Resource-use,body condition and parasite load metrics indicate contrasting health of stocked and native game fishes in Canadian prairie lakes     

Lushani Nanayakkara  Elizabeth R. Starks  Ryan N. Cooper  Sydney Chow  Peter R. Leavitt  Björn Wissel 《Fisheries Management and Ecology》2021,28(1):18-27

This study evaluated the status of native and stocked fish species in 13 prairie lakes in central Canada over eight years (2007–14) using three metrics: resource-use (benthic versus pelagic carbon via stable isotopes); body condition (relative weight index W_r); and parasite load (cestode gut enumerations). Analyses included game and non-game fishes, like naturally occurring northern pike, Esox lucius L., and yellow perch, Perca flavescens Mitchill, but focused on stocked walleye, Sander vitreus (Mitchill) because it supports a robust recreational fishery. Walleye and northern pike were significantly more reliant on benthic carbon than yellow perch or forage fishes (p < 0.05), but this reliance was not associated with any measured environmental variables for any species. In lakes with game fishes, forage fishes exhibited higher reliance on benthic energy, possibly due to predator avoidance strategy, particularly yellow perch. Walleye body condition index was consistently lower (<95–105) than values exhibited by the other two game fishes (81–139), and parasites were only common in walleye and associated with lake-water salinity (r² = 0.93, p < 0.05) and sex (p < 0.05). Based on the results, the most desirable game fish, walleye, appears less resilient to environmental variability than northern pike and yellow perch, making this species more susceptible to impacts of future climate change.  相似文献   

Specific adaptation of barley varieties in different locations in Ethiopia     

Fetien Abay  Asmund Bjørnstad 《Euphytica》2009,167(2):181-195

Barley is one of the most important cereal crops grown for the livelihoods of the poor farmers of Tigray region in northern Ethiopia. As many low input and marginal environments it has benefited less from the yield increases achieved by modern breeding. This has been largely attributed due to genotype × environment intraction (GEI). To investigate the causes of GEI, ten barley varieties including local checks (two farmers developed varieties, four modern varieties and three rare local varieties) were tested over 21 environments. Participatory methods were applied to sample an adequate number of environments spanning the regional diversity. The yielding ability and stability of the varieties was graphically depicted by GGE and PLSR biplot. There were two major groups of environments, the central and northern highlands, the latter with less rainfall and poorer soils. Rainfall per month and total nitrogen level were the environmental variables that differentiated these two groups. In Tigray, rainfall in June and July were negatively correlated with yield, reflecting waterlogging problems. The different varieties were either specifically or widely adapted across the two environments. The variety ‘Himblil’, originating in Tigray, was the highest yielding and also most stable in the region of origin. However, it was inferior to improved varieties (Shege and Dimtu) at high yield levels. The association of earliness with grain yield indicates that the trait can be effectively manipulated within the existing materials. We recommend breeding for drought/water logging resistance based on selection in the target environment as the best strategy to provide stable and high yielding varieties for Tigray.  相似文献   

Physiology during smoltification in Atlantic salmon: effect of melatonin implants     

S. O. Handeland  A. K. Imsland  B. Th. Björnsson  S. O. Stefansson  M. Porter 《Fish physiology and biochemistry》2013,39(5):1079-1088

Melatonin implants were used to override natural melatonin rhythm in groups of juvenile Atlantic salmon, Salmo salar, raised at simulated natural photoperiod (SNP) and constant light (LL) from mid-March until end of August. The experiment contained also both sham control (with non-melatonin implants) and control (no implants). No differences were found in the experimental variables between these two control groups. Growth and food intake were negatively affected by melatonin implantation. Overall, higher GH levels were observed in the SNP melatonin-implanted group, whereas no differences in GH levels were seen between the SNP control, LL control, or the LL melatonin-implanted groups. Highest food intake was seen in the LL control group. No differences in food intake were recorded between the LL melatonin-implanted and SNP control groups. Gill Na⁺, K⁺, ATPase (NKA) activity was influenced by time as well as the interaction between photoperiod and time. No differences in gill NKA activity or plasma chloride levels following transfer to seawater were seen between the groups with melatonin implants and their controls. Based on the present results, it seems apparent that melatonin does play a role in regulating food intake and growth in Atlantic salmon smolts.  相似文献   

