bluuebunny/crossref_metadata_2025 huggingface dataset:
Are Growth Parameters Estimated from Tagging and Age–Length Data Comparable?
Authors: Francis R. I. C. C.
Published: June 2008

The two most common ways of estimating fish growth use age–length data and tagging data. It is shown that growth parameters estimated from these two types of data have different meanings and thus are not directly comparable. In particular, the von Bertalanffy parameter l∞ means asymptotic mean length at age for age–length data, and maximum length for tagging data, when estimated by conventional methods. New parameterizations are given for the von Bertalanffy equation which avoid this ambiguity and better represent the growth information in the two types of data. The comparison between growth estimates from these data sets is shown to be equivalent to comparing the mean growth rate of fish of a given age with that of fish of length equal to the mean length at that age. How much these growth rates may differ in real populations remains unresolved: estimates for two species of fish produced markedly different results, neither of which could be reproduced using growth models. Existing growth models are shown to be inadequate to answer this question.
Growth Rates and Growth Efficiencies in Larvae and Juveniles of Rutilus rutilus and Other Cyprinid Species: Effects of Temperature and Food in the Laboratory and in the Field
Authors: Wieser W. , Forstner H. , Schiemer F. , Mark W.
Published: June 2008

Growth rates were determined in four 0+ class populations of roach (Rutilus rutilus): two from warm backwaters of the Danube and two from cold-water lakes. Larval growth was also determined in the laboratory for R. rutilus, Leuciscus cephalus, and Alburnus alburnus at 15, 20, and 25 °C. Q10 values of growth rates were low (1.29–1.67) between 20 and 25 °C but were high (3.9) between 15 and 20 °C. Net growth efficiency of the larvae of R. rutilus ranged from 68.6 to 71.9% at 15 °C and from 72.3 to 73.5% at 20 °C. A comparison of temperature-corrected relative growth rates in the four populations of roach revealed significant differences between the two warmwater and the two cold-water populations. Growth of warmwater populations was fastest right after hatching and then declined in a fairly regular way. Growth of cold-water populations was slow after hatching but increased later. These differences reflect interactions between temperature and food availability in the two types of water bodies. The sudden increase in growth rate in the population from the coldest lake can be correlated with a change in gut contents which in turn reflects the improved ability of the juvenile fish for catching Zooplankton.
Empirical Relationships of Phytomacrofaunal Abundance to Plant Biomass and Macrophyte Bed Characteristics
Authors: Cyr Hélène , Downing John A.
Published: June 2008

The abundance of phytophilous invertebrates was measured in 13 macrophyte beds and was related, using multiple regression analysis, to the biomass of macrophytes among which the invertebrates were collected, the average plant biomass growing per unit lake area, water and organic matter content of the sediments, total phosphorus concentration in the water, rooting depth of the macrophyte bed, and sampling date. Quantitative analyses are presented for chironomids, cladocerans, cyclopoid copepods, gastropods, water mites (Hydracarina), ostracods, and trichopterans. R2 values for the regression equations ranged from 0.43 to 0.81. The abundance of invertebrates was best related to the biomass of separate plant species, but equations based only on total plant biomass sometimes had equivalent R2 values, in general, the abundance of phytophilous invertebrates was positively related to areal plant biomass, sediment organic matter, and lake trophic status and negatively related to depth. The abundance of phytophilous invertebrates generally rose throughout the sampling season. The sign of the relationship with sediment water content, however, varied among invertebrate taxa. Macrophyte beds with high areal plant biomass, in lakes with high total phosphorus concentration, support the greatest abundance of potential invertebrate food for fish and waterfowl.
Biochemical Genetic Differentiation of Lake Trout (Salvelinus namaycush) Stocks of the Great Lakes Region
Authors: Ihssen P. E. , Casselman J. M. , Martin G. W. , Phillips R. B.
Published: June 2008

Allelic frequencies for lake trout (Salvelinus namaycush) samples collected from 27 small lakes or spawning shoals on larger lakes did not show significant annual changes. Levels of genetic variability were in the high range for Salmonidae, with 57% of the loci examined polymorphic (1% criterion) and 4.7% average heterozygosity per locus. Twenty-one percent of the total genetic variability was due to differences between stocks. Highly significant allelic frequency differences were found among allopatric as well as sympatric stocks. Genetic differences among sympatric stocks of Lake Superior indicated a significant degree of genetic isolation among these stocks. Genetic diversity within stocks, as measured by the proportion of polymorphic loci, was larger in stocks from large lakes than small lakes or transplanted stocks from large lakes into small lakes. Geographic patterns in allelic frequencies were observed. Samples from the northwestern range of our study area (upper Great Lakes, northwestern Ontario, and Manitoba) could be distinguished from those of the southeastern range by both allelic frequency differences and the presence or absence of alleles. We suggest that these two geographic ranges were colonized by lake trout that survived in different refugia during the Wisconsin glaciation. Unusual stocks of lake trout were found in three small lakes in the Haliburton Highlands of southern Ontario, with alleles at high frequencies that are rare or absent in most other stocks. We propose that the Haliburton Highlands lake trout originated from a glacial relict stock and survived during the last glaciation isolated from refugia used by other lake trout.
Silica and Phosphorus Flux from Sediments: Importance of Internal Recycling in Lake Michigan
Authors: Conley Daniel J. , Quigley Michael A. , Schelske Claire L.
Published: June 2008

