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At least 1,099 records · Page 61Linked to original sources
USGS2001

Detection of bacteria from biological mixtures using immunomagnetic separation combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

A rapid method for identifying specific bacteria from complex biological mixtures using immunomagnetic separation coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been developed. The technique employs commercially available magnetic beads coated with polycolonal antibodies raised against specific bacteria and whole cell analysis by MALDI-MS. A suspension of a bacterial mixture is mixed with the immunomagnetic beads specific for the target microorganism. After a short incubation period (20 mins) the bacteria captured by the beads are washed, resuspended in deionized H2O and directly applied onto a MALDI probe. Liquid suspensions containing bacterial mixtures can be screened within 1 h total analysis time. Positive tests result in the production of a fingerprint mass spectrum primarily consisting of protein biomarkers characteristic of the targeted microorganism. Using this procedure, Salmonella choleraesuis was isolated and detected from standard bacterial mixtures and spiked samples of river water, human urine, and chicken blood. Copyright ?? 2001 John Wiley & Sons, Ltd.

Rapid Communications in Mass Spectrometry↗
USGS2014

Isotopic nitrogen in fecal fiber as an indicator of winter diet in caribou and muskoxen

RATIONALE: The ratios of stable nitrogen isotopes (δ 15 N values) in excreta have been used to examine aspects of trophic and nutritional ecology across taxa. Nitrogen fractions in feces of herbivores include endogenous (e.g., sloughed intestinal cells, unresorbed digestive secretions, and microbial debris) and dietary sources. For animals such as large herbivores, that have diets and feces with high concentrations of indigestible fiber, endogenous 15 N may constrain the use of fecal δ 15 N values to estimate dietary δ 15 N values and reconstruct diets. METHODS: We compared two techniques (detergent and detergent-free) to isolate fractions of plant fibers in the forages of caribou ( Rangifer tarandus ) and muskoxen ( Ovibos moschatus ); estimated the discrimination factors between the δ 15 N values of fecal fiber residues and of the diets of captive animals; and used the more effective isotopic tracer of dietary δ 15 N values to examine the relationships between the δ 15 N values of fecal residues and diet composition in several populations of wild caribou and muskoxen throughout North America in winter. RESULTS: The detergent-based approach contaminated the fractions of plant fibers in forages and feces with 14 N, whereas the detergent-free method was a good proxy to estimate δ 15 N values of plant fibers (r 2 = 0.92) and provided a better estimate of the fecal-fiber to diet discrimination factor for both species (caribou = 3.6‰; muskoxen = 2.8‰). In wild populations, the δ 15 N values of fecal fibers reflected diet composition in muskoxen (adjusted R 2 = 0.43) but not caribou (adjusted R 2 = 0.06). CONCLUSIONS: Contamination from detergent residues prohibited the use of detergent extraction in isolating forage 15 N from endogenous 15 N in the feces of herbivores. Although δ 15 N values in fecal fibers can be used to track dietary δ 15 N values in wild herbivores, discrimination between fecal extracts and diet may vary with the contribution of endogenous nitrogen (N), and, therefore, residual endogenous 15 N in feces may limit dietary reconstructions from fecal δ 15 N values for some large herbivores.

Alaska↗
USGS2020

Gene transcript profiling in desert bighorn sheep

Respiratory disease is a key factor affecting the conservation and recovery of bighorn sheep ( Ovis canadensis ) populations. Innovative, minimally invasive tools such as gene transcription–based diagnostics have the potential to improve our understanding of the broad range of factors that can affect the health of wild sheep. Evaluation of transcript levels for genes representative of multiple internal systems enables measurement of physiological responses of individuals as well as populations to environmental stressors such as pathogens, nutritional deficiency, or contaminants. We developed real‐time polymerase chain reaction assays for 14 genes of interest representing systems including inflammation, cell signaling, detoxification, antiviral, antibacterial, or general stress. Initial results from desert bighorn sheep ( O. c. nelsoni ) sampled from the River, Muddy, and Bare mountains as well as from the Pintwater Range, in southern Nevada, USA, indicated unique transcript profiles associated with each population. This initial study provides the framework from which controlled variable or longitudinal studies can be made, thus augmenting the potential to inform management actions in the future.