Effects of Packaging Method on Salt-Cured Cod Yield and Quality During Storage     

Grete Hansen Aas  Olaug Taran Skjerdal  Iren Stoknes  Ingebrigt Bjørkevoll 《Journal Of Aquatic Food Product Technology》2013,22(3-4):149-161

Different packaging conditions of salt-cured cod fillets were studied during 2-years chilled storage. Yield and quality of salt-cured Atlantic cod fillets packed in sealed polystyrene boxes or in traditional cardboard boxes were compared. After 4 months, yield decreased by approximately 10% and decreased further when packed in cardboard boxes. Lipid oxidation was low after 12 months, and no microbiological spoilage was registered. The total amount of bacteria in the fish reduced with storage time, independent of packaging. The reddish color of halophilic bacteria was detected after 7–8 weeks at 18°C, but not if packed with MAP.  相似文献   

Rights‐based fisheries governance: from fishing rights to human rights     

Edward H Allison  Blake D Ratner  Björn Åsgård  Rolf Willmann  Robert Pomeroy  John Kurien 《Fish and Fisheries》2012,13(1):14-29

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Comparison of the nutrient resorption stoichiometry of <Emphasis Type="Italic">Quercus variabilis</Emphasis> Blume growing in two sites contrasting in soil phosphorus content     

Huawei Ji  Jiahao Wen  Baoming Du  Ningxiao Sun  Björn Berg  Chunjiang Liu 《Annals of Forest Science》2018,75(2):59

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Prevalence of house dust mites in the homes of atopic dogs in Finland          下载免费PDF全文

Kirsti J. M. Schildt  Riitta T. K. Seppänen  Anna K. Hielm‐Björkman  Leena E. Saijonmaa‐Koulumies  Svetlana Belova 《Veterinary dermatology》2017,28(2):225-e54

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The inheritance of anther extrusion in hexaploid wheat and its relationship to Fusarium head blight resistance and deoxynivalenol content     

H. Skinnes  K. Semagn  Y. Tarkegne  A. G. Marøy  Å. Bjørnstad 《Plant Breeding》2010,129(2):149-155

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An oxidative enzyme boosting the enzymatic conversion of recalcitrant polysaccharides     

Vaaje-Kolstad G  Westereng B  Horn SJ  Liu Z  Zhai H  Sørlie M  Eijsink VG 《Science (New York, N.Y.)》2010,330(6001):219-222

Efficient enzymatic conversion of crystalline polysaccharides is crucial for an economically and environmentally sustainable bioeconomy but remains unfavorably inefficient. We describe an enzyme that acts on the surface of crystalline chitin, where it introduces chain breaks and generates oxidized chain ends, thus promoting further degradation by chitinases. This enzymatic activity was discovered and further characterized by using mass spectrometry and chromatographic separation methods to detect oxidized products generated in the absence or presence of H(2)(18)O or (18)O(2). There are strong indications that similar enzymes exist that work on cellulose. Our findings not only demonstrate the existence of a hitherto unknown enzyme activity but also provide new avenues toward more efficient enzymatic conversion of biomass.  相似文献   

Assessment of a new qPCR tool for the detection and identification of the root-knot nematode Meloidogyne enterolobii by an international test performance study     

Andrea Braun-Kiewnick  Nicole Viaene  Laurent Folcher  Fabrice Ollivier  Géraldine Anthoine  Björn Niere  Melanie Sapp  Bart van de Vossenberg  Halil Toktay  Sebastian Kiewnick 《European journal of plant pathology / European Foundation for Plant Pathology》2016,144(1):97-108

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