bluuebunny/crossref_metadata_2025 huggingface dataset:
CTLA‐4 49 A/G dimorphism and type 1 diabetes susceptibility: a French case–control study and segregation analysis. Evidence of a maternal effect
Authors: Fajardy I. , Vambergue A. , Stuckens C. , Weill J. , Danze P. M. , Fontaine P.
Published: March 2003

Several studies have demonstrated an association of cytotoxic T lymphocyte‐associated molecule 4 (CTLA‐4) (IDDM 12) alanine 17 with type 1 diabetes, but we wished to study the parental effect of CTLA‐4 49 A/G dimorphism in diabetic families. The CTLA‐4 exon 1 polymorphism (49 A/G), HLA‐DRB1 and insulin gene (INS) variable number tandem repeats (VNTR) were analysed in 134 type 1 diabetic patients vs. 273 control subjects. The segregation analysis for transmission was carried out in 70 informative diabetic families using the transmission distortion test (TDT). All genotyping was performed by PCR‐RFLP. CTLA‐4 49 G allele frequency was not increased in diabetic patients compared to controls (41 vs. 38%, not significant). The distribution of GG, AG and AA CTLA‐4 genotypes was similar in the two groups (13, 57 and 30% vs. 11, 54 and 35%, respectively) and was independent of HLA‐DRB1 or INS VNTR polymorphism. The CTLA‐4 49 G allele showed weak distorted transmission to the diabetic offspring, whereas random transmission was observed in unaffected offspring. This distortion is attributable to a maternal effect (71% compared to the 50% expected ratio; tdt = 4.8; P < 0.03). The combined transmission of maternal CTLA‐4 G with HLA‐DRB1*03 (90%; tdt = 6.4; P < 0.01) and VNTR class I (80%; tdt = 5.4; P < 0.02) enhanced the susceptibility effect of each marker separately. We noted a slight CTLA‐4 49 G and HLA‐DRB1*04 distortion of transmission shared in paternal and maternal diabetic meiosis. In non‐diabetic offspring, the CTLA‐4 49 A allele confers a protective effect in the presence of maternal HLA‐DRB1*03 and paternal HLA‐DRB1*04 alleles. Despite the absence of a positive association of the CTLA‐4 49 G allele with type 1 diabetes, our segregation analysis supports the hypothesis of a modulation by CTLA‐4 49 G/A dimorphism of the susceptibility conferred by maternal HLA‐DRB1*03 inheritance. This potential parental effect needs to be confirmed in a larger data set.
Proficiency testing for HLA‐DRB high‐resolution typing: a 4‐year experience in Italy
Authors: Borelli I. , Fasano M. E. , Curtoni E. S.
Published: March 2003

Twenty‐one Italian laboratories participated for four consecutive years in the collaborative Italian proficiency testing of HLA class II (DRB1, DRB3, DRB4 and DRB5) high‐resolution typing. In this paper the results are analysed. Seven different kinds of errors are described and discussed. The errors were divided into technical errors and errors of allele reporting. Each year, a list of errors made was prepared by our laboratory and discussed collegially with all laboratories. The allele reporting errors diminished over time, as a result of the common discussions. The technical performance of the laboratories did not improve overall for the 21 laboratories participating: for 16 of them results were good or improved in quality, but for the remaining five results deteriorated over time. From this experience, some recommendations for the future emerged. A relevant conclusion was that, to improve the performance of a group of laboratories, the proficiency test is not effective alone, but should be integrated within a framework of continuous collaboration and mutual technical help.
Molecular cloning of agonistic and antagonistic monoclonal antibodies against human 4‐1BB
Authors: Lee U.‐H. , Kwack K. B. , Park J.‐W. , Kwon B. S.
Published: March 2003

Previously, we prepared two different monoclonal antibodies (mAbs) against human 4‐1BB (CD137): an agonistic mAb BBK‐1 and an antagonistic mAb BBK‐2. In this paper, we describe the molecular cloning of these two mAbs and present comparisons of their amino acid sequences. cDNAs encoding the heavy (H) and light (L) chains of the two mAbs were cloned by screening of cDNA libraries constructed from hybridomas secreting these mAbs. Comparisons of amino acid sequences of the two mAbs showed that, while the constant regions of the H and L chains were identical between the two mAbs, the variable region showed 45% identity in H chains and 48% identity in L chains. This suggests that these two mAbs recognize different epitopes of 4‐1BB and may have different effects on the activity of 4‐1BB.
Complementary DNA sequence of the HLA‐B*3924 allele1
Authors: Estefanía E. , Gómez‐Lozano N. , De Pablo R. , Moreno M. E. , Vilches C.
Published: March 2003

We have isolated the complete coding region of HLA‐B*39 from a Spanish Caucasoid, using a new PCR primer for its 5′ untranslated region. The cDNA matched partial genomic sequences of B*3924, an allele whose distribution appears to be restricted to Mediterranean and Arabian Caucasoids. A single amino acid change exclusive to B*3924 (threonine‐98) distinguishes it from B*3903.
β‐glucosidase activity in the presence of copper and goethite
Authors: Geiger G. , Livingston M. P. , Funk F. , Schulin R.
Published: March 2003

