Macroinvertebrates

大型无脊椎动物
  • 文章类型: Journal Article
    北斗星(Cincluscinclus)是与河岸生态系统密切相关的物种,已知以水生大型无脊椎动物为食,对水污染敏感。为此,已提出将滴水用作水质的有用生物指标。虽然北斗星的分布和生态在北欧河流中众所周知,在意大利中部,很少有研究关注这个问题,缺乏北斗星保护的数据。这里,我们的目标是(i)使用基于硅藻和大型无脊椎动物群落的生物指数评估与水质相关的北斗星发生,(ii)评估河流生态系统的整体状态,通过缓冲区的河流功能指数和土地利用分析。总的来说,仅靠水质并不能解释北斗星的发生,因为在许多具有良好或高水质的潜在合适地点都没有发现该物种。此外,硅藻和大型无脊椎动物群落的多样性也不是足够的限制。相反,北斗星的发生与河流功能指数显著相关,整合了几个河岸生态系统因素,这表明具有高功能水平的保存完好的生态系统对于北斗星的发生很重要。现场周围地区的土地利用分析显示,虽然不重要,相当自然的水平,可能有利于河岸区的维护。由于北斗星在意大利中部被认为正在下降并受到威胁,迫切需要进一步研究其自动生态和保护威胁。最后,考虑到物种和河岸生态系统之间的联系,像北斗星这样有魅力的物种可以用作保护和保护项目中的伞形物种,以造福整个河岸带,它代表了陆地和水生生态系统之间至关重要的缓冲区,尽管经常导致严重减少和分散。
    The dipper (Cinclus cinclus) is a species strongly linked to the riparian ecosystem, known to feed on aquatic macroinvertebrates, which are sensitive to water pollution. For this, dippers have been proposed as useful bioindicators of water quality. While the distribution and ecology of the dipper are well known in Northern European rivers, few studies focus on this in Central Italy, lacking data for dipper conservation. Here, we aimed to (i) assess the dipper occurrence related to water quality using biotic indices based on diatom and macroinvertebrate communities, and (ii) evaluate the river ecosystem\'s overall state, through the River Functionality Index and land-use analysis in buffer areas. Overall, water quality alone does not explain the dipper occurrence, as the species was not found in many potentially suitable sites with good or high-water quality. Moreover, the diversity of the diatom and macroinvertebrate communities was not a sufficient constraint either. Conversely, the dipper occurrence significantly correlated with the River Functionality Index, which integrates several riparian ecosystem factors, indicating that well-preserved ecosystems with high functionality levels are important for dipper occurrence. Land use analyses in the areas surrounding the presence sites have shown, although not significantly, a fair level of naturalness, potentially favouring the riparian zone maintenance. As the dipper was considered in decline and threatened in Central Italy, further research on its auto-ecology and conservation threats is urgently needed. Finally, given the link between the species and the riparian ecosystem, a charismatic species such as the dipper could be used as an umbrella species in protection and conservation projects for the benefit of the entire riparian belt, which represents a buffer area of fundamental importance between terrestrial and aquatic ecosystems, although often resulted severely reduced and fragmented.
