bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristic Size Distributions of Integral Benthic Communities
Authors: Schwinghamer Peter
Published: April 2011

Uniform size spectra comprising bacteria through macrofauna characterize six intertidal communities when biomass concentration is expressed as a function of logarithmic intervals of organism size. Although total community biomass ranged from 70 cm3/m2 to 1283 cm3/m2, biomass distribution patterns are consistent over the entire size spectrum. Three biomass peaks, at 0.5–1 μm equivalent spherical diameter (29–81 cm3/m2), 64–125 μm (0.5–4 cm3/m2), and > 2 mm (2.4–1283 cm3/m2) were separated by typically low biomasses near 8 μm (0–0.04 cm3/m2) and 500 μm–1 mm (0–1.5 cm3/m2). The peaks correspond to bacteria, interstitial meiofauna, and macrofauna, respectively. Size discontinuities between grain colonizers and interstitial microfauna or epibenthic microflora near 8 μm, and between interstitial meiofauna and burrowing or sedentary macrofauna near 500–1000 μm, are reflected in low biomass values in these size intervals. Comparison of the data with recast published data for other locales shows that similar size distributions characterize a wide variety of benthic communities, including estuarine to abyssal. This study is the first to describe quantitatively, in detail, the size composition of marine benthic communities.Key words: benthic, community, bacteria, meiofauna, macrofauna, size, biomass, Sheldon spectrum
SETCOL — A Technologically Simple and Reliable Method for Measuring Phytoplankton Sinking Rates
Authors: Bienfang Paul K.
Published: April 2011

A simple and reliable method for measuring the sinking rate of phytoplankton is described. This technique is suitable for both heterogeneous field populations and unialgal in vitro cultures. The procedure involves use of settling columns initially containing a uniformly mixed population of cells, and calculates a sinking rate based upon the change in vertical distribution of cells after a given time. The sinking rate calculation, though simple, is couched within a sound theoretical foundation. The biomass index used is optional and can be selected to focus on various parameters of interest. Sinking rates and flux values for particulate C, N, P, Si, chlorophyll, or pheopigment can be obtained simply by assessment of the biomass variables in those terms.Key words: phytoplankton, sinking, methodology, particulate flux, sedimentation
Hydrocarbons Depress Growth and Reproduction of Daphnia pulex (Cladocera)
Authors: Geiger J. G. , Buikema Jr. A. L.
Published: April 2011

Daphnia pulex were acutely and chronically exposed to water-soluble fractions of hydrocarbons. In acute studies, the most-to-least toxic were coal-tar creosote, No. 2 fuel oil, naphthalene, and phenanthrene. During chronic studies, Daphnia were monitored for molting frequency, growth rates, production of total and live young, number of nonviable eggs, partial and full abortions, and whether or not abortions occurred prior to completion of embryonic development. For creosote and phenanthrene, marked reduction occurred in growth rates, number of broods, and impairment of molting, and an increase occurred in abortion rates. No. 2 fuel oil produced similar effects, but results were less significant. Naphthalene only produced a slight reduction in growth rate at the concentrations studied. It is hypothesized that the effect on growth and reproduction may be due to PAH-induced disturbance on some aspect of metabolic control of reproduction and molting.Key words: phenanthrene, naphthalene, creosote, No. 2 fuel oil, Daphnia, toxicity
Myxosoma cerebralis: Inactivation of Spores by Hot Smoking of Infected Trout
Authors: Wolf Ken , Markiw Maria E.
Published: April 2011

We processed 2-yr-old rainbow trout (Salmo gairdneri) and brook trout (Salvelinus fontinalis) with clinical whirling disease, which is caused by Myxosoma cerebralis, in one of the following ways: iced, iced and brined, or iced, brined, and hot smoked at 66 °C for 40 min. Skeletal elements of each group were added to tanks containing soil samples from an aquatic environment free of M. cerebralis and aged for 4 mo at 12.5 °C. Following this we assayed for infectivity by holding susceptible rainbow trout fry for 3 mo in the tanks of aquatic soil and skeletal elements. The fry were then examined for M. cerebralis spores. Spores were found in the fry from tanks that had received iced and iced and brined samples, but not in fry from the tanks containing hot smoked tissue, healthy tissue, or no tissue — the last two being negative controls.Key words: whirling disease, Myxosoma cerebralis, heat inactivation, hot smoking
Analysis of Longitudinal Zonation and the River Continuum Concept in the Oldman–South Saskatchewan River System
Authors: Culp Joseph M. , Davies Ronald W.
Published: April 2011

During the summer–fall periods, the benthic macroinvertebrate communities of the Oldman–South Saskatchewan River system demonstrated a longitudinal zonation related to the subalpine forest, fescue prairie, and mixed prairie terrestrial ecosystems through which it flows. This zonation was primarily attributable to significant downstream increases in periphyton biomass, plant nutrients, and water temperature. Zonation was reduced in the Sate winter–spring periods and absent in May, during spring runoff. Longitudinal trends in macroinvertebrate functional feeding groups generally followed the predictions of the river continuum concept, with trophic composition apparently more strongly affected by autotrophic processes in the summer, and heterotrophic processes in the winter. By combining the river continuum concept with a watershed classification system based on geology, climate, soil type, and terrestrial vegetation, we suggest that biological comparisons of longitudinal zonation are enhanced.Key words: longitudinal zonation, reciprocal average ordination, river continuum concept, functional groups
Immigration of Juvenile Coho Salmon (Oncorhynchus kisutch) into Riverine Ponds
Authors: Peterson N. P.
Published: April 2011