We investigated the effect of goethite and copper on almond β‐glucosidase activity. The activity of β‐glucosidase was found to be inhibited at dissolved copper concentrations exceeding 0.2 mm. Copper was most influential in the pH range 5–5.5, at which the enzyme activity was reduced by 50% or more at total copper concentrations of 0.2 mm compared with copper‐free assays. At pH 4, the presence of 0.2 mm copper reduced the activity by 15% at most. Copper caused a shift of the pH optimum towards lower pH. Goethite did not influence β‐glucosidase activity significantly, although up to 95% of the enzyme was adsorbed on its surface. The adsorption seemed to be caused principally by non‐electrostatic forces which were too weak to affect the structure of the enzyme. Goethite reduced the inhibitory effect of copper because of the strong affinity of copper for goethite, as observed in batch adsorption experiments. The sorption of the enzyme on goethite was not competitive with copper at concentrations less than 0.2 mm; at larger concentrations, however, the presence of the enzyme reduced copper adsorption. The influence of copper on enzyme activity as well as the influence of copper in combination with goethite could be described with a model combining Michaelis–Menten enzyme kinetics with a simple conditionally first‐order reaction law for the binding of copper by the enzyme.
Effect of natural organic soil solutes on weathering rates of soil minerals
Authors: RAULUND‐RASMUSSEN K. , BORGGAARD O. K. , HANSEN H. C. B. , OLSSON M.
Published: March 2003

The rate at which minerals in the soil weather is affected by pH and concentration of organic solutes (DOC). The rates of release of Al, Ca, Fe, K, Mg, Na, P and Si from a mineral soil sample to solutions of natural organic solutes and HCI (control) were determined at pH 3 and 4 for up to 17 weeks. Soil solutions were collected by centrifuging materials of O horizons from various soil types under four tree species (spruce, birch, oak, beech) and passed through a cation‐exchange resin to yield H+‐saturated organic solutes. The acceleration of the elements' release by the organic solutes was shown directly by the relative ligand effect (RLE), that is, the release rate in the organic solute solution divided by the release rate in the HCI solution (control) at the same pH. The RLE was greater at pH 4 than at pH 3, and it decreased for the elements in the order Fe > Ca > Mg > Al ≈ Si > K ≈ Na. This indicates that natural organic solutes are more important weathering agents at higher than lower pH and for weathering of mafic minerals rich in Ca, Fe and Mg than of felsic minerals such as K‐ and Na‐feldspars. For all elements and at both pHs, RLE was strongly correlated with the concentration of DOC, which was also closely correlated with titratable acidity of the organic solutes. The important effect of soil type and tree species in producing weathering‐promoting organic solutes therefore seems to be expressed through the concentration and not the composition of the organic soil solutes.
Equilibria of weak acids and organic Al complexes explain activity of H+and Al3+in a salt extract of exchangeable cations
Authors: Nissinen A. , Ilvesniemi H. , Tanskanen N.
Published: March 2003

Two sequential extractions with unbuffered 0.1 mBaCl2were done to study the release of salt‐exchangeable H+and Al from mineral horizons of five Podzols and a Cambisol. Released Al was found to have a charge close to 3+ in all horizons and in both extractions. This finding was supported by the near‐equality of the titrated exchangeable acidity (EAT) and the sum of exchangeable acids (EA = He + 3Ale, calculated from the pH and Al concentration of the extract). The ratio between EA of the second and the first extraction was over 0.50 in the Bs2 and C horizons and smaller in the other horizons. H+was assumed to be in equilibrium with weak acid groups, and the modified Henderson–Hasselbach equation, pKHH = pH − n log (α/(1 − α)), was used to explain pH of the extract. The degree of dissociation (α) was calculated as the ratio between effective and potential cation exchange capacity. Value of the empirical constantnwas found to be near unity in most horizons. When the monoprotic acid dissociation was assumed in all horizons, pKHHhad the same value in both extractions. For Al3+, two equilibrium models were evaluated, describing (i) complexation reactions of Al3+with soil organic matter, and (ii) equilibrium with Al(OH)3. Apparent equilibrium constants were written as (i) pKo = xpH − pAl3+, and (ii) log Qgibbs= log Al3+ − 3log H+.The two extractions gave an average reaction stoichiometryxclose to 2 in all horizons. Results suggest that an equilibrium with organic Al complexes can be used to express dissolved Al3+, aluminium being apparently bound to bidentate sites. The value of log Qgibbswas below the solubility of gibbsite (log Kgibbs = 8.04) in many horizons. In addition, log Qgibbsof the second extraction was greater than that of the first extraction in all horizons except the C horizon. This indicates that equilibrium with Al(OH)3cannot explain dissolved Al3+in the soils. We propose that the models of pKHHand pKocan be used to simulate exchangeable H+and Al3+in soil acidification models.
Effects of mineral and monocarboxylic acids on the molecular association of dissolved humic substances
Authors: Piccolo A. , Conte P. , Cozzolino A.
Published: March 2003

