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1.
研究了鳄鱼血蛋白酶解产物的抗氧化特性和对血管紧张素转化酶（ ACE）的抑制活性。利用木瓜蛋白酶酶解鳄鱼血浆蛋白和血球蛋白,用分光光度法测定了酶解产物的抗氧化能力和用高效液相色谱（ HPLC）测定其ACE的抑制率。结果显示：鳄鱼血浆和血球蛋白酶解产物的亚铁离子螯合能力差异性不显著（ P＞0．05）;在0～5 mg/mL的浓度范围内,血球蛋白酶解产物清除ABTS自由基的能力大于血浆蛋白酶解产物,且在浓度为1 mg/mL时,两者清除ABTS自由基的能力差异性极显著（ P＜0．01）;血浆蛋白酶解产物清除DPPH自由基的能力在0～5 mg/mL的浓度范围内随着蛋白浓度的增加而升高,血球蛋白酶解产物在蛋白浓度为4 mg/mL处达到最大清除率,之后下降;在0～20 mg/mL的浓度范围内,两种酶解产物的还原力随着蛋白浓度的提高显著升高,但两者还原力的差异性不显著（ P＞0．05）;鳄鱼血浆和血球蛋白酶解产物对ACE具有良好的抑制力,其最大抑制率可分别达到75．56％和86．42％。研究表明,鳄鱼血蛋白酶解产物在体外具有抗氧化和抑制ACE的活性。  相似文献   

2.
  • 1 Despite conservation programmes (India 1975, Nepal 1978) gharial populations (Gavialis gangeticus) have declined over their entire distribution range. Information about the current status and main threats is needed to implement effective conservation measures.
  • 2 This study presents a survey (2003/2004) of the largest Nepalese gharial population in the Chitwan National Park that has benefited from regular re‐introduction of young gharials since 1981.
  • 3 Population size estimates fluctuate between 34 (2003) and 38 (2004). The reintroduction programme, although of limited success, has helped to maintain the gharial population.
  • 4 Gharials bask preferentially in large sand banks, and these sites must be protected.
  • 5 The main threats are from a dam that causes fish depletion and flushes gharials from the protected area, sand mining and grazing that destroy basking sites, fishing that causes food shortage, drift nets that kill gharial, and water pollution.
  • 6 Improvement in the survival of reintroduced gharials is needed. Strict protection of preferred basking sites and prohibition of fishing in the main settling zones are the principal conservation measures while in the long term, education and participatory management by local people are also necessary. Copyright © 2010 John Wiley & Sons, Ltd.
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3.
    
  1. Bottlenose dolphins encountered around the Irish coast are considered part of a wide‐ranging coastal community; however, knowledge on the significance of the north of Ireland for this species is limited by a lack of dedicated effort.
  2. Through social media, the opportunity now exists to gather large volumes of citizen science data in the form of high‐quality images, potentially extending the spatial and temporal scope of photo‐identification studies.
  3. The purpose of this study was to investigate social media as a data resource for photo‐identification studies and to provide a preliminary assessment of bottlenose dolphins in the north of Ireland. Specifically, the study sought to examine the photo‐identification data for spatial clustering.
  4. The study identified 54 well‐marked individuals and provided evidence of potential year‐round occurrence, with successful re‐sightings throughout the study period (2007–2016). There was a geographic concentration of re‐sightings along the north of Ireland, suggestive of interannual site fidelity. These results provide scientific rationale for strategically targeting the north of Ireland in future research on the Irish coastal community.
  5. For effective conservation of the bottlenose dolphin it is imperative that scientific research, and resultant management objectives, consider wide‐ranging communities such as the Irish coastal community. Our research highlights data collection via social media as a cost‐effective and scientifically valuable tool in the photo‐identification of coastal cetaceans. We recommend that this method is used in research on low‐density and wide‐ranging coastal cetaceans.
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4.
鸟类对生态系统变化较为敏感,是衡量生态环境质量变化的一种重要指示生物;气候变化已成为栖息地丧失的重要原因之一,对鸟类的迁徙、繁殖有一定的影响。为了探究未来气候变化条件下鸟类栖息地适宜性分布,以洞庭湖流域为研究区域,结合收集到的382个鸟类出现点数据、遥感影像数据、气候变化数据等,基于Maxent模型方法,综合分析驱动洞庭湖流域鸟类分布的气候因素,并预测2050年气候不同情景下鸟类栖息地适宜性分布特征。结果显示,历史情景下洞庭湖流域鸟类的适宜性栖息地为多个集中分布区组成的带状区域,而在未来情景下栖息地由以前的带状分布逐渐演变为团状分布。在2050年RCP2.6、RCP4.5排放情景下,适宜栖息地面积有所下降,占研究区域总面积的比例从历史情景的9.43%分别降至9.26%、8.91%;而在RCP8.5排放情景下面积有所增加,占研究区域总面积的比例增加至10.22%。从适宜性分布来看,栖息地变得更加集中,未来情景下鸟类栖息地适宜性在3种排放情景下略高于历史情景,适宜性RCP8.5情景(33.12%)>RCP2.6情景(32.87%)>RCP4.5情景(32.74%)>历史情...  相似文献   

