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91.
Physical and biological variables affecting juvenile Pacific herring (Clupea pallasi) in Prince William Sound (PWS) from 1995 to 1998 were investigated as part of a multifaceted study of recruitment, the Sound Ecosystem Assessment (SEA) program. Though more herring larvae were retained in eastern PWS bays, ages‐0 and ‐1 herring used bays throughout PWS as nursery areas. Water transported into PWS from the Gulf of Alaska (GOA) contributed oceanic prey species to neritic habitats. Consequently, variations in local food availability resulted in different diets and growth rates of herring among bays. Summer food availability and possible interspecific competition for food in nursery areas affected the autumn nutritional status and juvenile whole body energy content (WBEC), which differed among bays. The WBEC of age‐0 herring in autumn was related to over‐winter survival. The limited amount of food consumption in winter was not sufficient to meet metabolic needs. The smallest age‐0 fish were most at risk of starvation in winter. Autumn WBEC of herring and winter water temperature were used to model over‐winter mortality of age‐0 herring. Differences in feeding and energetics among nursery areas indicated that habitat quality and age‐0 survival were varied among areas and years. These conditions were measured by temperature, zooplankton abundance, size of juvenile herring, diet energy, energy source (GOA vs. neritic zooplankton), WBEC, and within‐bay competition.  相似文献   
92.
辽宁近海渔场海蜇增殖放流的回顾与发展   总被引:1,自引:0,他引:1  
辽宁近海渔场海蜇放流经过1988-1993年、2004年在海洋岛渔场和2002年在辽东湾各渔场的增殖试验与2005-2006年的生产性增殖放流,探索了放流海域选择、放流时间和放流规格,跟踪监测技术,回捕效果检验等相关技术。笔者就海蜇增殖放流情况作系统回顾,并对其大规模发展做以探讨。  相似文献   
93.
The endometrium of sheep consists of plenty of raised intercaruncular areas (IC). In order to better understand aglandular areas called caruncular (C), and intensely glandular the endometrium involved mechanisms of implantation, we used LC-MS/MS technique to profile the proteome of ovine endometrial C areas and IC areas separately during the peri-implantation period, and then compared the proteomic profiles between these two areas. We successfully detected 1740 and 1813 proteins in C areas and IC areas respectively. By comparing the proteome of these two areas, we found 170 differentially expressed proteins (DEPs) (P 〈 0.05), functional bioinformatics analysis showed these DEPs were mainly involved in growth and remodeling of endometrial tissue, cell adhesion and protein transport, and so on Our study, for the first time, provided a proteomic reference for elucidating the differences between C and IC areas, as an integrated function unit respectively, during the peri-implantation period. The results could help us to better understand the implantation in the ewes. In addition, we established a relatively detailed protein database of ovine endometrium, which provide a unique reference for further studies.  相似文献   
94.
Abstract  Fish sanctuaries are types of aquatic protected areas common throughout the landlocked country of Lao PDR. The key to their successful implementation in Laos appears to be local support. Therefore, they fit well within the context of community-based fisheries/co-management programmes. Fish sanctuaries are almost always established in deep-water pools, which serve as important dry season refuges for fish. The best-known fish sanctuaries in Laos are known as Fish Conservation Zones (FCZs), and are found in the mainstream Mekong River in Khong district, Champasak province, southern Laos. In Khong, there is increasing evidence that FCZs established by villagers, but with government support, are important places of concentration for various fish species. FCZs can benefit fish stocks, especially relatively sedentary species, but also highly migratory ones. FCZs are not panaceas for solving all the fisheries problems in Laos or the Mekong River Basin, but they represent important management tools that should not be overlooked.  相似文献   
95.
  1. The implementation of marine protected areas (MPAs) has been widely used as a tool to manage and conserve marine resources and services. Yet, to date, the reserve effect is still weakly evaluated, particularly for soft-sediment habitats.
