944 resultados para 616.24
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Abstract The spawning activities of cod were described in the Arkona Sea from 2009 to 2012 and were compared with estimates of the period 1992 – 1999. Cod spawned mainly from beginning of June till the middle of July every year. In the same period spawning was observed in the Bornholm Sea. The spawning activities in July were limited by water temperature above the critical limits. Spawning activities in spring which were observed in the 90 ties were of lower importance between 2009 and 2012. Higher proportions of spent cod were observed in the Arkona Sea in August and autumn between 2009 and 2012 compared to the earlier period, indicating immigration of cod from the Bornholm Sea after spawning. The study showed that higher proportion of cod with developing sex products were observed in the Arkona Sea between 2009 and 2012 compared to the 90 ties. Kurzfassung Die Laichaktivitäten der Dorsche in der Arkonasee werden für den Zeitraum 2009 – 2012 dargestellt und im Vergleich mit dem Zeitraum 1992 – 1999 diskutiert. Die Hauptlaichaktivitäten haben im Untersuchungszeitraum von Anfang Juni bis Mitte Juli stattgefunden und lagen damit in ihrem jahreszeitlichen Verlauf innerhalb der Zeitperiode der Laichaktivitäten in der angrenzenden Bornholmsee. In der Arkonasee wurden jeweils im Juli diese Ereignisse durch ansteigende Wassertemperaturenbegrenzt. Die, noch in den 90-er Jahren beobachteten, Laichaktivitäten im Frühjahr haben aktuell an Bedeutung verloren. Im Spätsommer und Herbst war ein, im Vergleich zu den 90-er Jahren, höherer Anteil an abgelaichten Tieren in der Arkonasee zu beobachten, der als Indiz für eine Zuwanderung von abgelaichten Dorschen aus der Bornholmsee gewertet wird. Insgesamt hat der Anteil an Tieren mit sich entwickelnden Geschlechtsprodukten (aktive Laicher) im Untersuchungszeitraum, im Vergleich zu den 90-er Jahren, zugenommen.
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东海陆架是世界上最宽阔的陆架之一,面积达770 000 km2左右。在末次冰盛期(LGM),东海海平面下降120~130 m左右,绝大部分陆架暴露出海面。而冲绳海槽是第四纪以来一直保持海洋环境的东海深海区。本文以冲绳海槽北部PC-1岩芯为材料,通过分析该孔的孢粉,加上详细的AMS 14C测年,恢复了周边地区24 cal.kaBP以来的古植被,并推测古环境和古气候变化,重点讨论了LGM时期出露大陆架上发育的植被。 PC-1孔(31°27.5′N,128°24.8′E)位于黑潮支流对马暖流东侧,水深590 m,柱长812 cm。孢粉分析按间隔8 cm取样,个别为4~6 cm,共分析了103个孢粉样品。利用9个AMS 14C数据建立年龄标尺,用Calib5.1.0软件进行年龄校正。通过相邻样品深度的线性内插获得每个样品的年龄,采用外延法得到顶部和底部的校正年龄分别为351cal aBP、24 280 cal aBP,孢粉样品的时间分辨率平均为230 a。 根据孢粉百分比和沉积率的变化,可划分出四个带:Ⅰ带(812~715 cm,24.2~21.1 cal. kaBP)、Ⅱ带(715~451 cm,21.1~15.2 cal. kaBP)、Ⅲ带(451~251 cm,15.2~10.8 cal. kaBP)、Ⅳ带(251~0 cm,10.8~0.3 cal. kaBP),分别对应MIS 3末期、末次冰盛期、冰消期和全新世。末次冰盛期草本植物花粉占优势,孢粉沉积率较高,此时草本花粉主要来源于出露的大陆架,其上发育了以蒿属为主的草地植被,气候比较寒冷干燥;冰消期海平面开始回升,松属花粉含量升高,草本植物花粉含量下降;全新世以木本植物花粉占绝对优势,栗属-栲属花粉迅速增加,蕨类孢子含量升高,草本植物花粉含量锐减,孢粉沉积率降低,由于海平面回升,大陆架被淹没,此时孢粉主要来源于日本岛,九州地区生长了以栲属、栎属为主的常绿阔叶与落叶阔叶林,气候温暖湿润。 叶枝杉属花粉在整个岩芯中零星出现。叶枝杉属植物分布于菲律宾吕宋北部至塔斯马尼亚和新西兰气候潮湿的山地林中,该属花粉在岩芯中的出现,可能暗示了黑潮的影响或者是较强的夏季风。 草本植物与松属花粉百分比变化很好的反映了海平面的升降,松属花粉含量较高指示海平面较高。对岩芯中主要类型的花粉百分比进行了频谱分析,显示存在千年尺度的准周期变化,有明显的6.8,3.8,2.2,1.6 ka的周期。 孢粉样品中的炭屑统计表明,末次冰消期炭屑含量最高,可能因为末次冰消期降雨量增加,炭屑可被降水带到沉积地点沉积下来;全新世的炭屑浓度较高,尤其在晚全新世,出现了一个峰值,究其原因可能与气候变化和人类活动有关。
