Migration patterns and habitat use of the tapertail anchovy Coilia mystus in the Oujiang River Estuary and the Zhujiang River Estuary, China

Habitat use of the tapertail anchovy(Coilia mystus Linnaeus, 1758) from the Oujiang River Estuary and the Zhujiang(Pearl) River Estuary was studied by examining the environmental signatures of Sr and Ca in otoliths using electron probe microanalysis. Individuals from the Oujiang River had higher and varied Sr:Ca ratios(expressed as(Sr:Ca)×1 000, 3.83–13.0 average) in the otolith core regions, suggesting that they were born in brackish or sea waters, and that a freshwater habitat might not be necessary for egg hatching and larval growth.While, individuals from the Zhujiang River had lower Sr:Ca ratios(0.39–2.51 average) in the core regions,suggesting a freshwater origin. After hatching, anchovies from the Zhujiang River migrate downstream to the river estuary close to brackish water. Our results demonstrated varied habitat use for spawning during stages of early life history between the two populations, and suggested that such variations are promoting diversity of life history strategies of this species.

Unravelling habitat use of Coilia nasus from the Rokkaku River and Chikugo River estuaries of Japan by otolith strontium and calcium

The migratory history of the engraulid fish Coilia nasus in the Rokkaku and Chikugo River estuaries of the Ariake Sea, Japan was assessed using otolith strontium（Sr） X-ray intensity maps and strontium：calcium（Sr：Ca） ratio life history transects by an electron probe microanalyzer（EPMA）. The results showed that seven of the ten specimens from the Rokkaku River Estuary（LJC） and all 15 specimens collected in the Chikugo River Estuary（ZHC） had low Sr：Ca ratios（≤3） at the central otolith area, indicating their riverine origin and initial freshwater residence. After the first regime shift adjacent to natal regions, the Sr level mapping displayed a wide variety of color patterns, and the Sr：Ca ratios obtained by the line transect analysis could be divided into one to six significantly different phases indicative of gradual life history transition. The other three specimens from the Rokkaku River Estuary had high Sr：Ca ratios（3–6.7） at the central otolith area but showed alternating changes between low and high values outside the natal region, suggesting that estuarine-origin individuals occurred in the Rokkaku River Estuary. The two-dimensional maps of the Sr level and average of the otolith Sr：Ca ratios along the life-history transects could be used as effective tools for reconstruction of past habitat use of the tapertail anchovy in estuaries of the Ariake Sea, Japan.

Assessing the benthic habitat quality in the Huanghe(Yellow River) Estuary and its adjacent areas using AMBI and M-AMBI

The protection of the biological diversity and the maintenance of the regional ecological integrity for the Huanghe （Yellow River） Estuary and its adjacent areas are practically significant and valuable. However, frequent human activities and natural climate changes have caused vigorous disturbances on the ecosystem in these sea areas. An objective assessment on the benthic habitat quality （BHQ） of the Huanghe Estuary and its adjacent areas is conducted, using AZTI＇s Marine Biotic Index （AMBI） and multivariate AMBI （M-AMBI） based on the data of macrobenthos in May and August 2011. The results show that both the indices do not correlate significantly, and their assessment results are greatly different. All of the samples assessed using the AMBI were ＂high＂ or ＂good＂, because the ecological group I （EGI） and the ecological group II （EGII） were dominant macrobenthic ecological groups in the research area. Owing to a low species＇ richness and a high individual abundance in some samples, the BHQ levels using the M-AMBI were worse than those of the AMBI. Significant correlations are observed between the M-AMBI, water depth, bottom water salinity and dissolved inorganic nitrogen, thus the M-AMBI could sensitively respond to environmental changes and distinguish influences from uninfluenced stations, but the AMBI could not. The consistent results between the AMBI and the M-AMBI mainly appeared in the uninfluenced （undisturbed or slightly disturbed） sta- tions. Therefore, the M-AMBI is more effective than the AMBI in assessing the benthic habitat quality in the Huanghe Estuary and its adjacent areas. Using the M-AMBI to assess the BHQ of the Huanghe Estuary and its adjacent areas, the results show that 3% of the stations are undisturbed and the BHQs are ＂high＂, and 61% of the stations are slightly disturbed and those of the BHQ are ＂good＂, and the rest are meanly disturbed and those of the BHQ are ＂moderate＂.

