologic balance based on measured precipitation, lake outflow, change in lake storage, and estimated evaporation; surface-water and groundwater inflow to each lake also were estimated. Results indicate that the lakes are hydrologically similar and are dominated by surface-water systems with highly variable runoff that responds rapidly to precipitation. Groundwater, which constituted about 16% of the total inflow to Cranberry Pond and from 31 to 38% of the total inflow to Woods Lake in 1984–86, moves through a shallow flow system that provides little stabilizing influence on the hydrology or water chemistry of the lakes. Error analysis of the hydrologic balance indicated that total annual inflow, calculated as a residual of the hydrologic balance, is accurate to within 12%. Calculated monthly inflow values are subject to greater potential error that ranges up to 46%.
Survival, Growth, Reproduction, and Diet of Brook Trout (Salvelinus fontinalis) Stocked into Lakes after Liming to Mitigate Acidity
Authors: Gloss Steven P. , Schofield Carl L. , Spateholts Robert L. , Plonski Barbara A.
Published: August 2008

Brook trout (Salvelinus fontinalis) were stocked into two previously acidic (pH 4.5–5.2) Adirondack Mountain lakes, Woods Lake and Cranberry Pond, following liming in June, 1985. Age 0+ Temiscamie × Domestic hybrid brook trout were stocked at 200∙ha−1 with one-half of the fish selected for presumed acid tolerance. Age 1+ Temiscamie strain brook trout were also stocked at 50∙ha−1. Liming increased pH to well above 7 and alkalinity to over 200 μeq∙L−1. Growth and condition of stocked fish were good while water quality conditions remained suitable. However, in Cranberry Pond, which reacidified 6 mo after liming, both growth and survival declined dramatically. Much of the population loss was due to emigration. Annual survival in Woods Lake averaged 35 and 25% for the age 0+ and 1+ fish, respectively. Initially large invertebrates made up most of the diet for stocked fish. These taxa were replaced by zooplankton within a few months. Limited natural reproduction was associated with low velocity groundwater inflows and high acidity in tributary streams. Fry emergence from artificial spawning substrates placed in Woods Lake peaked well after snowmelt inflows which produced toxic conditions in littoral areas.
Effects of Neutralization and Addition of Brook Trout (Salvelinus fontinalis) on the Limnetic Zooplankton Communities of Two Acidic
Authors: Schaffner William R.
Published: August 2008

The zooplankton communities in two acidified lakes in the Adirondack region of New York changed considerably following liming and the reintroduction of brook trout (Salvelinus fontinalis). Most rotifer taxa were greatly reduced in numbers within a week following base addition. Keratella taurocephala declined by orders of magnitude in both lakes. Rotifer species that replaced K. taurocephala were far less abundant. The crustacean communities were also affected by liming. Diaptomus minutus, the dominant in both lakes, declined following base addition. Longer-term population responses appeared to be related to the dynamics of the individual populations, and changes in predation pressure. Four additional crustacean species became prominent in the lakes after liming: the caldocerans Bosmina longirostris and Daphnia catawba in Cranberry Pond, and D. catawba and the cyclopoid copepod Cyclops scutifer in Woods Lake. Over the longer-term liming and the introduction of brook trout tended to have an overall positive effect on the zooplankton communities in the two lakes.
Calcite Dose Selection, Treatment Efficiency, and Residual Calcite Fate after Whole-Lake Neutralization
Authors: Young Thomas C. , DePinto Joseph V. , Rhea James R. , Scheffe Richard D.
Published: August 2008

A modeling approach guided whole-lake neutralization treatments of two acidic Adirondack lakes and aided examination of treatment efficiency as measured by initial water column dissolution and calcite delivery to sediments, prediction of posttreatment water chemistry, and assessment of the fate of calcite deposited on sediments. The lake model incorporated both dissolution and sedimentation of calcite in a vertically segmented lake assumed to behave as a closed system. Observed short-term calcite dissolution exceeded predictions (75 versus 45%) because (1) dispersion and thermocline presence slowed calcite particle settling; and, (2) CO2influx altered the chemical environment of the particles. Prior to calcite treatment, the two lakes had sediments with similar base neutralizing capacities (BNC). Quantitatively, minor sediment neutralization resulted from the treatment; however, sediment pH gradients changed from positive to negative downward, and Caτin surficial sediments increased as sediment BNC decreased. During the subsequent 16 mo of reacidification, sediment chemical characteristics partially returned to pretreatment conditions by contributing alkalinity to the overlying water.
Predicting Reacidification of Calcite Treated Acid Lakes
Authors: DePinto Joseph V. , Scheffe Richard D. , Booty William G. , Young Thomas C.
Published: August 2008