Nevada↗
USGS1993

Polyphosphate present in DNA preparations from fungal species of Collectotrichum inhibits restriction endonucleases and other enzymes

During the development of a procedure for the isolation of total genomic DNA from filamentous fungi (Rodriguez, R. J., and Yoder, 0. C., Exp. Mycol. 15, 232-242, 1991) a cell fraction was isolated which inhibited the digestion of DNA by restriction enzymes. After elimination of DNA, RNA, proteins, and lipids, the active compound was purified by gel filtration to yield a single fraction capable of complete inhibition of restriction enzyme activity. The inhibitor did not absorb uv light above 220 nm, and was resistant to alkali and acid at 25°C and to temperatures as high as 100°C. More extensive analyses demonstrated that the inhibitor was also capable of inhibiting T4 DNA ligase and Taq I DNA polymerase, but not DNase or RNase. Chemical analyses indicated that the inhibitor was devoid of carbohydrates, proteins, lipids, and nucleic acids but rich in phosphorus. A combination of nuclear magnetic resonance, metachromatic shift of toluidine blue, and gel filtration indicated that the inhibitor was a polyphosphate (polyP) containing approximately 60 phosphate molecules. The mechanism of inhibition appeared to involve complexing of polyP to the enzymatic proteins. All species of Colletotrichum analyzed produced polyP equivalent in chain length and concentration. A modification to the original DNA extraction procedure is described which eliminates polyP and reduces the time necessary to obtain DNA of sufficient purity for restriction enzyme digestion and Taq I polymerase amplification.

Analytical Biochemistry↗
USGS1996

Immune and endocrine responses of adult spring Chinook salmon during freshwater migration and sexual maturation

The immune –endocrine responses in spring chinook salmon ( Oncorhynchus tshawytscha ) were examined during their freshwater migration and final maturation. In 1990, migrating fish had high plasma cortisol titres (means 200 ng ml −1 ) and generated relatively few antibody-producing cells (APC) from peripheral blood leukocytes (PBL) (100 –200 per culture). After three weeks acclimation in constant environmental conditions, plasma cortisol was reduced and APC increased. There were no changes in number or affinity of glucocorticoid receptors. Concentrations of several sex steroids correlated with APC in females, but there were no such correlations in males. In 1993, fish in a hatchery had significantly greater cortisol concentrations in primary circulation than in secondary circulation, but sex steroid concentrations did not differ between circulations. Mean lysozyme activity in the primary and secondary circulation did not differ in June. In August, activity in the primary circulation was significantly less than that of the secondary, perhaps the result of acute stress associated with sampling. While some sex steroids correlated with lysozyme activity, the fact that in both years all endocrine and immune variables that correlated with each other also correlated with the date of sample, raises the question as to whether or not these are cause-and-effect relations.

Fish and Shellfish Immunology↗
USGS2000

Fish DNA vaccine against infectious hematopoietic necrosis virus: efficacy of various routes of immunization

The DNA vaccine, pIHNVw-G, contains the gene for the glycoprotein (G) of the rhabdovirus infectious hematopoietic necrosis virus (IHNV), a major pathogen of salmon and trout. The relative efficacy of various routes of immunisation with pIHNVw-G was evaluated using 1.8 g rainbow trout fry vaccinated via intramuscular injection, scarification of the skin, intraperitoneal injection, intrabuccal administration, cutaneous particle bombardment using a gene gun, or immersion in water containing DNA vaccine-coated beads. Twenty-seven days after vaccination neutralising antibody titres were determined, and 2 days later groups of vaccinated and control unvaccinated fish were subjected to an IHNV immersion challenge. Results of the virus challenge showed that the intramuscular injection and the gene gun immunisation induced protective immunity in fry, while intraperitoneal injection provided partial protection. Neutralising antibodies were not detected in sera of vaccinated fish regardless of the route of immunisation used, suggesting that cell mediated immunity may be at least partially responsible for the observed protection.

Fish and Shellfish Immunology↗
USGS1999

Cloning, in Vitro expression, and novel phylogenetic classification of a channel catfish estrogen receptor