基于River 2D模型的黄河花园口河段生态流量研究

针对目前生态流量研究方法难以充分考虑鱼类栖息地等生境因素的问题,以黄河花园口鲤鱼核心保护区为研究区域,选取黄河鲤鱼为研究物种,基于耦合水动力学模型和栖息地模型的River 2D模型确定黄河鲤鱼的生态流量,将水深和流速作为鱼类生存保护的限定性因子,采用栖息地模型模拟不同流量下对应的黄河鲤鱼的适宜栖息地面积。计算结果表明:花园口河段鲤鱼产卵期的最小生态流量为230 m^(3)/s,生长期的最小生态流量为430 m^(3)/s,越冬期的最小生态流量为150 m^(3)/s。计算结果可以为花园口核心鱼类保护区的鱼类保护以及黄河小浪底水库的生态调度提供参考。

Pre- and Post-Construction Assessment of Nutrient Concentrations at Shallow Water Habitat Restoration Sites on the Lower Missouri River

Loss of shallow water habitat (SWH) is hypothesized as a factor contributing to the decline of native Missouri River fishes, including the endangered pallid sturgeon. As a result, the restoration of SWH is a high priority in this large river system. Restoration activities often include constructing side channel chutes;however, limited information exists on the potential negative, unintended effects of chute construction activities on water quality. This study was designed to better understand the possible effects of chute construction, both initially and as chute development continues, on Missouri River nutrient concentrations. Our first objective was to determine if the addition of sediment from proposed chute locations to river water samples (i.e., elutriate samples) increased nutrient concentrations relative to water-only river samples collected just upstream of the proposed chute locations or river water samples collected from eight long-term water quality monitoring stations. Our second objective was to determine if nutrient concentrations of river samples monitored during 2009 and 2010 increased after water passed through previously-constructed chutes. Nutrient concentrations of elutriate samples were not significantly higher than river water samples collected just upstream of the proposed chute locations;the same was true for Missouri River water samples collected from seven of eight long-term water quality monitoring stations. Furthermore, monitoring of nutrient concentrations collected from water samples at the outlet of previously-constructed chutes were not significantly higher than water samples collected at the upstream inlet of these chutes. Our results suggest that individual SWH chute construction projects designed to restore some of the natural form and function of the Missouri River are unlikely to significantly increase Missouri Rivernutrient concentrations initially or as these chutes continue to develop.

Population dynamics and habitat use of the Black-necked Crane (Grus nigricollis) in the Yarlung Tsangpo River basin, Tibet, China

Background:The Black-necked Crane (Grus nigricollis)is an internationally threatened crane living on the plateau, mainly in winter, in the Yarlung Tsangpo River basin in Tibet,western China. In the past five years,some economic development projects have been conducted in this area,posing potential threats to the wintering populations of the cranes and their habitats. Therefore, the current population dynamics of wintering Black-necked Cranes and habitat suitability in the Yarlung Tsangpo River basin were investigated. Methods: Twenty counties were surveyed using the line transect method in December 2017 and January 2018, and we recorded the location,flock size,number of individuals,habitat types and presence of human disturbance in which they occurred.We compared the results from the middle wintering period in this survey with those from 2014. Results: The highest number of cranes recorded was 8291,and the results showed that the cranes were mainly distributed in Lhaze, Namling, Samzhubze, and Lhunzub.A total of 577 and 495 flocks were recorded in the early and middle wintering periods, respectively. In the early wintering period,there were signi ficant differences in the number of individuals across the di fferent habitats,with crop stubble land and plowed land representing more than 30% of the total habitat utilization.In the middle wintering period, there were also signi ficant differences in the number of individuals, and the utilization of crop stubble land represented over 60% of the total. Conclusions: Wintering Black-necked Cranes mainly fed on spilled grains in stubble habitat after harvest. In the middle wintering period, some of the farmlands were plowed and irrigated,which resulted in food shortages in these areas,and the cranes tended to gather in mixed flocks of large size instead of as a single family.There were still considerable regional wintering populations decreases in Quxu,Nedong,and Sakya in 2018 compared with 2014,and these decreases were mainly due to some recently emerging threats,including farmlands being converted into areas of greenhouse cultivation,highway and railway construction, river dredging,the rapid development of the manufacturing and mining industries,and the lack of protection of important wintering sites.

