Main stem movement of Atlantic salmon parr in response to high river temperature          下载免费PDF全文

Stephen J. Dugdale  Jan Franssen  Emily Corey  Normand E. Bergeron  Michel Lapointe  Richard A. Cunjak 《Ecology of Freshwater Fish》2016,25(3):429-445

Atlantic salmon become thermally stressed when water temperatures exceed 23 °C. To alleviate this stress, they behaviourally thermoregulate by moving to patches of cold water, often forming large aggregations. These patches are known as thermal refuges. Given the consensus that climate change will increase temperatures in Atlantic salmon catchments, thermal refuges will become increasingly important in minimising summer mortalities. While the behaviour of salmonids within thermal refuges is fairly well understood, less is known about their main stem movement in search of thermal refuges or its thermal and temporal cues. We detail the results of a PIT telemetry study to investigate the main stem movement behaviour of thermally stressed Atlantic salmon parr in a temperature‐impacted river. PIT antennas placed around two thermal refuges and at the upstream and downstream limits of their surrounding reach were used to record the movement of salmonids during a heatwave. We observed parr movement at the upstream and downstream antennas 135 min prior to the occurrence of the midpoint of aggregations in the thermal refuges, indicating that Atlantic salmon parr make reach‐scale movements in search of cool water prior to aggregating. Logistic regression showed that the number of degree hours >28 °C predicted the occurrence of main stem movement with a good degree of accuracy, indicating that this temperature represents a fundamental threshold causing Atlantic salmon parr to move towards cool water. Such data could be instrumental in allowing river managers to place limits on human activity within rivers, allowing salmon populations time to recover following heat stress events.  相似文献   

The source of autumn and spring downstream migrating juvenile Atlantic salmon in a small lowland river     

Anton T. Ibbotson  William D. Riley  William R.C. Beaumont  Alastair C. Cook  Mark J. Ives  Adrian C. Pinder  Luke J. Scott 《Ecology of Freshwater Fish》2013,22(1):73-81

Over 3 years, 32,444 age‐0 group Atlantic salmon (Salmo salar) parr tagged with passive integrated transponder tags throughout the River Frome catchment were assigned to one of three groups, nonmigrants, autumn migrants and spring smolts, depending on the detection and the timing of detection at downstream tag readers (situated 8.6 km above the tidal limit). We examined the effect of density at the time of tagging (n·m^?2), distance upstream from the tidal limit (km), fish length (mm), Fulton condition index, habitat type (divided into two types, main river and carrier), days after 1 September that each fish was tagged and year (replication) on the proportions of fish in each of the migration groups. Distance upstream from tidal limit was strongly negatively related to the proportion of autumn migrants and positively related to the proportion of spring smolts. Nonmigrants had a lower average body size than migrants, although there were no differences in the sizes of autumn migrants and spring smolts in September prior to migration. Fish density had no effect on migration strategy. A lower proportion of fish migrated as autumn migrants from the smaller carrier habitats than the main river channel. There is some evidence that those parr destined to become autumn migrants underwent a lower mortality rate during September before tagging than those destined to become spring migrants indicating possible physiological or behavioural differences between these two groups of fish at that time. More research into the factors responsible for initiating the autumn migration is required.  相似文献   

Estimating spatial distribution of Atlantic salmon escapement using redd counts despite changes over time in counting procedure: application to the Allier River population     

Guillaume J.R. Dauphin  Catherine Brugel  Marion Hoffmann‐Legrand  Etienne Prévost 《Ecology of Freshwater Fish》2013,22(4):626-636

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木麻黄海岸林林下套种技术与综合效益探讨     

林文途 《现代园艺》2013,(18):15-16

以福建泉州木麻黄海岸林为研究对象,探讨了木麻黄林下套种技术以及林下套种植被的生长效果和综合效益。经实践证明,木麻黄海岸林林下套种技术能够提高海岸土地资源的利用效率,降低风速,提高林分生产力和综合防护能力,因此值得进行深入研究和推广。  相似文献   

Calanus oil as a natural source for flesh pigmentation in Atlantic salmon (Salmo salar L.)     