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  • 文章类型: Journal Article
    这项研究评估了通过Chanchaga河的农业活动施用农药的影响,尼日利亚,使用六个月(2021年9月至2022年2月)获得的大型无脊椎动物数据集。四(4)站,以各种农业活动为特征,沿河取样。在两个季节的高峰期,使用气相色谱-质谱法(GC/MS)对水样中的有机氯农药残留(OCP)进行分析,发现高浓度的11种有机氯异构体,范围从0.01到0.81μg/L,平均浓度高于世界卫生组织设定的国际饮用水标准,联邦环境保护局,和欧盟。检测到的OCP的平均浓度记录为DDT(0.72μg/L),狄氏剂(0.59μg/L),百草枯(0.54μg/L),艾氏剂(0.49μg/L),Metribuzin(0.48μg/L),丁草胺(0.47μg/L),甲草胺(0.28μg/L),阿特拉津(0.23μg/L),苯酚(0.10μg/L),异狄氏剂(0.09μg/L),和苯(0.08μg/L)。阿特拉津,甲草胺,metribuzin,艾氏剂,苯酚,和异狄氏剂在两个季节表现出显著差异(p<0.05),而狄氏剂,丁草胺,百草枯,苯,DDT和DDT在两个季节中没有显着差异(p>0.05)。共收集了来自8个目18科19种的622个大型无脊椎动物个体。在旱季(58.17%)和雨季(41.83%)收集了更多的个体。规范对应分析(CCA)排序揭示了物种丰度与某些有机氯农药残留(例如DDT)之间的紧密关系,异狄氏剂,metribuzin,阿特拉津,苯,还有狄德林.大型无脊椎动物对OCP的响应表明Chanchaga河是一条受干扰的河流,和指示生物(Leestessp.,Coenagrionsp.,Zyxommasp.,Appasussp.,Chironomussp.,Lmnaeanatalensis,和Caridinanilotica)也可用于进一步的生物监测。
    This study evaluated the impact of pesticide application through agricultural activities in Chanchaga River, Nigeria, using macroinvertebrate data sets obtained for six months (September 2021-February 2022). Four (4) stations, characterized by various agricultural activities, were sampled along the river. Analysis of the water samples for organochlorine pesticide residues (OCP) using Gas Chromatography-Mass Spectrometry (GC/MS) at the peak of the two seasons revealed a high concentration of eleven isomers of organochlorine, which ranged from 0.01 to 0.81 μg/L, and a mean concentration that was above international drinking water standards set by the World Health Organization, the Federal Environmental Protection Agency, and the European Union. The mean concentration of detected OCP was recorded as DDT (0.72 μg/L), Dieldrin (0.59 μg/L), Paraquat (0.54 μg/L), Aldrin (0.49 μg/L), Metribuzin (0.48 μg/L), Butachlor (0.47 μg/L), Alachlor (0.28 μg/L), Atrazine (0.23 μg/L), Phenol (0.10 μg/L), Endrin (0.09 μg/L), and Benzene (0.08 μg/L). Atrazine, alachlor, metribuzin, aldrin, phenol, and endrin showed significant differences across the two seasons (p < 0.05), while dieldrin, butachlor, paraquat, benzene, and DDT showed no significant differences across the two seasons (p > 0.05). A total of 622 macroinvertebrate individuals from 19 species in 18 families from 8 orders were collected. More individuals were collected during the dry season (58.17 %) and the wet season (41.83 %). Canonical Correspondence Analysis (CCA) ordination revealed a strong relationship between species abundance and some organochlorine pesticide residues such as DDT, endrin, metribuzin, atrazine, benzene, and dieldrin. The response of macroinvertebrates to OCP indicates that Chanchaga River is a disturbed river, and the indicator organisms (Lestes sp., Coenagrion sp., Zyxomma sp., Appasus sp., Chironomus sp., Lymnaea natalensis, and Caridina nililotica) can also be used for further biomonitoring.