A mathematical model (acid lake reacidification model, ALaRM) for predicting reacidification times of calcite treated acid lakes has been calibrated and field tested using data from two Lake Acidification Mitigation Project (LAMP)) lakes (Woods Lake and Cranberry Pond, Big Moose, N.Y.) The model is based on dynamic water column and sediment mass balances of acid neutralizing capacity (ANC) and dissolved inorganic carbon (DIC). Inclusion of a sediment submodel that includes sediment–pore water proton exchange, production of DIC through sediment respiration, ANC generation or utilization through redox reactions, long-term dissolution of calcite deposited in the surface sediments during application, and pH adjustment through an equilibrium proton balance, permits the deterministic simulation of sediment response to whole-lake liming and its subsequent effect on water column reacidification. Application of ALaRM to the postliming response of the two lakes demonstrated that reacidification was controlled primarily by hydrologic flushing and secondarily by sediment–water ANC transfer. Cranberry Pond, which has a mean hydraulic retention time of 2 mo, reacidified to near 0 ANC and pH < 5 within 6 mo after treatment. Woods Lake, which has a mean hydraulic retention time of almost 6 mo, still had an ANC > 20 μeq∙L−1 and a pH > 5.6 just prior to its reliming 15 mo after its initial treatment.
Production and Growth Efficiency of Brook Trout (Salvelinus fontinalis) in Two Adirondack Mountain (New York) Lakes Following Liming
Authors: Schofield Carl L. , Gloss Steven P. , Plonski Barbara , Spateholts Robert
Published: August 2008

Yearling and spring fingerling brook trout (Salvelinus fontinalis) stocked in two Adirondack lakes after liming in the spring of 1985 produced 10–14 kg∙ha−1yr−1at average standing crops of 8–10 kg∙ha−1during the first year after stocking. These values were similar to levels observed in other limed and circumneutral Adirondack lakes, which collectively support a limited range of biomass (10–20 kg∙ha−1) and production (7–16 kg∙ha−1) compared with more fertile waters in other regions. The estimated level of food consumption required to maintain initial production rates observed in the two limed lakes was 80–100 kg∙ha−1. This level of predation was sufficient to significantly alter the size structure and composition of the invertebrate prey community within a few months after stocking. However, mean production efficiency in these populations remained at levels of 20–25% and the development of adverse water quality conditions in the first year after liming appeared to be of greater significance than food limitation in regulating production and biomass of these stocked brook trout populations. Reacidification of one lake 5 mo after liming resulted in rapid declines in biomass and production as a result of both increased mortality and reduced growth.
Isolation of a Y-Chromosomal DNA Probe Capable of Determining Genetic Sex in Chinook Salmon (Oncorhynchus tshawytscha)
Authors: Devlin Robert H. , McNeil B. Kelly , Groves T. David D. , Donaldson Edward M.
Published: August 2008

We have used subtractive hybridization methodologies to selectively clone a DNA fragment from the Y chromosome of chinook salmon (Oncorhynchus tshawytscha). This clone specifically detects a single 8-kb Bam HI restriction fragment in Southern blots of male genomic DNA that is absent in females. This sex-specific pattern was observed in over 50 individuals from five separate chinook stocks, suggesting that the organization of this sequence is conserved in this species. The strength of the hybridization signal, and the pattern observed in multiple enzyme digests, indicates that this sequence is repeated in the male chinook genome. With long autoradiographic exposures, fainter additional sequences can also be detected both in males and females, suggesting that other similar sequences not organized in a sex-specific fashion are found on the X chromosome and/or autosomes. Examination of the segregation of this DNA sequence in families showed that the male-specific pattern segregates from father to son, providing strong evidence that the DNA probe is from the Y chromosome. The application of Y-chromosomal probes to the commercial culture of this species will simplify the synthesis of new monosex strains and allow verification of existing genotypic female, phenotypic male stocks.
Tissue Response of Fish to Invasion by Larval Pseudoterranova decipiens (Nematoda; Ascaridoidea)
Authors: Ramakrishna N. R. , Burt M. D. B.
Published: August 2008