We obtained two channel catfish estrogen receptor (ccER) cDNA from liver of female fish using RT–PCR. The two fragments were identical in sequence except that the smaller one had an out-of-frame deletion in the E domain, suggesting the existence of ccER splice variants. The larger fragment was used to screen a cDNA library from liver of a prepubescent female. A cDNA was obtained that encoded a 581-amino-acid ER with a deduced molecular weight of 63.8 kDa. Extracts of COS-7 cells transfected with ccER cDNA bound estrogen with high affinity ( K d = 4.7 nM) and specificity. Maximum parsimony and Neighbor Joining analyses were used to generate a phylogenetic classification of ccER on the basis of 18 full-length ER sequences. The tree suggested the existence of two major ER branches. One branch contained two clearly divergent clades which included all piscine ER (except Japanese eel ER) and all tetrapod ERα, respectively. The second major branch contained the eel ER and the mammalian ERβ. The high degree of divergence between the eel ER and mammalian ERβ suggested that they also represent distinct piscine and tetrapod ER. These data suggest that ERα and ERβ are present throughout vertebrates and that these two major ER types evolved by duplication of an ancestral ER gene. Sequence alignments with other members of the nuclear hormone receptor superfamily indicated the presence of 8 amino acids in the E domain that align exclusively among ER. Four of these amino acids have not received prior research attention and their function is unknown. The novel finding of putative ER splice variants in a nonmammalian vertebrate and the novel phylogenetic classification of ER offer new perspectives in understanding the diversification and function of ER.

General and Comparative Endocrinology↗
USGS2000

Gonadotropin-Releasing hormones in the brain and pituitary of the white sucker

The present study investigated GnRH forms within the brain of a representative of the order Cypriniformes, the white sucker, Catostomus commersoni, using HPLC, RIA, and immunocytochemistry . Several immunoreactive (ir) GnRH forms were identified in the brain of the white sucker by chromatography and radioimmunoassay , including ir-salmon GnRH, ir-lamprey GnRH-I and -III, and ir-chicken GnRH-II. Results from immunocytochemical studies were consistent with multiple GnRH forms distributed in different patterns, particularly for fibers. Neuronal perikarya containing ir-salmon GnRH and ir-lamprey-like GnRH were found laterally within the preoptic area and rostral hypothalamus . Cells containing exclusively ir-salmon GnRH appeared slightly more rostrally, but in the same region. Fibers containing ir-salmon GnRH and ir-lamprey-like GnRH were seen throughout the caudal telencephalon and extended into the diencephalon , toward the pituitary . Fibers containing ir-chicken-II-like GnRH were also seen in the caudal telencephalon, but were concentrated more dorsally in the diencephalon. Within the pituitary, fibers containing ir-salmon GnRH and ir-lamprey-like GnRH entered the neurohypophysis , but differed in their destinations. Fibers containing ir-salmon GnRH remained within the neurohypophysis, while fibers containing ir-lamprey-like GnRH targeted adenohypophyseal tissue. These findings are consistent with the hypothesis that multiple GnRH forms with multiple functions exist within the brain and pituitary of teleosts and provide further evidence of a lamprey-like GnRH within an early evolved teleost species.

General and Comparative Endocrinology↗
USGS2000

Phylogenetic sequence analysis, recombinant expression, and tissue distribution of a channel catfish estrogen receptor beta

An estrogen receptor β (ERβ) cDNA fragment was amplified by RT-PCR of total RNA extracted from liver and ovary of immature channel catfish. This cDNA fragment was used to screen an ovarian cDNA library made from an immature female fish. A clone was obtained that contained an open reading frame encoding a 575-amino-acid protein with a deduced molecular weight of 63.9 kDa. Maximum parsimony and Neighbor Joining analyses were used to generate a phylogenetic classification of channel catfish ERβ on the basis of 25 full-length teleost and tetrapod ER sequences. The consensus tree obtained indicated the existence of two major vertebrate ER subtypes , α and β. Within each subtype, and in accordance with established phylogenetic relationships , teleost and tetrapod ER were monophyletic confirming the results of a previous analysis (Z. Xia et al ., 1999, Gen. Comp. Endocrinol . 113, 360–368). Extracts of COS-7 cells transfected with channel catfish ERβ cDNA bound estrogen with high affinity ( K d = 0.21 nM) and specificity. The affinity of channel catfish ERβ for estrogen was higher than previously reported for channel catfish ERα. As determined by qualitative RT-PCR, the tissue distributions of ERα and ERβ were similar but not identical. Both ER subtypes were present in ovary and testis. ERα was found in all other tissues examined from juvenile and mature fish of both sexes. ERβ was also found in most tissues except, in most cases, whole blood and head kidney. Interestingly, the pattern of expression of ER subtypes in head kidney always corresponded to the pattern in whole blood. In conclusion, we isolated a channel catfish ERβ with ligand-binding affinity and tissue expression patterns different from ERα. Also, we confirmed the validity of our previously proposed general classification scheme for vertebrate ER into α and β subtypes and within each subtype, into teleost and tetrapod clades.