5.
热带东太平洋海域拟锥齿鲨的繁殖生物学特性   总被引：1，自引：0，他引：1  
刘维  戴小杰 《南方水产》2008,4(2):21-25
研究根据科学观察员在热带东太平洋海域2次调查,调查时间和海域分别为2003年7～11月的03°S～17°S,96°W～146°W范围,2006年2～11月的05°N～10°S,134°W～173°W范围。调查共测定了202尾拟锥齿鲨（Pseudocarcharias kamoharai）的样本,并对其进行分析。结果表明,拟锥齿鲨全长（TL）与全重（W）的关系,雌性是W=9×10^-5TL^2.3116,雄性是W=9×10^-6TL^2.9007。其雌雄性比接近1：1。雌性拟锥齿鲨的总性腺重量随体长增加而增加,增加幅度较大;雌性拟锥齿鲨性成熟的最小TL约为89cm,雄性大约在85～100cm。雌体怀仔数量平均为3.85尾。出生时的TL约为40cm左右。  相似文献   

6.
    
  1. In transitional water ecosystems, habitat loss is one of the major threats to fish biodiversity. This is particularly true in the case of temperate salt marshes. Good quality artificial novel habitats may compensate for the loss of natural habitats, acting as a refuge for fish populations.
  2. The aim of this study was to use coloured ornamental traits exhibited by the males of a small lagoon-resident fish, the Mediterranean killifish Aphanius fasciatus (Valenciennes, 1821), to assess habitat quality in both the natural and artificial creeks of the Venice lagoon.
  3. The conspicuousness of two secondary sexual traits, the yellow/orange caudal fin pigmentation and the contrast between white and dark vertical bars on body sides, proved to be greater in artificial habitats compared to natural salt marshes, highlighting the refuge function of artificial creeks.
  4. The use of secondary sexual traits could be extended to other fish species and to other aquatic habitats as a non-invasive approach. This would allow the identification of good quality habitats in the context of fish population management and conservation.
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7.
Abstract – The required freshwater habitats of juvenile Atlantic salmon ( Salmo salar ) are, in general, well known, but vary in quality, related to interacting effects of several variables, which may depend on different parts of a river system. Examples are given of ranges of densities and growth that can be found at various sites in eastern Canada, illustrating the biological and physico-chemical factors affecting production of juvenile salmon. Relative growth rates can indicate habitat quality and population densities. Salmon parr have negative effects on brook trout in riffle habitats. The effects of migrations within the river and of changes with stream succession on juvenile salmon production are illustrated with examples from a Newfoundland river. Migration of age-classes can be quantified from 'self-thinning' curves. Lakes have enhancing effects on downstream fluvial habitats, and, at least in Newfoundland, and probably in many boreal areas, the lacustrine proportion of the basin can be used as an index for deriving estimates of required spawning escapement. The factors described should be taken into account for more refined estimates of river production and management of the salmon resource.  相似文献   

8.
    