Riverine ponds on the Olympic Peninsula provide important winter refuge for juvenile coho salmon (Oncorhynchus kisutch). A total of 9530 juvenile coho migrated into two riverine ponds of the Clearwater River in 1977, principally during fall freshets. Extensive movement by marked fish (as much as 32.6 km downstream) before entering the ponds suggests that a system-wide approach to habitat management is important in maintaining freshwater production potential of large river systems.Key words: juvenile coho, immigration, winter behavior, migration, freshet, pond
Phosphorus Release Patterns and the Effects of Reproductive Stage and Ecdysis in Daphnia magna
Authors: Scavia Donald , McFarland Margaret J.
Published: April 2011

Rates of continuous phosphorus release by individual Daphnia magna (0.3 – 0.9 mg dry weight) were measured using high performance liquid chromatography components in conjunction with a specially designed incubation flow cell. Within the temporal resolution of the technique (3 min), phosphorus release often appeared pulsed rather than only steady. We found significant variation in release rates among the different stages of an individual's parthenogenetic reproductive cycle. Rates observed for animals carrying more mature embryos were lower than those earlier in the reproductive cycle. Rates of phosphorus release observed at and after ecdysis averaged 6.7 times higher than rates observed at other times.Key words: phosphorus, excretion, reproductive stage, ecdysis, Daphnia magna
Recognition of the Possible: An Advantage of Empiricism in Ecology
Authors: Rigler F. H.
Published: April 2011

In many sciences there exist unpredictable phenomena, phenomena that for one of several reasons are deduced to be unpredictable from a current paradigm theory. In ecology, the long-term abundance of a given species in an ecosystem is an example of an unpredictable variable. From the theory of the ecosystem as a highly interactive complex of species in which rare species can potentially become abundant, we can deduce that species-based, systems analysis modeling cannot make long-term forecasts of species abundance. From the theory of evolution by natural selection it can be further deduced that no theory, regardless of its structure, can make these predictions. Because our general theories are informal and often only implicit, deductions such as those I have drawn may be incorrect. Nevertheless these deductions give compelling reasons for applied ecologists to pay serious attention to our general ecological theories and their consequences. They also suggest that empirical ecologists who concentrate their efforts on predictable properties of ecosystems remain on firm theoretical grounds and are not merely avoiding the more difficult problems.Key words: ecological theory, empiricism, prediction
Critique de la méthode de distinction entre poissons anadromes et dulcicoles de la même espèce par la teneur en strontium de leurs écailles
Authors: Castonguay Martin , FitzGerald Gérard J.
Published: April 2011

It was not always possible to distinguish between saltwater and freshwater brook char, Salvelinus fontinalis, based on strontium content of scales because of high intra-group variability and low inter-group variability. This method of discrimination between anadromous and freshwater forms should be used with great care. It does not seem possible to determine the freshwater conditions that an anadromous char had previously met by the separate analysis of different parts of the scales. The strontium content of the scales of the saltwater char did not decrease after they were returned to freshwater.
Low pH and the Absence of Fish Species in Naturally Acidic Wisconsin Lakes: Inferences for Cultural Acidification
Authors: Rahel Frank J. , Magnuson John J.
Published: April 2011

In a group of 138 northern Wisconsin lakes (pH 4.0–9.2), we observed differences in the lowest pH at which 31 fish species occurred. The central mudminnow (Umbra limi), yellow perch (Perca flavescens), and various centrarchids occurred below pH 5.0, whereas many cyprinids and darters were not found below pH 6.2. Rankings of species occurrence with minimum pH in these naturally acidic lakes were similar to data from Canadian lakes affected by acid precipitation, and rankings based on survival during laboratory exposure to low pH. Wisconsin oligotrophic lakes that are susceptible to acid precipitation typically lack many fish species sensitive to low pH, even when lake pH is near 7.0. Species interactions and biogeographic factors, not recent cultural acidification, are probably responsible for species absences in these lakes. Knowledge of the pH ranges naturally tolerated by fishes and the structure of fish assemblages in lakes sensitive to acid precipitation will aid in detecting changes caused by cultural acidification.Key words: acid lake, acidification, pH, fish communities, Wisconsin
Survival, Respiration, and Food Assimilation of Daphnia magna Exposed to Petroleum- and Coal-Derived Oils at Three Temperatures
Authors: Ullrich Jr. Sterling O. , Millemann Raymond E.
Published: April 2011

