bluuebunny/crossref_metadata_2025 huggingface dataset:
A Potent Analog of Recombinant Bovine Somatotropin Accelerates Growth in Juvenile Coho Salmon (Oncorhynchus kisutch)
Authors: (Ted) Down N. E. , Donaldson Edward M. , Dye Helen M. , Boone Thomas C. , Langley Keith E. , Souza Lawrence M.
Published: August 2008

Recombinant bovine somatotropin and a recently engineered analog of bovine somatotropin were compared for their growth-promoting ability in underyearling coho salmon (Oncorhynchus kisutch). Treated fish were given five biweekly intraperitoneal injections of one of the hormone preparations at either 0.2 or 2.0 μg/g body weight. Both substances significantly enhanced growth, and by the end of the treatment period the fish injected with the high dose of the analog were significantly larger than all other groups, being 43.5% heavier than the sham-treated (saline injected) fish. Fish treated with the high dose of the native form of somatotropin were 25.3% heavier than the sham-treated group, but were not significantly different in size from fish treated with the low dose of analog. A four-point bioassay indicated that the analog had approximately nine times the growth-promoting potency of the native form of bovine somatotropin in coho salmon. Food conversion efficiency was improved by somatotropin therapy, but all groups exhibited a similar osmoregulatory capacity when subjected to a 24-h seawater challenge during the posttreatment period. Given the economic feasibility of producing recombinant proteins in large quantities, this analog has the potential to improve the production characteristics of cultured salmon.
Matrix Analysis of Co-occurrences of Fishes of the Scotian Shelf and Bay of Fundy
Authors: Scott J. S.
Published: August 2008

Numbers of co-occurrences of 29 common fishes of the Bay of Fundy and Scotian Shelf were derived from annual research trawl survey data for the summers of 1970–79 and the spring, summer, and autumn seasons of 1980–84. Matrices prepared from the data were used to examine degrees of association between different species and seasonal and geographical variation in the associations. Three categories of associations were identified: shallow water with a dominant winter flounder (or yellowtail flounder) – longhorn sculpin – sea raven assemblage; middepth with a dominant cod – haddock – thorny skate assemblage; deepwater characteristic species but with no strong recurring assemblages. Strength of co-occurrence was directly related to species abundance and changes corresponded to known seasonal movements in several species, including silver hake, spiny dogfish, and pollock. In general, the strength and number of co-occurrences decreased from southwest to northeast along the Scotian Shelf. The Bay of Fundy was exceptional, with strong co-occurrences of shallow-water species and poor representation of deepwater fishes.
A Method for Estimating Uptake and Production Rates for Urea in Seawater using [14C] Urea and [15N] Urea
Authors: Hansell Dennis A. , Goering John J.
Published: August 2008

Improved estimates of the rates of urea production and uptake by natural populations of phytoplankton were made after determining the change in 15N-atom% enrichment of urea during incubations. A [14C] urea method is described by which the change in enrichment is measured. Estimates of uptake rates are increased (relative to uptake rates determined without correction for isotope dilution) by up to 83% using a 15N accumulation model and by >210% using a 15N disappearance model. A discrepancy exists between [15N] urea removed from the aqueous phase and 15N accumulated in the particulate phase at stations occupied in the northeastern Bering Sea. The ability to find in the particulate fraction the 15N removed from solution as [15N] urea was improved by 72% following removal of the >20-μm particulate fraction. This corresponded to only a 4% reduction in the concentration of chlorophyll a and a 37% reduction in the concentration of particulate N. Removal of microzooplankton may have improved the efficiency of urea-N retention by phytoplankton.
Relationships among Tubificid Abundances, Sediment Composition, and Accumulation Rates in Lake Erie
Authors: Robbins J. A. , Keilty T. , White D. S. , Edgington D. N.
Published: August 2008

Sediment cores taken at 15 sites within the three main depositional basins of Lake Erie from 1976 to 1982 were sectioned in 1-cm intervals and analyzed for the abundance and vertical distribution of benthic organisms, 137Cs, and 210Pb (in some cores) and for surficial (upper 2 cm) organic and inorganic carbon. Zoobenthos populations were dominated (>85%) by tubificids (Limnodrilus hoffmeisteri, Quistadrilus multisetosus, and Tubifex tubifex) and varied in abundance from 6600 to 55 300 individuals∙m−2. The depth above which 90% of the individuals occurred correlated significantly with their abundance and with radiometrically determined mixed depths. Rates of sediment reworking by tubificids exceeded sedimentation rates by 5–80 times, indicating that worms alone can produce the observed zone of constant tracer activity at the sediment–water interface. Tubificid abundance was not significantly related to organic carbon but instead correlated strongly with the sediment accumulation rate and organic carbon flux. In Lake Erie the abundance of tubificids may be limited by the rate of supply of nutrients as measured roughly in terms of the organic carbon flux.
Effects of Triploidy on the Swimming Performance of Coho Salmon (Oncorhynchus kisutch)
Authors: Small Susan A. , Randall D. J.
Published: August 2008