Integrated assessment of river health based on water quality, aquatic life and physical habitat

The health conditions of Liao River were assessed using 25 sampling sites in April 2005, with water quality index, biotic index and physical habitat quality index. Based on the method of cluster analysis （CA） for water quality indices, it revealed that heavily polluted sites of Liao River are located at estuary and mainstream. The aquatic species surveyed were attached algae and benthic invertebrates. The result showed that the diversity and biomass of attached algae and benthic index of biotic integrity （B-IBI） were degrading as the chemical and physical quality of water bodies deteriorating. Physiochemical parameters, BODs, CODcr, TN, TP, NH3-N, DO, petroleum hydrocarbon and conductivity, were statistically analyzed with principal component analysis and correlation analysis. The statistical results were incorporated into the integrated assessing water quality index, combining fecal coliform count, attached algae diversity, B-IBI and physical habitat quality score. A comprehensive integrated assessing system of fiver ecological health was established. Based on the systimetic assessment, the assessed sites are categorized into 9 ＂healthy＂ and ＂sub-healthy＂ sites and 8 ＂sub-sick＂ and ＂sick＂ sites.

Fish Assemblage Responses to a Low-head Dam Removal in the Lancang River

Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam removal on fish communities in Asian mountainous rivers, which are dominated by Cypriniformes fishes, are still not well known. To determine whether dam removal on a mountainous river benefit restoration of fish diversity, we investigated the response of fish assemblage to dam removal using a before-after-control-impact design in two tributaries of the Lancang River(dam removal river: the Jidu River, and control river: the Fengdian River). Fish surveys were conducted one year prior to dam removal(2012) and three years(2013–2015) following dam removal. We observed rapidly and notably spatio-temporal changes in fish biodiversity metrics and assemblage structure, occurring in the Jidu River within the first year after dam removal. Overall, fish species richness, density and Shannon-Wiener diversity all increased immediately in above-and below-dam sites, and maintained a stable level in subsequent years, compared to unchanged situation in the control river. All sites in the Jidu River experienced shifts in fish composition after dam removal, with the greatest temporal changes occurred in sites below-and above-the former dam, resulting in a temporal homogenization tendency in the dam removed river. These findings suggest that dam removal can benefit the recovery of habitat conditions and fish community in Asian mountainous rivers, but the results should be further evaluated when apply to other dammed rivers since the dam age, fluvial geomorphology and situation of source populations could all affect the responses of fish assemblages.

Coupling interaction between biodiversity and aquatic habitat area in Western Route Project vicinity

The Western Route of the South-to-North Water Transfer Project will divert water from the upper Yangtze River and its tributaries, the Dadu River and Yalong River, to the upper Yellow River. The project may ease the water shortage in the Yellow River Basin. However, it may also have some effects on the ecosystem in the upper Yangtze River Basin. Benthic invertebrates play an important role in the river ecosystem, particularly in the circulation of materials and nutrition. Benthic invertebrates are widely used to quickly assess river ecosystems because of their rapid response to changes in the water environment. The diversity of benthic invertebrates is closely associated with the aquatic habitat area. This study examined this interaction by sampling the benthic invertebrates in an expanding area. The conclusions are that the diversity of benthic invertebrates begins to decrease when the aquatic habitat area is reduced to 45% of the original area, and decreases dramatically when the aquatic habitat area is reduced to 10% of the original area. The aquatic habitat area should be kept at more than 45% of the original area in order to maintain the significant diversity of benthic invertebrates.