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  • 文章类型: Journal Article
    河流是支持生物多样性和人类福祉的重要生态系统,然而,他们面临着全球日益严重的退化。传统的基于大型无脊椎动物形态识别的河流生物监测方法在分类学分辨率和可扩展性方面面临挑战。本研究探讨了在大量和环境DNA(eDNA)样品中DNA元编码分析在大型底栖动物生物多样性综合评估中的应用。入侵和濒危物种的检测,西班牙西北部河流生态状况评价。均质散装样品和水eDNA的DNA元编码显示,每个样品平均分别为100和87种大型底栖动物。然而,具体组成显着不同,仅共享总物种的27.3%。不可能将所有OTU识别到物种水平;在批量和eDNA样本中,只有17.43%和49.4%的OTU可以识别到物种水平。分别。此外,通过分子工具共检测到11种外来物种(伊比利亚半岛的两个第一记录和阿斯图里亚斯地区的另外三个第一记录)和一种濒危物种。分子方法与IBMWP指数的EQR值(生态质量比)的形态鉴定显着相关,然而,推断的河流生态状况存在差异,大量样品倾向于表明较高的状态。总的来说,DNA元编码为河流生物监测提供了一种有前途的方法,提供对生物多样性的见解,入侵物种,和生态状况在单一分析中。在常规生物监测计划中实施需要进一步优化和相互校准,但是它的可扩展性和多任务能力使其成为河流生态系统综合监测的宝贵工具。
    Rivers are crucial ecosystems supporting biodiversity and human well-being, yet they face increasing degradation globally. Traditional river biomonitoring methods based on morphological identification of macroinvertebrates present challenges in terms of taxonomic resolution and scalability. This study explores the application of DNA metabarcoding analysis in both bulk and environmental DNA (eDNA) samples for comprehensive assessment of macrozoobenthic biodiversity, detection of invasive and endangered species, and evaluation of river ecological status in northwestern Spain. DNA metabarcoding of homogenized bulk samples and water eDNA revealed a mean of 100 and 87 macrozoobenthos species per sample respectively. However, the specific composition was significantly different with only 27.3% of the total species being shared. It was not possible to identify all the OTUs to species level; only 17.43% and 49.4% of the OTUs generated could be identified to species level in the bulk and eDNA samples, respectively. Additionally, a total of 11 exotic species (two first records for the Iberian Peninsula and another three first records for Asturias region) and one endangered species were detected by molecular tools. Molecular methods showed significant correlations with morphological identification for EQR values (Ecological Quality Ratio) of IBMWP index, yet differences in inferred river ecological status were noted, with bulk samples tending to indicate higher status. Overall, DNA metabarcoding offers a promising approach for river biomonitoring, providing insights into biodiversity, invasive species, and ecological status within a single analysis. Further optimization and intercalibration are required for its implementation in routine biomonitoring programmes, but its scalability and multi-tasking capabilities position it as a valuable tool for integrated monitoring of river ecosystems.
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  • 文章类型: Journal Article
    海带物种是沿海海洋生态系统中重要的基础生物,它们提供生物栖息地并改善环境条件。经常促进各种下层组合的发展。海带林的结构受多种环境因素的影响,这些变化可能导致生态结构和功能的深刻变化。特别是强烈的风暴引起的波浪作用,会严重影响海带森林生态系统。鉴于预计风暴会随着人为气候变化而增加频率和强度,了解它们对海带森林生态系统的潜在影响至关重要。在2021/22东北大西洋风暴季节,英国(UK)遭受了几次强烈的风暴,其中第一个也是最严重的是风暴阿尔文。由于不寻常的偏北风向,风暴阿尔文的最大影响是在英国东北海岸,那里的阵风超过90公里/小时,记录了近岸重要的波浪高度为7.2m,波浪周期为9.3s。这里,我们调查了2021/22年风暴季节英国东北海岸的长生乳杆菌森林和相关的林下组合结构的时空变化。我们发现封面发生了重大变化,密度,长度,生物量,风暴季节后,长毛乳杆菌种群的年龄结构和下层组合的组成,特别是在我们最北面的地方。我们建议对这些系统进行持续监测,以进一步了解时间变化和潜在的恢复轨迹,同时加强管理,以提高对未来扰动的抵御能力。
    Kelp species function as important foundation organisms in coastal marine ecosystems where they provide biogenic habitat and ameliorate environmental conditions, often facilitating the development of diverse understorey assemblages. The structure of kelp forests is influenced by a variety of environmental factors, changes in which can result in profound shifts in ecological structure and functioning. Intense storm-induced wave action in particular, can severely impact kelp forest ecosystems. Given that storms are anticipated to increase in frequency and intensity in response to anthropogenic climate change, it is critical to understand their potential impacts on kelp forest ecosystems. During the 2021/22 northeast Atlantic storm season, the United Kingdom (UK) was subject to several intense storms, of which the first and most severe was Storm Arwen. Due to the unusual northerly wind direction, the greatest impacts of Storm Arwen were felt along the northeast coast of the UK where wind gusts exceeded 90 km/h, and inshore significant wave heights of 7.2 m and wave periods of 9.3 s were recorded. Here, we investigated temporal and spatial variation in the structure of L. hyperborea forests and associated understorey assemblages along the northeast coast of the UK over the 2021/22 storm season. We found significant changes in the cover, density, length, biomass, and age structure of L. hyperborea populations and the composition of understorey assemblages following the storm season, particularly at our most north facing site. We suggest continuous monitoring of these systems to further our understanding of temporal variation and potential recovery trajectories, alongside enhanced management to promote resilience to future perturbations.