The histopathology of Pseudoterranova decipiens (L3) in experimentally infected rainbow trout (Oncorhynchus mykiss) and naturally infected Atlantic cod (Gadus morhua) was similar. The chronic granulomatous inflammatory reaction included polymorphonuclear neutrophils, macrophages, lymphocytes, epithelioid cells, and fibroblasts. Giant cells were also found but only in the experimentally infected rainbow trout. Mature capsules around the larvae consisted of an inner layer, composed of macrophages which underwent epithelioid transformation and later gradually degenerated, and an outer layer, composed of fibroblasts and collagen fibres. A layer of lipofuscin was adjacent to the parasite in older cod infections but this was absent in all of the newly formed capsules in the experimentally infected rainbow trout.
A Polymorphism in the Ribosomal RNA Genes Distinguishes Atlantic Salmon (Salmo salar) from North America and Europe
Authors: Cutler Michael G. , Bartlett Sylvia E. , Hartley Sheila E. , Davidson William S.
Published: August 2008

There is good evidence to suggest that Atlantic salmon (Salmo salar) from North America and Europe form distinct breeding populations. However, it has been very difficult to discover a genetic marker that allows the continent of origin of an individual salmon to be determined unambiguously. Repetitive elements in the nuclear genome have provided population-specific markers in several species. Therefore, we examined the ribosomal RNA gene (rDNA) complex in Atlantic salmon by Southern blot analysis using a cloned repeating unit of the Drosophila melanogaster rDNA as a probe. A restriction fragment length polymorphism that could distinguish between salmon from Newfoundland and Scotland was detected using a combination of the restriction enzymes SacI and XbaI. The Newfoundland salmon had additional fragments of 3.6 kilobase pairs (kbp) and 2.6 kbp. Of 27 salmon from 10 populations in Europe, none possessed the 3.6- or the 2.6-kbp fragment whereas all 33 North American Atlantic salmon (from six populations) had the 2.6-kbp band and the majority showed the 3.6-kbp fragment. This preliminary survey strongly suggests that this genetic marker can be used to identify the continent of origin of individual Atlantic salmon.
Riverine and Estuarine Migratory Behavior of Coho Salmon (Oncorhynchus kisutch) Smolts
Authors: Moser Mary L. , Olson Alan F. , Quinn Thomas P.
Published: August 2008

Using radio and ultrasonic transmitters, we tracked coho salmon (Oncorhynchus kisutch) smolts in the Chehalis River and Grays Harbor estuary, Washington, to document patterns of seaward migration. In spite of dramatic differences in the two habitats, the fish behaved similarly in both systems. Migratory progress was saltatory, characterized by movement in the direction of the current and extended periods of holding in areas of low current velocity. Consequently, smolts were displaced rapidly downstream by swift, unidirectional river currents but were retained in the estuary by relatively low-velocity, reversing tidal currents. Smolts did not use tidal currents to move seaward and appeared to swim most rapidly against strong ebbing currents. Estimated mean total metabolic cost incurred by migrating smolts was 0.027 cal∙s−1∙smolt−1 (1 cal = 4.184 J). Estimated daily caloric expenditure by smolts in 1988 was twice that of smolts tracked in 1989, apparently due to faster water velocities in 1988. The observation that coho salmon migration through estuaries is slower than riverine migration suggests that a period of estuarine residence may be necessary for them to adjust their osmoregulatory capability, orient for their return migration, feed, or reduce their vulnerability to predators.
Stock Abundance Estimation Using Depth-Dependent Trends and Spatially Correlated Variation
Authors: Sullivan Patrick J.
Published: August 2008

