Observations on swim bladder stress syndrome in Arctic charr (Salvelinus alpinus), induced by inadequate water depth     

Arne Kolbeinshavn  Jeff C. Wallace 《Aquaculture (Amsterdam, Netherlands)》1985,46(3):259-261

In two separate experiments, juvenile Arctic charr (Salvelinus alpinus) were held at three different water depths (12, 24 and 37 cm) and at three different stocking densities (10, 50 and 100 kg/m³). Mortalities from swim bladder stress syndrome (SBSS) were noted over 2 months. Low water depth caused high mortality while stocking density did not induce the stress syndrome to any notable degree. An analysis of catecholamines in the blood plasma of a small number of fish indicated elevated dopamine levels in stressed fish.  相似文献   

Technological solutions and operational measures to prevent escapes of Atlantic cod (Gadus morhua) from sea cages     

Heidi Moe  Tim Dempster  Leif Magne Sunde  Ulf Winther  & Arne Fredheim 《Aquaculture Research》2007,38(1):91-99

Escapes of cod (Gadus morhua) from sea cages represent an economic problem for farmers and a potential environmental problem. We estimate that 0–6% of cod held in sea‐cage farms in Norway were reported to have escaped each year from 2000 to 2005, which is a high proportion compared with salmon. We interviewed employees at 19 coastal sea‐cage cod farms in Norway to investigate both how and why cultured cod escape and to document cage handling and management strategies that were effective in minimizing escapes. Based on the interviews, we describe five working hypotheses that may explain why a greater proportion of cod than salmon escape: (1) cod are more willing to escape than salmon; (2) cod bite the net cage and create wear and tear; (3) net cages have insufficient technical standards for cod culture; (4) cod are placed in sea cages at considerably smaller sizes than salmon; and (5) cod are more popular feed for predators. Preliminary testing of the hypothesis that cod bite netting and create holes was done by placing pre‐damaged net panels with cut twines and control panels inside sea cages. Holes in the pre‐damaged net panels increased in size over a period of 3 months. The type of damage indicated that biting of netting twines was the likely cause.  相似文献   

Mercury in swedish forest soils and waters — Assessment of critical load     

Kjell Johansson  Mats Aastrup  Arne Andersson  Lage Bringmark  Ake Iverfeldt 《Water, air, and soil pollution》1991,56(1):267-281

As a result of air pollution, the content of Hg in fish has significantly increased in a large part of Scandinavia and North America. In this paper, the occurence and fluxes of Hg in Swedish forest soils and waters are reviewed and synthesized. The main objective is to describe and evaluate the present transport of anthropogenic Hg from atmospheric deposition, through the terrestrial compartment and running waters to lake basins and also to comprehend the main factors influencing these fluxes. The transportation and distribution. of Hg in forest soils and waters is closely related to the flow of organic matter. The content of Hg in humic matter is higher in southern and central areas compared to the north of the country. Compared to background concentrations, the Hg content has increased in the southern and central part by about a factor of 4–7, while the overall increase in the north is by about a factor of 2 to 3. The increased content of Hg in forest soils may have an effect on organisms and biological processes in the soil. Regarding budget calculations for whole catchment areas and for the mor layer of the soil, a reduction of about 80% from present atmospheric wet deposition must be obtained to reach “critical load” with respect to conditions in Scandinavia.  相似文献   

Absorption, tissue distribution and excretion of flumequine and oxolinic acid in corkwing wrasse (Symphodus melops) following a single intraperitoneal injection or bath treatment     