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  • 文章类型: Journal Article
    由于它们体积小,人为压力大,小水道特别容易严重淤积,茂密地长满了大型植物。这些水道中的许多都需要进行定期维护工程(RMW),包括季节性清沙和植被清除,以确保水流通畅。这项研究的目的是评估三种类型的维修工程的影响:疏浚和泥浆清除(DMR),河道植被去除(RCVR)和河岸植被去除(RBVR)对类群物种丰富度的影响,大型无脊椎动物密度和香农-维纳多样性指数,以及他们的变化和长期的海底重新定殖工作完成后的一年和两年。这项研究是在欧洲中原生态区8条河流的21个栖息地进行的。在所有地点共发现了107个动物底栖分类群,它们的物种组成是具有低水文和水化学质量参数的高水生植物水的特征。工程一年后,观察到大型无脊椎动物类群的丰富度显着下降,随着分类单元的平均数量从13个下降到8个,在RMW两年后,进一步下降到七个分类单元。密度也是如此,在RMW之后的一年里,平均每平方米2496人减少到786人,while,在RMW事件发生两年后,记录了逐渐的重新定殖,平均密度为每平方米1295个人。Shannon-Wiener指数,在RMW之前平均为2.528,也减少了,一年和两年后跌至1.982和1.832。BACI统计分析表明,在三种类型的维护工作中,清沙和底部沉积物去除产生的负面影响最大,显著减少分类组成(平均减少53%),密度(平均43%),和生态指数值(平均40%)。过度频繁的维护可以阻止大型无脊椎动物种群的恢复,从而耗尽了有价值的类群的环境,包括那些为鱼类和其他脊椎动物提供食物的动物。
    Due to their small size and high anthropogenic pressure, small watercourses are particularly prone to severe siltation and are densely overgrown with macrophytes. Many of these watercourses are subject to regular maintenance works (RMW), consisting of seasonal desilting and vegetation clearance, in order to ensure unobstructed water flow. The aim of the study was to assess the impact of three types of maintenance works: dredging and mud removal (DMR), river channel vegetation removal (RCVR) and river bank vegetation removal (RBVR) on taxa species richness, macroinvertebrate density and the Shannon-Wiener diversity index, as well as their changes and long-term benthic recolonization one and two years after completion of the works. The study was carried out in 21 habitats on eight rivers in the European Central Plains Ecoregion. A total of 107 zoobenthic taxa were found at all sites, and their species composition was characteristic of highly hydrophytic waters with low hydrological and hydrochemical quality parameters. A significant decrease in macroinvertebrate taxa richness was observed one year after the works, as the average number of taxa had dropped from thirteen to eight, with a further fall to seven taxa two years after the RMW. The same was true for density, which had decreased from an average of 2496 to 786 individuals per square meter one year after the RMW, while, a gradual recolonization was recorded two years after the RMW, with an average density of 1295 individuals per square meter. The Shannon-Wiener index, which had averaged 2.528 before the RMW, also decreased, falling to 1.982 and 1.832 one and two years after. BACI statistical analyses showed that of the three types of maintenance work, desilting and bottom sediment removal had the largest negative impact, significantly reducing taxonomic composition (by an average of 53%), density (by an average of 43%), and ecological index values (by an average of 40%). Over-frequent maintenance can prevent macroinvertebrate populations from recovering, thus depleting the environment of valuable taxa, including those that provide food for fish and other vertebrates.