Estimated lake-wide sediment fluxes of silica and phosphorus (P) were determined and then compared with other components in the biogeochemical cycle to investigate the importance of sediment regeneration in Lake Michigan. Dissolved silica (Si) and soluble reactive phosphorus (SRP) fluxes from sediments were measured by the incubation of intact sediment cores. Estimated Si flux from sediments can supply 21% of the total mass of silica in the water annually and 26% of the Si used during annual diatom production. By contrast, estimated SRP flux from lake sediments can supply only 4.1% of the mass of total P in the water annually and <1% of the P utilized for annual primary production. Because the internal regeneration of P occurs rapidly in the water column, compared with the much slower regeneration of Si (0.8∙yr−1), P can be used many times during an annual cycle whereas Si is used only once. Thus, differences in the supply rates and in the biogeochemical recycling rates of Si and P can lead to seasonal Si depletion in the water mass and influence the outcome of seasonal phytoplankton species succession by limiting Si availability necessary for diatom production.
Carnivorous Suspension Feeding by the Subarctic Calanoid Copepod Neocalanus cristatus
Authors: Greene Charles H. , Landry Michael R.
Published: June 2008

Carnivorous suspension feeding is described for the large subarctic calanoid copepod Neocalanus cristatus. This foraging mode relies on the use of a feeding current to entrain potential prey items and transport them into the copepod's capture area. The extensive use of a feeding current to entrain and transport prey into the capture area distinguishes carnivorous suspension feeding from the predatory modes typically described for other calanoid copepods. The consequences of carnivorous suspension feeding on N. cristatus' prey-selection patterns are significant. Feeding experiments reveal that the vulnerability of naupliar prey declines with increasing prey size, just the opposite result observed for other marine calanoids exhibiting more typical predatory feeding modes. The role of omnivorous feeding by N. cristatus within the pelagic ecosystem of the subarctic Pacific is also discussed. In contrast with earlier hypotheses, the results reported here are consistent with the emerging view that this large suspension-feeding copepod may be having at least as great an impact on the microzooplankton as on the phytoplankton of the region.
Contrasting Diel Patterns of Vertical Migration in the Dinoflagellate Ceratium hirundinella in Relation to Phosphorus Supply in a North Temperate Reservoir
Authors: Taylor W. D. , Barko J. W. , James W. F.
Published: June 2008

Very different diel patterns of vertical migration in Ceratium hirundinella were observed during two midsummer periods of study in a north temperate reservoir. During the first study (29–30 July), Ceratium migrated within a 2-m-deep oxygenated zone, moving upward near to the surface during the day and downward to the oxic–anoxic interface at night. During the second study (7–8 August), Ceratium did not migrate towards the surface during the day. High photosynthetic oxygen production and mixing processes increased oxygen distribution from 2 to 3 m providing Ceratium with access to a significantly greater water volume, with a greater nutrient content. Riverine phosphorus loading during the week prior to the first study was about 10 times greater than during the week prior to the second study. Limiting cell phosphorus concentrations and no measurable soluble reactive phosphorus in the upper (0–3 m) water column suggested a relationship between phosphorus limitation and the cessation of positive phototaxis. Diel patterns of vertical migration in this species may be influenced by episodic variations in phosphorus and/or other nutrient loadings via riverine inputs as interflows to this reservoir.
Pressions sélectives et nouveautés évolutives : une hypothèse pour comprendre certains aspects des fluctuations à long terme des poissons pélagiques côtiers
Authors: Cury Philippe
Published: June 2008

The extinction during periods much longer than the duration of a species life cycle followed by a quick resurgence to high abundance levels is sometimes observed in marine coastal pelagic stocks. Japanese sardine (Sardinops melanosticta), Pacific sardine (Sardinops sagax), and Peruvian and Chilian anchovy (Engraulis ringens) are presented as examples. Interpretations of these stocks' fluctuations are reviewed. Climatic events and the influence of commercial harvesting do not always appear sufficient to explain such recoveries. Approaches derived from marine and terrestrial ecology as well as from evolutionary biology may lead to a better understanding of the biological reasons for the maintenance and recovery of depleted biomasses. The importance of interspecific competition during periods of low biomass levels is discussed. The possible consequences of strong selective pressures on population dynamics and the adaptive potential of pelagic species are emphasized. Lastly, evolutionary novelties that appear when a species is becoming depleted are considered. From these considerations, we hypothesize that the long attractive periods of low abundance can result from strong selective pressures and from the reduced influence of climatic events. The recovery of depleted biomasses would be the result of an adaptive process (microevolution). Natural selection could therefore act as another regulation mechanism for marine pelagic populations. A model using catastrophe theory is proposed to ilustrate the long-term regulation of these pelagic systems.
Life History Variation of Polymorphic Arctic Charr (Salvelinus alpinus) in Thingvallavatn, Iceland
Authors: Jonsson B. , Skúlason S. , Snorrason S. S. , Sandlund O. T. , Malmquist H. J. , Jónasson P. M. , Cydemo R. , Lindem T.
Published: June 2008