The swimming performance of triploid coho salmon (Oncorhynchus kisutch) was compared with diploid controls to assess the ability of these fish to survive if released into the wild. Triploid salmon had similar haematocrits to diploid salmon but they had lower total haemoglobin content in their blood. There was no difference in the maximum sustained swimming ability between triploid and diploid salmon.
Short-Term Changes in the Chemistry of Trace Metals Following Calcium Carbonate Treatment of Acidic Lakes
Authors: Driscoll Charles T. , Fordham Gerald F. , Ayling William A. , Oliver Leah M.
Published: August 2008

Marked changes were evident in the concentrations of trace metals (aluminum, manganese, and zinc) following base application to two acidic lakes in the Adirondack region of New York. Immediately after calcite treatment, epilimnitic pH values increased above 9.0. This response coincided with a shift in the speciation of aluminum from acid-soluble to labile (inorganic) monomeric forms. Following the manipulation, pH values decreased below 8.0 as the epilimnion equilibrated with atmospheric CO2. Within 1–2 mo, aluminum, manganese, and zinc concentrations were greatly reduced, typically by an order of magnitude. The mechanism(s) for immobilization of trace metals following base treatment is not entirely clear. However, chemical equilibrium calculations suggest that at the higher pH resulting from base addition, lake water was oversaturated with readily forming aluminum and manganese minerals. Therefore, removal of these metals from the water column may have been due to direct precipitation. Solutions were highly undersaturated with zinc minerals, so zinc retention probably occurred by adsorption or coprecipitation reactions. Acidic Adirondack Lakes are generally net sinks for aluminum, and conservative with respect to transport of manganese and zinc. Base addition greatly enhanced retention of all three metals.
Effects of Liming on the Epipelic Algal Community of Woods Lake, New York
Authors: Roberts Deborah A. , Boylen Charles W.
Published: August 2008

The biovolume and species composition of algae on the sediment along a depth gradient were determined before and after liming of acidic (pH 4.9), oligotrophic Woods Lake in the Adirondack Park in New York State (Herkimer Co., NY, USA). The epipelic algal community was dominated by diatoms and cyanobacteria prior to and following liming. Distinct depth zonation patterns of community composition were evident and unaffected by CaCO3 addition. Treatment with calcite increased pH from 4.9 to above 9.0, caused ANC to rise from 0 to >400 μeq∙L−1, and immediately reduced overall water clarity which subsequently improved during the summer. There was a significant decrease (p <0.001) in total algal biovolume after liming corresponding to a significant reduction in biovolume of Hapalosiphon pumilus at the deepest sites. Total diatom biovolume was not significantly changed as a result of the addition of calcite; however, a shift in community composition from dominance by Navicula tenuicephala and Fragilaria acidobiontica to dominance by Achnanthes microcephala and Anomoeoneis vitrea was observed following liming.
Short-Term Changes in the Acid/Base Chemistry of Two Acidic Lakes Following Calcium Carbonate Treatment
Authors: Fordham G. F. , Driscoll C. T.
Published: August 2008

Woods Lake and Cranberry Pond, two chronically acidic lakes located in the Adirondack region of New York, USA, were intensively monitored following CaCO3 treatment in May 1985 to evaluate the mechanisms controlling short-term changes in water column chemistry. Immediately following base application (24 h), both lakes responded like systems closed to atmospheric CO2, because the dissolution of very small CaCO3 particles (median diameter 2 μm) exceeded the rate of atmospheric CO2 intrusion. Rapid dissolution of CaCO3 coupled with very low concentrations of dissolved inorganic carbon (DIC) prior to treatment, resulted in pH increases in the upper mixed waters from 4.9 to 9.4 in Woods Lake and from 4.6 to 9.1 in Cranberry Pond, as waters readily became saturated with CaCO3. pH increases were accompanied by stoichiometric increases in dissolved Ca2+, acid neutralizing capacity (ANC), and DIC. Following this initial perturbation, the upper mixed waters equilibrated with atmospheric CO2 over a 4 wk period, facilitating additional release of dissolved Ca2+ and ANC due to dissolution of suspended CaCO3. The amount of CaCO3 that dissolved during the 4 wk immediately following treatment, calculated from Ca2+ budgets, was very high; 86% in Woods Lake and 79% in Cranberry Pond.
Effects of Calcite Treatment on Primary Producers in Acidified Adirondack Lakes. II. Short-Term Response by Phytoplankton Communities
Authors: Bukaveckas Paul A.
Published: August 2008

The effects of calcite addition on two acidic Adirondack lakes were studied by investigators participating in the Lake Acidification Mitigation Project. Changes in phytoplankton biomass, productivity, and species composition were monitored during the ice-free period prior to and following lake treatment. Changes in water chemistry following limestone addition were largely restricted to the upper water column since calcite particles applied to the lake surface did not effectively penetrate the thermocline. Increased phytoplankton production and biomass were observed during the posttreatment period. Phytoplankton densities and rates of production were similar in both the neutralized (pH > 7.5) and acidic (pH < 5.5) portions of the water column; however, species composition was markedly different. The phytoplankton assemblage of the upper water column was largely comprised of chlorophytes and chrysophytes which had not been observed prior to treatment. In contrast, the deep-water assemblage comprised many of the same taxa that had been dominant during the pretreatment periodsss.
Organochlorines and Marine Mammal Reproduction
Authors: Addison R. F.
Published: August 2008