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  • 文章类型: Journal Article
    河流是重要而复杂的自然系统,可提供广泛的生态系统服务。这项研究提出了一种评估河流供应和支持生态系统服务的方法,其适用性已在印度的Budhabalanga河流域得到证明。土壤和水评估工具(SWAT)用于在各种未测量的地点生成流量时间序列,然后对流流进行表征,以评估供应服务。Further,大型无脊椎动物的多样性和丰度,连同Lotic-无脊椎动物流动评估指数(LIFE),用于研究河流支撑生态系统服务。对于低流量,溪流表现出间歇性行为和强烈的季节性,限制了水的供应,特别是在季风季节。基本流量指数(BFI)大于0.6,表明地下水占总流量的60%以上。有趣的是,尽管BFI很高,这些河流不符合普遍的意见,即更大的基流贡献会导致水文年低流量期的晚些时候开始。此外,该研究描述了不同采样点的大型无脊椎动物的多样性和丰度的显着变化。然而,各个站点的LIFE得分在狭窄的范围内保持一致,即,8到9,表明支持生态系统服务的稳定供应。研究结果可以帮助决策者做出明智的决策,并且可以在其他流域中复制本研究中提出的简单方法,以识别脆弱的流域并优先考虑管理行动。
    Rivers are vital and complex natural systems that provide a wide range of ecosystem services. This study presents a methodology for assessing the riverine provisioning and supporting ecosystem services, whose applicability has been demonstrated over the Budhabalanga River Basin of India. The Soil and Water Assessment Tool (SWAT) is used to generate streamflow time series at various ungauged sites, and then the streamflow is characterized for the evaluation of provisioning services. Further, the diversity and abundance of macroinvertebrates, along with the Lotic-invertebrate Index for Flow Evaluation (LIFE), is used to study the riverine supporting ecosystem services. The streams show intermittent behavior and strong seasonality for low flows, which limits the water availability, particularly during pre-monsoon season. The Baseflow Index (BFI) is greater than 0.6, indicating that groundwater contributes more than 60% of the total streamflow. Interestingly, despite the high BFI, the streams did not conform to the prevailing opinion that a greater baseflow contribution results in a later commencement of the low-flow period in the hydrological year. Furthermore, the study depicts significant variations in the diversity and abundance of the macroinvertebrates across the various sampling sites. However, the LIFE score across the sites remained consistent within a narrow range, i.e., 8 to 9, suggesting a steady supply of supporting ecosystem services. The results of the study can help the policymakers towards an informed decision making and the simplistic methodology proposed in this study can be replicated in other river basins for identifying vulnerable watersheds and prioritizing management actions.