  1. Sources of data other than those derived from conventional research protocols may contribute valuable information to fill gaps in knowledge about cetacean occurrences and diversity in a given area and help address conservation issues.
  2. The performance of a method to examine cetacean communities based on presence records systematically derived from shared photographs and videos posted by boaters and maritime operators on social media (e.g. YouTube and Facebook) combined with patchy distributed visual/acoustic data collected by researchers has been evaluated.
  3. Records (N = 1,274) gathered over a 10‐year period (2008–2017) have been used to obtain insights into species' presence and habitat selection in a scattered study area of the central Mediterranean Sea (Italy). The effectiveness of the method, practical and theoretical advantages, limitations, and challenges of using data originated from social media for research and conservation purposes are discussed.
  4. Seven out of the eight cetacean species regularly residing in the Mediterranean have been reported in the area, with different relative densities. Maximum entropy modelling techniques have been applied to the datasets derived from (a) social media, (b) research surveys, and (c) the combination of the two, using six fixed variables as proxies for cetacean presence. Distance from the coast and depth emerged as the main variables predicting encounters, with specificities related to the ecology of the species.
  5. The approach was reliable enough to obtain broad‐scale, baseline information on cetacean communities in the region, on the basis of which initial conservation recommendations and future research programmes can be proposed.
  6. With the increasing need for studying whale and dolphin population ecology coming from national/international directives, support from citizens to aid research may act as a practical, inexpensive solution to gathering extensive spatial–temporal data for regional‐scale monitoring and for the development of management priorities.
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9.
    
  1. The Critically Endangered gharial (Gavialis gangeticus) residing within Bardiya National Park (BNP) in Nepal constitutes the sixth major sub-population of this unique lineage; however, this population is not well studied. A 46 km protected stretch of the Babai River and a 60 km stretch of the Karnali River in and around BNP were surveyed for gharials in early 2017 and in 2019.
  2. Gharial counts in 2017 – 17 from the Babai and one from the Karnali rivers – consisted of 10 adults, five sub-adults and three juveniles. In 2019, 19 gharials were counted – 18 for the Babai and one for the Karnali – comprising 11 adults, six sub-adults and two juveniles. In the Babai River within BNP, four breeding groups were identified. Gharials in BNP prefer sandy vs. rocky banks for basking and completely avoid sand-grass and clay banks. Habitat preference did not vary with size class.
  3. Protected stretches of both rivers inside BNP (76 km) have resident gharial, intact habitats and few human threats. In contrast, the unprotected stretch of the Karnali (30 km) is threatened by boulder quarrying, sand mining and unlicensed fishing, and is avoided by gharials despite the availability of habitat.
  4. This study established baseline data, including indices of population size, distribution and habitat preferences, and documented resident gharials that are breeding in the Babai River in BNP. The conservation of this Babai population is crucial for the species’ survival in BNP.
  5. Based on this study, we recommend the following conservation actions on the Babai stretch: (a) determine hatching success; (b) assess juvenile recruitment; (c) consider supplementation by releasing captives; (d) study riverine features important as baselines; (e) accommodate upstream movements on the protected Babai stretch; and (f) protect the downstream Babai outside the boundary of the BNP.
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10.
    