Reproductive failures in four populations of marine mammals (Californian sea lions (Zalophus californianus), Bothnian Bay ringed seals (Pusa hispida), Dutch Waddensee harbour seals (Phoca vitulina), and most recently, Gulf of St. Lawrence beluga whales (Delphinapterus leucas)) have been attributed to the effects of contamination by organochlorine (OC) residues. In this article, I review the evidence for these effects. I conclude that since (a) crucial biological information in the light of which OC residue data can be interpreted is often missing, (b) the nature of the supposed reproductive effect is variable, and (c) the OC residues to which these effects are attributed vary qualitatively and quantitatively, correlations between observed residue concentrations and apparent reproductive changes do not provide any firm evidence for a cause – effect relationship. In a single experimental study, a diet with a higher OC content than that used as a control impaired reproduction in harbour seals; however, dietary components other than OC content also differed. Although there appears to be no firm correlative evidence sinking residue concentrations in marine mammals with reproductive effects, there is enough concern about possible links to justify more experimental studies, with the aim of identifying the possible biochemical mechanisms involved.
A System-of-Equations Approach to Modeling Age-Structured Fish Populations: The Case of Alaskan Red King Crab, Paralithodes camtschaticus
Authors: Greenberg Joshua A. , Matulich Scott C. , Mittelhammer Ron C.
Published: August 2008

This paper presents a simultaneous system-of-equations approach to modeling age-structured populations using trawl survey age/size frequency data. The analysis builds upon a Ricker spawner–recruit structure and provides a cohort-based estimation method that retains the underlying dynamic properties of a delay-difference model. The framework shares a common spawner–recruit function across age-class equations. This exploits the commonality among cohort members and serves as an instrumental variable, lessening the effect of measurement errors in estimation. The dynamic features of the underlying age-structured population are retained through age-specific net survivability and growth parameters that link age-classes. The technique uses multiple observations on a cohort to further mitigate the effect of measurement error and improve overall estimation efficiency. A seemingly unrelated regression estimation method is required to address contemporaneous correlation of errors across age-classes. This framework is applied to trawl survey data for adult male Alaskan king crab, Paralithodes camtschaticus.
Recurrent Depth Maxima of the Hepatotoxic CyanobacteriumOscillatoria agardhii
Authors: Lindholm Tore , Meriluoto Jussi A. O.
Published: August 2008

Toxic cyanobacteria, which have been implicated in human illness and animal mortalities, are common in many lakes, but their seasonal and vertical distribution is poorly known. We report persistent and recurrent metalimnetic blooms of Oscillatoria agardhii in the eutrophic Lake Östra Kyrksundet (southwest Finland) and associated toxin peaks analyzed quantitatively using liquid chromatography. Marked metalimnetic maxima of toxic O. agardhii developed during 1988–90. The desmethyl-microcystin-RR (a cyclic heptapeptide hepatotoxin) levels in the metalimnion were 20–40 μg∙L−1and paralleled the chlorophyll a concentrations.
Recovery of Crustacean Zooplankton Species Richness in Sudbury Area Lakes following Water Quality Improvements
Authors: Keller W. , Yan N. D.
Published: August 2008

Temporal patterns in the species richness of crustacean zooplankton communities were assessed in eight Sudbury area lakes based on data collected between 1973 and 1986. Excluding a consistently nonacidic reference lake, the study lakes showed general reductions in acidity and trace metal concentrations during this period, related to reduced contaminant emissions from the Sudbury smelters. Despite water quality improvements, several of the study lakes continue to have low pH and elevated trace metal concentrations which have inhibited recovery of zooplankton species richness. However, in lakes with more favourable current pH and lower trace metal concentrations, substantial increases in the average species richness of crustacean plankton communities have occurred, apparently due to both invasion of new species and more frequent occurrence of existing species. These results clearly demonstrate that reductions in acid-forming emissions lead to both chemical and biological improvements in some aquatic systems.
Physicochemical Patterns within a Hyporheic Zone of a Northern Michigan River, with Comments on Surface Water Patterns
Authors: Hendricks Susan P. , White David S.
Published: August 2008

Interstitial temperature and chemistry were examined longitudinally and with depth in a hyporheic zone beneath a riffle–pool sequence of a third-order, sand-bottom river in northern Michigan (USA). Longitudinal and depth patterns were compared with surface and groundwater chemistries at the site and with surface chemistry over a 10-km length of the river. Interstitial water was more characteristic of surface water at the upstream end of the hyporheic zone and of groundwater at the downstream end. Hyporheic longitudinal and depth patterns occurred for temperature, chloride, silica, soluble reactive phosphorus, and winter dissolved oxygen. Dissolved organic carbon decreased with depth, but not with longitudinal distance downstream within the hyporheic zone. Hyporheic nitrate and ammonium patterns were variable, but concentrations generally increased downstream. Hyporheic specific conductance and alkalinity decreased with distance downstream, but not with depth. Gradients for temperature, chloride, silica, nitrate, and phosphate over the 10-km surface water reach were similar to those observed within the single hyporheic zone. Hyporheic chemistry patterns were consistent with models of underflow through porous substrata implying ground water/surface water interaction. Importance of the hyporheic zone should not be overlooked in solute transport or stream nutrient budgets.
Discrimination among Atlantic Coast Populations of American Shad (Alosa sapidissima) Using Mitochondrial DNA
Authors: Nolan Kathleen , Grossfield Joseph , Wirgin Isaac
Published: August 2008