The Arctic charr (Salvelinus alpinus) in Thingvallavatn, Iceland, exhibits four morphs. Small benthivorous charr grow slowly, have an asymptotic length of 13 cm, and mature at an age of 2–4 yr. Large benthivorous charr grow faster and almost rectilinearly with age. They mature at an age of 3–11 yr. Planktivorous and piscivorous charr have even higher initial growth rate, but planktivorous charr cease growing at 20 cm and piscivorous charr at a fork length of 30 cm. They mature at 3–5 yr and 5–10 yr of age, respectively. The gonadosomatic index and the annual allocation of energy into gonads relative to soma were higher for planktivorous and piscivorous than for benthivorous charr. The results indicate that piscivorous and planktivorous charr belong to the same gene pool; piscivorous charr are probably recruited from the most fast-growing planktivorous individuals and start feeding on fish at a length of 23 cm. The benthivorous morphs may belong to different stocks due to significant differences in several life history variables as well as genetics, spawning time, and feeding habitat. The four morphs seem to be differentiated within the lake through trophic radiation, but should be considered as conspecifics.
Multivariate Morphometrics in Aquaculture: A Case Study of Six Stocks of the Common Carp (Cyprinus carpio) from Italy
Authors: Corti M. , Thorpe R. S. , Sola L. , Sbordoni V. , Cataudella S.
Published: June 2008

Multivariate morphometry was used to investigate the distinctness and interrelationships of six stocks of the common carp (Cyprinus carpio). A "size" component was clearly identified by multiple group principal component analysis. Canonical variate analysis computed only on the "shape" components showed that the stocks were morphometrically distinct and that the phenetic relationships based on allozymic and morphometric data are highly congruent. We therefore suggest that multivariate morphometrics could represent an appropriate and convenient tool to detect variation between strains in carp culture.
Effects of Aluminum and Low pH on Net Ion Fluxes and Ion Balance in the Brook Trout (Salvelinus fontinalis)
Authors: Booth C. E. , McDonald D. G. , Simons B. P. , Wood C. M.
Published: June 2008

Adult brook trout (Salvelinus fontinalis) were exposed for up to 11 d to one of a matrix of 18 Al, low pH, and Ca2+ combinations, chosen as representive of acidified softwater environments in the wild. Reduction in water pH led to pH-dependent net losses of Na+ and Cl− exacerbated by the presence of Al in the water and reduced by elevating Ca2+. Any animal losing more than 4% of its total body Na+ over the first 24 h of Al exposure had a greater than 90% likelihood of eventual mortality. Na+ losses arose from inhibition of influx and stimulation of efflux. The inhibition was persistent and pH dependent. Addition of Al to acidified water had a slight further inhibitory effect on Na+ influx and a large stimulatory effect on efflux. The latter was dependent on Al concentration, was the main cause of initial ion losses and mortality, and declined with time in surviving animals. All Al-exposed fish accumulated Al on their gills, but this was apparently mainly surface or subsurface bound, since no internal Al (plasma or liver) could be detected. Nonsurviving fish had substantially higher gill Al levels than survivors.
Physiological Evidence of Acclimation to Acid/Aluminum Stress in Adult Brook Trout (Salvelinus fontinalis). 2. Blood Parameters by Cannulation
Authors: Wood C. M. , Simons B. P. , Mount D. R. , Bergman H. L.
Published: June 2008

Brook trout (Salvelinus fontinalis) exposed for 10 wk to sublethal acid (pH = 5.2) plus Al (150 μg/L) in flowing soft water (Ca2+ = 25 μequiv/L) did not exhibit chronic respiratory disturbance or elevated stress indices, as revealed by sampling of arterial blood gases, acid–base status, glucose, and cortisol via an indwelling catheter. Acclimation occurred, which prevented mortality and greatly attenuated the disturbances of respiratory, acid–base, and stress parameters normally seen upon challenge with more severe acid (pH = 4.8) plus Al conditions (333 μg/L} for 3 d. Ionoregulatory, fluid volume, and hematological disturbances were similarly reduced. Higher water Ca2+ (400 μequiv/L) slightly delayed but did not prevent this suite of toxic responses in naive fish. These disturbances did not occur in naive fish challenged with acid alone (pH = 4.8). However, long-term adaptation to acid alone (pH = 5.2) resulted in elevated glucose and cortisol levels and offered no protection against the more severe acid plus Al challenge. Thus the acclimation was to Al rather than to acidity itself, and low levels of Al may be beneficial to fish under chronic acid stress.
Morphometric Changes in Gill Secondary Lamellae of Brook Trou (Salvelinus fontinalis) After Long-Term Exposure to Acid and Aluminum
Authors: Tietge J. E. , Johnson R. D. , Bergman H. L
Published: June 2008

Adult brook trout (Salvelinus fontinalis) were exposed for 147 d to three different combinations of acid and Al in soft water (2 mg Ca/L). Samples of gill tissue from each of the three exposure conditions (pH 6.64 + 0 μg Al/L, pH 4.91 + 4.3 μg Al/L, and pH 4.45 + 393 μg Al/L) were examined by light microscopy using high-resolution techniques and morphometric analysis. As compared with fish in control conditions (pH 6.64 + 0 μg Al/L), exposure to pH 4.91 without Al significantly increased volume density of lamellar chloride cells. Low pH and elevated Al (pH 4.45 + 393 μg Al/L) resulted in increased diffusion distance, white blood cell infiltration of the lymphatic space of the gill tissue (an indicator of tissue damage), and a dramatic increase in lamellar dense cells. These results are consistent with the physiological data that show ionoregulatory stress and decreased respiratory efficiency as typical responses of brook trout exposed to low pH and combinations of low pH and elevated Al.
Hatching Success of Mayfly Eggs at Low pH
Authors: Rowe Locke , Hudson Jeffrey , Berrill Michael
Published: June 2008