The conformational structure of dissolved humic substances is an important property that controls the reactivity of humus in the soil solution. High performance size‐exclusion chromatography was used here to study the changes in molecular size of different humic substances brought about by addition of mineral (HCl) and monocarboxylic (formic, acetic, propionic, and butyric) acids. The CPMAS‐NMR spectra showed that humic substances had varying chemical composition and that the ratio of hydrophilic to hydrophobic carbon (HI/HB) was greater for a humic acid from soil than for ones from oxidized coal and lignite. All humic substances showed a decrease in UV absorbance of chromatographic peaks when treated with either HCl or monocarboxylic acids. This was due to the hypochromic effect by which the absorptivity of associated molecules is decreased when they are separated. We attributed the molecular separation upon acid treatment to the formation of intermolecular hydrogen bonding that alters the original conformation stabilized mainly by weaker hydrophobic interactions. Addition of organic acids not only further decreased peak absorbances of humic acids but also caused their shift to larger elution volumes, indicating a larger conformational disruption than with HCl. The extent of the molecular size changes showed a relation to the number of carbons of monocarboxylic acids and to the HI/HB ratios of humic materials. The larger the carbon content of organic acids and the smaller the HI/HB ratio of humic materials, the larger was the decrease of the average molecular size of humic acids. These results suggest that dissolved humic substances associate predominantly by hydrophobic forces and that the apolar components of humic substances largely control their aggregation and reactivity in the environment.
Application of two methods to determine hydraulic conductivity with disc permeameters on sloping land
Authors: Joel A. , Messing I.
Published: March 2003

The purpose of the present study was to compare two methods for estimating the hydraulic conductivity near saturation with disc permeameters, and to identify their merits when studying runoff on sloping land. The soil's hydraulic conductivity (K) was measured with disc permeameters at a sequence of nominal pressures (ψ) in three blocks with average slope gradients of 11.0% (two occasions), 21.5% (two occasions) and 29.3% (one occasion), respectively, within a sloping area, 40 m wide and 100 m long. Two different methods were used. In the first, the split‐location method, the permeameter was moved to an adjacent spot after measurement at each applied ψ. The estimate of K(ψ) was based on measured sorptivity, steady‐state volumetric flow, initial volumetric water content and the volumetric water content at the applied ψ. In the second method, the one‐location method, the permeameter was not moved during the measurements at each sequence of applied ψ and the estimate of K(ψ) was based only on steady‐state volumetric flow and piece‐wise application of the exponential relation between K and ψ. The latter method generally gave smaller estimates of K than the former on the gentle slopes. These differences were smaller or negligible on steeper slopes. The slope gradient and the conditions in the uppermost soil layers had a definite influence on the values of K obtained. The one‐location method is recommended in studies in which disturbance of the soil surface must be kept to a minimum, as is the case in experimental plots.
Temporal changes in chemical properties of air‐dried stored soils and their interpretation for long‐term experiments
Authors: Blake L. , Goulding K. W. T. , Mott C. J. B. , Poulton P. R.
Published: March 2003

The usefulness of stored soils from long‐term experiments is often questioned because of changes that might occur during storage. We examined changes during long‐term storage (8–69 years) in the chemical properties of soils with a range of pH values (3.4–8.1 in water) from woodland and grassland experiments at Rothamsted Experimental Station in the UK. No significant changes during storage were measured for total C and N. Large but erratic changes in exchangeable Na+ content between 1959 and 1991 were probably caused by contamination of the 1959 samples by perspiration and from sodium‐based glassware. Exchangeable K+ increased during storage but only by a small amount. Small changes in exchangeable Ca2+ and Mg2+ were measured in some samples but not in others. Generally the amount of exchangeable cations increased slightly during storage. This is probably linked to the decreases of  0.4 units in the pH of acid soils, which we attribute to the hydrolysis of approximately 0.25% of the exchangeable Al3+. A doubling of the amount of exchangeable Mn2+ during storage for 32 years was probably caused by re‐equilibration of Mn species. The most practicable way to prepare soil samples for long‐term storage is to dry them in air. However, those who study changes in soil by re‐analysing samples of the soil stored for a long time must (i) use the same methods of analysis, or (ii) demonstrate that different methods lead to the same results, and (iii) know what changes can arise during storage.
Effects of lanthanum and mixtures of rare earths on ammonium oxidation and mineralization of nitrogen in soil
Authors: Xu Xingkai , Wang Zijian
Published: March 2003

Rare earths are applied widely in Chinese agriculture to improve crop nutrition and incidentally in fertilizers, yet little is known of their effect on the biological functioning of the soil. We have studied the effects of lanthanum and of mixtures of rare earths on the potential ammonium oxidation and nitrogen mineralization in soil by incubation experiments in the laboratory. The no‐observed‐effect and median effective concentrations of the rare earths on these two processes are reported, and their corresponding mechanisms are discussed. For mixtures, the no‐observed‐effect concentrations relating to potential ammonium oxidation and N mineralization were at 393 and 373 mg rare earths kg−1 soil, respectively, and their median effective concentrations were at 1576 and 1108 mg kg−1 soil, respectively. When lanthanum was applied alone, the no‐observed‐effect concentrations relating to potential ammonium oxidation and N mineralization were at 432 and 443 mg La kg−1 soil, respectively, and their median effective concentrations were at 18 212 and 1237 mg kg−1 soil, respectively. Therefore, the influence of mixtures of rare earths on potential ammonium oxidation or on N mineralization was slightly stronger in comparison with that of lanthanum. Mineralization of nitrogen is apparently more sensitive to the stress caused by rare earths than ammonium oxidation. We conclude that the influence of individual rare earths in the mixtures on the above two processes can be additive and that the present dosage of mixed rare earths (< 230 g ha−1 year−1 or 0.15 mg kg−1 soil year−1) currently applied in China can hardly affect the potential ammonium oxidation and N mineralization in the soil even over a long period.
Seasonal differences in the soil water balance under perennial and annual pastures on an acid Sodosol in southeastern Australia
Authors: Heng L. K. , White R. E. , Helyar K. R. , Fisher R. , Chen D.
Published: March 2003