黄河流域特色保护类村庄种群分布动态与生境选择

基于种群生态学理论,将黄河流域971个国家级特色保护类村庄视作一个地理种群。综合GIS空间分析和数理统计方法,明晰这一种群的分布动态和生境选择特征,进而应用地理探测器对比揭示影响该种群分布的生态因子。结果表明:(1)黄河流域特色保护类村庄的分布密度随种群增长而大幅提高,分布模式随尺度变大由显著聚集转为不显著离散,分布格局随时间推移由多中心向单中心演化,但集聚中心一直位于河谷盆地;(2)黄河流域特色保护类村庄具有“聚中低山区、向阳坡斜坡、喜温暖湿润、近黄河干流”的偏好,趋向中等人口密度、经济欠发达地区分布,主要位于国道沿线30 km、省道沿线10 km、中心城市周边20~80 km、历史城镇周边60 km、旅游景区和文保单位周边20 km范围内;(3)影响特色保护类村庄种群分布的生态因子具有综合性、非等价性和限定性,在黄河流域以文保单位和海拔为主导。

Orange River Francolins(Scleroptila levaillantoides)persist in fragmented Highveld farming landscapes,South Africa

Background:How do Orange River Francolins(Scleroptila levaillantoides) adapt to an intensive farming landscape with grass(grazing) camps and crop cultivation? To answer this question, a study was carried out in south-east of Johannesburg in South Africa to clarify the interaction of francolins with a landscape consisting of land use mosaics.Methods:A transect-road of 45 km was traversed weekly during November 2015–October 2016 through flat maize(Zea mays) and cattle(Bos primigenius) grazing fields. Francolins were counted in three land use mosaic types along the transect-road(including the road):grass camps on both sides of the road(grass/grass edges); arable fields on both sides(arable/arable edges) and arable land on one side with grass camps on the opposite side of the road(arable/grass edges).Results:Francolins used all three mosaic types, but the arable/arable edges were least frequented. Nonetheless, the arable/arable edges played an important part:francolins, including females with chicks, moved along the arable/arable edges, which enabled contact between sub-populations, and the arable/arable edges provided temporary cover(e.g. stubble and maize plants) and ploughed firebreaks to forage(e.g. for bulbs).Conclusion:Cultivation of crop within grasslands does not constrain breeding, movement and habitat use by the Orange River Francolin. For conservation purposes it is critical that the fine-scale mosaic of grazing and cultivation areas remain intact.

Seed dispersal by Tana River mangabeys in fragmented gallery forests

Data collected on a free ranging group of Tana River mangabeys (Cercocebus galeritus) indicates that this endangered primate species, which has previously been regarded as a seed predator, plays an important role in seed dispersal and do contribute to the regeneration of a highly fragmented gallery forest. We observed fruit handling behavior and the post-dispersal fate of seeds ingested by the mangabeys. The two main fruit handling behaviors observed, fruit swallowing and processing fruits in cheek pouches, positively contributed to seed disper- sal. Seed predation was not common during this study, apart from a few particular plant species such as Acacia robusta and Alangium salviifolium with non-fleshy fruits. We found a correlation between seed predation and fruit availability, respectively seasonal differential specific dispersal efficiency. The role of the mangabeys in dispersing seeds and facilitating forest regeneration is enhanced by their movement across forest patches through non-forested matrix, which contributes to the deposition of seeds and regeneration in these habitat gaps.