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A meeting was convened on February 22-24, 2005 in Charleston, South Carolina to bring together researchers collaborating on the Bottlenose Dolphin Health and Risk Assessment (HERA) Project to review and discuss preliminary health-related findings from captured dolphins during 2003 and 2004 in the Indian River Lagoon (IRL), FL and Charleston (CHS), SC. Over 30 researchers with diverse research expertise representing government, academic and marine institutions participated in the 2-1/2 day meeting. The Bottlenose Dolphin HERA Project is a comprehensive, integrated, multi-disciplinary research program designed to assess environmental and anthropogenic stressors, as well as the health and long-term viability of Atlantic bottlenose dolphins (Tursiops truncatus). Standardized and comprehensive protocols are being used to evaluate dolphin health in the coastal ecosystems in the IRL and CHS. The Bottlenose Dolphin Health and Risk Assessment (HERA) Project was initiated in 2003 by Dr. Patricia Fair at the National Oceanic and Atmospheric Administration/National Ocean Service/Center for Coastal Environmental Health and Biomolecular Research and Dr. Gregory Bossart at the Harbor Branch Oceanographic Institution under NMFS Scientific Research Permit No. 998-1678-00 issued to Dr. Bossart. Towards this end, this study focuses on developing tools and techniques to better identify health threats to these dolphins, and to develop links to possible environmental stressors. Thus, the primary objective of the Dolphin HERA Project is to measure the overall health and as well as the potential health hazards for dolphin populations in the two sites by performing screening-level risk assessments using standardized methods. The screening-level assessment involves capture, sampling and release activities during which physical examinations are performed on dolphins and a suite of nonlethal morphologic and clinicopathologic parameters, to be used to develop indices of dolphin health, are collected. Thus far, standardized health assessments have been performed on 155 dolphins during capture-release studies conducted in Years 2003 and 2004 at the two sites. A major collaboration has been established involving numerous individuals and institutions, which provide the project with a broad assessment capability toward accomplishing the goals and objectives of this project.
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EXTRACT (SEE PDF FOR FULL ABSTRACT): Pluvial Lake Estancia in central New Mexico experienced large and rapid fluctuations in surface area and elevation during the build-up to and termination of the last glacial maximum (LGM). Due to continuous groundwater discharge, a minimum pool covering about 400 square kilometers was maintained in the central basin until about 12,000 years ago, ensuring a continuous depositional sequence even during low stands of the lake. ... The sensitive response to fluctuations in climate by several independent proxies at Estancia show that transport of Pacific moisture over western North America changed dramatically during the last Ice Age, perhaps comparable to the large and rapid changes in climate documented from high-latitude ice and North Atlantic marine sediments for the LCM and its transitions.