Replacement of native deep‐rooted grasses by shallow‐rooted ones has resulted in greater losses of water and nitrogen by drainage. To counter this effect we have tested the hypothesis that liming, and the conversion of annual grass pastures to perennial grass pastures, could improve the sustainability of grazing systems in the high rainfall zone (> 600 mm per annum) in southeastern Australia, through better use of water and nitrogen. A field experiment consisting of sixteen 0.135 ha (30 m × 45 m) grazed paddocks representing four pasture combinations (annual pasture (mainly Lolium rigidum) without lime (AP–); annual pasture with lime (AP+); perennial pasture (mainly Phalaris aquatica) without lime (PP–), and perennial pasture with lime (PP+)) was carried out from 1994 to 1997 on an acid Sodosol (Aquic Hapludalf) in southern New South Wales, Australia. Measurements were made of surface runoff, subsurface flow (on top of the B horizon) and soil water content. The results showed that perennial grass pastures, especially PP+, extracted approximately 40 mm more soil water each year than the annual grass pastures. As a result, surface runoff, subsurface flow and deep drainage were at least 40 mm less from the perennial pastures. These measurements were further supported by a simulation of soil water deficit and deep drainage for AP– and PP+ paddocks, using 10 years' past meteorological records. Overall, the results suggested that well‐grown, phalaris‐based pastures could reduce recharge to groundwater and make pastoral systems more sustainable in the high rainfall zone.
The origin and nature of organic nitrogen in soil as assessed by acidic and alkaline hydrolysis
Authors: Greenfield L. G.
Published: March 2003

The origin and nature of much of the organic nitrogen in soil is unknown or speculative. Alkaline hydrolysis was used to fractionate soils into alkali‐soluble and insoluble fractions. Alkali‐insoluble residues from a wide variety of soils contained largely fixed ammonium or chitin or both. Acid hydrolysis of alkali‐insoluble residues from soils, microbes, insects and well‐rotted plant litter confirmed the presence of hexosamine‐N.

The hexosamine‐N derived from estimates of soil biomass accounted for less than 10% of the chemically determined hexosamine‐N values. It is suggested that most of the hexosamines are held in complexes formed between chitin complexed with other materials, e.g. pigments, that occur predominantly in the cell walls of microbes and insects. These complexes show resistance to enzymes during the life of soil organisms that persists after their death.
Ion transport through unsaturated soils: field experiments and regional simulations
Authors: Kumke T. , Streck T. , Richter J.
Published: March 2003

This paper describes the movement of anions and cations through soils at the regional scale using block‐scale and regional simulations of one‐dimensional ion transport through cultivated soils. The simulations were based on field experiments in a region of about 10 km2in Lower Saxony, Germany. Transport was modelled with the convection–dispersion equation, and the cation exchange was described using the Gapon equation. We evaluated the spatial variation of cation exchange parameters, obtained estimates valid at the block scale, and simulated the one‐dimensional transport of anions and cations. The movement of anions and cations was simulated over blocks using effective transport parameters calculated from local transport parameters. The approach led to a good agreement between measured and predicted concentrations of Br–, Na+, K+, Ca2+and Mg2+on four different 1 ha blocks. However, the mean concentrations of K+in the soil solution in the uppermost horizons could not be described satisfactorily by the model. For the regional simulations, transport and exchange parameters were estimated by block kriging. All variograms of the exchange parameters were spatially structured with correlation lengths varying from 100 m to 300 m. Results of the regional simulations imply that Cl–and K+were transported substantially deeper in the southern part than in the northern part of the area. The transport depth of the ions strongly depended on the pore water velocities. The simulation of solute transport to the water table showed the influence of the depth of water table on the estimated travel times, superimposing the influence of the transport parameters in the region. The results of the regional simulations also emphasize the importance of careful fertilization, especially in regions with shallow water tables such as in the north of the area.
Effect of reduced air pressure on soil thermal conductivity over a wide range of water content and temperature
Authors: Momose T. , Kasubuchi T.
Published: March 2003

To clarify the role of air molecules in coupled heat and mass transfer in soil, we measured the thermal conductivity of three kinds of soil (Ando soil, Red Yellow soil, and Toyoura sand) under reduced air pressure over a wide range of water content and temperature (10–75°C). The thermal conductivity increased sharply under reduced air pressure above a critical water content of the soil, becoming several times larger than that under normal pressure (101 kPa). The maximum thermal conductivity for each soil was obtained below 75°C and was similar to the thermal conductivity of some metals such as Mn, Hg and stainless steel. When the soil was drier than its critical water content, the thermal conductivity did not increase under reduced air pressure. The hydraulic diffusivity at the critical water content for each soil was of the order of 10−8 m2 s−1. This suggests that the latent heat transfer is enhanced by the circulation of the condensed water. However, very little is known about the effect of circulating water on the latent heat transfer under reduced air pressure. To make this clear, the thermal conductivity would need to be measured in the steady state under reduced air pressure.
Laboratory experiments on drought and runoff in blanket peat
Authors: Holden J. , Burt T. P.
Published: March 2003

