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1.
本研究于2015—2017年通过扫网法系统调查了北疆棉田周边17种常见杂草上草蛉种群密度与季节动态。结果表明:北疆棉区杂草带上共有6种草蛉分布,其中普通草蛉Chrysopa carnea(占64.8%)、叶色草蛉C.phyllochroma(占25.8%)为优势种。草蛉种群密度在不同杂草上存在显著差异,紫花苜蓿、大麻上的草蛉密度分别在2015年、2016年显著高于其他杂草,2017年甘草、罗布麻、苦豆子上的草蛉密度较高。另外,草蛉密度呈现出明显的季节性波动,棉花花铃期(7月—8月)、吐絮期(9月)杂草上草蛉密度显著高于棉花苗期与蕾期(5月—6月)。本研究明确了北疆棉区草蛉种类组成结构,筛选出紫花苜蓿、大麻、甘草、罗布麻、苦豆子5种对草蛉存在潜在保育作用的功能杂草,为利用田埂杂草促进棉田草蛉类天敌的保育控害提供了科学依据。  相似文献   
2.
为了更好地保护和利用伊犁野生阿魏菇资源,于2017-2019年采用踏查及实地样方取样和实验室数据测定相结合的方法,对伊犁野生阿魏菇资源的生长发育规律和生境特征进行了研究。结果表明:伊犁野生阿魏菇是一种分布在伊宁县新疆阿魏原生境保护区内的中低温型食、药兼用菌。生长最适温度为15℃-20℃。发生区土壤偏碱性,且含水率只有1.56%-9.87%,有机质含量在0.9%-1.76%,速效氮含量在32.53-42.60mg/kg,速效磷的含量在3.84-4.28mg/kg,均比较缺乏,速效钾含量比较丰富,在158.67-162.92mg/kg之间。土壤中所含的细菌数量为106个/g,放线菌为105个/g,真菌为103个/g。这种恶劣的生存环境加之人为破坏,致使阿魏菇分布面积急剧缩小,需采取积极措施进行保护。  相似文献   
3.
陆化杰  刘凯  欧玉哲  陈子越  陈新军 《水产学报》2021,45(12):2099-2111
随着微塑料在海洋环境和海洋生物中的发现,海洋微塑料污染问题越来越受到关注。本文对海洋微塑料的来源、类型、分布规律、毒性以及对不同食性、不同栖息地海洋鱼类的影响进行了梳理,对后续研究方向进行了分析和瞻望。结果表明,微塑料来源广泛、种类繁多、分布在海洋的各个角落,其毒性主要由自身毒性和联合毒性两部分组成。微塑料在海洋中垂直分布特点为底层沉积物含量较高,其次为底层、上层水域,中层水域较少;水平方向上分布特点为河口区含量较高,流场区次之,大洋区较少。不同栖息环境的海洋鱼类对微塑料的摄取数量不同,从大到小依次为:近岸底栖性>底层性>大洋性>大洋底栖性;摄取种类也不同,并主要受微塑料密度的影响,中上层鱼类主要摄取密度较小的微塑料,中下层鱼类主要摄取密度较大的微塑料。不同食性鱼类对微塑料摄取量也不相同,滤食性鱼类摄取量最高,植食性和掠食性鱼类摄取量略不相同。海洋鱼类的摄食特性对不同形状、大小、密度的微塑料摄取具有一定的选择性。后续研究应结合渔业生物、生态学,物理海洋,化学海洋等  相似文献   
4.
目的】研究醉马草(Achnatherum inebrians)芽库动态变化,分析不同生境中芽库动态变化规律与芽库与植物大小之间的关系,为合理防控及利用醉马草提供科学依据。【方法】以分布在荒漠、草原和草甸生境中的草原毒害草醉马草为对象,采用野外调查取样的方法,分析不同生育期(返青期、开花期、结实期和枯黄期)醉马草变化特征,研究不同生境的芽数量和生物量的动态变化规律。【结果】(1)草原和草甸生境结实期和枯黄期的芽数量和生物量显著高于荒漠生境的芽数量和生物量(P<0.05),同一生境中,开花期和枯黄期的芽数量和生物量显著高于返青期(P<0.05)。(2)荒漠生境芽数量和生物量随着的丛径变大表现增加趋势,而草原和草甸生境丛径大小与芽数量和生物量之间具有不同的变化规律。【结论】良好的生境条件能促进芽库数量和生物量的增加,丛径大小对芽数量和生物量具有一定的影响。  相似文献   
5.