Eggs of the mayflies Leptophlebia cupida, Habrophlebia vibrans, Stenonema femoratum, and Baetis flavistriga were reared in soft water at several pH levels (4.0, 4.5, 5.0, and 6.5) in the laboratory. The proportion of eggs undergoing eclosion did not vary with pH. However, in B. flavistriga, significant mortality of nymphs occurred before the hatch was complete at pH 4.0 (91%) and 4.5 (12%). Hatching rate of H. vibrans was significantly retarded at pH 4.0, 4.5, and especially at pH 5.0, but was unaffected in the other three species. The effects of elevated [H+] on these species are in agreement with their relative acid sensitivity inferred from field surveys.
Larval Size and Recruitment Mechanisms in Fishes: Toward a Conceptual Framework
Authors: Miller Thomas J. , Crowder Larry B. , Rice James A. , Marschall Elizabeth A.
Published: June 2008

Understanding the mechanisms controlling recruitment in fishes is a major problem in fisheries science. Although the literature on recruitment mechanisms is large and growing rapidly, it is primarily species specific. There is no conceptual framework to integrate the existing information on larval fish ecology and its relationship to survival and recruitment. In this paper, we propose an integrating framework based on body size. Although all larval fish are small relative to adult fish, total length at hatching differs among species by an order of magnitude. As many of the factors critical to larval survival and growth are size dependent, substantially different expectations arise about which mechanisms might be most important to recruitment success. We examined the evidence for the importance of size to feeding and starvation, to activity and searching ability, and to risk of predation. Regressions based on data from 72 species of marine and freshwater species suggest that body size is an important factor that unifies many of the published observations. A conceptual framework based on body size has the potential to provide a useful integration of the available data on larval growth and survival and a focus for future studies of recruitment dynamics.
Temporary Residence by Juvenile Salmon in a Restored Estuarine Wetland
Authors: Shreffler David K. , Simenstad Charles A. , Thom Ronald M.
Published: June 2008

Juvenile Pacific salmon utilizing the recently restored Lincoln Avenue wetland system in the Puyallup River estuary, Tacoma, Washington, were studied during their spring seaward migration in 1987 and 1988. Mark/recapture experiments indicated that 0.06% of the outmigrating juvenile chum salmon (Oncorhynchus keta) and 0.59% of the outmigrating juvenile chinook salmon (O. tshawytscha) entered the wetland. Estimated residence times of individual juvenile chum salmon averaged approximately 2 d (range 1–9 d) and juvenile chinook salmon approximately 5 d (volitional) and 38 d (spray-marked) (total range 1–43 d). The restored wetland system currently provides habitat for the temporary residence of migrating juvenile chum and fall chinook salmon, but rigorous evaluation of the benefit of residency is constrained by the lack of data from comparable natural wetlands.
Distributional Differences and Population Similarities for Two Deep-Sea Crabs (Family Geryonidae) in the Northeastern Gulf of Mexico
Authors: Lockhart F. D. , Lindberg W. J. , Blake N. J. , Erdman R. B. , Perry H. M. , Waller R. S.
Published: June 2008

For golden crab, Chaceon fenneri, and red crab, Chaceon quinquedens, numbers per trap, sex, and crab size were tested for broad bathymetric, geographic, and seasonal patterns on the upper continental slope, northeastern Gulf of Mexico. Red crab occupied only the deepest of three sampled depths (i.e. 677 m vs. 494 and 311 m) while golden crab predominated at the upper two. Golden crab occurred adjacent to peninsular Florida, but not along the northern Gulf slope, while red crab occurred across the geographic arc sampled. Relative abundance increased southward for golden crab and northwestward for red crab, while the proportion of females increased counter-clockwise within the sampled range of each species. Golden crab exhibited a Chaceon-typical bathymetric pattern of partial sex segregation and size inversely related to depth, but male and female bathymetric patterns shifted seasonally with lags between geographic areas. Interspecific competition cannot explain the species depth zonation, while geographic and seasonal patterns may relate to Loop Current–Florida Current circulation.
Factors influencing Fish Assemblages and Species Richness in Subtropical Florida Lakes and a Comparison with Temperate Lakes
Authors: Keller A. E. , Crisman T. L.
Published: June 2008

From detailed analyses of 36 lakes, we determined that while species assemblages and richness change with lake size, trophic state, and pH, the responses were not as dramatic in Florida as in temperate lakes. At a given pH, there were more species in Florida lakes than in comparable lakes of the temperate zone. The impact of lake size on species richness was also less obvious in Florida lakes. The greater importance of centrarchids, increased contribution of the littoral zone to primary production, and lower dissolved aluminum levels may contribute to greater species richness in Florida lakes than in temperate lakes of comparable pH or size.
Growth of Juvenile (0-Group) Atlantic Mackerel (Scombrus) in the Gulf of St. Lawrence
Authors: D'amours Denis , Landry Jean G. , Lambert Timothy C.
Published: June 2008