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  • 文章类型: Journal Article
    如果不严格评估时间变化,检测人类对淡水生态系统的影响是有问题的。即使在未开采的环境中,由于当地集水区地质对地表水的强烈影响,对采矿影响的评估也变得更加复杂。通过使用基于区域化和流类型的大规模参考框架,无法有效地考虑这种影响。使用BACI(前后控制冲击)设计,我们研究了采矿排放对淡水藻类和大型无脊椎动物群落的影响,这些影响是通过管道将经过处理的废水改道到芬兰北部和东北部的较大水体。受影响的站点和控制站点在管道开始运营之前1至2年和之后1至3年进行采样。重新路由废水后,从管道上游的过去负载(不再受到废水的影响)中回收的硅藻群落,而没有检测到管道下游的变化。从管道上游,硅藻物种丰富度增加,并观察到最常见硅藻分类单元的相对丰度以及整个群落组成的变化。对于大型无脊椎动物群落,管道的影响不太明显。有迹象表明,国家生物监测中使用的区域参考条件可能并不代表地球化学背景影响强烈的地区的硅藻群落。在管道建设之前,深湖大型无脊椎动物群落受到过去负荷的影响,并且管道的影响仅在一些单个物种的丰度变化时观察到,例如幻影mid(响应于通过管道的排放而增加的丰度)。我们的结果强调了采矿排放对水生群落的可变影响。统计上强有力的监测方案,如BACI设计,显然需要检测这些影响。
    Detecting human impact on freshwater ecosystems is problematic without rigorous assessment of temporal changes. Assessments of mining impacts are further complicated by the strong influence of local catchment geology on surface waters even in unmined environments. Such influence cannot be effectively considered by using broad-scale reference frameworks based on regionalization and stream types. Using the BACI (Before-After Control-Impact) design, we examined the impact of mining discharges on freshwater algae and macroinvertebrate communities resulting from the rerouting of treated wastewaters through a pipeline to larger water bodies in Northern and North-Eastern Finland. Impacted sites and control sites were sampled 1 to 2 years before and 1 to 3 years after the pipelines became operational. Stream diatom communities recovered from past loadings upstream of the pipeline (which was no longer impacted by wastewaters) after rerouting of the wastewaters, while no changes downstream from the pipeline were detected. Upstream from the pipeline, diatom species richness increased and changes in relative abundances of the most common diatom taxa as well as in the overall community composition were observed. The effects of the pipeline were less evident for stream macroinvertebrate communities. There was an indication that regional reference conditions used in national biomonitoring may not represent diatom communities in areas with a strong geochemical background influence. Lake profundal macroinvertebrate communities were impacted by past loadings before the construction of the pipeline, and the influence of the pipeline was observed only as changes in the abundances of a few individual species such as phantom midges (which increased in abundance in response to discharges directed through the pipeline). Our results highlight the variable influence of mining discharges on aquatic communities. Statistically strong monitoring programmes, such as BACI designs, are clearly needed to detect these influences.
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  • 文章类型: Journal Article
    大型无脊椎动物捕食者,如反向游泳动物(异翅目:Notonectidae),蜻蜓(Odonata:Aeshnidae),捕食性潜水甲虫(鞘翅目:Dytiscidae)自然栖息在水生生态系统中。这些大型无脊椎动物捕食者类群所居住的一些水生生态系统同样形成了疟疾媒介幼虫栖息地。这些捕食者在疟疾病媒幼虫栖息地的存在会对发育产生负面影响,成人体型,繁殖力,和疟疾病媒的寿命,这构成了他们适合度和未来矢量能力的重要决定因素。水生大型无脊椎动物捕食者对疟疾病媒造成的这些潜在负面影响,值得在防治疟疾的综合计划中将其视为生物防治剂。然而,这些大型无脊椎动物捕食者在疟疾生物防治中的使用目前受到技术瓶颈的限制,这些技术瓶颈与它们的通才掠夺性倾向和通常长的生命周期有关,要求复杂的饲养系统。我们回顾了有关使用水生大型无脊椎动物捕食者对An疟疾病媒进行生物防治的文献。冈比亚s.l.复杂。实验室和半现场研究的现有信息表明,水生大型无脊椎动物有可能消耗大量蚊子幼虫,因此可以为综合疟疾病媒管理战略提供额外的方法。东非和西非可用的半田间结构越来越多,这为进行生态实验研究提供了机会,以重新考虑使用水生大型无脊椎动物捕食者作为生物防治工具的潜力。为了实现更可持续的方法来控制疟疾病媒种群,额外,非化学干预可以提供一种更可持续的方法,与失败的化学控制工具相比,并应紧急考虑与当前的蚊媒控制运动相结合。