Acute toxicity tests with the water-soluble fractions (WSFs) of both oils showed that mortality of Daphnia magna was directly related to temperature and the WSF concentration. The coal-derived oil was more toxic than the diesel fuel oil. The 48-h LC50s for the former were 0.70, 0.44, and 0.18% at 10, 20, and 25 °C, respectively; the values for the diesel oil WSF were 87, 32, and 9.7% at 10, 20, and 25 °C, respectively. Respiration rates of animals exposed to sublethal concentrations of the WSFs at 10, 20, and 25 °C were significantly affected by the WSF concentration of the oils and temperature. The interaction between the concentration of each oil with temperature was statistically significant. Low concentrations of diesel oil WSF stimulated respiration rates at each temperature, but higher concentrations depressed them. At all temperatures, oxygen consumption rates of animals exposed to the coal-derived oil WSF decreased with increased concentration. The exposure to sublethal concentrations of both oils affected food assimilation of the animals in a manner similar to that observed when respiration was the criterion of toxic effect. The interaction between diesel oil WSF concentrations and temperature, but not between coal oil WSF concentrations and temperature, was statistically significant. At 20 and 25 °C, low concentrations of diesel oil WSF stimulated assimilation rates, whereas low concentrations of the coal oil WSF depressed them. Generally, high concentrations of both WSFs depressed assimilation rates below control values. These results emphasize the importance of natural stresses, such as temperature, in enhancing toxicity of synthetic chemicals to aquatic organisms, and they reinforce the need to consider such variables as season of the year in evaluating biotic effects of oil spills.Key words: temperature, Daphnia magna, petroleum, coal oil, synthetic oil, respiration, food assimilation, acute toxicity, chronic toxicity
Evaluation of the Phosphorus–Chlorophyll Relationship for Lakes Off the Precambrian Shield in Western Canada
Authors: Prepas E. E. , Trew D. O.
Published: April 2011

Summer chlorophyll (Chl), spring and summer total phosphorus (TP), and total nitrogen (TN) data were collected from 25 lakes off the Precambrian Shield in Alberta. Contrary to the results reported in previous studies in western Canada, the spring TP–summer Chl relationship (n = 29, r2 = 0.67) and TN:TP ratios were similar to those reported for other north-temperate lakes. However, there was less variation in the summer TP–summer Chl relationship (n = 34, r2 = 0.81) than in the spring TP–summer Chl relationship. This is a result of the variability in the summer TP:spring TP ratio which ranged from 0.5 to 2.9 in these lakes. In the shallow productive freshwater lakes TP concentrations increased dramatically between spring and summer (the average summer TP:spring TP ratio was 1.7), whereas in the thermally stratified freshwater lakes (most of which were partially meromictic) summer TP concentrations were much lower than spring TP concentrations (the mean ratio was 0.7). There was less chlorophyll per unit TP in saline lakes (i.e. lakes with more than 500 mg/L total dissolved solids) than in freshwater lakes.Key words: phosphorus, chlorophyll, western lakes, saline lakes, meromictic lakes
Use of NaCl as a Reference Toxicant for Goldfish, Carassius auratus
Authors: Threader R. W. , Houston A. H.
Published: April 2011

The 240-h NaCl LC50 for goldfish, Carassius auratus, was estimated as 201.1 (SE 6.7) mmol∙L−1, a concentration well in excess of one recently published value, but consistent with earlier observations on the tolerance of this species for hypersaline conditions. Evidence for operation of several lethal effects that vary in intensity with time, the absence of a well-defined relationship between dose and mortality within an intermediate range of lethal NaCl concentrations, and the strong likelihood of size-related variation in individual sensitivity to NaCl suggest that NaCl is an inappropriate reference toxicant for use in static bioassays involving this species.Key words: NaCl, goldfish, toxicity
Consideration of the Stable Age Distribution Assumption in "Analytical" Yield Models
Authors: Sinclair M. , O'Boyle R. , Iles T. D.
Published: April 2011

The implications on the "analytical" yield model of deviations from the stable age distribution were investigated for stocks of five species with a range of life history characteristics, these being Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), pollock (Pollachius virens), Atlantic herring (Clupea harengus harengus), and Atlantic mackerel (Scomber scrombus). Recruitment variability for the stocks considered ranged from 21% for pollock to 104% for haddock. The comparison of the growth rates at age for the five species showed the expected continuum in relative growth rates from cod to mackerel. With the population in a stable age distribution without fishing there is also a continuum from cod to mackerel in the manner in which age-specific production decreases through the life span. It is thus to be expected that deviations from the stable age distributions for mackerel would have a much greater impact on population production than would a similar deviation for cod. Also, species whose growth rates decrease more rapidly with age tend to have a higher recruitment variability. To demonstrate the implications of deviations from the stable age distribution on the accuracy of model output, MSY yields (that would have been generated given historical estimates of population numbers-at-age) were compared to estimates of annual population production. Cod and pollock production deviate relatively little from the "analytical" model predictions. In contrast, annual production for haddock, herring, and mackerel deviate markedly from MSY yields as the age composition deviates in each direction from the stable age distribution. The analysis suggests that for some species the "analytical" model may contribute to growth overfishing.Key words: "analytical" yield models, stable age distribution, growth overfishing
Canola Meal in Rainbow Trout (Salmo gairdneri) Production Diets
Authors: Hardy Ronald W. , Sullivan Craig V.
Published: April 2011