We used restriction endonuclease analysis of mitochondrial DNA (mtDNA) to differentiate among spawning stocks of American shad (Alosa sapidissima). Highly purified mtDNA was isolated from shad from four major spawning rivers: the St. John's (Florida), the Delaware, and the Hudson in the United States and the Miramichi in New Brunswick, Canada. Primarily four-and-five-base-cutting restriction enzymes were used to prepare both individual enzyme profiles and composite genotypes. Three separate spawning stocks, St. John's, Delaware–Hudson, and Miramichi, could be distinguished based on frequency differences in mtDNA genotypes generated by single restriction enzyme digests. We could not distinguish Delaware from Hudson River shad. Only a single definitive restriction site polymorphism was observed among all samples, but polyacrylamide gel electrophoretic mobility variants were common. Eco RI, Dde I, and Rsa I revealed stock-specific mtDNA genotypes. The frequencies of some genotypes occurred in latitudinal clines. Fifty-seven of 81 fish showed individual-specific composite genotypes. Geographic partitioning of genotypes suggests that mtDNA analysis may be useful for the identification of some American shad stocks and their relative contributions to mixed coastal fisheries.
Some Factors Regulating Piscivory of Brook Trout,Salvelinus fontinalis, in Lakes of the Laurentian Shield
Authors: East Pierre , Magnan Pierre
Published: August 2008

A survey of 13 lakes containing brook trout, Salvelinus fontinalis, and northern redbelly dace, Phoxinus eos, five lakes containing trout and creek chub, Semotilus atromaculatus, and six lakes containing trout, dace, and chub indicated that prey-fish could represent up to 30% of trout diet by weight. We observed that trout preyed almost exclusively on dace, predation increased with trout size, predation on dace was significantly higher in the Salvelinus-Phoxinus-Semotilus association than in the Salvelinus-Phoxinus association even though trout were significantly smaller in the former than in the latter association, and predation in the Salvelinus-Phoxinus-Semotilus association was higher in two lakes and nearly always absent in the other four. Laboratory experiments indicated that small trout (150–250 mm total length (TL)) preferred small prey-fish (40–60 mm TL), large trout (250–380 mm TL) showed no significant preference with regard to the size of prey-fish (up to 170 mm TL), trout of both size classes preferred dace when dace and chub were present, presence of refuge (Cassandra calyculata) for prey-fish significantly reduced the number of attacks and captures upon dace, and large trout switched from an active to a sit-and-wait foraging pattern when a prey refuge was present.
Two Generations of Hybrids between Even- and Odd-Year Pink Salmon (Oncorhynchus gorbuscha): A Test for Outbreeding Depression?
Authors: Gharrett A. J. , Smoker W. W.
Published: August 2008

Hybrids of genetically isolated odd- and even-year pink salmon (Oncorhynchus gorbuscha) from the same stream were made by fertilizing eggs with cryopreserved milt. Anadromous first-generation (F1) hybrids and controls returned to the hatchery at equal rates (153 of 5483 and 160 of 5492, respectively), on the same average date, and with the same size. However, variances of F1size (female length and weight and male length) exceeded variances of control sizes, suggesting increased genetic variation in F1's. Only 11 of 5165 F2's returned. F2's were similar meristically and in size to fish of their parents' generation, but were bilaterally more asymmetric in number of gill rakers and in combined numbers of gill rakers and of branchiostegals. Increased F1variation followed by low F2returns and increased bilateral asymmetry is a pattern to be expected when coadapted allele complexes are disrupted by outbreeding depression.
An Analytical Model of Acoustic Fish Reflection for Estimation of Maximum Dorsal Aspect Target Strength
Authors: Thiebaux M. L. , Boudreau P. R. , Dickie L. M.
Published: August 2008

We develop a simple analytical model of the acoustic reflectivity offish targets based on empirical observations in field and laboratory settings. It enables unbiased estimation of maximum dorsal aspect target strength in cases where individual fish are observed a minimum of three times in successive pings of a survey transect. The model results are consistent with observations of example fish targets of two demersal species. It promises improved estimates of target strength from field measurements.
Tumor Frequencies in Walleye (Stizostedion vitreum) and Brown Bullhead (Ictalurus nebulosus) and Sediment Contaminants in Tributaries of the Laurentian Great Lakes
Authors: Baumann Paul C. , Mac Michael J. , Smith Stephen B. , Harshbarger John C.
Published: August 2008