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本文探讨了五十年来北京地区广泛推广的17个冬小麦(Triticun aestivum L)品种在品种改良的过程中农艺性状和某些光合特性的变化趋势。从中选出形态、产量和推出年代差异最大的3个冬小麦品种:京冬8号、农大139和燕大1817,种植在相同的环境条件下,进一步研究与冬小麦产量提高有关的生理生态特性,以及它们的气体交换特性对于外界环境变化的响应。本试验于1999-2001年在北京农林科学院试验农场(39o09’N, 116o04’E)进行。结果如下: 1. 在冬小麦品种改良的过程中,小麦品种的经济产量、收获指数、千粒重提高,而生物产量、株高、单株穗数、单株籽粒产量和穗长降低。籽粒产量与株高、穗数极显著负相关,与穗粒重、收获指数、千粒重极显著正相关。株高与穗长、单株籽粒产量、穗数显著正相关,而与收获指数和千粒重极显著负相关。收获指数与穗数极显著负相关,而与千粒重极显著正相关。说明株高降低、收获指数提高和千粒重的提高对于冬小麦品种改良过程中产量的提高起重要作用。 2. 随品种推出年代的延迟,各品种苗期-拔节期的净光合速率(PN)、 气孔导度(gs)、蒸腾速率( E)、量子产率(Fv/Fm)均呈增加的趋势,水分利用率(WUE)呈降低的趋势。在孕穗期-蜡熟期,旗叶的PN也随品种推出年代而呈增大的趋势,而在成熟期呈减小的趋势。gs在孕穗期-灌浆期增大,在蜡熟期和成熟期减小;各个时期的E均呈递增趋势;而WUE呈降低趋势。旗叶的Fv/Fm在孕穗期和开花期呈递增的趋势,而在成熟期下降。在苗期至孕穗期,PN、 E均与产量显著正相关;在拔节始期和孕穗期gs与产量显著正相关(R=0.616, 0.499, P<0.05),在苗期-拔节期、开花期和成熟期,WUE与历史产量和试验产量显著负相关(P<0.05, 或P<0.001),在苗期和拔节期Fv/Fm与产量正相关(P<0.05)。在冬小麦品种的改良过程中,其光合作用的改良不仅表现在净光合速率上,而且还表现在荧光动力学参数Fv/Fm上, 即PSII的原初光能转化效率有所提高。 3. 孕穗期至灌浆期,高产品种京冬8号旗叶的PN、gs、E、叶绿素含量和水分含量均最高,而水分利用率(WUE)较低,且具有较高的光呼吸和较低的暗呼吸,其旗叶的叶比重也较高。京冬8号(上世纪90年代推出)叶片气体交换的日变化表现为:在拔节期,全天的净光合速率均最高,而后随生育进程差异变小,通常上午较高,而在中午和下午较低。其旗叶Fv/Fm的变化趋势与净光合速率相似。燕大1817(上世纪40年代推出)的光合作用的午休现象较不明显,且在下午恢复较快,说明它可能具有一定的抗光抑制能力。孕穗至灌浆期是冬小麦籽粒形成和充实的关键时期,此时,叶片光合产物充足与否直接影响千粒重。进一步研究它们“源库”关系的结果表明,京冬8号“源库”关系协调,能够充分发挥“源“和“库”的潜力,且具有最高的收获指数、穗粒重和千粒重,而其它两个品种燕大1817和农大139都存在提高其品种产量潜力的限制因素。因此我们认为,高产品种的高产不仅因为其叶片具有较高的光合速率和较低的暗呼吸消耗,而且有较大的“库”容量和收获指数。 4. 当CO2浓度从360增加到720 µmol.mol-1时,单位叶面积的净光合速率和叶片的水分利用率 随CO2浓度升高而升高。但不同品种差异很大,京冬8号PN 和WUE最高,增加最多,分别提高了173 %和81 %;其次为农大139(上世纪70年代推出),燕大1817增加最少,分别提高了76 %和65 %。E随CO2 浓度的增加而提高;农大139和燕大1817的gs随CO2浓度的增大而减小,而京冬8号则增大。京冬8号和农大139旗叶胞间CO2浓度(Ci) 随CO2 浓度的增加而增大,而燕大1817 的Ci先增大,而后又急剧降低,且京冬8号的Ci最低,燕大1817 最高。在高CO2浓度下,京冬8号的光合速率显著高于其它两个品种,而Ci却低于其它两个品种,说明京冬8号的光合潜力高于其它两个品种。灌浆期高产品种京冬8号旗叶在田间不同自然光强下,净光合速率都是最高的(差异最大时,比燕大1817提高24.8 %)。因此,冬小麦光合作用的潜力,也在一定程度上得到改良。
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This publication is a report of the proceedings of the ICSF Pondy Workshop, which focused on the FAO’s Voluntary Guidelines for Securing Sustainable Small-scale Fisheries in the Context of Food Security and Poverty Eradication (SSF Guidelines). The workshop brought together 71 participants from 20 countries representing civil society organizations, governments, FAO, academia and fishworker organizations from both the marine and inland fisheries sectors. This report will be found useful for fishworker organizations, researchers, policymakers, members of civil society and anyone interested in small-scale fisheries, food security and poverty eradication.