Production diets containing up to 20% canola meal were fed for 108 d to rainbow trout (Salmo gairdneri) to evaluate the effects on weight gain, food conversion, thyroid function, and organoleptic quality of market-sized fish. Weight gain was not affected by dietary canola meal level. Food conversion values and organoleptic properties were not influenced by dietary treatments. Feed costs were reduced by $18.70 (U.S.) per metric ton compared to control diet at the highest level of dietary canola meal (20%). Thyroid function was significantly affected by dietary canola meal. Dose-related changes in the histological appearance of the thyroid and alterations of plasma thyroxine and 3,5,3′-triiodothyronine levels indicated that compensatory adjustments in thyroid function allowed normal growth to proceed in the canola-fed fish. Possible mechanisms of dietary glucosinolate influence on thyroid function are discussed and areas for future research are suggested.Key words: canola meal, plasma T4, plasma T3, thyroid histology, goitrogen, glucosinolates, trout growth, food conversion, least-cost diets, organoleptic quality
Cooling Water Flow Velocity in Relation to Collection of Entrained Larval Fish at Power Plants
Authors: Leslie J. K.
Published: April 2011

Velocity of condenser cooling water at numerous sampling sites at some Great Lakes power plants was examined in relation to larval fish entrainment. Current velocity was found to differ significantly in many cases at all depths, for sampling locations spaced 1 m apart in the vertical plane. Extensive use of current meters showed that a simple, presampling study of current velocity at the intake or discharge could improve the accuracy of entrainment estimates.Key words: current velocity, larval fish, entrainment sampling, power plant
Normal Ranges for Diagnostically Important Hematological and Blood Chemistry Characteristics of Rainbow Trout (Salmo gairdneri)
Authors: Miller III W. Roscoe , Hendricks Albert C. , Cairns Jr. John
Published: April 2011

Wytheville strain rainbow trout (Salmo gairdneri) were used in an 11-mo study designed to establish normal ranges for several hematological and blood chemistry characteristics. Two nonparametric techniques, percentile estimation and tolerance interval, were used and produced comparable ranges to those based on the Gaussian distribution. Serum glucose levels appeared to coincide with the condition of the gonads; low glucose levels corresponded with approximate spawning times at the hatchery. Total serum protein and gonadal condition were similarly related. High variability of the serum enzymes LDH and SGOT was partially explained by a positive linear relationship between enzyme activity and acclimation temperatures. In addition to physiological significance, determination of normal ranges for rainbow trout has promise in diagnosis of pathological, disease, and toxicant-induced stresses.
A Management Analysis of the Pacific Whiting (Merluccius productus) Fishery Using an Age-Structured Stochastic Recruitment Model
Authors: Swartzman Gordon L. , Getz Wayne M. , Francis Robert C. , Haar Robert T. , Rose Kenneth
Published: April 2011

This paper applies an age-structured stochastic recruitment model to the Pacific whiting (Merluccius productus) fishery off the North American Pacific continental shelf. A policy algorithm has been developed as an aid to management of the fishery which aims to set quotas in such a way as to use strong year-classes in a practical and efficient manner while protecting the stock when it is in a poor condition and environmental conditions do not appear to be conducive to stock improvement in the immediate future. Recruitment in the whiting stock is linked primarily to water temperature in their spawning area. Existing data are used as the basis of a transition matrix for recruitment which depends on both stock level and water surface temperature on the spawning grounds. Comparison with historical data on fishery catch and stock estimates shows model output to be realistic. As a test of the policy algorithm, simulation runs with different quota control criteria in the algorithm were compared with 47-yr runs at constant effort and constant quotas. The policy algorithm was found to protect the stock better and to provide higher average catch per unit effort (CPUE) than the constant effort and quota cases. In the policy algorithm, average yield can be increased at the expense of CPUE. The choice of quota control criteria depends on management preference for improving yields versus having less variable effort and higher average CPUE.
Adaptive Probing Strategies for Age-Structured Fish Stocks
Authors: Ludwig D. , Hilborn R.
Published: April 2011

This paper examines methods of preventing a stock of fish from being held far below its optimal size. Such sustained overexploitation could arise because the model used to manage the stock poorly represented the stock dynamics, because there are significant errors in the estimates of stock abundance, or because there is insufficient contrast in catch and fishing mortality to generate reliable estimates of the productive potential of the stock. We develop a method to correct for biases due to errors in estimates of abundance and show that this correction does improve estimates of productivity, but not sufficiently to enable a manager to recognize the presence of overexploitation. We demonstrate that the management system must generate significant contrast in catch and effort, and once the contrast is generated the managers can easily find near optimal abundance of the stock. With reasonable levels of contrast even very simple surplus production models will perform well when managing complex age-structured fish stocks.
Anthropogenic Zinc and Cadmium Burdens in Sediments of Selected Southern Ontario Lakes
Authors: Evans Hayla E. , Smith P. Jane , Dillon Peter J.
Published: April 2011

The concentrations of Cd and Zn were measured in the sediments of 10 softwater lakes in southern Ontario. Elevated Cd and Zn levels were present in the recently deposited sediments of all the lakes, despite the absence of local point-source inputs. Whole-lake anthropogenic Zn and Cd burdens, calculated by prorating site-specific burdens according to the ratio of the site-specific Pb burden to the whole-lake Pb burden, range between 322 and 617 mg∙m−2 for Zn and between 6.2 and 11.3 mg∙m−2 for Cd. There were no significant differences in anthropogenic Zn or Cd burdens between lakes. The lack of a relationship between Zn or Cd burdens and the ratio of watershed area to lake area or the water replenishment time of the lakes indicates that deposition from the atmosphere directly onto the lakes' surfaces is an important input of these metals to the lakes.
Optimizing Survey Design for Determining Age Structure of Fish Stocks: an Example from British Columbia Pacific Herring (Clupea harengus pallasi)
Authors: Schweigert J. F. , Sibert J. R.
Published: April 2011