  1. The Siamese Crocodile (Crocodylus siamensis) is a critically endangered medium‐size crocodilian endemic to Southeast Asia. Extirpated from much of its natural range, conservation efforts in the Cardamom Mountains of Cambodia include the release of captive‐reared juveniles and sub‐adults into river reaches known to support adult C. siamensis populations. Despite conservation concerns, the biology of wild C. siamensis is not well studied and the ecology of ecosystems at release locations is poorly understood.
  2. Fish are thought to comprise a major component of the diet of C. siamensis. Here, the aim was to characterize fish communities within three potential C. siamensis release locations, focusing on community composition, density, size class structure and food web dynamics. The survey sites varied in both C. siamensis density and human fishing pressure, and the results are interpreted in light of these drivers.
  3. Genomic interrogation of fishes of the Cardamom Mountains distinguished 13 distinct fish species, contributing to genetic databases and adding to the documented taxon list for the region. The presence of two previously unconfirmed fish genera in the region is confirmed. The first estimates of fish density, biomass and size class distribution for three rivers in the Cardamom Mountains are provided.
  4. The three potential C. siamensis release reaches that were sampled showed clear differences in fish community composition, structural and trophic dynamics. Fish density and biomass were highest in the high‐density C. siamensis survey reach and lowest in the high human fishing pressure reach. Survey reaches with food webs that were more reliant on autochonously driven food webs supported higher densities and biomass of fish. These results have important implications for future C. siamensis conservation efforts in Cambodia and contribute valuable ecological information on a relatively unexplored region.
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11.
为了解桑沟湾养殖区大型底栖动物的动态变化以及底栖生境的健康状况,于2019年5-9月采集了中国北方典型养殖海湾桑沟湾不同养殖区（藻类、贝类和网箱养殖区）大型底栖动物样品,分析了不同养殖区大型底栖动物的种类、组成、数量分布、群落结构及生物多样性等群落特征,运用多样性指数、AMBI和M-AMBI指数法评价了不同养殖区底栖生境健康状况的时空变化。调查共鉴定出大型底栖动物56种,其中多毛类31种,甲壳类10种,软体动物9种,棘皮动物4种,其他类2种,大型底栖动物的优势种主要为多毛类,以污染耐受种为主;调查期间,贝类养殖区和网箱养殖区的群落多样性指数H''呈现下降趋势,表明贝类养殖活动和网箱养殖活动已经造成沉积物中有机物颗粒过度积累。ABC曲线显示,7月桑沟湾养殖区开始受到干扰,8月和9月受到中等程度的干扰。AMBI和M-AMBI指数评价显示桑沟湾养殖区域底栖生态系统处于轻度或中度干扰状态,底栖生境健康状况处于高等或者良好的状态。  相似文献   

12.
Abstract This study examined juvenile salmonid use of a freshwater tidal creek system draining a wetland on the floodplain of the lower Fraser River, British Columbia, Canada. Chum, Oncorhynchus keta (Walbaum), chinook, O. tshawytscha (Walbaum), and sockeye, O. nerka (Walbaum), salmon fry were abundant in the tidal creeks in spring. The fry were found in non-natal habitat up to 1.5 km from the main channel of the river. The salmon fry ate dipteran adults, larvae and pupae, cyclopoid and harpacticoid copepods, and Collembola. Mysids Neomysis mercedis Holmes (Walbaum), and amphipods, Crangonyx richmondensis occidentalis (Hubricht and Harrison), were also consumed. The upper reaches of an undisturbed creek were the winter rearing habitat for presmolt coho salmon, O. kisutch (Walbaum), where this species ate dipteran pupae and larvae as well as a freshwater isopod, Asellus communis Say (Walbaum).  相似文献   

13.
    
Viral haemorrhagic septicaemia virus (VHSV) genotype IVb has been responsible for large‐scale fish mortality events in the Great Lakes of North America. Anticipating the areas of potential VHSV occurrence is key to designing epidemiological surveillance and disease prevention strategies in the Great Lakes basin. We explored the environmental features that could shape the distribution of VHSV, based on remote sensing and climate data via ecological niche modelling. Variables included temperature measured during the day and night, precipitation, vegetation, bathymetry, solar radiation and topographic wetness. VHSV occurrences were obtained from available reports of virus confirmation in laboratory facilities. We fit a Maxent model using VHSV‐IVb reports and environmental variables under different parameterizations to identify the best model to determine potential VHSV occurrence based on environmental suitability. VHSV reports were generated from both passive and active surveillance. VHSV occurrences were most abundant near shore sites. We were, however, able to capture the environmental signature of VHSV based on the environmental variables employed in our model, allowing us to identify patterns of VHSV potential occurrence. Our findings suggest that VHSV is not at an ecological equilibrium and more areas could be affected, including areas not in close geographic proximity to past VHSV reports.  相似文献   

14.
    