Global warming might change the hydrology of upland blanket peats in Britain. We have therefore studied in laboratory experiments the impact of drought on peat from the North Pennines of the UK. Runoff was dominated by surface and near‐surface flow; flow decreased rapidly with depth and differed from one type of cover to another. Infiltration depended on the intensity of rain, and runoff responded rapidly to rain, with around 50% of rainwater emerging as overland flow. Drought changed the structure of the peat and the subsequent behaviour of the peat in response to rain. Surface runoff was reduced, infiltration increased and flow increased within the deeper peat layers. Old and new water produced from the peat during simulated storms was identified by bromide tracing; the amount of old mobile water flushed out of the top few centimetres was small and there was less from deeper peat layers. No significant difference in the old and new water mixing processes could be identified between the control plots and the drought treatment plots. Lissamine staining showed preferential bypass flow through macropores in the peat, though only in the top 5 cm. Following drought, however, macroporosity increased within the upper peat layers, and preferential flow extended deeper than in controls. Peat structure recovered somewhat after drought, but the effects of the drought were long‐lasting. If these effects extend to the field during drier summers then we can expect changes to the hydrology and associated chemistry of blanket peat catchments in the British uplands.
Modelling cation exchange in columns of disturbed and undisturbed subsoil
Authors: Ludwig B. , Kölbl A.
Published: March 2003

Cation exchange is often studied with disturbed and dried soils, but the applicability of the results to undisturbed soils is not straightforward. We investigated the value of exchange coefficients obtained from standard procedures for predicting cation exchange in soil. Columns of undisturbed and disturbed subsoil of a Luvisol (SBt horizon) were leached under saturated conditions with 0.4, 4, 20, 41, 102 and 205 mm BaCl2 at a Darcy velocity of 1400 mm day−1. The model PHREEQC was used to calculate one‐dimensional transport, inorganic complexation and multiple cation exchange. Two model variants were tested: m1 (exchangeable cations obtained by percolation with NH4Cl) and m2 (exchangeable cations obtained by shaking the soil with BaCl2). The exchange coefficients (Gaines–Thomas formalism) were calculated from the ion activities in solution and exchangeable cations obtained by NH4Cl percolation (m1) or shaking with BaCl2 (m2). Variant m1 predicted cation exchange of the disturbed (homogenized) soil for the entire BaCl2 concentration range, whereas variant m2 resulted in a two‐fold overestimation of desorbed K for all experiments, which was related to large amounts of K released from the soil by shaking with BaCl2. In experiments with undisturbed soil, variant m1 predicted the concentrations of Mg, Ca, K, and Na in the solution phase and the sum of cations released from exchange sites. However, variant m2 predicted changes in ion concentrations and exchangeable cations somewhat less well. This study suggests that the amounts of exchangeable cations and exchange coefficients obtained from experiments with homogenized soil by percolation are useful to predict cation concentrations in column experiments with undisturbed soils.
Effect of dissolved organic matter on the precipitation and mobility of the lead compound chloropyromorphite in solution
Authors: Lang F. , Kaupenjohann M.
Published: March 2003

Chloropyromorphite, CPM, Pb5(PO4)3Cl, is one of the most insoluble lead minerals. Inducing the formation of CPM by application of phosphate to soil has been suggested for immobilizing Pb at contaminated sites. We have examined the effect of organic matter on the completeness and the rate of CPM precipitation and on the particle size and the mobility of CPM crystals. We did experiments at pH 3–7 and with varying content of dissolved organic C, 0–72 mg C l−1, mixing Pb(NO3)2 (0.5 mmol l−1) and phosphate (2 mmol l−1) solutions. The organic matter was extracted from samples of a forest floor. The precipitates were identified by X‐ray diffraction, and their size and shape were analysed by scanning electron microscopy and by photon correlation spectroscopy. The presence of organic matter in the solutions did not affect the mass of CPM that precipitated within 30 minutes at pH 5, 6 and 7. At pH 3 and 4, however, organic matter strongly inhibited the precipitation. The particles were markedly smaller in solutions containing organic matter than without at all pHs and passed through water‐saturated columns filled with calcareous sand, whereas the precipitates from the carbon‐free solutions did not. We suggest that the organic matter blocked the surfaces of crystal seeds and impaired crystal growth. At high pH, organic matter may additionally decrease the crystal size of the individual crystals by increasing the number of crystal seeds. We conclude that organic matter in the solution might limit the potential of phosphate to immobilize Pb in soil because it favours the formation of mobile colloids.
Effects of artificial instream cover on the density of 0 + brown trout
Authors: EKLÖV  , GREENBERG
Published: March 2003