Juvenile (0-group) Atlantic mackerel were captured between 1977 and 1980, and in 1988, in the Gulf of St. Lawrence. Daily rings were identified and validated on their sagittae over the size range 93–170 mm; the age of larval and juvenile mackerel was estimated over the size range 7–192 mm (fork length). A one-cycle Gompertz curve was fitted to length-at-age data and the parameters were: L∞ = 180.8 mm, K = 0.043, and to = 37.7 d. The maximum calculated growth rate was 2.86 mm/d. The growth rate of 0-yr mackerel from the Gulf of St. Lawrence could be faster from that reported for 0-yr mackerel from the Middle Atlantic Bight: the mean growth rate offish from both regions was respectively 1.38 and 1.02 mm/d in the age interval 10–20 d; 2.30 and 2.07 mm/d in the age interval 20–30 d; and 2.79 and 2.69 mm/d in the age interval 30–40 d. This difference in somatic growth rate could provide the basis for determining the origin of adult fish if it resulted in permanent and discernible records on the otoliths, and if otolith growth is coupled with somatic growth.
Optimal sampling period for predicting phosphores and chlorophyll concentrations in north-temperate lakes
Authors: France Robert L. , Peters Robert H. , Rishikof Robert H.
Published: June 2008

Because total phosphorus and chlorophyll a concentrations vary seasonally within north-temperate lakes, estimates of lake trophic status are usually based on several to many sampling visits. However, because such effort is not always logistically possible, the empirical relationships developed between these trophic status indicators may depend upon seasonal patterns of sampling. Clearly, it is desirable to know if some periods of the year are more likely to produce representative estimates of total phosphorus and chlorophyll a, or, alternatively, if sampling in other periods should be restricted or even avoided. Data from north-temperate lakes are used to examine the degree to which single monthly samples for total phosphorus and chlorophyll a represent seasonal means. Analyses indicate that the least precise and least accurate estimates of the means occur when single-visit synoptic surveys are conducted during April. Not until August to September do single sampling visits provide data that approximate those represented by the means garnered through more frequent sampling.
Biogeochemieal origin of δ34S isotopic signatures in a prairie marsh
Authors: Cornwell Jeffrey C. , Stevenson J. C. , Neill C.
Published: June 2008

Sulfur isotope ratios were determined in a prairie marsh at Delta, Manitoba, Canada, to determine whether organic matter produced in the marsh had distinctive isotopic signatures. High sulfate levels in sediments from the Delta Marsh arise from high salt concentrations in soils. Sulfate reduction is the major anaerobic metabolic pathway in this sediment system and sulfate diffused into sediment both from deeper soil horizons and from overlying water. Surface water δ34S-SO42− values of 15 ± 1‰ increased to a maximum of almost 40‰ in deeper sediment horizons, in marked contrast to sediment pore water δ34S-H2S values of 2 ± 4‰. The high degree of discrimination between δ34S in sulfate and in hydrogen sulfide is similar to that found in brackish and marine ecosystems. Emergent macrophytes such as phragmites and cattail had isotopic signatures similar to reduced sulfur in this system. The data from this study suggest that in some nontidal wetland ecosystems, sulfur isotopes may be useful in determining producer–consumer relationships in a manner similar to their application in marine ecosystems.
Mercury methylation and demethylation in aerobic surface waters
Authors: Matilainen Tuula , Verta Matti
Published: June 2008

Potential rates of methylmercury formation and demethylation were studied in runoff waters, sediment trap material, and aerobic water layers of five small forest lakes by radioisotope methods. In addition, the roles of microbes and particulate matter in methylation and demethylation processes were examined. Methylation rates were low (≤0.12%∙d−1) in all sites studied. Water pH (4.9–6.9) had no clear effect on methylmercury formation. Methylation took place in filtered water (nominal pore size 0.2 μm) and in formaldehyde-treated or autoclaved samples, but was strongly suppressed by both dissolved organic matter (color) and particulate matter. Demethylation rates in surface waters (≤13.2%∙d−1) were decreased by low temperatures and the process was blocked by sterile filtration, formaldehyde treatment, and autoclaving. The results indicate that mercury methylation in aerobic humic waters is an accidental process caused by bacterial exoenzymes or other dissolved compounds. Methylmercury demethylation was clearly microbial in nature.
Mitochondrial DNA differentiation of sympatric populations of brown trout,Salmo truttaL., from Lough Melvin, Ireland
Authors: McVeigh H. P. , Hynes R. A. , Ferguson A.
Published: June 2008

RFLP analysis of mitochondrial DNA (mtDNA) was used to study variation within and between ferox, sonaghen, and gillaroo, the local names of three types of brown trout, Salmo trutta L., which live sympatrically in Lough Melvin, northwest Ireland. They spawn in separate rivers or sections of rivers and thus maintain reproductive integrity by their innate homing behaviour. In this study, 12 restriction enzymes were used to survey 4.9% of the genome in 37 trout. Five of the enzymes were informative (AvaII, HaeIII, HinfI, MboI, and XbaI) and these were used to examine an additional 139 trout. Seven mtDNA haplotypes were found in the first 37 trout and one further haplotype, owing to variation at MboI sites, was found in the larger sample of trout. All of the ferox were monomorphic at all sites examined whereas six haplotypes were found among the gillaroo, three of which were unique to this group. Five haplotypes were found among the sonaghen, two of which were found only in this group. Sonaghen and gillaroo share three haplotypes but they are present in each at different frequencies. Relative to morphological, allozyme, and multilocus probe results, mtDNA provides the most discriminating marker system for these trout.
Effect of aluminium and lead on activity in the freshwater pond snail Lymnaea stagnalis
Authors: Truscott R. , McCrohan C. R. , Bailey S. E. R. , White K. N.
Published: June 2008