O. B. Samuelsen  & A. Ervik 《Journal of veterinary pharmacology and therapeutics》2001,24(2):111-116

The pharmacokinetic properties of the antibacterial agents oxolinic acid and flumequine were studied in corkwing wrasse (Symphodus melops) after either intraperitoneal injection or bath treatment. Following intraperitoneal administration the peak plasma concentrations (Cmax) and the time to peak plasma concentrations (Tmax) were estimated to be 2.0 microg/mL and 12 h, respectively, for oxolinic acid and 2.6 microg/mL and 12 h, respectively, for flumequine. In muscle, Cmax and Tmax were estimated to 6.7 microg/g and 12 h, respectively, for oxolinic acid with corresponding values of 8.5 microg/g and 13 h, respectively, for flumequine. In liver, Cmax and Tmax were calculated to 7.0 microg/g and 12 h, respectively, for oxolinic and 12.2 microg/g and 11 h, respectively, for flumequine. Elimination half-lives (t1/2 beta) of 26, 24 and 29 h, respectively, for plasma, muscle and liver were calculated for flumequine. For oxolinic acid two distinct elimination phases were found and calculated to be 16 h (t1/2 beta) and 57 h (t1/2 gamma) in plasma, 15 and 59 h, respectively, in muscle and 20 and 72 h, respectively, in liver. Bath treatment using 150 mg/L of flumequine or 200 mg/L of oxolinic acid for 72 h resulted in flumequine concentrations of 1.0 microg/mL in plasma, 5.0 microg/g in muscle and 12.4 microg/g in liver. Corresponding values for oxolinic acid were 1.0 microg/g in plasma, 2.5 microg/g in muscle and 4.9 microg/g in liver.  相似文献   

The phosphorus status of German cropland—An inventory of top‐ and subsoils     

Martina I. Gocke  Axel Don  Arne Heidkamp  Florian Schneider  Wulf Amelung 《植物养料与土壤学杂志》2021,184(1):51-64

Background : In search for more sustainable crop production, the subsoil has recently come into focus as considerable reservoir of nutrients and water. Aims : Dimensions of subsoil phosphorus (P) reserves are yet largely unknown but crucial for identifying regions suitable to include subsoil into sustainable management strategies. Methods : We analyzed stocks of total and plant‐available (calcium acetate lactate‐extractable) P in 96 representative soil profiles of German arable land down to 1 m depth. Results : We found that the German arable soils stored, on average, 8 t ha^?1 of total P, of which nearly 500 kg ha^?1 were readily plant‐available. Notably, one third of plant‐available P was located below the plow layer and one fifth even at depths below 0.5 m. The depth gradients of plant‐available P stocks were affected more by major reference soil group than by texture. Generally, Chernozem but also Anthrosol, Gleysol and Fluvisol exhibited the largest P stocks in German cropland. The contribution of plant‐available P to total P stocks was larger in sandy and extremely acidic (pH < 4.5) soils compared with more fine‐grained and slightly acidic to alkaline soils, possibly because fertilization compensated for overall lower total P stocks at these sites. Generally, the more P was stored in topsoils, the more P was stored also in subsoils. Conclusions : A hypothetical crop utilization of 10% from plant‐available P stocks and 0.1% from total P stocks from shallow subsoil could compensate for P fertilization by ca. 8 kg ha^?1, but the rate of plant‐available P replenishment in subsoil likely remains the crucial factor for the role of subsoil P stocks in crop nutrition. Generally, the large P reserves found in subsoil could act as an ‘insurance' system for crops.  相似文献   

The omnivorous predator Macrolophus pygmaeus induces production of plant volatiles that attract a specialist predator     

Zhang  Nina Xiaoning  Andringa  Joke  Brouwer  Jitske  Alba  Juan M.  Kortbeek  Ruy W. J.  Messelink  Gerben J.  Janssen  Arne 《Journal of pest science》2022,95(3):1343-1355

Journal of Pest Science - It has become clear that omnivorous predators can induce plant defences that affect the performance and host plant choice of herbivores. They are also known to induce the...  相似文献   

Psychology. Conditioned fear of a face: a prelude to ethnic enmity?     