The effect of instream cover on the density of juvenile sea trout, Salmo trutta L., in two streams in southern Sweden was studied. One of the streams, Vallkärrabäcken, was narrow (2–3 m) and had few sympatric species, whereas the other stream, Braån, was wider (6–8 m) and had many sympatric species. Three treatments were used: (1) addition of artificial vegetation; (2) an undisturbed control; and (3) removal of natural vegetation. Only the first two treatments were tested in Braån, whereas all three treatments were tested in Vallkärrabäcken. The 0 + trout density was higher in sections containing artificial vegetation than in control sections, which in turn had higher densities than sections where natural vegetation was removed. Moreover, the effect of adding artificial vegetation on trout density was most pronounced at the end of the summer. The results indicate that instream cover from submerged macrophytes may be important for maintaining high 0 + trout densities in small and medium‐sized streams where other types of instream cover are in short supply.
The utility of visible implant (VI) tags for marking tropical river fish
Authors: HALLS  , M. E. AZIM
Published: March 2003

In tropical fisheries where ageing fish is often difficult, tagging programmes offer an important means to estimate growth parameters and mortality rates. The majority of tags are large and attached externally via a puncture in the muscle. These characteristics may cause significant biological effects which bias parameter estimates. Visible implant (VI) tags offer a more benign means to individually mark fish. The utility of VI tags for marking five species of tropical river fish was examined. The results indicate that the tag and tagging operation had no influence on either growth or mortality, although tag retention was poor compared with other studies. For three of the five species, the only suitable tagging location was highly inconspicuous and therefore inappropriate for tagging programmes that rely upon fishermen to return tagged fish. Alternative tagging locations may improve retention rates and the visibility of the tag.
Distribution and abundance of the larval black porgy, Acanthopagrus schlegeli (Bleeker), in coastal waters and an estuary of western Taiwan
Authors: HUANG W. B. , CHIU T. S.
Published: March 2003

This study compared the distribution, abundance and body length of larval black porgy, Acanthopagrus schlegeli (Bleeker), to relative environmental conditions in the coastal waters near Wan‐kung and the Da‐du estuary of western Taiwan to evaluate the utilization of these two water bodies as nursery grounds. Sampling was carried out on spring tides from October 1993 to September 1994. In the coastal waters, salinity (mean = 31.50/00) and current speed (39.1 cm s−1) were significantly higher than those in the estuary (28.30/00 and 29.6 cm s−1). Most of the larvae occurred from late winter to early spring. The period of occurrence was longer and the density was higher in the coastal waters. The mean body length in the coastal waters (9.28 mm) was greater than that in the estuary (7.33 mm), but the coefficient of variation of body length was smaller (coastal waters, 8.15%; estuary, 19.87%). The occurrence of the larvae in the two regions was negatively correlated with water temperature and positively with salinity and dissolved oxygen, and the change of density of larval black porgy was similar to that of all larval species discriminated by principal component analysis. The range and mode of the length‐frequency distributions were different between the two regions. It was concluded that coastal waters are overall a better nursery habitat for black porgy.
Factors contributing to the outcome of stocking programmes in Cuban reservoirs
Authors: QUIROS R. , MARI A.
Published: March 2003

Abstract  In less‐developed countries, fisheries enhancement using stocking is a common practice to manage reservoirs for biomass production. In many cases, there appears to be little control over whether the stocking activity is appropriate or necessary. Cuban reservoir fisheries have been usually managed to maximize fish biomass. Blue tilapia have been introduced and supplemented in reservoirs, and Chinese carp are introduced and maintained in reservoirs throughout the entire island. Supplemental stocking with introduced fish species is a usual practice to manage large and medium‐sized reservoirs. Small and very small reservoirs have been managed as semi‐intensively enhanced fisheries with carp and tilapia stocking. The main purposes of the present paper are to study the factors contributing to the outcome of stocking programmes in reservoirs and to test the hypotheses that supplementary stocking for self‐sustained fish populations usually cannot contribute to increase fish yield. Yield and stocking data by groups of fish species were available for Cuban reservoirs. Total fish yield was only slightly related to total fish stocking density for the complete set of reservoirs. However, this result was mainly because of the relationship between total yield and cyprinid stocking for semi‐intensively‐used reservoirs. Tilapia yield was not significantly related to tilapia stocking for both extensively and semi‐intensively‐used reservoirs. However, yield and stocking for cyprinids were highly related for both reservoir subsets. Therefore, cyprinid stocking was effective in certain reservoirs, but tilapia stocking was not effective in any reservoir. Moreover, tilapia stocking was a superfluous activity for reservoirs where tilapia have an adequate natural reproduction cycle.
Recreational catfish harvest in reservoirs in the USA
Authors: Miranda L. E.
Published: March 2003

The recreational catfish harvest was classified in 349 reservoirs larger than 200 ha distributed over 40 states of the contiguous USA. Harvesting occurred in 282 reservoirs, averaged 2.8 kg ha−1 year−1 and represented 15.6% of the total fish yield. The genus Ictalurus contributed most to catfish fisheries (mean = 2.0 kg ha−1), followed by Ameiurus (1.1 kg ha−1) and Pylodictis (0.4 kg ha−1). Five distinct clusters of reservoirs were identified, differing relative to geographical distribution, catfish harvests, angler favouritism towards catfish and physicochemical characteristics. Reservoir clusters across the northern USA had low harvests and essentially featured reservoirs in the upper periphery of the native range of catfish. Harvesting in reservoirs in the south‐west of the country, where catfish have been introduced, was higher than in the north, yet yield remained low. Within their native range, three overlapping clusters included one with medium and another with high harvests, both types dominated by Ictalurus, and a cluster with very high harvest dominated by Ameiurus. Variability in harvests was attributed to zoogeography, reservoir physicochemical characteristics and fishing effort. Management of catfish fisheries of the three less‐productive clusters may focus on enhancement through habitat manipulation and stocking; the two more productive clusters offer the greatest flexibility for management through regulation of harvest.
Stocking of brown trout, Salmo trutta L.: effects of acclimatization
Authors: Jonssonn S. , Brønnøs E. , Lundqvist H.
Published: March 2003