Time-lapse video was used to examine the effect of short- (19 h) and long-term (1 year) exposure to Al or Pb at neutral pH in static water conditions on the total distance moved by the freshwater snail Lymnaea stagnalis. Aluminium at 100, 200, 500, or 1000 μg∙L−1 normally depressed and Pb at 50 and 200 μg∙L−1 often increased activity over the first 19 h of exposure. Smaller (younger) snails generally showed greater sensitivity to Al. Exposure to 100 or 500 μg Al∙L−1 for up to 30 days caused hyperactivity, but thereafter and 1 year later, activity was similar to controls, suggesting that the snails had become tolerant. Lead (200 μg∙L−1) caused continued hyperactivity for up to 50 days, although movement was significantly reduced after 1 year, suggesting that acclimation had occurred. The effect of Al is interesting given the supposed limited bioavailability of this metal at neutral pH.
Mitochondrial DNA divergence among popylations of American shad (Alosa sapidissima): how much variation is enough for mixed-stock analysis?
Authors: Epifanio John M. , Brown Bonnie L. , Smouse Peter E. , Kobak Carol J.
Published: June 2008

We investigated the geographic distribution of the mitochondrial DNA (mtDNA) diversity of American shad from 15 North American rivers in 1992 with the intent of assessing sampling efficiency for future mixed-stock analysis. We observed 116 haplotypes among the 988 individuals assayed. Because no single or group of haplotypes completely discriminated river stocks or regional complexes, we investigated haplotype frequencies as stock descriptors. Analysis of four unique indices of haplotype divergence indicated that including rather than suppressing restriction site heteroplasmy increased resolution; however, the final results were not overwhelmingly dependent on this choice. A redundancy of variation among restriction enzymes diminished information returns rapidly after considering the six best enzymes, caused by physical linkage of restriction sites on the mtDNA molecule. Stock discriminatory power was tested by computing allocation efficiencies of mtDNA characters. When each individual was temporarily removed from the data set and reallocated to the various candidate populations on the basis of haplotypic similarity, 28% of the reallocations were correct, a fourfold increase over random success. We demonstrate that although the specific stock identity of individuals cannot be confidently established, the haplotypic arrays from baseline stocks can support stock identification and mixed-stock analysis for shad because rivers support stock-specific haplotype frequencies.
Mitochondrial DNA control region sequences indicate extensive mixing of swordfish (Xiphias gladius) populations in the Atlantic Ocean
Authors: Bremer Jaime R. Alvarado , Baker Allan J. , Mejuto Jaime
Published: June 2008

Pacific, Atlantic, and Mediterranean populations of the swordfish (Xiphias gladius) are currently considered as separate fisheries management units, and populations in different regions of the Atlantic are thought to constitute different stocks on the basis of recapture data. To test these hypotheses we sequenced hypervariable segments of the control region of mitochondrial DNA in 35 swordfish from three regions of the Atlantic, as well as in 8 and 7 individuals from the Pacific and Mediterranean regions, respectively. Sixty of the 81 variable sites were confined to a 280 base pair stretch in the left domain of the control region, indicating that this segment is a rich source of genetic markers. Thirty-three haplotypes were found that could be assigned to two clades differing by 3.8% on average, and that diverged approximately 550 000 years ago. Clade I haplotypes were ubiquitous, but haplotypes from clade II predominated in the Mediterranean, and thus likely originated there during Pleistocene marine regressions. Overall, we conclude that there is extensive mixing of swordfish within the Atlantic Ocean. Sister-group relationships of haplotypes from different oceans indicate historical gene flow between these populations, but the co-occurrence of the same haplotypes in different oceans must reflect recent or ongoing dispersal.
Sulphate mass balances of Precambrian Shield wetlands; the influence of catchment hydrogeology
Authors: Devito Kevin J.
Published: June 2008

The sulphate budgets of two valley-bottom conifer swamps, located in headwater catchments with contrasting till depth, typical of the southern Canadian Shield were determined from June 1990 to August 1992. Temporal variations in the retention of SO42− in both swamps were related to the magnitude of upland runoff and water level in the wetlands. Contrasts in catchment till depth and nature of groundwater flow resulted in differences in SO42− retention between years and swamps. Transient groundwater inputs entering the swamp in the thin-till catchment resulted in a large water-table drawdown during dry summers, export of SO42− the following fall, and low annual SO42− retention. Continuous discharge of groundwater into the swamp in the moderate-till catchment maintained saturated surfaces and efficient SO42− retention during both years with dry and wet summers. Greater SO42− retention in this swamp may also be contributed by the greater interaction of groundwater, rich in SO42−, with deeper peat. Data from these two sites indicate that within the shallow till – rock ridge physiographic region of the Canadian Shield, small variations in catchment till depth can result in a large range in temporal and spatial variations in SO42− retention in valley wetlands.
Oxygen consumption, nitrogenous excretion, and filtration rates of Dreissena polymorpha at acclimation temperatures between 20 and 32 °C
Authors: Aldridge David W. , Payne Barry S. , Miller Andrew C.
Published: June 2008