An assessment of climate change impacts on the habitat suitability of fish species is an important tool to improve the understanding and decision‐making needed to reduce potential climate change effects based on the observed relationships of biological responses and environmental conditions. In this study, we use historical (2010–2015) environmental sea surface temperature (SST), upwelling index (UI), chlorophyll‐a (Chl‐a) and biological (i.e., anchovy adults acoustic presence) data (i.e., Maxent) to determine anchovy habitat suitability in the coastal areas off central‐northern (25°S–32°S) Chile. Using geographic information systems (GIS), the model was forced by changes in regionalized SST, UI and Chl‐a as projected by IPCC models under the RPC (i.e., RCP2.6, RCP4.5, RCP6.0 and RCP8.5) emissions scenarios for the simulation period 2015–2050. The model simulates, for all RCP scenarios, negative responses in anchovy presence, reflecting the predicted changes in environmental variables, dominated by a future positive (warming) change in SST and UI, and a decrease in chlorophyll‐a (i.e., phytoplankton biomass). The model predicts negative changes in habitat suitability in coastal areas from north of Taltal (25°S) to south of Caldera (27°45′S) and in Coquimbo littoral zone (29°–30°12′S). The habitat suitability models and climate change predictions identified in this study may provide a scientific basis for the development of management measures for anchovy fisheries in the coastal areas of the South American coast and other parts of the world.  相似文献   

15.
    
Understanding large‐scale migratory behaviours, local movement patterns and population connectivity are critical to determining the natural processes and anthropogenic stressors that influence population dynamics and for developing effective conservation plans. Atlantic tarpon occur over a broad geographic range in the Atlantic Ocean where they support valuable subsistence, commercial and recreational fisheries. From 2001 through 2018, we deployed 292 satellite telemetry tags on Atlantic tarpon in coastal waters off three continents to document: (a) seasonal migrations and regional population connectivity; (b) freshwater and estuarine habitat utilization; (c) spawning locations; and (d) shark predation across the south‐eastern United States, Gulf of Mexico and northern Caribbean Sea. These results showed that some mature tarpon make long seasonal migrations over thousands of kilometres crossing state and national jurisdictional borders. Others showed more local movements and habitat use. The tag data also revealed potential spawning locations consistent with those inferred in other studies from observations of early life stage tarpon leptocephalus larvae. Our analyses indicated that shark predation mortality on released tarpon is higher than previously estimated, especially at ocean passes, river mouths and inlets to bays. To date, there has been no formal stock assessment of Atlantic tarpon, and regional fishery management plans do not exist. Our findings will provide critical input to these important efforts and assist the multinational community in the development of a stock‐wide management information system to support informed decision‐making for sustaining Atlantic tarpon fisheries.  相似文献   

16.
    
1. Development of environmental protected areas has been driven ‘more by opportunity than design, scenery rather than science’ (Hackman A. 1993. Preface. A protected areas gap analysis methodology: planning for the conservation of biodiversity. World Wildlife Fund Canada Discussion Paper; i–ii). If marine environments are to be protected from the adverse effects of human activities, then identification of types of marine habitats and delineation of their boundaries in a consistent classification is required. Without such a classification system, the extent and significance of representative or distinctive habitats cannot be recognized. Such recognition is a fundamental prerequisite to the determination of location and size of marine areas to be protected. 2. A hierarchical classification has been developed based on enduring/recurrent geophysical (oceanographic and physiographic) features of the marine environment, which identifies habitat types that reflect changes in biological composition. Important oceanographic features include temperature, stratification and exposure; physiographic features include bottom relief and substrate type. 3. Classifications based only on biological data are generally prohibited at larger scales, due to lack of information. Therefore, we are generally obliged to classify habitat types as surrogates for community types. The data necessary for this classification are available from mapped sources and from remote sensing. It is believed they can be used to identify representative and distinctive marine habitats supporting different communities, and will provide an ecological framework for marine conservation planning at the national level. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

17.
    