To better characterize neoplasm epizootics in the Great Lakes basin and their association with families of contaminants, we sampled five locations: the Fox and Menominee rivers, Lake Michigan; Munuscong Lake, St. Mary's River; and the Black and Cuyahoga rivers, Lake Erie. Frequencies of external and liver tumors were determined for brown bullhead (Ictalurus nebulosus) from all locations except the Black River and for walleye (Stizostedion vitreum) from the Lake Michigan and St. Mary's River sites. Sediment samples were analyzed for metals, polychlorinated aromatics, and polynuclear aromatic hydrocarbons (PAH). Liver neoplasms occurred in brown bullhead from the Cuyahoga River and Munuscong Lake; brown bullhead captured from Munuscong Lake were older than those collected from the other locations. Brown bullhead from these same two rivers had elevated hepatosomatic indexes. No liver neoplasms were found in brown bullhead from the Fox and Menominee rivers, although polychlorinated aromatics were highest in both Fox River sediment and Fox and Menominee brown bullhead, and arsenic was highest in Menominee River sediment and fish. Liver neoplasms in brown bullhead from the Cuyahoga River fit the prevailing hypothesis that elevated PAH in sediment can induce cancer in wild fish. The cause of the liver neoplasms in Munuscong Lake brown bullhead is undetermined.
Development of salinity tolerance in underyearling smolts of Atlantic salmon (Salmo salar) reared under different photoperiods
Authors: Berge Åse I. , Berg Arne , Barnung Trygg , Hansen Tom , Fyhn Hans Jørgen , Stefansson Sigurd O.
Published: August 2008

Groups of Atlantic salmon (Salmo salar), first fed in mid-February 1989, were reared under continuous light (LL) at 12–15 °C until late June. One group remained on LL, while the FEB, MAR, and MAY groups were subjected to segments of a simulated naturally increasing photoperiod (61°N), with initial daylength corresponding to February 1, March 15, and May 1, respectively. The MAR and FEB groups developed important smolt characters (increase in gill Na+,K+-ATPase activity, hypoosmoregulatory ability, and salinity tolerance) during the experiment whereas LL and MAY groups showed only incomplete changes in smolt status. The combination of continuous light during first feeding and early parr stages with a subsequent reduction to short daylength followed by a segment of simulated natural photoperiod allow important parts of the parr–smolt transformation to be completed. The period of exposure to short photoperiod is critical for the synchronization of smolt characters in underyearling Atlantic salmon.
Comparison between lamprey ammocoetes and bivalve molluscs as biomonitors of organochlorine contaminants
Authors: Renaud Claude B. , Kaiser Klaus L. E. , Comba Michael E. , Metcalfe-Smith Janice L.
Published: August 2008

Lamprey ammocoetes were determined to be as suitable as adult bivalve molluscs for monitoring persistent organochlorine contaminants in the freshwater environment. Ammocoetes of four lamprey species and adults of three bivalve mollusc species, collected from the same seven rivers of the St. Lawrence River basin in Québec, were assayed for 21 organochlorine pesticides and for polychlorinated biphenyl (PCB) congeners. All organochlorine compounds assayed were detected in one or more of the 15 lamprey samples whereas Aldrin, β-BHC, and PCB congeners 1, 3, 12(13), 29, 54, 189, 191, and 199 were not detected in any of the nine bivalve samples. Nine pesticides (Aldrin, Dieldrin, γ-BHC, α-Chlordane, γ-Chlordane, o,p′-DDD, p,p′-DDD, p,p′-DDT, and a-Endosulfan) had higher concentrations in the lampreys. PCB congeners 167(185) and 209 had higher concentrations in bivalves. PCBs accounted for 96.6–99.4% of the organochlorine lipid burden in bivalves, but only 33.4–76.8% in lampreys. On average, ammocoetes had 44 times more lipids per body dry weight than did bivalves. The differences observed in concentrations and types of organochlorine compounds found in the two taxa may be due to differences in the amounts (observed) and types (postulated) of body lipids they each possess.
Genetic and environmental correlates of variation in body weight of brook trout (Salvelinus fontinalis)
Authors: Ferguson Moira M. , Liskauskas Arunas P. , Danzmann Roy G.
Published: August 2008

Families of brook trout (Salvelinus fontinalis) were produced from adults collected from Mykiss Lake, Algonquin Provincial Park, Ontario, and reared in the laboratory for 1 year. Egg size and hatching time explained a significant amount of variation among families in mean weight of hatched embryos. Heavier embryos were produced from larger eggs, and embryos with earlier hatching times were also larger. First-feeding alevins reared at higher densities were smaller than those at lower densities. Multilocus enzyme heterozygosity was neither a significant predictor of mean family body weight at any age nor significantly associated with body weight of juveniles within families. Analyzing each enzyme locus separately revealed significant effects for G3PDH-1 in two families but in different directions. Fish from two mitochondrial DNA phylogenetic assemblages, A and B, differed significantly in weight as hatched embryos and first-feeding alevins. Similarly, the progeny of different males and females differed significantly in body weight at all ages sampled. Thus, parental effects were the most persistent correlates of body size of all those examined. The statistical analyses and the nested designs suggest that variation in body weight among the progeny of specific parents can partially be attributed to genetic effects.
Effects of aluminum and fluoride on phosphorus acquisition by Chlamydomonas reinhardtii
Authors: Joseph Elaine M. , Morel François M. M. , Price Neil M.
Published: August 2008