Mussels were acclimated to each of four experimental temperatures (20, 24, 28, and 32 °C) for 30 days. Mussels averaged 10.29 mg tissue dry weight. Oxygen consumption rates at 32 °C were 3.65 times larger than consumption rates at 20 °C (p < 0.01). Ammonia excretion rates at 32 °C were 4.9 times greater than those at 20 °C (p < 0.01). O:N ratios were >60 at 20 and 24 °C but declined (p < 0.01) at 28 and 32 °C to <40. Filtration rates, an estimate of feeding rates, were not significantly different at 20 and 24 °C (p > 0.50) but declined at 28 and 32 °C (p < 0.01). Filtration rates at 32 °C were only 27% of the rates at 20 °C. These results indicate that (i) the metabolic expenditure of Dreissena polymorpha rose 265% as the temperature rose from 20 to 32 °C, (ii) metabolism relied more heavily on lipids and carbohydrates at 20 and 24 °C while protein catabolism increased at 28 and 32 °C, and (iii) the potential feeding rates of D. polymorpha declined by 73% as temperature rose from 20 to 32 °C. Above 28 °C D. polymorpha was unable to match energy expenditures with concurrent food intake and forced to rely on stored fuels.
A model for the determination of fish species at risk based upon life-history traits and ecological data
Authors: Parent Serge , Schriml Lynn M.
Published: June 2008

Fish species at risk (n = 29) and not at risk (n = 88) of extinction in the Great Lakes –St. Lawrence biozone were compared to determine if they could be distinguished by their life-history characteristics. A matrix of 51 variables representing 2 phylogenetic, 18 life-history, and 31 ecological variables was compiled from literature sources. Nonparametric analysis shows that 14 variables distinguish between species at risk and not at risk. Logistic regression indicates that seven factors are significant in defining the two groups: age at maturation, feeding habitat, fish feeding regime, feeding substrate, water flow over feeding area, breeding habitat, and breeding substrate. The resulting model is concordant at 97.1% (p = 0.0001, −2 log likelihood = 38.9). The model states that any fish species maturing at 18 years or more is at risk of extinction in the biozone. When applied to a set of fish species from the American Midwest using a decision level of p = 49%, the model had a reclassification success of 77.8%. The modeling technique could be useful to evaluate species at risk and to complement decision making with regard to vulnerability, especially in the case of wide-ranging species such as Atlantic sturgeon (Acipenser oxyrhynchus) and American eel (Anguilla rostrata).
Characteristics and function of large woody debris in subalpine Rocky Mountain streams in northern Colorado
Authors: Richmond Ann D. , Fauseh Kurt D.
Published: June 2008

Large woody debris has been well studied in coastal forests of the Pacific Northwest, but little is known of its role in Rocky Mountain streams. Large woody debris was measured in 11 undisturbed streams draining subalpine old-growth forests in north central Colorado to assess abundance, characteristics, and function. Although large woody debris in Colorado had smaller diameter, length, and volume than in the Pacific Northwest, its abundance and function were similar. The majority of pools (76%) were plunge and dammed pools formed by large woody debris, most of which spanned the channels perpendicular to stream flow. Smaller streams had a greater proportion of such perpendicular pool-forming pieces than larger streams. Four disturbed streams had significantly less and smaller large woody debris than undisturbed streams. Flows in larger undisturbed streams were capable of moving large woody debris, so pieces were more often located at the stream margins, oriented diagonally, or distributed in clumps than in smaller streams. Individual pools were larger and deeper in larger streams, but their size was not related to the size of large woody debris pieces forming them. Therefore, the function of large woody debris in forming fish habitat in small Rocky Mountain streams is strongly influenced by the stream's location within the watershed.
Construction of a first genetic map of distylousTurneraand a fine-scale map of theS-locus region
Authors: Labonne J. D.J. , Vaisman A. , Shore J. S.
Published: June 2008

As a prelude to discovery of genes involved in floral dimorphism and incompatibility, a genetic map of distylous Turnera was constructed along with a fine-scale map of the S-locus region. The genetic map consists of 79 PCR-based molecular markers (48 AFLP, 18 RAPD, 9 ISSR, 4 RAMP), 5 isozyme loci, one additional gene, and the S-locus, spanning a total distance of 683.3 cM. The 86 markers are distributed in 5 linkage groups, corresponding to the haploid chromosome number. Molecular markers tightly linked or co-segregating with the S-locus in an initial mapping population of 94 individuals were used to assay an additional 642 progeny to construct a map of the S-locus region. The fine-scale map consists of 2 markers (IS864a and RP45E9) flanking the S-locus at distances of 0.41 and 0.54 cM, respectively, and 3 additional markers (OPK14c, RP45G18, and RP81E18) co-segregating with the S-locus in the total mapping population of 736 individuals. The genetic map constructed will serve as a framework for localization of genes outside the S-locus affecting distyly, while molecular markers of the fine-scale map will be used to initiate chromosome walking to find the genes residing at the S-locus.
Characteristics and analysis of simple sequence repeats in the cotton genome based on a linkage map constructed from a BC1population betweenGossypium hirsutumandG. barbadense
Authors: Zhang Yanxin , Lin Zhongxu , Xia Qizhong , Zhang Mingju , Zhang Xianlong
Published: June 2008

In the past decade, several molecular maps of cotton have been constructed using diverse DNA molecular markers and mapping populations. In this study, an interspecific linkage map of allotetraploid cotton was developed using a BC1population ((Gossypium hirsutum × G. barbadense) × G. hirsutum). This map was genome-wide and was based entirely on simple sequence repeat (SSR) markers. Forty-four linkage groups were assigned to 26 chromosomes, with 917 loci spanning 5452.2 cM of the genome. The average distance between loci was 5.9 cM, providing uniform coverage of the A subgenome and D subgenome. Characteristics of this map were analyzed in detail, including the distributions of genomic SSRs, expressed sequence tag (EST)-SSRs, and distorted markers. Furthermore, the relationships between motif characteristics (size, type, length) and the level of polymorphism in EST-SSRs were also surveyed. The results showed that tetranucleotide and dinucleotide repeats had similar levels of polymorphism, and ACAT, AC, and ACT repeats had the highest polymorphism rates. Loci with lengths of 27 bp, 33 bp, and 24 bp were more likely to be polymorphic. This work will provide information to assist in designing future EST-SSRs.
Detection of light speed anisotropy via a high-speed Ives–Stillwell experiment
Authors: Sfarti A
Published: June 2008