Clear Lake Hitch is an imperilled minnow endemic to Clear Lake, Lake County, California, United States listed as threatened under the California Endangered Species Act (ESA) and a candidate for listing under the United States ESA. It exhibits a potamodromous life cycle whereby adults, which reach up to 6 + years in age and over 350 mm in length, migrate into Clear Lake's ephemeral tributaries briefly during spring to spawn. Conservation and management of Clear Lake Hitch is inhibited, in part, by a lack of information on the lacustrine habitat of nonbreeding individuals within Clear Lake. To address this problem, we sampled Clear Lake Hitch with gill nets in a stratified random sampling design to determine the distribution and habitat associations in early summer 2017 and 2018. We identified abundance-habitat relationships for juveniles and adults using Bayesian zero-inflated negative binomial generalised linear mixed modelling. Results indicated that dissolved oxygen concentration was the most important habitat feature measured; juveniles and adults were substantially more abundant in normoxic (≥2 mg/l) than in hypoxic (<2 mg/l) habitat. Both also exhibited weak positive relationships with chlorophyll fluorescence, suggesting relatively productive habitats may support higher numbers of Clear Lake Hitch. Spatially, juveniles were most abundant in nearshore habitats while adults were ubiquitous, indicating an ontogenetic habitat expansion that may be associated with a resource availability-predation risk trade-off. Management actions undertaken to improve hypoxia problems in Clear Lake would also improve Clear Lake Hitch habitat.  相似文献   
6.
Volitional dispersal is a ubiquitous strategy characteristic of species across major faunal groups. Dispersal during the juvenile life stage is of interest because early performance can be critical for determining future success (survival/reproduction). For salmonids, dispersal can influence local density, competition, individual growth and survival, though drivers of dispersal at meso-scales are rarely quantified. Here, we evaluate dispersal of tagged juvenile steelhead (Oncorhynchus mykiss) through habitat units in extended stream reaches (500 m) at sites across a watershed from July to October 2017. Our aim was to quantify the frequency and spatial extent of dispersal, identify links to biotic and abiotic factors, evaluate the implications for individual growth and test for associations between dispersal and migration initiation. Dispersal rates varied between sites, but were consistently higher for age 1+ than for age 0 steelhead (avg. 21% vs. 6% respectively). Age 1+ dispersal probability was positively correlated with time between recapture events and body mass, and negatively correlated with growth rate, maximum temperature experienced and age 1+ density. At sites where there appeared to be growth benefits to remaining sedentary compared to moving, proportionally fewer fish performed dispersal. We found no links between dispersal and timing or probability of migration initiation the following spring. Our results support the hypothesis that although dispersal over intermediate scales (10–1,000 m) might be rare, it could be an important strategy that permits fish to seek out better opportunities (foraging, shelter or otherwise) in underutilised areas.  相似文献   
7.
  1. The Euphrates softshell turtle (Rafetus euphraticus) is the most threatened chelonian species in the Middle East, where it is endemic to the Tigris and Euphrates basins. Since the ecology of this species is little known, it is difficult to plan any reliable action for its correct management and conservation.
  2. To enhance the scientific knowledge on R. euphraticus, and to establish a science-based management strategy, a detailed investigation was undertaken on the distribution, habitat, activity and home range of R. euphraticus in Turkey. The previous distribution records in Turkey are for the 1990s; thus, this study is the first comprehensive field research on the species after nearly 3 decades.
  3. There was a significant sexual size dimorphism in the Turkish population, with males larger than females.
  4. Four individuals were radiotracked for 1 year. The mean home range was highly variable depending on how it was calculated, but that of males was considerably greater than that of females by all methods used.
  5. A quantitative evaluation was made of habitat change with time. The land cover classes potentially available to turtles in the Euphrates River basin increased by more than 100% between the 1990s and 2018: 92% of this enhancement was derived from water bodies and coastal lands.
  6. Fifteen dams have been built in the lower part of the basins in the last 30 years. In addition, continuing human interactions have caused the fragmentation or destruction of suitable habitats for R. euphraticus.
  7. The factors threatening R. euphraticus were assessed and a conservation action plan was developed. Some objectives such as monitoring and creating awareness of this action plan have been met while others are still waiting to be achieved.