  2. The Arrábida MPA, considered as a biodiversity hotspot, was fully established in 2009 on the west coast of Portugal and is characterized by large expanses of soft-sediment habitats. This MPA was established to protect biodiversity and to ensure the livelihood of the local small-scale fisheries community.
  3. Beyond before–after-control–impact (BACI) analyses were carried out on catch data (abundance and biomass) of 351 trammel net sets from experimental fishing campaigns (2007–2019) to study the reserve effect on demersal fish populations.
  4. The results show a declining trend in abundance inside and outside the protected area, with significant positive effects only found for undersize commercial species and Solea senegalensis, and a general increase in fish species total length. Despite the lack of any obvious reserve effect, the increase in fish length can be considered as a first sign.
  5. Anthropogenic pressures are generalized around the area, and transgressions of the restrictions are frequently observed inside the no-take zone. These can, among other aspects, delay or prevent the expected reserve effects. Therefore, enforcement and/or modification of the spatial plan must be incentivized to achieve the goals of the MPA.
  相似文献   
96.
This study reports, for the first time, the profiles and source analysis of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) associated with PM10 (particulate matter with aerodynamic diameter ≤10 μm) at a protected and ecologically sensitive area – the Yamuna Biodiversity Park – located in the megacity Delhi, India. Weekly PM10 sampling was carried out at this location for 1 year (2009–2010) and the annual mean PM10 level was found to be ~9 times the World Health Organization limit. Seasonal variation of PAHs (range 37.2–74.0 ng m?3) was significant with winter values being 72% and 68% higher than summer and monsoon respectively. Principal component analysis coupled with multiple linear regression identified diesel, natural gas and lubricating oil combustion (49.5%), wood combustion (25.4%), gasoline (15.5%) and coal combustion (9.6%) sources for the observed PAHs. Heavy traffic on the national highway and arterial roads and domestic emissions from suburban households in the vicinity of the park appeared to have significantly affected its air quality. A substantial portion (~55%) of the aerosol PAH load was comprised of carcinogenic species, which yielded a considerably high lifetime inhalation cancer risk estimate (8.7E?04). If considered as a conservative lower-bound estimate, this risk translates into ~211 excess cancer cases for lifetime inhalation exposure to the observed PAH concentrations in Delhi.  相似文献   
97.
Spatially explicit fisheries simulation models for policy evaluation   总被引:3,自引:0,他引:3  
This paper deals with the design of modelling tools suitable for investigating the consequences of alternative policies on the dynamics of resources and fisheries, such as the evaluation of marine protected areas (MPA). We first review the numerous models that have been developed for this purpose, and compare them from several standpoints: population modelling, exploitation modelling and management measure modelling. We then present a generic fisheries simulation model, Integration of Spatial Information for FISHeries simulation (ISIS‐Fish). This spatially explicit model allows quantitative policy screening for fisheries with mixed‐species harvests. It may be used to investigate the effects of combined management scenarios including a variety of policies: total allowable catch (TAC), licenses, gear restrictions, MPA, etc. Fisher's response to management may be accounted for by means of decision rules conditioned on population and exploitation parameters. An application to a simple example illustrates the relevance of this kind of tool for policy screening, particularly in the case of mixed fisheries. Finally, the reviewed models and ISIS‐Fish are discussed and confronted in the light of the underlying assumptions and model objectives. In the light of this discussion, we identify desirable features for fisheries simulation models aimed at policy evaluation, and particularly MPA evaluation.  相似文献   
98.