Al (10 μM) and F (50 μM) added singly or in combination have no effect on growth of Chlamydomonas reinhardtii in acid or alkaline media containing organic or inorganic P. Cell surface phosphatase activity, however, is increased in glucose-1-phosphate-amended cultures exposed to Al, but only at low pH. This result is an indirect effect caused by Al binding to the organic P, which inhibits organic P utilization and induces phosphatase synthesis in C. reinhardtii as a compensatory response. Phosphatase activity is inversely correlated with lake pH, suggesting that such a mechanism may operate in nature. Al thus appears to enhance phosphatase activity in acidified waters by impeding dissolved organic P catabolism.
Survival to hatching of fishes in sulfate-saline waters, Devils Lake, North Dakota
Authors: Koel Todd M. , Peterka John J.
Published: August 2008

Laboratory-based bioassays were conducted to determine concentrations of sodium-sulfate type salinities that limit the hatching success of several fish species. Survival to hatching (SH) was significantly lower (P < 0.05) in sodium-sulfate type waters from Devils Lake, North Dakota, of ≥ 2400 mg/L total dissolved solids (TDS) than in fresh water of 200 mg/L. In waters of 200, 1150, 2400, 4250, and 6350 mg/L TDS, walleye (Stizostedion vitreum) SH was 41, 38, 7, 1, and 0%; northern pike (Esox lucius) SH was 92, 68, 33, 2, and 0%; yellow perch (Perca flavescens) SH was 88, 70, 73, 0, and 0%; white sucker (Catostomus commersoni) SH was 87, 95, 66, 0, and 0%; common carp (Cyprinus carpio) SH was 71, 69, 49, 63, and 25%.
Growth and condition in the Northwest Atlantic harp seal
Authors: Hammill M. O. , Kingsley M. C. S. , Beck G. G. , Smith T. G.
Published: August 2008

We analysed the relationship of length to age in a sample of 204 harp seals collected in 1976–1979 and of 437 animals collected in 1988–1992, by fitting asymptotic growth curves. The only significant variations were in asymptotic length, which for 1988–1992 was significantly larger for males (170.4 cm) than for females (165.3 cm). This sexual dimorphism was not significant in 1976–1979, because the fitted asymptotic length of females varied greatly from year to year, being large in the 1976–1979 samples. An index of body condition (total weight/length2.6) and a volume index constructed by regressing body weight on length × axillary girth squared indicated that harp seals collected in 1988–1992 were in poorer condition than animals collected during 1976–1979. Although this suggests a decline in available resources, the possibility of differences arising from sampling bias cannot be excluded.
Dynamic modelling of phycotoxin kinetics in the blue mussel, Mytilus edulis, with implications for other marine invertebrates
Authors: Silvert W. L. , Cembella A. D.
Published: August 2008

Modelling the uptake and detoxification kinetics of phycotoxins in marine filter-feeding bivalve molluscs is discussed and illustrated by a case study involving blue mussels (Mytilus edulis) in the lower St. Lawrence estuary in eastern Canada. A dynamic model was fit to empirical data acquired on differential responses of mussels transplanted from sites characterized by differing history of exposure to toxigenic blooms responsible for paralytic shellfish poisoning (PSP). Although it is difficult to collect sufficient data to calibrate complicated models, it appears that one- and two-compartment models are fully adequate for this type of modelling. Measuring phycotoxin levels in shellfish can be a useful and cost-effective adjunct to direct monitoring of phytoplankton toxicity in the water column, because ongoing filtration by shellfish provides an integrated estimate of the toxin to which they are exposed.
Plankton and water chemistry in Lake Njupfatet before and after liming
Authors: Blomqvist Peter , Bell Russell T. , Olofsson Hans , Stensdotter Ulrika , Vrede Katarina
Published: August 2008

Moderately acidified Lake Njupfatet was studied during 2 consecutive years, before and after liming (calcite), and compared with corresponding data from six reference lakes. After liming, the concentration of total phosphorus in the lake water decreased by some 30% as did the concentrations of particulate carbon, particulate nitrogen, particulate phosphorus, and phytoplankton biomass. Because of significant increases of inorganic nitrogen and dissolved organic carbon, the concentrations of total nitrogen and total organic carbon remained unchanged after liming. Before liming, there was a close balance between phosphorus and nitrogen limitation of phytoplankton growth, but we conclude that after liming the reduced concentrations of phosphorus induced phosphorus limitation of phytoplankton growth. Liming changed the phytoplankton community structure, most importantly causing the complete loss of the dominant species before liming, the cyanophyte Merismopedia tenuissima. The decrease in total biomass of phytoplankton was not compensated for by a corresponding increase in other species. After liming total biomasses of bacterioplankton and protozoan zooplankton did not change, while total biomass of metazoan zooplankton increased; hence, total plankton community carbon remained unchanged. Phytoplankton, protozoan, and metazoan zooplankton diversity (Shannon index) did not change after liming. Zooplankton biomass remained heavily dominated by calanoid copepods, typical of acidified lakes.
Stock-recruitment models for Pacific sardine (Sardinops sagax)
Authors: Jacobson Larry D. , MacCall Alec D.
Published: August 2008