    Macroinvertebrate predators such as backswimmers (Heteroptera: Notonectidae), dragonflies (Odonata: Aeshnidae), and predatory diving beetles (Coleoptera: Dytiscidae) naturally inhabit aquatic ecosystems. Some aquatic ecosystems inhabited by these macroinvertebrate predator taxa equally form malaria vector larval habitats. The presence of these predators in malaria vector larval habitats can negatively impact on development, adult body size, fecundity, and longevity of the malaria vectors, which form important determinants of their fitness and future vectorial capacity. These potential negative impacts caused by aquatic macroinvertebrate predators on malaria vectors warrant their consideration as biocontrol agents in an integrated program to combat malaria. However, the use of these macroinvertebrate predators in malaria biocontrol is currently constrained by technical bottlenecks linked to their generalist predatory tendencies and often long life cycles, demanding complex rearing systems. We reviewed the literature on the use of aquatic macroinvertebrate predators for biocontrol of malaria vectors from the An. gambiae s.l. complex. The available information from laboratory and semi-field studies has shown that aquatic macroinvertebrates have the potential to consume large numbers of mosquito larvae and could thus offer an additional approaches in integrated malaria vector management strategies. The growing number of semi-field structures available in East and West Africa provides an opportunity to conduct ecological experimental studies to reconsider the potential of using aquatic macroinvertebrate predators as a biocontrol tool. To achieve a more sustainable approach to controlling malaria vector populations, additional, non-chemical interventions could provide a more sustainable approach, in comparison with the failing chemical control tools, and should be urgently considered for integration with the current mosquito vector control campaigns.
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  • 文章类型: Journal Article
    Food webs depict the tangled web of trophic interactions associated with the functioning of an ecosystem. Understanding the mechanisms providing stability to these food webs is therefore vital for conservation efforts and the management of natural systems. Here, we first characterised a tropical stream meta-food web and five individual food webs using a Bayesian Hierarchical approach unifying three sources of information (gut content analysis, literature compilation and stable isotope data). With data on population-level biomass and individually measured body mass, we applied a bioenergetic model and assessed food web stability using a Lotka-Volterra system of equations. We then assessed the resilience of the system to individual species extinctions using simulations and investigated the network patterns associated with systems with higher stability. The model resulted in a stable meta-food web with 307 links among the 61 components. At the regional scale, 70% of the total energy flow occurred through a set of 10 taxa with large variation in body masses. The remaining 30% of total energy flow relied on 48 different taxa, supporting a significant dependency on a diverse community. The meta-food web was stable against individual species extinctions, with a higher resilience in food webs harbouring omnivorous fish species able to connect multiple food web compartments via weak, non-specialised interactions. Moreover, these fish species contributed largely to the spatial variation among individual food webs, suggesting that these species could operate as mobile predators connecting different streams and stabilising variability at the regional scale. Our results outline two key mechanisms of food web stability operating in tropical streams: (i) the diversity of species and body masses buffering against random and size-dependent disturbances and (ii) high regional diversity and weak omnivorous interactions of predators buffering against local stochastic variation in species composition. These mechanisms rely on high local and regional biodiversity in tropical streams, which is known to be strongly affected by human impacts. Therefore, an urgent challenge is to understand how the ongoing systematic loss of diversity jeopardises the stability of stream food webs in human-impacted landscapes.