农村居民点破碎化导致中国农村地区公共服务设施与市政基础设施建设缺乏规模效益与服务效率,成为制约中国农村地区社会经济发展的重要因素。该研究采用空间分层取样法在中国东部平原地区选择了240个10 km×10 km的样点,以高分辨率遥感影像为数据基础,通过遥感影像目视解译、景观指数分析、热点分析等多种方法对中国东部平原农村居民点破碎化状况及其影响因素进行了研究,并分析了中国东部平原不同地区适宜的农村居民点数量与服务范围。结果表明:1)中国东部平原农村居民点破碎化程度表现为:长江中下游平原>东北平原>华北平原,破碎化程度最高的区域位于长江中下游平原,破碎化程度最低的区域位于华北平原与东北平原北部。2)气候、人口密度、耕作半径、土地开发时序、土地开发时期交通状况等自然、经济、社会因素在中国东部平原地区农村居民点空间分布格局形成过程中发挥着重要作用。3)中国东部平原地区每100 km2农村居民点数量不宜低于3~4个,每个村庄的服务范围不宜超过33.6~45.8 km2。4)华北平原为中国东部平原中开展农村居民点破碎化治理难度最大的区域,该区域尽量避免以整村迁并的形式开展农村居民点破碎化治理,而应以农户为单位,在农民自愿的基础上开展农村居民点迁并;长江中下游平原地区为中国东部平原农村居民点破碎化治理潜力最大的区域,该区域农村居民点布局优化应与农田布局调整协同推进,并根据不同地区耕作通勤状况合理确定中心村数量与位置,避免因农村居民点布局调整导致农民耕作不便。研究结果可为中国东部平原地区乡村空间重构过程中合理确定农村居民点数量与规模提供研究基础。  相似文献   
99.
张若曦  秦富仓    李龙    杨振奇  钱秋颖 《水土保持研究》2022,29(6):21-27,35
为了定量描述坡面微地貌变化与侵蚀的响应关系,通过三维激光扫描仪,以严重侵蚀的砒砂岩区裸露坡面为研究对象,在自然降雨条件下进行野外原位监测,试验分析了两个雨季13次有效降雨下坡面微地貌与坡面侵蚀的空间变化特征。结果表明:(1)13次降雨中,重度侵蚀3次、中度侵蚀5次、轻度侵蚀3次、微度侵蚀2次,且均与降雨强度密切相关。(2)各地形因子均在R4降雨时达到变化峰值,且其变化规律因坡位不同而有所差异,其中坡中与坡下变化规律基本一致,而上坡部地形因子波动起伏较为明显。(3)各地形因子间均存在一定的相关性,且坡位不同与产流产沙关系也不尽相同,其中产流量与微坡度相关性显著,随着坡位越靠下相关性越强。产沙量则在坡上及坡中与地表粗糙度表现为极显著相关,在下坡部与地表起伏度呈现出极显著相关。综上,坡面微地貌的变化一定程度上可以反映坡面侵蚀强度。  相似文献   
100.
为研究喀斯特山区坡耕地在岩性、土壤类型、坡位和居民点影响下的分布特征,为区域水土流失治理提供参考,以贵州省贵阳市花溪区为研究对象,结合花溪区高清影像图、高程图(DEM)、地质图和土壤类型图为主要数据源,利用ArcGIS 10.2平台,基于其空间叠加分析、数理统计等功能,对多因子影响下的喀斯特山区坡耕地分布特征进行了分析。结果表明:花溪区坡耕地面积占全区总面积的21.07%,占全区耕地面积的63.85%,是花溪区主要耕地类型; 在各岩组上,坡耕地的分布面积从大到小依次为:石灰岩组>白云岩组>普通砂页岩组>紫色砂页岩组,其中在普通砂页岩组和石灰岩组上分布较为集中连片,在白云岩组和紫色砂页岩组上分布较为零散; 坡耕地的各土壤类型面积依次表现为:水稻土>黄壤>石灰土>紫色土>潮土,其中黄壤最为集中连片,水稻土则较为分散; 不同坡位区域中,坡耕地面积依次表现为; 下坡位>中坡位>上坡位,其中在下坡位区域分布最为集中连片,上坡位区域分布最为零散; 同时坡耕地和居民点在空间分布上具有显著相关性,距离居民点越远,坡耕地分布越稀疏。综上所述,在多种因素共同作用下,花溪区坡耕地呈现出“西部多东部少”的空间格局,其中普通砂页岩组和石灰岩组上的坡耕地连片区可优先考虑进行治理。  相似文献   
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