Jezero Blaca is a unique spring lake situated at the northern coast of the Pelješac Peninsula near the village Duba Pelješka in South Dalmatia, Croatia. The lake supported by a karstic spring located near the Adriatic seashore is inhabited by unusually rich brackish water truncatelloid assemblage. The position of the lake near seashore evokes a model of sea invertebrate gradual adaptation to freshwater spring head allowing them to further invade the stygobiont karst conduits. Similar lakes could be the marine gateways of the extraordinarily rich Dinaric stygobiont fauna. The main aim of this study was to sample and barcode the aquatic snails found in this locality to check their species affiliation and describe conservation needs. The results confirmed that the locality hosts four interesting representatives of the gastropod superfamily Truncatelloidea, which has never been found syntopically so far. One of the species characterized by unique COI sequences and was described herein as Truncatella dalmatica new sp. The conservation need of this unique and understudied habitat type is discussed.  相似文献   

18.
为了找出不同产地鲍鱼(Haliotis Spp.Abalone)的区域性差异,并探究一种有效的鲍鱼产地的鉴别方法,采用主成分分析法对对广东、福建、山东、辽宁4个主要养殖省份鲍鱼样品肌肉中的特征元素(Na、K、Mg、Ca、Fe、Zn、Cu、Ni、As、Al、Mn、Cr、Se)进行分析。结果显示,鲍鱼样品的元素含量存在差异,Mn的变异程度最大,变异系数为74%,Ni次之,为65%,其次是Se (60%),其余元素的变异系数均高于10%。同时,通过对这些数据进行降维处理,有效地从13个特征元素中提取了6个元素作为主成分,累计方差贡献率达89.87%;同时发现Ca、Se、Na、Fe、Mn、K、Ni这7种元素是不同产地鲍鱼的特征元素,并建立了主成分综合评价模型:F=0.2777F_1+0.2652F_2+0.1295F_3+0.1066F_4+0.0656F_5+0.0541F_6。模型的建立可以为利用特征元素对不同产地鲍鱼的产地溯源提供一定的理论参考。  相似文献   

19.
海洋牧场与休闲渔业融合发展是我国海洋牧场发展方向之一,现阶段海洋牧场休闲产业规模较小,类型较为单一,主要以游钓和潜水休闲为主,其景观观赏性功能有待深入挖掘和开发。海洋牧场景观格局研究主要针对海洋牧场景观资源的形成、分布及其在景观空间上排列和布局等方面,发现并了解其生态系统或空间属性变异程度表观现象。本研究以粤东柘林湾海洋牧场示范区为案例,采用景观格局分析法对景观要素特征指数及景观异质性指数进行计算,研究表明,粤东柘林湾海洋牧场示范区自然景观为景观基质,半自然景观斑块面积最多,故破碎度指数最高,受人类活动影响最大,对生物多样性保护及景观生境维护应加强;文化景观与整体景观分离度较大,导致整体景观连通性较差,影响景观效果;滨海景观斑块较少,丰富度不高,但根据调查显示周边旅游资源丰富,因此缺乏与粤东柘林湾海洋牧场结合开发利用。总之,本研究通过解析海洋牧场景观格局空间内不同景观的分布状况及相互之间的作用和影响,为下一步进行景观生态规划提供数据支持,并为开发和利用海洋牧场休闲渔业与生态景观可持续化发展,综合提升海洋牧场的生态、经济和社会价值提供支撑。  相似文献   

20.
    
Striped marlin (Kajikia audax) is an epipelagic species distributed in tropical and temperate waters of the Pacific Ocean. In the central and eastern Pacific Ocean, it is captured principally in commercial longline fisheries, and in small artisanal fisheries, however, it is also taken throughout its range in this region as an incidental catch of the tuna purse‐seine fishery. Previous studies suggest that overexploitation and climate change may reduce abundance and cause changes in spatial distributions of marine species. The main objective of this study was to describe the habitat preferences of striped marlin and the changes in its distribution in response to environmental factors. Habitat modeling was conducted using a maximum entropy model. Operational level data for 2003–2014, collected by scientific observers aboard large purse seine vessels, were compiled by the Inter‐American Tropical Tuna Commission and were matched with detailed (4 km) oceanographic data from satellites and general circulation models. Results showed that the spatial distribution of habitat was dynamic, with seasonal shifts between coastal (winter) and oceanic (summer) waters. We found that the preferred habitat is mainly in coastal waters with warm sea surface temperatures and a high chlorophyll‐a concentration.  相似文献   

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