General and Comparative Endocrinology↗
USGS1998

Three closely related herpesviruses are associated with fibropapillomatosis in marine turtles

Green turtle fibropapillomatosis is a neoplastic disease of increasingly significant threat to the survivability of this species. Degenerate PCR primers that target highly conserved regions of genes encoding herpesvirus DNA polymerases were used to amplify a DNA sequence from fibropapillomas and fibromas from Hawaiian and Florida green turtles. All of the tumors tested (n= 23) were found to harbor viral DNA, whereas no viral DNA was detected in skin biopsies from tumor-negative turtles. The tissue distribution of the green turtle herpesvirus appears to be generally limited to tumors where viral DNA was found to accumulate at approximately two to five copies per cell and is occasionally detected, only by PCR, in some tissues normally associated with tumor development. In addition, herpesviral DNA was detected in fibropapillomas from two loggerhead and four olive ridley turtles. Nucleotide sequencing of a 483-bp fragment of the turtle herpesvirus DNA polymerase gene determined that the Florida green turtle and loggerhead turtle sequences are identical and differ from the Hawaiian green turtle sequence by five nucleotide changes, which results in two amino acid substitutions. The olive ridley sequence differs from the Florida and Hawaiian green turtle sequences by 15 and 16 nucleotide changes, respectively, resulting in four amino acid substitutions, three of which are unique to the olive ridley sequence. Our data suggest that these closely related turtle herpesviruses are intimately involved in the genesis of fibropapillomatosis.

Florida, Hawai'i↗
USGS2014

Plenary: Progress in Regional Landslide Hazard Assessment—Examples from the USA

Landslide hazard assessment at local and regional scales contributes to mitigation of landslides in developing and densely populated areas by providing information for (1) land development and redevelopment plans and regulations, (2) emergency preparedness plans, and (3) economic analysis to (a) set priorities for engineered mitigation projects and (b) define areas of similar levels of hazard for insurance purposes. US Geological Survey (USGS) research on landslide hazard assessment has explored a range of methods that can be used to estimate temporal and spatial landslide potential and probability for various scales and purposes. Cases taken primarily from our work in the U.S. Pacific Northwest illustrate and compare a sampling of methods, approaches, and progress. For example, landform mapping using high-resolution topographic data resulted in identification of about four times more landslides in Seattle, Washington, than previous efforts using aerial photography. Susceptibility classes based on the landforms captured 93 % of all historical landslides (all types) throughout the city. A deterministic model for rainfall infiltration and shallow landslide initiation, TRIGRS, was able to identify locations of 92 % of historical shallow landslides in southwest Seattle. The potentially unstable areas identified by TRIGRS occupied only 26 % of the slope areas steeper than 20°. Addition of an unsaturated infiltration model to TRIGRS expands the applicability of the model to areas of highly permeable soils. Replacement of the single cell, 1D factor of safety with a simple 3D method of columns improves accuracy of factor of safety predictions for both saturated and unsaturated infiltration models. A 3D deterministic model for large, deep landslides, SCOOPS, combined with a three-dimensional model for groundwater flow, successfully predicted instability in steep areas of permeable outwash sand and topographic reentrants. These locations are consistent with locations of large, deep, historically active landslides. For an area in Seattle, a composite of the three maps illustrates how maps produced by different approaches might be combined to assess overall landslide potential. Examples from Oregon, USA, illustrate how landform mapping and deterministic analysis for shallow landslide potential have been adapted into standardized methods for efficiently producing detailed landslide inventory and shallow landslide susceptibility maps that have consistent content and format statewide.