Sampling commercial catches of fishes is considered for the first time from the viewpoint of survey statistics. The determination of the age-structure of Pacific herring (Clupea harengus pallasi) is approached as a multistage subsampling problem. Optimum allocation of sampling resources is obtained by minimizing the product of total cost and total variance. Optimal survey designs are analyzed for a variety of reasonable cost structures for all age-classes. The most reasonable design that applies to all areas of the coast is to use a two-stage design, including a single sample of about 60 aged fish per vessel. The number of vessels to sample is a function of the required precision and available resources.
Taxonomy of a Swimbladder Nematode, Cystidicola stigmatura (Leidy), and Evidence of its Decline in the Great Lakes
Authors: Black Geoff A.
Published: April 2011

Cystidicola stigmatura (Leidy, 1886) Ward and Magath, 1917 is considered a valid species after examination of specimens from Leidy's collection. Cystidicola cristivomeri White, 1941 is considered a synonym of C. stigmatura. Cystidicola stigmatura is distinguished from the only other species in the genus, namely C. farionis Fischer, 1798, by the presence of lateral lobes on the eggs rather than filaments. A neotype of F. stigmatura is designated. Cystidicola stigmatura has not been found in fishes in the Great Lakes since 1925. The parasite was found in museum specimens of lake trout (Salvelinus namaycush) collected before 1925, suggesting that the species became rare or disappeared with the decline of lake trout in these lakes.
Measurements of Benthic Macroinvertebrate Standing Crop from the Canadian Continental Shelf and Slope of Southern Davis Strait and Ungava Bay
Authors: Stewart Patrick L.
Published: April 2011

Benthic macroinvertebrate standing crop at 14 stations on the Canadian continental shelf, southeast of Baffin Island, ranged from 19.8 to 479.9 g/m2 and was about the same size for given depths, as reported for the Grand Banks of Newfoundland, and higher than reported in more southerly portions of the eastern North American continental shelf. Standing crop was correlated negatively with depth and sediment content of both fine and medium sand.
Experimental Management of Oregon Coho Salmon (Oncorhynchus kisutch): Designing for Yield of Information
Authors: Peterman Randall M. , Routledge Richard D.
Published: April 2011

Large-scale experimental manipulation of juvenile salmon (Oncorhynchus spp.) abundance can provide a test of the hypothesis of linearity in the smolt-to-adult abundance relation. However, not all manipulations will be equally informative owing to large variability in marine survival. We use Monte Carlo simulation and an analytical approximation to calculate for Oregon coho salmon (O. kisutch) the statistical power of the test involving different controlled smolt abundances and durations of experiments. One recently proposed experimental release of 48 million smolts for each of 3 yr has a relatively low power and, as a consequence, is unlikely to show clearly whether the smolt-to-adult relationship is linear. The number of smolts required for a powerful test of the hypothesis of linearity is closer to the 88 million suggested in another proposal. To prevent confounding of interpretation of results, all other human sources of variability in fish should be minimized by establishing standardized rearing and release procedures during the experiment. In addition, appropriate preexperiment data on coho food, predators, and competitors will increase effectiveness of experiments by providing information on mechanisms of change in marine survival.
An Analysis of the Hecate Strait Pacific Cod Fishery Using an Age-structured Model Incorporating Density-dependent Effects
Authors: Fournier D. A.
Published: April 2011

An age-structured model was used to analyze the Hecate Strait Pacific cod (Gadus macrocephalus) fishery for the years 1960–80. The data consisted of estimates of fishing effort, together with estimates of numbers of fish at age caught in each year. The latter estimates were derived from length–frequency analysis. A stock–recruitment relationship of the Ricker type with an additional environmental factor was estimated. The data is also analyzed for evidence of the existence of age-dependent trends in natural mortality, density-dependent trends in natural mortality and catchability, and for time-dependent trends in catchability. Evidence of a density-dependent trend in natural mortality was discovered. The average level of natural mortality was also estimated to be 0.65.
Factors Affecting the Supply and Distribution of Sediment in Some Tropical Ports
Authors: Kendrick Mary P. , Derbyshire B. V.
Published: April 2011

A brief review has been made of five hydraulic investigations of port siltation carried out by various international laboratories. The ports studied are distributed throughout the tropics from South America to Indonesia and the factors affecting sediment supply and distribution either directly or indirectly have been summarized. In spite of local variations, the similarity of many features suggests the existence of a common mechanism of sediment transport.Twenty months of field measurements at one of the ports demonstrated that turbidity in the water column is low from surface to 0.15 m above the bed. These measurements, together with those from flume tests on the behavior of local mud in currents, indicated that siltation is not solely due to deposition of silt suspended in the main body of flow. Further wave flume tests showed that under certain conditions, a shallow, highly turbid layer forms on the bed, capable of being transported by weak tidal currents without significant vertical mixing. Supplementation of field measurements of water movement with more detailed hydraulic model measurements permitted the formulation of a siltation mechanism.Appraisal of results suggests the most important immediate source of the silt to be the shallow coastal mud banks. Waves produce the turbid, near-bed layer which is transported by littoral currents into port approach channels for redistribution by the prevailing residual current, itself a function of fluvial/tidal interaction.Key words: siltation, dredging, silt movement, flocculation, waves, tides, river flow, residual currents
Transfer of Water and Sediment from the Yangtze River to the East China Sea, June 1980
Authors: Zuo-sheng Yang , Milliman John D. , Fitzgerald Michael G.
Published: April 2011