The Mansouri–Sexl theory is a well-known test of the theory of relativity. In one of their three papers (R. Mansouri and S.U. Sexl. Gen. Rel. Grav. 8, 809 (1977).), Mansouri and Sexl deal with the transverse Doppler effect under a set of restrictive conditions. In this paper, we deal with the same effect under the most general conditions and will argue for a novel way of detecting high-order effects in a vacuum via an increased laboratory-speed re-enactment of the Ives–Stilwell experiment. We will demonstrate the presence of a high-order error term and we will set the experimental conditions for detecting such a term.PACS No.: 03.30+p
Cosmological expansion and local systems: exact solutions
Authors: Faraoni V
Published: June 2008

We study the competition between cosmological expansion and local attraction for relativistic objects embedded in a generic Friedmann universe. The recently discovered “all or nothing” behaviour (i.e., weakly coupled systems are comoving while strongly coupled ones do not expand at all) is found to be limited to the de Sitter background. New exact solutions are presented describing black holes co-moving with a surrounding universe.PACS Nos.: 98.80.–k,04.20.Jb, 04.20.–q
Cosmological birefringence induced by neutrino current
Authors: Geng C Q , Ho S H , Ng J N
Published: June 2008

We review our recent work, Geng et al. (J. Cosmol. Astropart. Phys. 09, 010 (2007)) on the cosmological birefringence. We propose a new type of effective interactions in terms of the CPT-even dimension-six Chern–Simons-like term to generate the cosmological birefringence. We use the neutrino number asymmetry to induce a nonzero rotation polarization angle in the data of the cosmic microwave background-radiation polarization.PACS Nos.: 98.80.Cq, 98.80.Es, 11.30.Fs
Can a quantum computer simulate quantum field theory – efficiently?
Authors: Ahrensmeier D
Published: June 2008

The question posed in the title is discussed from a conceptual point of view. Typical complex problems in quantum field theory are described, the basic principles of quantum computing and simulation are explained and illustrated by examples, and suggestions for further investigations are made.PACS Nos.: 03.67.Lx, 11.10.–z
Symmetrization methods for characterization and benchmarking of quantum processes
Authors: Emerson J
Published: June 2008

The detailed characterization of controlled quantum processes is a fundamental problem in experimental physics, and is a crucial requirement for the development of robust quantum information processing. Standard approaches for complete characterization of a quantum process require an number of experiments that grows exponentially with the number of interacting subsystems. Hence these methods are infeasible for many situations of practical interest. This paper reviews recent approaches to process estimation that overcome this problem by identifying subsets of the information that is of practical interest, and then demonstrating how this partial information can be estimated through the application of symmetrizing operations. PACS Nos.: 03.67.Pp, 03.65.Yz, 03.65.wj
Pion fluctuation and its multiplicity dependence in ultrarelativistic nuclear collisions
Authors: Ghosh D , Deb A , Dutta S
Published: June 2008

This paper studies the multiplicity dependence of the fluctuation pattern of pions produced for 16O–AgBr interactions at 60 A GeV and 32S–AgBr interactions at 200 A GeV. We divided the data for the pions produced into four sets depending on the number of shower tracks (ns). We investigated the fluctuation pattern of emitted pions corresponding to different sets in both η (pseudorapidity) and ϕ (azimuthal angle) space. The multiplicity dependence was studied with respect to parameters αq, Dq, multifractal specific heat c, and effective fluctuation strength αeff. The study clearly indicates that the fluctuation pattern depends on multiplicity both in pseudorapidity and azimuthal angle space for 16O initiated interactions. However, for 32S initiated interactions, no multiplicity dependence is evidenced by the data in azimuthal angle space. For both, the multiplicity dependence is not very strong and significant only at large average multiplicity. Multiplicity dependence was further studied in a small window around the central pseudorapidity, and we found that multiplicity dependence is more prominent in the central region. The multiplicity dependence of αeff is more pronounced in the case of 32S–AgBr interactions than in case of 16O–AgBr interactions.

PACS Nos.: 25.75–q, 24.60 Ky
Tubulin electrostatics and isotype specific drug binding
Authors: Tuszyński J A , Malinski W , Carpenter E J , Luchko T , Torin Huzil J , Ludeña R F
Published: June 2008

We present the results of molecular dynamics computations based on the atomic structures of tubulin. The values of the net charge, the spatial charge distributions, and the dipole moment components are reported for tubulin alpha–beta dimers. The physical consequences of these results and subsequent computations are discussed for microtubules in terms of the effects on test charges, test dipoles, and neighbouring microtubules. Our calculations indicate typical distances over which electrostatic effects can be felt by biomolecules, ions, and other microtubules. We also demonstrate the importance of electrostatics in the interaction between microtubules and drugs such as taxanes and colchicine. PACS Nos.: 82.35.Rs, 87.14.Ee, 87.15.Aa, 87.15.By, 82.39.–h, 77.84.Jd