    As teias alimentares representam um emaranhado de interações tróficas associadas ao funcionamento de um ecossistema. Compreender os mecanismos que proporcionam estabilidade a estas teias alimentares é, portanto, vital para os esforços de conservação e gestão dos sistemas naturais. Aqui, primeiro caracterizamos uma meta teia alimentar de riachos tropicais e cinco teias alimentares individuais usando uma abordagem hierárquica Bayesiana unificando três fontes de informação (análise de conteúdo estomacal, compilação de literatura, dados de isótopos estáveis). Com dados sobre biomassa em nível populacional e massa corporal medida individualmente, aplicamos um modelo bioenergético e avaliamos a estabilidade da cadeia alimentar usando um sistema de equações Lotka‐Volterra. Em seguida, avaliamos a resiliência do sistema às extinções de espécies individuais usando simulações e investigamos os padrões de rede associados a sistemas com maior estabilidade. O modelo resultou em uma meta teia alimentar estável com 307 ligações entre os 61 componentes. Na escala regional, 70% do fluxo total de energia ocorreu através de um conjunto de dez taxa com grande variação nas massas corporais. Os restantes 30% do fluxo total de energia dependiam de 47 taxa diferentes, apoiando uma dependência significativa de uma comunidade diversificada. A meta teia alimentar foi estável contra extinções de espécies individuais, com uma maior resiliência em teias alimentares que abrigam espécies de peixes onívoros capazes de conectar múltiplos compartimentos da teia alimentar através de interações fracas e não especializadas. Além disso, estas espécies de peixes contribuíram amplamente para a variação espacial entre as cadeias alimentares individuais, sugerindo que estas espécies poderiam operar como predadores móveis conectando diferentes riachos e estabilizando a variabilidade à escala regional. Nossos resultados descrevem dois mecanismos principais de estabilidade da cadeia alimentar operando em riachos tropicais: (i) a diversidade de espécies e massas corporais que protegem contra distúrbios aleatórios e dependentes do tamanho (ii) alta diversidade regional e fracas interações onívoras de predadores que protegem contra a variação estocástica local na composição de espécies. Estes mecanismos dependem de uma elevada biodiversidade local e regional em riachos tropicais, que são conhecidos por serem fortemente afetados pelos impactos humanos. Portanto, um desafio urgente é compreender como a contínua perda sistemática de diversidade põe em risco a estabilidade das teias alimentares em paisagens impactadas pelo homem.
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  • 文章类型: Journal Article
    道路盐(通常为NaCl,CaCl2和MgCl2)在美国北部被广泛用作道路和其他小路的除冰剂。美国每年使用数百万吨的道路盐,导致淡水盐度急剧增加。本研究旨在使用美国EPA公开获取的流监测数据来确定大型无脊椎动物的最佳氯化物和耐受范围。我们分配了分类单元特定区域的公差值,然后我们用它来计算盐带指数(SBI)。除了SBI,我们确定了新的,特定地区,慢性Cl-阈值,使用阈值指标分类单元分析(TITAN)确定。使用广义线性模型,我们发现SBI在估计盐带状态下的氯化物浓度(mg/LCl-)方面非常准确。大型无脊椎动物群落丰富度与氯化物浓度的增加呈显着负相关。新提出的氯化物阈值,基于丰富度-氯化物关系,远远低于目前的阈值。SBI能够区分低,Medium-,和高影响力的网站,根据建议的氯化物阈值进行分组。根据我们的发现,很明显,目前的盐度阈值太高,管理实践应考虑到区域差异,分类单元特异性生理学,以及实施盐度阈值时的历史河流化学。
    Road salt (commonly NaCl, CaCl2, and MgCl2) is widely used in the northern United States as a deicing agent for roadways and other byways. Millions of tons of road salt are used annually in the United States, resulting in drastic increases in freshwater salinity. This study aims to determine the chloride optima and tolerance ranges of macroinvertebrates using publicly accessible stream monitoring data from the US EPA. We assigned taxa region-specific tolerance values, which we then used to calculate the Salt Belt Index (SBI). In addition to the SBI, we determined new, region-specific, chronic Cl- thresholds, determined using threshold indicator taxa analysis (TITAN). Using generalized linear models, we found the SBI was highly accurate at estimating chloride concentration (mg/L Cl-) across the salt belt states. Macroinvertebrate community richness exhibited a significant negative relationship with increasing chloride concentrations. Newly proposed chloride thresholds, based on the richness-chloride relationship, were far lower than current thresholds. The SBI was able to differentiate between Low-, Medium-, and High-Impact sites, grouped based on proposed chloride thresholds. Based on our findings, it is clear current salinity thresholds are too high, and management practices should factor in regional variability, taxon-specific physiology, and historical instream chemistry when implementing salinity thresholds.
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