The Yangtze River, fourth largest in the world in terms of sediment discharge, contributes about 500 × 106 t annually to the East China Sea. A disproportionate part of the load is carried after peak summer discharge, presumably the result of draining the rice fields. During a week-long study of the estuary, greatest water discharge was observed in the North Passage. Suspended sediment concentrations were highest in the South Channel of the South Passage, although in contrast to the North Passage little of the suspended sediment was coarse. The high sediment concentrations in the South Channel appear to be the result of oscillatory (net transport upstream) movement of material, in contrast to the marked seaward transport measured in the North Passage.Key words: Yangtze River, sedimentation, discharge, transport, estuary
The Mudflat System of China
Authors: Wang Ying
Published: April 2011

Most of the 2000 km of intertidal mudflat on the Chinese coastline is developed in the mesotidal Bohai Sea, where the Yellow River now discharges, and on its pre-1855 delta 600 km to the south on the Yellow Sea coast. The Yellow River has the largest sediment suspended load of any river in the world, with an average of 24.7 kg of sediment per cubic metre of water at its mouth. Four hundred million tons of sediment are deposited annually in the lower reaches of the river, and 1200 million tons are transported to sea in the surface mud plume. This accumulates either in the deeper waters of Bohai Bay or on the intertidal mudflats. These mudflats are typically 3 km wide, but are up to 18 km wide at the delta. They are divided into four zones: the polygonal zone with mud cracks and sparse vegetation above normal HTL; the inner depositional zone of mud on the higher part of the flat; a central erosional zone; and an outer depositional zone of silt on the lower intertidal flat. Landwards a salt marsh is developed. Seawards the sediment passes from sandy silt at LTL to fine mud (silt and clay) in water depths of 10 m. The historical changes in the course of the Yellow River are well known, and the formation of cheniers on the Bohai Bay coast can be correlated with times when there was little or no fluvial sediment supply. For almost 700 yr prior to 1855, the Yellow River discharged to the Yellow Sea in North Jiangsu. Submarine sand bars reworked by tidal currents from the submerging former delta mouth protect about 200 km of coastline from erosion, and intertidal flats are prograding. Elsewhere in North Jiangsu, coastal retreat is rapid, and in places a modern chenier-like shell beach is developing. The history of development of this entire coastal system is dominated by the Yellow River and anthropogenic modifications of its basin.Key words: sediment, mudflats, Yellow River, Bohai Bay, China
Behavior of Nitrogen Nutrients and Dissolved Silica in the Ems–Dollard Estuary
Authors: Helder W. , Vries R. T. P. de , Loeff M. M. Rutgers van der
Published: April 2011

Using natural fluorescence and salinity as tracers to distinguish between two freshwater inputs (River Ems, 125 m3∙s−1; and River WWA, 12.5 m3∙s−1) in the Ems–Dollard Estuary, deviations from conservative behavior for nutrients (ammonia, nitrite, nitrate, and silicate) were calculated. With the aid of time scales, derived from a one-dimensional mixing and flushing model, rates of net nitrification (2.5 mmol∙m−2∙d−1), net denitrification (2.0 mmol∙m−2∙d−1), and silica dissolution (2.3 mmol∙m−2∙d−1) were estimated. The observed production of dissolved silica during estuarine mixing has not been reported in most studies on other estuaries.Key words: estuaries, denitrification, nitrification, silica-dissolution, mixing and flushing model, natural fluorescence, Wadden Sea, Ems–Dollard Estuary
Primary Production and Respiration in Pelagic and Benthic Communities at Two Intertidal Sites in the Upper Bay of Fundy
Authors: Hargrave B. T. , Prouse N. J. , Phillips G. A. , Neame P. A.
Published: April 2011

Primary production by microalgae on intertidal sediments during ebb tide at two sites in Cumberland and Minas Basin, Bay of Fundy, amounted to 47–83 g C∙m−2∙yr−1 Phytoplankton production measured during flood tide over intertidal sediments in Cumberland Basin varied from 4–10 g C∙m−2∙yr−1 with respiration in the water column between 6 and 12 g∙C∙m−2∙yr−1 depending on concentrations of suspended matter. Respiration by undisturbed sediments (47–62 g C∙m−2∙yr−1) was measured at both locations to estimate aerobic metabolic consumption of organic matter.Maximum rates of benthic primary production occurred during early and late summer at both locations but Values at the Cumberland Basin sites were two to three times greater than those observed in Minas Basin; Chlorophyll a in surface sediments was also lower at the stations in Minas Basin where coarser grained deposits reflect extensive sediment transport. Annual benthic respiration at the two stations in Cumberland Basin, however, was only slightly greater than that at four stations in Minas Basin. Spartina marshes, phytoplankton, and benthic microalgae may provide supplies of organic matter for aerobic consumption in these intertidal sediments which are more similar than are measures of benthic primary production.Key words: benthic microalgae, primary production, intertidal community metabolism, Bay of Fundy
Suspended Load and Solubility Affect Sedimentation of Petroleum Hydrocarbons in Controlled Estuarine Ecosystems
Authors: Gearing J. N. , Gearing P. J.
Published: April 2011