One‐year‐old hatchery brown trout, Salmo trutta L., (n = 16 520) from a sea‐run, local brood stock were marked and released (scatter‐planted) into the River Laisälven in northern Sweden. Eight different groups were created using Alcian blue and Visible Implant Elastomer tags. Half the fish were kept in small enclosures in four stocking areas for 6 days before release. The other half were released just after transportation. To evaluate the effect of acclimatization on post‐stocking performance, the areas were electric fished 2 months later. During the electric fishing survey, a higher number of the acclimatized hatchery fish were recaptured than those released immediately. The growth rate of stocked fish differed significantly between stocking areas and fish held in enclosures grew more than those released directly. The rate of recapture of hatchery fish varied between stocking areas (6.4–17.4%). Movements of juveniles within and between the stocking areas were low, and only 3.6% of the recaptured fish were found in an area not originally stocked. These results showed that acclimatization of fish before release increases the number and size at recapture within a stocking area.
Drainage basin morphology: a starting point for balancing water needs, land use and fishery protection
Authors: Lundqvist J. , Falkenmark M.
Published: March 2003

The drainage basin, including the coastal zone, may be seen as a large‐scale system of interlinked natural resources and ecosystem services which support human activities on land and in the sea. Social and economic activities in the drainage basin have to be consistent with the hydrological and ecological needs for human well‐being. Proper attention must also be paid to the impacts of these factors on ecosystems further downstream. A macro‐scale ecosystem approach to a basin has to consider: (1) direct uses of water both instream and after extraction when pollutants may be added to the return flow; and (2) indirect use of water for agriculture and forestry where the river may be depleted as a result of evapotranspiration from land surface, crops and trees. Both uses have repercussions on the quantitative flow and quality of water, which may damage water‐based instream ecosystem services. The present paper addresses relationships between different types of human intervention in a drainage basin and their consequences. Two analytical models are introduced: (1) a conceptual model which distinguishes between urban and rural water uses, and their respective tools; and (2) a conceptual model for handling spatially ordered land/water use segments subject to different types of interference. Finally, the present paper comments on the need to develop methodologies for cross‐disciplinary dialogue, and for balancing water needs, land use and fishery protection.
Commercial fisheries versus water quality in lakes with special reference to coregonid management
Authors: Bninska M.
Published: March 2003

Environmental agencies in Poland have adopted a new system, based on a ranking procedure, for classifying the quality of lake ecosystems. The new system is used alongside the old one, and divides lakes into four categories of water quality: (1) high quality, pure water (< 1.50 points); (2) moderately polluted (< 2.50 points); (3) low quality, polluted (< 3.25 points); and (4) degraded (> 3.25 points). This new system has been used to analyse commercial fisheries, and especially, coregonid management, on the basis of water quality. Data were collected from 38 lakes subjected to environmental quality controls between 1985 and 1994. Data on commercial fisheries in these lakes were collected between 1968 and 1994. These comprised detailed statistics on fish catches by species and size categories, and numbers stocked in the lakes. The lakes were divided into two groups, i.e. high and low quality, based on the mean point score for the whole sample (2.273 points). The group of good‐quality lakes (< 2.273 points) included 22 lakes with a total area 15 520 ha and that of low‐quality (> 2.273 points) included 16 lakes with a total area 10 967 ha. The two groups differed not only with respect to water quality, but also the effectiveness of fisheries management. In low‐quality lakes, more stocking material (in terms of numbers) was needed to obtain 1 kg of coregonid catch. The commercial yield of coregonids [i.e. whitefish, Coregonus lavaretus (L.), and vendace, Coregonus albula (L.)] amounted to 7.07 kg ha−1 year−1 in good‐quality lakes and made up 28.4% of total fish landings, while in the low‐quality group, the values were 5.86 kg ha−1 year−1 and 19.0%, respectively. The effectiveness of vendace stocking only depended on the chlorophyll‐a content of the water: at higher chlorophyll‐a levels, and thus, also at primary production levels, more vendace larvae were needed to produce 1 kg of commercial catch.
Fish catches among riverside communities around Lago Grande de Monte Alegre, Lower Amazon, Brazil
Authors: Cerdeira R. G. P. , Ruffino M. L. , Isaac V. J.
Published: March 2003

Forty‐six families living around the Amazon floodplain lake of Lago Grande de Monte Alegre, Brazil, were monitored between April 1993 and March 1995 with respect to their fish catches. The average catch per fisherman was 22 kg day‐1. There were significant differences between subsistence and commercial fishing, and also across different seasons of the year. Catch was higher in the dry season and in the lake environment, followed by the river environment. The flooded forest was exploited in the rainy season. Out of a total of more than 70 fish species, 10 taxa comprised 75% of the catch. The catch in the Monte Alegre region concentrated on smaller species for local consumption. Prochilodus nigricans (Spix & Agassiz) was the most important species, followed by Liposarcus pardalis (Castelnau) and Plagioscion spp. Comparisons between quantities of fish consumed and fish marketed indicated that the fishery has a much more important role in the region than previously thought.
Introducing size limits as a management tool for the recreational line fishery of silver kob, Argyrosomus inodorus (Griffiths and Heemstra), in Namibian waters
Authors: Kirchner C. H. , Holtzhausen J. A. , Voges S. F.
Published: March 2003