  相似文献   
8.
Although Psychrobacter strain M9-54-1 had been previously isolated from the microbiota of holothurians and shown to degrade quorum sensing (QS) signal molecules C6 and C10-homoserine lactone (HSL), little was known about the gene responsible for this activity. In this study, we determined the whole genome sequence of this strain and found that the full 16S rRNA sequence shares 99.78–99.66% identity with Psychrobacter pulmonis CECT 5989T and P. faecalis ISO-46T. M9-54-1, evaluated using the agar well diffusion assay method, showed high quorum quenching (QQ) activity against a wide range of synthetic N-acylhomoserine lactone (AHLs) at 4, 15, and 28 °C. High-performance liquid chromatography-mass-spectrometry (HPLC-MS) confirmed that QQ activity was due to an AHL-acylase. The gene encoding for QQ activity in strain M9-54-1 was identified from its genome sequence whose gene product was named AhaP. Purified AhaP degraded substituted and unsubstituted AHLs from C4- to C14-HSL. Furthermore, heterologous expression of ahaP in the opportunistic pathogen Pseudomonas aeruginosa PAO1 reduced the expression of the QS-controlled gene lecA, encoding for a cytotoxic galactophilic lectin and swarming motility protein. Strain M9-54-1 also reduced brine shrimp mortality caused by Vibrio coralliilyticus VibC-Oc-193, showing potential as a biocontrol agent in aquaculture.  相似文献   
9.
自然保护区是保护物种栖息地的重要基础,但频繁的人类活动干扰导致自然保护区内生物栖息地斑块破碎化的问题依然存在,景观连接度定量评价对于保护区生物栖息地保护具有重要作用。以纳板河自然保护区为例,基于图论的指数方法利用2014年和2018年高空间分辨率遥感数据,对保护区栖息地的景观连接度指数的变化及其驱动力因素进行分析。结果表明:1)2014—2018年的景观连接度指数中整体性连接度指数(IIC)、概率连接度指数(PC)都呈现下降趋势,IIC和PC指数分别下降0.29和0.53,指示保护区内栖息地破碎化加剧;2)最大斑块的重要性指数从85.14减少到84.19,重要性前十的斑块时空变化表明了自然保护区栖息地斑块面积不断减小,中部、中西部地区破碎化显著;3)土地利用变化对保护区景观连接度产生重要影响,其中橡胶林、耕地、水库、茶园4类土地利用增加是栖息地破碎化的驱动力因素。研究结果可为纳板河自然保护区栖息地保护管理提供科学依据。  相似文献   
10.
  目的  在中国快速城镇化背景下,北京市边缘地区的生态环境不断恶化,绿化隔离带成为控制北京市建成区无序扩张、改善城市生态环境的手段,在绿化隔离带范围内建设郊野公园是落实规划的有效途径。郊野公园的核心目标是在生态保育的同时提供少量的游憩活动,因此对于绿化隔离带范围内生境质量高的区域进行保护应作为郊野公园选址的基础原则。  方法  本文在总结国内外学者相关研究的基础上,以北京市第二道绿化隔离地区为例,构建生境保护优先的郊野公园选址框架,利用InVEST评价模型对研究区域的生境质量进行评价,根据生境质量指数将生境划分为低生境、一般生境、中生境、高生境、极重要生境5个等级。以模型评价结果中极重要生境地区作为郊野公园选址的基础原则选取生境保护优先的备选区范围,叠加周边公园资源、已建和拟建郊野公园、土地利用规划、基本农田保护规划、城市道路网可达性和土地利用现状6个外部建设条件和内部开发条件的指标因子选出适宜建设的区域,再根据植被覆盖类型的空间数据划定所选区域内的生境斑块群类型,最终完成研究区域内生境保护优先型郊野公园的选址和分类。  结果  不同类型的生境空间分布呈现一定差异性,根据不同生境划定混交林、灌丛、阔叶林或针叶林、农田、农田与纯林以及滨水6种类型的郊野公园,在通州区碱厂村、昌平区史家桥村、房山区梨村等村镇划定共41处以生境保护优先的郊野公园用地范围。  结论  以生境保护优先的郊野公园选址方法具有明显的空间定量化优势,其评价结果可以为北京市第二道绿化隔离地区的郊野公园选址提供科学依据。   相似文献   
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