The concentrations of No. 2 fuel oil and a suite of hydrocarbons with varying chemical properties (perhydrofluorene, pristane, biphenyl, 1-methylnaphthalene, 9-methylanthracene, and pyrene) were measured over time in the water column, on suspended particles, and in the sediments of two controlled microcosms receiving different amounts of mixing energy. The initial aqueous concentrations of the No. 2 fuel oil and other hydrocarbons were 330–500 μg/L and 0.80–10.8 μg/L, respectively. The levels of suspended particles were 3–5 mg/L in the control microcosm and up to 160 mg/L in the highly mixed system. The simulated storm made no major difference in the overall fate of the hydrocarbons. The concentration on particles collected in sediment traps was considerably lower in the tank with high suspended loads, and roughly equal amounts of hydrocarbons were eventually measured in the sediments of each microcosm. The percentage sedimented and residence time in the sediment varied with the lipophilicity and degradability of each hydrocarbon. Fifty percent or more of the least soluble hydrocarbons (aromatics with three or more rings, and saturates) were transported to the sediments. Most of the saturates were more persistent in the sediment than the two-ring aromatics. Aromatics of this class with additional substituent aliphatic groups showed increases in their degrees of sorption and sedimentary residence times in a regular manner. Three- and four-ringed aromatics were similar to the saturates in their sedimentary behavior. After 23 wk, the sediments contained a reduced but still significant fraction (~1/7) of the added petroleum hydrocarbons, enriched in branched and cyclic saturates and high molecular weight aromatics.
Trace Element Distributions in the Gulf Stream Adjacent to the Southeastern Atlantic Continental Shelf—Influence of Atmospheric and Shelf Water Inputs
Authors: Wallace Gordon T. , Dudek Nan , Dulmage Rhonda , Mahoney Ormonde
Published: April 2011

As part of an effort to define processes that control the exchange of trace elements between southeastern Atlantic shelf waters and the Gulf Stream at the shelf boundary we determined the vertical distribution of particulate Al, Fe, Mn, Ni, Cu, Zn, Pb, and Cd and total dissolvable Fe, Ni, Cu, Zn, Pb, and Cd in the Gulf Stream adjacent to the shelf. Simultaneous determination of the particulate forms of Cu, Ni, and Cd and potential carrier phase indicators such as particulate Al, Fe, Mn, and organic C permitted assessment of the relative importance of clay minerals, hydrous oxides, and organic matter in the control of the trace element content of suspended matter. Particulate trace element concentration data were used in conjunction with a first-order removal model to estimate downward vertical fluxes of Fe, Mn, Ni, Cu, Pb, and Cd. Comparison of these flux estimates with atmospheric inputs of these same elements indicated that, with the possible exceptions of Mn and Cu, vertical processes largely control the distribution of trace elements in the Gulf Stream and that these processes are primarily biological in nature. Estimates of "new" production, in concert with an estimated vertical flux of C and the observed nitrate concentration profile, were used to predict a vertical eddy diffusion coefficient of ~0.4 cm2∙s−1 in the highly stratified region of the Gulf Stream. Injection of trace elements from shelf waters into surface Gulf Stream waters, with the possible exceptions of Mn and Cu, are apparently masked by a combination of atmospheric input and large-scale physical mixing processes.
Distributions and Fate of Volatile Organic Compounds in Narragansett Bay, Rhode Island
Authors: Wakeham S. G. , Goodwin J. T. , Davis A. C.
Published: April 2011

A wide range of volatile organic compounds (VOC) were measured in the water column along a north–south transect in Narragansett Bay, Rhode Island, during two summers and two winters. The dominant VOC are chlorinated C2-hydrocarbons, chlorobenzenes, and aromatic hydrocarbons. Major sources for these anthropogenic compounds are municipal and industrial wastewaters discharged into the upper bay. Concentration trends along the transect are variable depending on the compound class and the season of sampling, indicating that different processes control the distributions of different compounds. Volatilization apparently is a major removal process for all VOC. Calculations suggest water column residence times with respect to volatilization of 150–300 h in Narragansett Bay. Biodegradation, particularly in summer, is important for aromatic hydrocarbons, which are degraded in a few days. Sorption onto particulate matter and eventual sedimentation is minor, except for the higher molecular weight alkanes.
Deposition of Fine and Coarse Sand in an Open-Work Gravel Bed
Authors: Carling Paul A.
Published: April 2011

The siltation of an experimental gravel bed, with three grades of sands moving in suspension and as bedload, was examined in a flume. For low suspended sediment concentrations (<300 mg∙L−1) the mean deposition rate was 1.34% of the initial gravel volume filled per hour. Deposition rates for sands 0.15–1.4 mm in diameter with suspended sediment concentrations of 38–9110 mg∙L−1 and Froude numbers in the range 0.008–1.21 were constant with respect to Froude number. For all concentrations the deposition rate was strongly linearly correlated with the suspended sediment concentration. The downstream decrease in siltation rate from a point source was a negative exponential function of distance from that source. Turbulent resuspension of sediment prevented deposition in a surface layer of gravel of thickness approximately equal to the mean grain size of the gravel. Mean flow data, especially where derived from velocity profile data measured in the outer boundary layer, have limited value for siltation investigations concerned with processes occurring very close to the bed. Practically, results indicate that open-work gravels will rapidly become silted in flows with low concentrations of suspended solids. Consequently, mechanical cleansing of spawning beds has limited value where sediment pollution is likely to be a recurrent problem. A simple equation describing the downstream extent of silting from a point pollution source is presented that requires verification in natural streams.
Resource Management Biology for the Edible Kelp Cymathere triplicata
Authors: Roland William G.
Published: April 2011