Conference Paper↗
USGS2016

Coral calcification and ocean acidification

Over 60 years ago, the discovery that light increased calcification in the coral plant-animal symbiosis triggered interest in explaining the phenomenon and understanding the mechanisms involved. Major findings along the way include the observation that carbon fixed by photosynthesis in the zooxanthellae is translocated to animal cells throughout the colony and that corals can therefore live as autotrophs in many situations. Recent research has focused on explaining the observed reduction in calcification rate with increasing ocean acidification (OA). Experiments have shown a direct correlation between declining ocean pH, declining aragonite saturation state (Ωarag), declining [CO32_] and coral calcification. Nearly all previous reports on OA identify Ωarag or its surrogate [CO32] as the factor driving coral calcification. However, the alternate “Proton Flux Hypothesis” stated that coral calcification is controlled by diffusion limitation of net H+ transport through the boundary layer in relation to availability of dissolved inorganic carbon (DIC). The “Two Compartment Proton Flux Model” expanded this explanation and synthesized diverse observations into a universal model that explains many paradoxes of coral metabolism, morphology and plasticity of growth form in addition to observed coral skeletal growth response to OA. It is now clear that irradiance is the main driver of net photosynthesis (Pnet), which in turn drives net calcification (Gnet), and alters pH in the bulk water surrounding the coral. Pnet controls [CO32] and thus Ωarag of the bulk water over the diel cycle. Changes in Ωarag and pH lag behind Gnet throughout the daily cycle by two or more hours. The flux rate Pnet, rather than concentration-based parameters (e.g., Ωarag, [CO3 2], pH and [DIC]:[H+] ratio) is the primary driver of Gnet. Daytime coral metabolism rapidly removes DIC from the bulk seawater. Photosynthesis increases the bulk seawater pH while providing the energy that drives calcification and increases in Gnet. These relationships result in a correlation between Gnet and Ωarag, with both parameters being variables dependent on Pnet. Consequently the correlation between Gnet and Ωarag varies widely between different locations and times depending on the relative metabolic contributions of various calcifying and photosynthesizing organisms and local rates of carbonate dissolution. High rates of H+ efflux continue for several hours following the mid-day Gnet peak suggesting that corals have difficulty in shedding waste protons as described by the Proton Flux Model. DIC flux (uptake) tracks Pnet and Gnet and drops off rapidly after the photosynthesis-calcification maxima, indicating that corals can cope more effectively with the problem of limited DIC supply compared to the problem of eliminating H+. Predictive models of future global changes in coral and coral reef growth based on oceanic Ωarag must include the influence of future changes in localized Pnet on Gnet as well as changes in rates of reef carbonate dissolution. The correlation between Ωarag and Gnet over the diel cycle is simply the result of increasing pH due to photosynthesis that shifts the CO2-carbonate system equilibria to increase [CO32] relative to the other DIC components of [HCO3] and [CO2]. Therefore Ωarag closely tracks pH as an effect of Pnet, which also drives changes in Gnet. Measurements of DIC flux and H+ flux are far more useful than concentrations in describing coral metabolism dynamics. Coral reefs are systems that exist in constant disequilibrium with the water column.

Book chapter↗
USGS1993

Osmoregulatory actions of growth hormone and its mode of action in salmonids: A review

Osmoregulatory actions of growth hormone (GH) and its mode of action in salmonids are reviewed. We present evidence suggesting that insulin-like growth factor I (IGF-I) mediates some of the actions of GH on seawater acclimation. Plasma concentration and turnover of GH rise following exposure to seawater. Exogenous GH ( in vivo ) increases gill Na + ,K + -ATPase activity and the number of gill chloride cells, and inhibits an increase in plasma osmolarity and ions following transfer of fish to seawater. A single class of high affinity GH receptors is present in the liver, gill, intestine, and kidney. The levels of IGF-I mRNA in the liver, gill and kidney increased after GH-injection. After transfer to seawater, IGF-I mRNA increased in the gill and kidney following the rise in plasma GH, although no significant change was seen in the liver. Injection of IGF-I improved the ability of the fish to maintain plasma sodium levels after transfer to seawater. GH treatment also sensitizes the interrenal to adrenocorticotropin (ACTH), increasing cortisol secretion. Both cortisol and IGF-I may be involved in mediating the action of GH in seawater adaptation, although studies on the effect of GH on osmoregulatory physiology of non-salmonid species are limited. An integrated model of the osmoregulatory actions of GH is presented, and areas in need of research are outlined.

Fish Physiology and Biochemistry↗
USGS1972

Microcrystalline sphalerite in resin globules suspended in Lake Kivu, East Africa

The origin and chemical nature of micron-sized spheres found as suspended particles in Lake Kivu are examined. It can be shown that the hollow spheres, with a wall thickness of 500 Å, consist of a complex polymeric resinous material which has little functionality, except for hydroxyl groups. The spheres arise in the process of degassing of water samples at depth. Tiny gas bubbles, about 1 micron in size, act as scavengers of dissolved resinous material. The newly created resinous membrane promotes the selective coordination of zinc dissolved in the water column. In the prevailing H 2 S regime, formation of sphalerite crystals in induced. The size range of the crystals, 5 to 50 Å, corresponds to 1 to 10 unit cells and suggests that the resinous membrane also acts as a template in sphalerite growth processes. The sources of the zinc and dissolved gases (CO 2 , CH 4 , H 2 S) are hydrothermal springs seeping from the lake bottom into the basin. Water discharge is substantial; about 100 years are required to fill the lake to its present level (ca. 550 km 3 water). The average Kivu water contains 2 ppm zinc. Thus, 1 million tons of zinc are contained in Lake Kivu in the form of sphalerite.