We used generalized additive models to study the recruitment of Pacific sardine (Sardinops sagax) along western North America and to compare the effects of fishing and environmental factors on the stock. We found significant relationships between the logarithm of sardine reproductive success (recruits per unit of spawning biomass) and average sea surface temperature (SST), as well as between sardine recruitment, spawning biomass, and average SST. Simulation and time series analyses were used to evaluate bias, variance, and statistical power for one of our models. Correlation with log reproductive success was highest when average SST data included temperatures after the period of larval development, indicating that recruitment estimates were affected by environmentally driven changes in availability of older sardine to the fishery. Predicted equilibrium biomass and MSY for sardine are lower under environmental conditions that prevail when temperatures are colder. Long-term fluctuations in the environment may cause long-term fluctuations in sardine productivity, and little or no sardine harvest may be sustainable during periods of adverse environmental conditions and cold temperatures.
Pacific salmon and Pacific herring mortalities in the Fraser River plume caused by river lamprey (Lampetra ayresi)
Authors: Beamish Richard J. , Neville Chrys-Ellen M.
Published: August 2008

River lamprey (Lampetra ayresi) enter the Strait of Georgia from the Fraser River and feed almost exclusively on Pacific herring (Clupea harengus) and salmon (Oncorhynchus spp.). Although the major prey of river lamprey is Pacific herring, the greater effect of lamprey predation was on the populations of chinook (O. tshawytscha) and coho (O. kisutch) salmon. In 1990 and 1991, river lamprey killed a minimum of 20 million and 18 million chinook salmon, respectively, and a minimum of 2 million and 10 million coho salmon in the same years. In 1991, river lamprey in the Fraser River plume killed an equivalent of approximately 65 and 25% of the total Canadian hatchery and wild production of coho and chinook salmon, respectively. These estimates are probably low because river lamprey also feed in other areas and the abundance estimates are conservative. These high mortality rates indicate that river lamprey predation must be considered as a major source of natural mortality of chinook and coho salmon in the Strait of Georgia.
The functional form of hook and gillnet selection curves cannot be determined from comparative catch data alone
Authors: Millar R. B.
Published: August 2008

Catch data from simultaneous fishing with two sizes of hook were analysed to determine plausible shapes for hook selection curves. The estimation problem suffers from ambiguity of fit because the lack of nonselective catch data allows an infinite number of selection curve shapes to give precisely the same fit to the catch data. Restricting consideration to just a few possible functional forms (e.g., normal, gamma, lognormal, and logistic) for the selection curve does not eliminate the problem and it is shown that two very different selection models, one using normal selection curves and the other using gamma selection curves, give precisely the same fit. Moreover, allowing for unequal fishing efficiencies of the two hooks permits identical fits to arise from vastly different selection curves of the same functional form. It is seen that the estimated length of maximum retention (of unimodal selection curves) is quite insensitive to the shape of the curve, but is extremely sensitive to relative fishing efficiencies. The same phenomena exist in many gillnet selectivity studies because, although several different mesh sizes are typically deployed, the selection curves are often fitted using the catch data from pairs of gillnets of adjacent size. Further research is required to determine whether it is preferable to use methods of analysis that fit simultaneously to all sizes of gear deployed.
Planktivory by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario
Authors: Mills Edward L. , Adams Connie , O'Gorman Robert , Owens Randall W. , Roseman Edward F.
Published: August 2008

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.
Estimating number of species and relative abundances in stream-fish communities: effects of sampling effort and discontinuous spatial distributions
Authors: Angermeier Paul L. , Smogor Roy A.
Published: August 2008

We sampled fishes and measured microhabitat in series of contiguous habitat units (riffles, runs, pools) in three Virginia streams. We used Monte Carlo simulations to construct hypothetical series of habitat units, then examined how number of species, similarity in relative abundances, and number of microhabitats accumulated with increasing number of habitat units (i.e., sampling effort). Proportions of all species and microhabitats represented were relatively low and variable at low sampling effort, but increased asymptotically and became less variable with greater sampling effort. To facilitate comparisons among streams, we fitted simulation results to negative exponential curves. The curves indicated that 90% of the species present were usually found by sampling 5 to 14 habitat units (stream length of 22–67 stream widths). Estimates of species relative abundances required less sampling effort for a given accuracy than estimates of number of species. Rates of species accumulation (with effort) varied among streams and reflected discontinuity in species distributions among habitat units. Most discontinuity seemed to be due to low population density rather than to habitat selectivity. Results from an Illinois stream corroborated our findings from Virginia, and suggested that greater sampling effort is needed to characterize fish community structure in more homogeneous stream reaches.
Chironomidae (Diptera): quantitative palaeosalinity indicators for lakes of western Canada
Authors: Walker Ian R. , Wilson Susan E. , Smol John P.
Published: August 2008