Sporophytes of Cymathere triplicata appeared only in spring and density declined thereafter; overwinter mortality was 100%. Standing crop estimates were highest during May–July. Plants were heaviest and generally had the longest and widest laminae in July and August. Thickness of laminae increased through December, the greatest increase being in the basal part of the lamina. Sori were initiated in August and approximately 90% of plants were fertile by September. Epibiota were most abundant during August–October. Moisture content decreased 2–3% from spring through winter. A plot subjected to almost total harvest in August had approximately 50% recovery of standing crop after 1 yr and full recovery after 2 yr, compared with a control area. A comparable recovery rate was seen for a similar September harvest. Sustained yields for a region of coastline should be maintained if no more than 50% of the standing crop is removed by intensive harvesting within plots, and if harvesting is not allowed prior to spore production. Best quality laminae in terms of length, thickness, weight per area, and moisture content occurred in August and September.
Forms of Aqueous Aluminum in Acidified Catchments of Central Ontario: A Methodological Analysis
Authors: LaZerte Bruce D.
Published: April 2011

Separating the different forms of aqueous aluminum is essential for determining their relative toxicity in acidified streams and lakes. A short extraction with oxine at pH 8.3 separates inorganic monomeric and organic aluminum from the polymeric and amorphous forms. The organic fraction can be eliminated by equilibrium dialysis prior to extraction. In many cases, the inorganic fraction can also be estimated from free and total fluoride measurements. The two methods agree well in artificial solutions (R2 = 0.997) and reasonably well in natural waters (R2 = 0.82), although the computed estimates tend to be slightly lower than the directly measured values. During spring snowmelt in the Muskoka–Haliburton region of central Ontario, very little polymeric and amorphous aluminum was found, and most of the inorganic monomeric fraction was in the fluoride complexes. I present an empirical model that predicts inorganic monomeric aluminum in these waters (R2 = 0.90) using total organic carbon and the aluminum measured by a short extraction without dialysis.
Ionic Strength Correction for Extent of Ammonia Ionization in Freshwater
Authors: Messer Jay J. , Ho Jimmy , Grenney William J.
Published: April 2011

Previously published tabulations of percent ammonia ionization inherently define pH in terms of concentration (molality) rather than the measured entity, hydrogen ion activity. In hard waters this may result in overestimation of the un-ionized NH3 concentration by 10–20%. The thermodynamic basis for current empirical methods for temperature correction is examined, and a tabulation of NH3 ionization fraction as a function of pH, temperature, and dissolved solids, together with a corresponding predictive equation, is presented.
Winter Distribution of Ringed Seals (Phoca hispida) in the Barrow Strait Area, Northwest Territories, Determined by Underwater Vocalizations
Authors: Calvert Wendy , Stirling Ian
Published: April 2011

In order to assess underice distribution of ringed seals (Phoca hispida) in winter, we made recordings from 23 to 30 April 1982 at 32 sites chosen to represent different habitats in the High Arctic. By regressing the vocalization rate at each site against variables for habitat quality, we found that sites in smooth interisland channels had significantly more vocalizations than sites in bays, and sites with frequent human activity had vocalization rates similar to the overall average. Although differences in vocalization rates correlated with some measured and estimated habitat variables, there was too much overlap between sites for vocalization rate alone to be useful in separating suitable and unsuitable pupping habitat. Recordings made at one site over 4 d showed a diel cycle in which vocalization rate was highest from about 08:30 to 16:30 and lowest at night.
Ultrasound Imaging Used to Detect Cysts of Henneguya salminicola (Protozoa: Myxozoa) In the Flesh of Whole Pacific Salmon
Authors: Boyce N. P.
Published: April 2011

Whole sockeye salmon, Oncorhynchus nerka, were scanned using an ultrasound imaging system. In real images, representing cross-sections of the soma, cysts (confirmed by subsequent dissection) were depicted as dark spheres against a lighter background of somatic muscle. This technique proved to be unsatisfactory with fish that were previously frozen.
Adenovirus-Like Particles Associated with a Disease of Cultured White Sturgeon, Acipenser transmontanus
Authors: Hedrick R. P. , Speas J. , Kent M. L. , McDowell T.
Published: April 2011

Juvenile white sturgeon, Acipenser transmontanus, suffering from a chronic mortality had enlarged nuclei particularly in the epithelium of the straight intestine and spiral valve. These nuclei were often five times larger than those of uninfected cells and contained numerous virus particles with an average diameter of 74 nm. Although nuclear changes induced by the virus are similar to those described for certain members of the Herpesviridae, the virion morphology and absence of an envelope were, however, more characteristic of the Adenoviridae. Attempts to isolate the virus using established cell lines from selected freshwater fish and two lines recently developed from white sturgeon were unsuccessful. Nuclear enlargement indicating virus infection was, however, observed in juvenile sturgeon receiving intraperitoneal injections of homogenates of viscera from infected fish.