Individual silver kob Argyrosomus inodorus (Griffiths and Heemstra) first mature at just over 1 yr of age and the median age at maturity is approximately 1.5 yr. Spawning of silver kob was observed in the southern and central region of the stock’s range, but little spawning activity was found in silver kob sampled from the northern region. The spawning period is protracted over 6 months (October–March), which coincides with warmer water temperatures (>15 °C) and the occurrence of large‐sized spawning silver kob in the southern and central part of Namibia. Implementing a minimum size limit for the silver kob fishery is not recommended as it will have serious economic implications for the coastal communities. The protection of the spawning areas, Meob Bay and Sandwich, should be continued and a strict bag limit on large‐sized silver kob is recommended for the Namibian silver kob recreational fishery.
Diet and growth of stocked and wild 0+ pikeperch, Stizostedion lucioperca (L.)
Authors: SUTELA T. , HYVÄRINEN P.
Published: March 2003

Wild and stocked 0+ pikeperch, Stizostedion lucioperca (L.), were sampled with a purse seine from Lake Oulujärvi, situated at the northern edge of the distribution range of the species. The stocked fry started immediate feeding on 0+ smelt, Osmerus eperlanus (L.) after their introduction into the lake in early August at about 50 mm length, whereas the smaller wild pikeperch fry continued to feed on zooplankton. Individual wet weight of the stocked pikeperch was about six‐fold compared with the wild pikeperch throughout August. The length of the ingested smelt was as on average 50%, and maximum 66%, of the pikeperch length. Wild 0+ pikeperch were too small to forage on 0+ smelt. Predation by older conspecifics on 0+ pikeperch was observed.
Recent evolution of the fishing exploitation in the Thau lagoon, France
Authors: CRESPI V.
Published: March 2003

Fisheries activity in the Thau marine lagoon (Mediterranean coast of France) has an old tradition and involves different types of gears (set nets, traps and lines) that are used seasonally with varying frequencies in different areas. A survey of fishing activity, main fishing methods and main commercial species composition in the lagoon was carried out to assess the current fishing effort and seasonal yield. Many important changes in fishing effort and in the most important target species occurred during the last 10 years. A gradual decline in eel, Anguilla anguilla (L.), catches followed by an increase of other commercially‐exploited species, particularly the gilthead sea‐bream, Sparus aurata L., was observed.
The effect of stocking size on the first winter survival of whitefish, Coregonus lavaretus (L.), in the Gulf of Bothnia, Baltic Sea
Authors: JOKIKOKKO E. , LESKELÄ A. , HUHMARNIEMI A.
Published: March 2003

The anadromous whitefish, Coregonus lavaretus (L.), is the most numerous fish species stocked in the Gulf of Bothnia, Baltic Sea. One‐summer‐old‐whitefish fingerlings are mostly 8–10 cm long when released annually in September–October, whereas the wild whitefish are 10–12 cm at that time. About 6 million, one‐summer‐old, spray‐marked, whitefish were released in the northern and central parts of the Gulf in 1995–1998. To study the effect of the stocking length on the survival of the marked fish, the length of the recaptured whitefish as 1‐year‐olds was back‐calculated. Altogether 1106 whitefish recaptured in the Gulf of Bothnia were analysed. The back‐calculated length was slightly greater than the stocking length but not as large as the length of the wild fish. In the central part of the Gulf of Bothnia, where the mean stocking length was more than 10 cm, the back‐calculated length was 10.5–11.1 cm. In the northern part of the Gulf the mean stocking length varied between 8.8 and 10.0 cm annually, and the corresponding back‐calculated mean lengths were 9.3–9.7 cm. It also seemed that bigger fingerlings started their feeding migration earlier or they migrated faster than the smaller ones to the southern parts of the Gulf of Bothnia.
Food composition, habitat use and growth of stocked and native Arctic charr, Salvelinus alpinus, in Lake Muddusjärvi, Finland
Authors: KAHILAINEN K. , LEHTONEN H.
Published: March 2003

Habitat use, growth and food composition of native and stocked Arctic charr, Salvelinus alpinus (L.), were studied in the subarctic Lake Muddusjärvi, northern Finland, to investigate reasons for poor stocking success. Samples were collected with pelagic and epibenthic gill nets. Stocked and native charr occurred in similar epibethic habitats, whereas pelagic habitat was avoided. Native charr grew fast after shifting to piscivory. Growth rate of stocked charr was slow because only a small proportion of stocked fish became piscivorous during the first year after stocking. During the first lake year, stocked charr divided into slow‐growing planktivores and fast‐growing piscivores. Piscivorous stocked and native charr consumed only whitefish, Coregonus lavaretus (L.), as their prey. Small‐sized (<10 cm) whitefish were preferred when shifting to piscivory.