Hydroacoustic data commonly contain a large number of observations that are correlated in space and time. Such data are complicated to analyze, and a good estimate of the error in abundance is often difficult to obtain. Hydroacoustic data collected on Shelikof Strait walleye pollock (Theragra chalcogramma) are used to develop statistical techniques for analyzing survey data containing spatial trends and spatial correlations. The data show a trend in fish density with depth, while detrended observations exhibit spatial correlation. Spatial means and variances of fish density, and total abundance and its variance, are determined using the geostatistical theory of kriging. The total abundance estimate is the same order of magnitude as estimates arrived at using a stratified estimation approach. Detrending the data with respect to depth through depth stratification decreased the estimated variance by nearly a factor of 10. Detrending the data with respect to depth and kriging the residual variation over space reduced the variance by an additional factor of 2. Modeling trends and making more efficient use of the data contribute to the gain in information
Trophic Interaction and Competition Between Largemouth Bass (Micropterus salmoides) and Rainbow Trout (Oncorhynchus mykiss) in a Manipulated Lake
Authors: Hodgson James R. , Hodgson Carol J. , Brooks Scott M.
Published: August 2008

We examined the impact of competition between largemouth bass (Micropterus salmoides) and rainbow trout (Oncorhynchus mykiss) on diet and condition factor of the two species. Data were collected from Paul Lake (a control lake containing only bass) and Peter Lake (an experimental lake to which trout were introduced) (Michigan, USA). We compared diets of 1988 bass and trout in Peter Lake, 1987 and 1988 bass in both Peter and Paul lakes, and 1988 trout and 1987 bass in Peter Lake. Patterns in diet overlap demonstrated with pooled sample methodology could not always be matched with a random individual pairing technique. With the pooled methodologies, we demonstrated a diet composition shift with significant changes in diet diversity and evenness in the Peter Lake bass after the introduction of trout: such bass ate fewer zooplankton (Daphnia spp.) and more odonate naiads than before trout introduction, and their condition factor was reduced. Seasonal divergence in diets between bass and trout was observed. Growth rates of Paul Lake bass did not differ significantly between years, and relative to the experimental lake there were fewer statistically significant dietary differences.
Mortality and Recruitment of Pacific Sardine,Sardinops sagax caerulea, Larvae in the California Current
Authors: Butler John L.
Published: August 2008

The mortality rates of Pacific sardine, Sardinops sagax caerulea, larvae (< 20 d) increased during 1951–67, and this increase was positively correlated with the increase in biomass of northern anchovy, Engraulis mordax. Other potential correlates with larval sardine mortality rates were examined using multiple correlation. These included temperature and zooplankton volumes at stations positive for sardine larvae, water column stability, upwelling, transport, salinity anomalies, and Pacific mackerel, Scomber japonicus, abundance. None contributed significantly to the multiple regression with anchovy abundance. Thus, no evidence existed for either Lasker's stable ocean hypothesis of larval mortality or Hjort's larval transport hypothesis. The logarithm of the ratio of sardine recruits at age 2 to the spawning biomass was used as an index of recruitment success. Sardine recruitment success at age 2 was not correlated with larval mortality rates. Sardine recruitment, however, was negatively correlated with both northern anchovy biomass and the combined biomass of Pacific sardine, Pacific mackerel, and northern anchovy. A plausible explanation for this result is that predation by pelagic fishes results in greater mortality rates of sardine larvae and juveniles which in turn decrease sardine recruitment.
Physiological Responses to Challenge Tests in Six Stocks of Coho Salmon (Oncorhynchus kisutch)
Authors: McGeer James C. , Baranyi Leanne , Iwama George K.
Published: August 2008