Lake Kivu↗
USGS1994

Flow cytometry for monitoring contaminant exposure in black-crowned night-herons

The flow cytometry method (FCM) was employed to determine cellular DNA content of black-crowned night-heron ( Nycticorax nycticorax ) embryos and 10-day-old chicks collected at sites differing in types of chemical contamination. The coefficient of variation of DNA content (CV) in blood collected from embryos suggested cytogenetic damage at a site in Louisiana known to be contaminated with petroleum. Blood CV from chicks suggested genetic damage at a site in Texas also known to be contaminated with petroleum. Spleen CVs in chicks were significantly lower than respective means from the reference site. The CVs of chick blood and liver and spleen negatively correlated, suggesting recovery of spleen and liver cells after exposure to a clastogenic compound. Thus, the lower CVs may also have been indicative of genetic damage. Based on the findings of this study, FCM is a potential indicator of certain environmental contaminants in black-crowned night-herons.

Archives of Environmental Contamination and Toxico↗
USGS1993

Geobacter metallireducens gen. nov. sp. nov., a microorganism capable of coupling the complete oxidation of organic compounds to the reduction of iron and other metals

The gram-negative metal-reducing microorganism, previously known as strain GS-15, was further characterized. This strict anaerobe oxidizes several short-chain fatty acids, alcohols, and monoaromatic compounds with Fe(III) as the sole electron acceptor. Furthermore, acetate is also oxidized with the reduction of Mn (IV), U (VI), and nitrate. In whole cell suspensions, the c -type cytochrome(s) of this organism was oxidized by physiological electron acceptors and also by gold, silver, mercury, and chromate. Menaquinone was recovered in concentrations comparable to those previously found in gram-negative sulfate reducers. Profiles of the phospholipid ester-linked fatty acids indicated that both the anaerobic desaturase and the branched pathways for fatty acid biosynthesis were operative. The organism contained three lipopolysaccharide hydroxy fatty acids which have not been previously reported in microorganisms, but have been observed in anaerobic freshwater sediments. The 16S rRNA sequence indicated that this organism belongs in the delta proteobacteria. Its closest known relative is Desulfuromonas acetoxidans . The name Geobacter metallireducens is proposed.

Archives of Microbiology↗
USGS1979

The thermal expansion of anhydrite to 1000° C

The thermal expansion of anhydrite, CaSO 4 , has been measured from 22° to 1,000° C by X-ray diffraction, using the Guinier-Lenné heating powder camera. The heating patterns were calibrated with Guinier-Hägg patterns at 25° C, using quartz as internal standard. Heating experiments were run on natural anhydrite (Bancroft, Ontario), which at room temperature has lattice constants in close agreement with those of synthetic material. The orthorhombic unit cell at 22° C (space group Amma ) has a =7.003 (1) Å, b =6.996 (2) Å and c =6.242 (1) Å, V =305.9 (2) Å 3 . At room temperature, the thermal expansion coefficients α and β (α in °C −1 ×10 4 , β in °C −2 ×10 8 ) are for a , 0.10, −0.69; for b , 0.08, 0.19; for c , 0.18, 1.60; for V , 0.37, 1.14. Second-order coefficients provide an excellent fit over the whole range to 1,000° C.

Physics and Chemistry of Minerals↗
USGS1992

Measurement of filtration rates by infaunal bivalves in a recirculating flume

A flume system and protocol for measuring the filtration rate of infaunal bivalves is described. Assemblages of multi-sized clams, at natural densities and in normal filter-feeding positions, removed phytoplankton suspended in a unidirectional flow of water. The free-stream velocity and friction velocity of the flow, and bottom roughness height were similar to those in natural estuarine waters. Continuous variations in phytoplankton (Chroomonas salinay) cell density were used to measure the filtration rate of the suspension-feeding clam Potamocorbula amurensis for periods of 2 to 28 h. Filtration rates of P. amurensis varied from 100 to 580 liters (gd)-1 over a free-stream velocity range of 9 to 25 cm s-1. Phytoplankton loss rates were usually constant throughout the experiments. Our results suggest that suspension-feeding by infaunal bivalves is sensitive to flow velocity. ?? 1992 Springer-Verlag.

Marine Biology↗