N. HYNES  E.S. EGELAND  W. KOPPE  G. BAARDSEN  & V. KIRON 《Aquaculture Nutrition》2009,15(2):202-208

The present study was to understand how efficiently the astaxanthin in Calanus oil is utilized for flesh colouration in Atlantic salmon ( Salmo salar ). Postsmolts of the fish (309 g) were held at 7.9 °C and they were fed diets containing 20 or 60 mg astaxanthin per kilogram feed derived from a synthetic source or from Calanus oil for 181 days. Besides growth and feed intake assessments, at day 81 and 181, fish flesh were subjected to colour analysis and astaxanthin determination. Growth and feed performance did not vary between the groups. There were significant differences in the amount of astaxanthin in muscle between almost all groups both at day 81 ( P  < 0.05) and at day 181 ( P  < 0.001). However, a notable similarity between fish receiving 20 mg astaxanthin from the synthetic source and those receiving 60 mg astaxanthin from Calanus oil ( P  > 0.05) at day 181 indicated that comparable amounts were deposited only with the greater level of the natural source. Tristimuli colorimeter a* values support the analytical results at day 181. Although Calanus oil did serve as a natural dietary pigment source for farmed salmon, its inclusion level should provide more than 60 mg astaxanthin per kilogram feed to achieve colouration preferred by the market.  相似文献   

云南省退耕还林工程监理的探讨     

喻懋坤 《林业调查规划》2003,28(1):89-91

退耕还林工程是我国林业建设上涉及面最广、政策性最强、操作难度大、群众参与度最高的一项生态建设工程。在简述了退耕还林工程建设中实行工程监理的必要性、目的及意义的基础上,对退耕还林工程监理的机构建立及管理、监理内容、方法及操作步骤进行了初步探讨。  相似文献   

Atmospheric lead and cadmium deposition within forests in the Kanto district, Japan     

Yuko Itoh  Satoru Miura  Shuichiro Yoshinaga 《Journal of Forest Research》2006,11(2):137-142

Atmospheric lead and cadmium deposition in bulk precipitation and throughfall was investigated at four forests in the Kanto district, Japan, to assess the impact of human activities on the environmental health of forests. Annual lead and cadmium depositions in bulk precipitation ranged from 8.9 to 25.7 g ha⁻¹ year⁻¹ and from 0.77 to 1.30 g ha⁻¹ year⁻¹, respectively. Lead and cadmium deposition increased in the summer at every forest due to large amounts of rainfall. At one of the forests, the depositions were also high in the winter due to heavy snowfall. These depositions were similar to recent depositions observed at other rural and urban sites in Japan and several forests in Europe and North America after 1990. These results indicate that although anthropogenic lead and cadmium are deposited at these rates over wide areas, depositions are still higher than in remote areas.  相似文献   

Simulating responses of Northeastern China forests to potential climate change   总被引：5，自引：0，他引：5  

赵士洞  延晓冬  杨思河  陶大立  代力民 《林业研究》1998,9(3):166-172

IntroductionItissurethatpresentelevatiollsofCO2a11dotllergrcc11-housegasesinducedbyhumanactivitiesaren1akli1gglobalclimategothroughinexperielICedcl1anges(Scl1le-subgerl987).Thecurrentquasi-equilibriulllstatesofbio-sphereecosystCm,esPeciallyterrestrialecosystems,wouldbebrokenbecausetl1estructure,fu11ction,distributio11andtlledynamicsofanyexistedecosystemsareIberesultsoflongtermadaptationofbio-systemtocurrentclin1ate.Theec()systemsdistributedinhighlatitlldeareawouldhavemuchbiggerchai1ge(Bona…  相似文献   

谈国有林区分类经营改革问题     

谭俊 《四川林勘设计》1996,(4):1-4

从大兴安岭林区分类经营改革中的7个方面,分析论述国有林区分类经营改革的问题,并提出分类经营改革要结合林区实际进行研究试点,在有利于森林的可持续发展和发挥三大效益的前提下稳步推进。  相似文献   

林下经济发展存在问题及建议     

耿继斌 《现代农业科技》2021,18(18)

发展林下经济是解决当地农民摆脱贫困,实现小康生活的有效途径之一。从威宁县林下经济发展实际出发,总结了发展林下经济的主要模式,同时根据林下经济发展过程中存在问题,提出相关建议,为林下经济发展提出参考。  相似文献