Coho salmon (Oncorhynchus kisutch) from six hatcheries were reared in a common facility and then subjected to six different challenge tests. Results indicated that there are differences in the response to stressful challenges among stocks of coho salmon. The challenge tests were exposure to salt water (30‰), high pH (9.4 and 10.0), low pH (3.55, 3.65, 3.75, and 4.1), thermal increase (1°C∙h−1), disease (bacterial kidney disease), and handling (30-s netting and emersion). The measured responses were changes in plasma sodium and chloride ion concentrations for the saline and pH challenges, critical thermal maximum in the thermal tolerance test, mortalities in the disease challenge, and plasma glucose alterations in the handling challenge. The Chehalis River stock was most successful in tolerating salt water but showed the largest plasma ion decrease in acidic waters. The stock from Eagle River had the lowest plasma glucose increase during handling challenges. In the disease challenge the Tenderfoot Creek and Eagle River stocks had high mortalities but the Capilano River stock had the lowest mortality. No stock differences were found during thermal tolerance and high pH challenges. An assessment of overall stock performance across challenges showed that each stock had a unique response profile.
Effect of Overwinter Mortality on Reproductive Life History Characteristics of Pumpkinseed (Lepomis gibbosus) Populations
Authors: Fox Michael G. , Keast Allen
Published: August 2008

Pumpkinseed (Lepomis gibbosus) inhabiting two shallow ponds that experienced major winterkills matured 1–2 yr earlier and at a smaller size (difference > 20 mm in length) than conspecifics living in an adjacent, nonwinterkill lake. Pond females were more fecund relative to body weight, and their gonadosomatic index was about double that of lake females. Pond males showed a significant, but less drastic increase in gonadosomatic index over lake males. Winterkills occurred in different years in the two ponds, but in both cases, pumpkinseeds showed significantly lower age and size at maturity following winterkill in comparison with a preceding or subsequent nonwinterkill year. These results are consistent with life history predictions for organisms living in fluctuating environments and indicate that reproductive life history traits are very plastic in pumpkinseeds living in high-risk environments. Advanced maturity following winterkill may be the result of abundant food supply to survivors or release from social factors that prevent maturation of small pumpkinseeds.
Metabolic Effects Associated with Chronically Elevated Cortisol in Rainbow Trout (Oncorhynchus mykiss)
Authors: Andersen Donald E. , Reid Scott D. , Moon Thomas W. , Perry Steve F.
Published: August 2008

Carbohydrate and protein metabolism were examined in rainbow trout, Oncorhynchus mykiss, fitted with mini-osmotic pumps which maintained plasma cortisol levels at approximately 100 or 200 ng∙mL−1 for 10 d. Plasma glucose, lactate, and protein levels were unaffected by 10 d of cortisol administration, despite a significant elevation in plasma cortisol. Plasma amino acids in cortisol-treated fish (1023.8 ± 90.7 μg∙mL−1) were significantly elevated compared with shams (716.7 ± 68.5 μg∙mL−1) after 9 d. Liver glycogen content was significantly reduced by cortisol treatment. The activities of the liver enzymes assayed were unchanged; likewise the flux of radioactive substrates to radiolabeled CO2, glucose, and protein in isolated hepatocytes was unaffected in trout with chronically elevated cortisol compared with shams. The glucose replacement rate (Ra) was unchanged after 2 wk of cortisol treatment. These data do not support the purported role of cortisol as a glucocorticoid in rainbow trout. While chronically elevated cortisol may increase the supply of plasma amino acids, the hormone does not appear to alter the manner in which this potential gluconeogenic substrate is metabolized. The absence of other stressors may be partially responsible for the differences between this study and others in the literature.
A maximum likelihood approach for estimating growth from tag–recapture data
Authors: Wang You-Gan , Thomas Mervyn R. , Somers Ian F.
Published: August 2008

The Fabens method is commonly used to estimate growth parameters k and l∞ in the von Bertalanffy model from tag–recapture data. However, the Fabens method of estimation has an inherent bias when individual growth is variable. This paper presents an asymptotically unbiassed method using a maximum likelihood approach that takes account of individual variability in both maximum length and age-at-tagging. It is assumed that each individual's growth follows a von Bertalanffy curve with its own maximum length and age-at-tagging. The parameter k is assumed to be a constant to ensure that the mean growth follows a von Bertalanffy curve and to avoid overparameterization. Our method also makes more efficient use of the measurements at tag and recapture and includes diagnostic techniques for checking distributional assumptions. The method is reasonably robust and performs better than the Fabens method when individual growth differs from the von Bertalanffy relationship. When measurement error is negligible, the estimation involves maximizing the profile likelihood of one parameter only. The method is applied to tag–recapture data for the grooved tiger prawn (Penaeus semisulcatus) from the Gulf of Carpentaria, Australia.