基于卫星跟踪的黄河三角洲东方白鹳适宜栖息地分布预测

【目的】根据黄河三角洲东方白鹳卫星跟踪位点,预测其在全国范围内夏季和冬季适宜栖息地分布,以期为东方白鹳的协同保护提供科学依据。【方法】利用2016—2022年山东黄河三角洲80只东方白鹳卫星跟踪数据,通过空间自相关分析筛选出夏季5283个点位,冬季4730个点位,使用最大熵模型(MaxEnt)预测黄河三角洲东方白鹳夏季与冬季潜在适宜栖息地分布,并划分适宜等级。【结果】1)MaxEnt模型预测夏季和冬季AUC值分别为0.866和0.838,结果准确性好。2)海拔、等温性、距河湖距离、平均气温日较差、降水量季节性以及土地利用类型是影响黄河三角洲东方白鹳夏季与冬季分布的关键环境因素。3)黄河三角洲东方白鹳夏季栖息地高适宜区面积为14.75×10^(4)km^(2)(占适宜区总面积的13.01%),主要位于松嫩平原(57.52%)、渤海湾(17.56%)、辽河平原(14.94%)等地区;栖息地类型包括湿地(35.30%)、农田(33.74%)和水域(12.43%)等。4)冬季栖息地高适宜区面积为11.63×10^(4)km^(2)(占适宜区总面积的11.62%),主要位于长江中下游平原(49.02%)、淮河流域江苏洪泽湖(23.75%)、渤海湾(11.52%)等地区;栖息地类型主要包括湿地(40.56%)、农田(29.68%)和水域(18.45%)等。(5)夏季与冬季栖息地高适宜区的重叠面积为2.13×10^(4)km^(2)(占总重叠面积的4.11%),主要分布在渤海湾(59.81%)、山东半岛沿海(23.24%)、江苏东部沿海(9.34%)等区域。【结论】夏季适宜栖息地向北扩到东北松嫩平原、三江平原和辽河平原,该结果打破了东方白鹳出生后扩散的传统认知,建议加强该物种的协同保护。

Evaluation of habitat quality for selected wildlife species associated with island back channels

The islands and associated back channels on the Ohio River, USA, are believed to provide critical habitat features for several wildlife species. However, few studies have quantitatively evaluated habitat quality in these areas. Our main objective was to evaluate the habitat quality of back and main channel areas for several species using habitat suitability index (HSI) models. To test the effectiveness of these models, we attempted to relate HSI scores and the variables measured for each model with measures of relative abundance for the model species. The mean belted kingfisher (Ceryle alcyon) HSI was greater on the main than back channel. However, the model failed to predict kingfisher abundance. The mean reproduction component of the great blue heron (Ardea herodias) HSI, total common muskrat (Ondatra zibethicus) HSI, winter cover component of the snapping turtle (Chelydra serpentina) HSI, and brood-rearing component of the wood duck (Aix sponsa) HSI were all greater on the back than main channel, and were positively related with the relative abundance of each species. We found that island back channels provide characteristics not found elsewhere on the Ohio River and warrant conservation as important riparian wildlife habitat. The effectiveness of using HSI models to predict species abundance on the river was mixed. Modifications to several of the models are needed to improve their use on the Ohio River and, likely, other large rivers.

基于土地利用变化的湖南长江岸线生境质量评价

岸线是长江湿地生态系统的重要组成部分,研究其土地利用变化及其生境质量时空响应对长江岸线生态保护和土地资源可持续利用具有重要意义。本文以1990、2000、2010、2020年4期土地利用数据为基础,采用生态系统服务和权衡的综合评估(integrated valuation of ecosystem services and tradeoffs,InVEST)模型,研究了湖南长江岸线30年来土地利用变化及生境质量时空演变特征。结果表明:(1)1990—2020年湖南长江岸线土地利用格局发生了明显变化,草地、建设用地、未利用土地面积持续增加,占比分别增加了3.69%、0.81%和0.56%,耕地和水域面积持续减小,占比分别降低了2.46%和1.88%。(2)1990—2020年湖南长江岸线生境质量均值为0.8075,其中1990—2010年生境质量呈下降趋势,2010年后生境质量明显提高。生境质量空间分布表现为长江干线到防洪大堤逐渐降低。(3)生境质量等级以“优”和“良好”为主。相较于1990年,2020年生境质量“优”等级和“良好”等级面积占比共减少了0.25%。(4)土地利用转化产生的负面影响大于正面影响,土地利用转化导致生态环境退化和改善的土地利用变化贡献指数(land use change contribution index,CI)分别为-1.8151和0.9569,其中草地、水域转为耕地和建设用地是造成研究区生境质量下降的主要原因。该研究有助于进一步了解长江岸线土地利用变化与生境质量之间的关系,可为长江经济带生态保护和可持续发展提供科学支撑。