A survey of chironomid remains preserved in the surficial sediments of 86 British Columbia lakes was conducted to assess the feasibility of reconstructing palaeosalinities from assemblages of fossil chironomid head capsules. Many taxa common in freshwater lakes were either rare or absent at higher salinities. Lakes having salinities greater than about 10.0 g∙L−1 were distinguished by the overwhelming relative abundance of Cricotopus/Orthocladius. In less saline waters, common taxa included Chironomus, Procladius, Psectrocladius, and the subtribe Tanytarsina. Heterotrissocladius, Lauterborniella/Zavreliella, Pagastiella, and Sergentia were only collected in freshwater habitats. Canonical correspondence analysis revealed that three environmental variables (late summer lakewater salinity and concentrations of Sr and total P) explained significant variation in the weighted averages of taxa. Tanytarsina and Dicrotendipes were common at low Sr concentrations in carbonate lakes. A weighted-averaging calibration function was developed to infer salinity on the basis of fossil fauna. This model will allow palaeolimnologists to detect transitions between freshwater and moderately saline states and can be used to assist palaeoclimatic reconstructions for athalassic lake sites.
Spawning ecology of cutthroat trout (Oncorhynchus clarki) in the Ram River, Alberta
Authors: Brown Richard S. , Mackay William C.
Published: August 2008

Spawning movements of cutthroat trout (Oncorhynchus clarki) were evaluated using radiotelemetry in a montane river and a headwater tributary. The movements of 23 fish were monitored in spring 1991 and 1992. Fish moved upstream and downstream to spawning areas. These movements fell into two distinct patterns: in one, fish emigrated to tributaries and in the other they traveled to main-stem or side-channel spawning grounds. The pre- and post-spawning movements made by fish that spawned in tributaries were longer than those made by fish that spawned in the main-stem or side-channel areas. While spawning, the fish stayed within 400-m sections of a stream but frequently moved within this area. After spawning, trout moved upstream or downstream to summer rearing habitats where they stayed until observations were ended.
Density-dependent habitat selection by juvenile haddock (Melanogrammus aeglefinus) on the southwestern Scotian Shelf
Authors: Marshall C. Tara , Frank Kenneth T.
Published: August 2008

Positive correlations between total abundance and indices representing distributional area have been reported for several marine fish stocks. Different indices can produce different results for the same stock and many indices scale positively with total abundance. We describe an alternative approach to modelling the distributional response to variation in total abundance using data for juvenile haddock (Melanogrammus aeglefinus) from the southwestern Scotian Shelf. Annual bottom trawl surveys having a stratified random design were used to estimate the local density of haddock age 1 and 2 in each strata. Estimates of total abundance-at-age were obtained from sequential population analysis. The relationship between local density and total abundance-at-age was described for each strata using an exponential model with a Poisson error structure. Systematic variation among strata in the model parameters was indicative of density-dependent habitat selection and supported a previous study showing a positive correlation between distributional area and total abundance. Density-dependent habitat selection by juvenile haddock did not generate correlations between mean length-at-age and total abundance-at-age because the proportional abundance of haddock in areas of differing growth rates remained approximately constant as total abundance-at-age increased.
Predicted versus actual determinations of algal production, algal biomass, and zooplankton biomass in a hypereutrophic, hyposaline prairie lake
Authors: Evans Marlene S. , Robarts Richard D. , Arts Michael T.
Published: August 2008

We compared the accuracy of various regression models in predicting algal production, algal biomass and composition, and zooplankton biomass in a hypereutrophic, hyposaline prairie lake. The total phosphorus (TP) models investigated underestimated mean summer algal biomass and inedible biomass: the models overestimated mean summer edible algae biomass and annual primary production in the euphotic zone. Differences between predicted and actual biomass values are attributed to intense zooplankton grazing on the edible algal community and to the gradual accumulation of slow-growing, inedible algae. The TP model investigated provided an accurate prediction of zooplankton biomass. The algal biomass model overestimated zooplankton biomass, possibly because edible algae accounted for a very small fraction of algal biomass in Humboldt Lake during the ice-free season. The chlorophyll model investigated underestimated zooplankton biomass, apparently because Humboldt Lake algae have a relatively low chlorophyll content. The use of a 0.01 conversion factor to estimate algal biomass on the basis of chlorophyll appears to be inadequate and requires further study. There was no evidence that hyposaline Humboldt Lake has a relatively high zooplankton to phytoplankton biomass ratio when compared with freshwater lakes.
Age-specific effects of sockeye abundance on adult body size of selected British Columbia sockeye stocks
Authors: McKinnell Skip
Published: August 2008

Annual mean body lengths of adult sockeye salmon (Oncorhynchus nerka) covary systematically from year to year in major northern and central British Columbia stocks (Nass River, Skeena River, and Rivers Inlet). These positive correlations are greatest between sexes within rivers, followed by age-classes among rivers. A common factor or factors affecting sockeye length in the North Pacific Ocean is suggested. The mean length of age 1.3 sockeye salmon but not age 1.2 sockeye caught annually in these B.C. fisheries was negatively correlated with the magnitude of Bristol Bay (western Alaska) sockeye catches. During the spring of maturation, age 1.3 sockeye from these B.C. stocks were further from their natal streams, and likely subject to more intense competition with Bristol Bay sockeye than age 1.2 sockeye. The pattern of annual marine growth measured from Skeena River sockeye scales collected during the 1960s provides additional evidence that the length of age 1.3 sockeye was related to Bristol Bay sockeye abundance in the year of maturation. No such correlation was evident in scales collected from age 1.2 sockeye. These results suggest that sockeye populations have more systematic distributions in the North Pacific Ocean than has been previously reported.