Ohman A 《Science (New York, N.Y.)》2005,309(5735):711-713

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Historical development and past ecological state of two danish shallow lakes     

Peer?B.?MortensenEmail author  Louise?Schlüter  Arne?Jensen  Henning?F.?Aaser  Kjeld?S.?Hansen 《Journal of Soils and Sediments》2004,4(2):101-106

Background and Scope  

Lake sediment contains information on the historical development and former conditions of lakes, which is very useful when information about the undisturbed (reference) conditions of a lake is needed. Phytoplankton contains a range of different pigments, some of which are specific for individual algal groups and can be used as diagnostic markers. Phytoplankton pigments in lake sediments are indicators of prototrophic changes in lakes, since the pigments document changes in algae biomass and the composition of phytoplankton communities. Lake sediments can be dated along with pigment analysis by use of the naturally occurring radioactive isotope²¹⁰Pb.  相似文献   

Influence of temperature,humidity and inoculation on the degradation of14C-labeled 2-aminobenzimidazole in soil     

Arne Helweg 《Water, air, and soil pollution》1979,12(3):275-281

Degradation of¹⁴C-labeled 2-aminobenzimidazole was measured in sandy loam soils by means of the evolution of¹⁴C into CO₂. The correlation between soil temperature and 2-AB-degradation was investigated utilizing a temperature gradient incubator for temperatures between 1 and 40°C with a water content of 100% of field capacity. Within the temperature interval 1 to 20°C, the evolution of¹⁴C was exponentially related to the inverse of the absolute temperature, in accordance with the Arrhenius' equation. Maximum evolution of¹⁴C was at 22°C while between 25 and 35°C the evolution remained almost constant and at 40°C it was almost nil. The correlation between soil water content and 2-AB-degradation was measured at 25°C in air dry soil and with water contents varying from 5 to 41% (equivalent to 28 to 227% of field capacity (FC)). From 28 to 94% of FC an exponential increase in the evolution of¹⁴C was observed while the evolution was slightly decreasing in soil with water contents above this level. Degradation of 2-AB in soil was greatly enhanced when the soil was inoculated with liquid or with soil aliquots from a soil perfusion apparatus through which 2-AB had been percolating for 6 mo. This indicates the presence of organisms able to decompose 2-AB in the pre-treated soil and in the perfusing water.  相似文献   

C-Pro (grapefruit seed extract) as supplement or replacement against rose- and cucumber powdery mildew     

Brita Toppe  Arne Stensvand  Maria-Luz Herrero  Hans Ragnar Gisler⊘d 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):105-110

Abstract

Numerous fungicide applications are often needed to control powdery mildews in greenhouse-grown crops, and consequently there is an increasing demand for alternative means to control them. In commercial greenhouses, attack of powdery mildew caused by Podosphaera xanthii in cucumbers and P. pannosa in cut roses was controlled by weekly sprays of C-Pro CE601, a dilution of grapefruit seed extract (GSE). The raw material of GSE, delivered by Citricidal®, is a glycerolic extract from seed and juiceless pulp of grapefruits (Citrus paradise). In both cultures C-Pro at 2000 ppm achieved as good control as treatments with penconazole or triforine. The mean level of attack by powdery mildew on leaves of cut roses one week after the last of three weekly treatments, was 9.8, 12.9 and 40.5% for penconazole, C-Pro (2000 ppm), and untreated, respectively. In cucumbers, there was less difference between the untreated control and the different treatments, but for all times of assessments, C-Pro and triforine were better than untreated (p=0.001). There was no significant difference in cucumber between C-Pro and triforine. Phytotoxicity symptoms such as leaf twisting and rolling in roses (cv. Jade and Cezann) and dark green leaves and indications of growth retardation in cucumbers (cv. Ventura) were observed at the higher concentrations used (3000–4000 ppm). Thin layer chromatography of C-Pro CE601 has previously shown presence of benzethonium chloride, a synthetic antiseptic agent. Further research is necessary to determine if the observed effects of the product tested are due to natural compounds or are merely due to a synthetic preservative agent added. Our results revealed that C-Pro might be a supplement or even a replacement to some of the current fungicides used against powdery mildew.  相似文献