小浪底水库运行下花园口河段黄河鲤生态流量研究

【目的】大坝和水库等水利工程的修建在带来防洪减灾效益的同时,也给所在区域的水生生物栖息繁衍带来了一定影响,诊断关键水生生物的生态流量对大坝下游的生态环境修复工作具有重要意义。【方法】以黄河下游花园口河段为例,探讨了小浪底水库运行下不同流量情景下的黄河鲤栖息地质量情况,并由此推求黄河鲤的生态流量。基于栖息地模拟法,通过构建耦合栖息地适宜度模型的二维水动力模型,分析了黄河鲤鱼苗期、亲鱼期的栖息地适宜度指数空间分布,分别建立了黄河鲤两个生命阶段流量与栖息地加权可用面积关系曲线。【结果】结果表明:随着模拟流量的增大,黄河鲤不同生命阶段的栖息地适宜度指数空间分布及栖息地加权可用面积呈现先增加,达到峰值后逐渐减小的变化规律。【结论】黄河下游花园口河段的最小生态流量为1 150 m~3/s,适宜生态流量为1 450 m~3/s,最适宜生态流量为3 000 m~3/s,研究成果加深了对大流量情景下黄河鲤栖息地质量的认识,对黄河下游生态保护与修复具有重要意义。

2000—2040年黄河流域(河南段)生境质量时空格局演变及驱动力分析

实现经济发展与生态保护的共赢是一个世界性难题。随着经济社会的发展,人类活动强度对区域生境质量产生不同程度的影响,在欠发达地区这种影响往往是负面的,因此实现人口稠密的欠发达地区经济发展与生境保护相结合具有重要意义。以黄河流域(河南段)为例,基于InVEST模型生境质量模块与PLUS模型对该区域2000—2021年(历史时期)生境质量时空演变特征进行分析,并以5年为步长对2025年、2030年、2035年和2040年的生境质量进行模拟。研究结果表明:(1)历史时期研究区生境质量均值下降了0.05,呈下降趋势,生境质量高值区集中分布在研究区西南和西北部的山地,呈西高东低的分布格局。(2)历史时期研究区44.74%区域生境质量显著下降,下降区域分布在城乡建设和道路扩张用地区域,西部山区此趋势最为突出。33.81%区域生境质量显著上升,上升区域分布在东部耕地区域和西部林地。研究区生境破碎化趋势加强,海拔与植被等自然要素对区域生境质量水平影响显著,与生境质量水平正相关。(3)2025—2040年不同土地利用情景下的未来生境质量格局差异明显,生态保护情境下生境质量水平呈上升趋势,耕地保护情景下生境质量均值稳定中呈现小幅度提升,城市发展情景下生境质量均值呈现明显下降趋势,不同发展情景下人类活动对区域生境质量影响显著。本研究有助于进一步了解区域生境质量的发展趋势与对土地利用变化的响应。

基于耳石微化学的大洋河刀鲚生境履历研究

为探明大洋河刀鲚(Coilia nasus)的“生境履历”,利用电子探针微区分析技术(EPMA)对2020年7月和9月采自大洋河下游水域20尾刀鲚的矢耳石进行了锶(Sr)和钙(Ca)的微化学分析研究。定量线分析结果显示,刀鲚样本均为淡水起源,淡水生境Sr/Ca比值在(1.49±0.61—2.75±0.53),淡水系数(Fc)在(0.08—0.52),淡水区域径长在(150—900μm)。进入第二变化阶段后“生境履历”波动显著,Sr/Ca比值变化可将大洋河刀鲚分为3种模式,第一种是中高值区(半咸水或海水)越冬,繁殖季溯河洄游至低值区(淡水);第二种是长期栖息于中高值区,无溯河洄游现象;第三种是在中高值区和低值区多次转换,DYH 05、19个体最高完成9次转换。Sr面分析结果也与上述Sr/Ca比值结果相同。这三种模式直观地反映出大洋河刀鲚群体“生境履历”的多样性特点。

黄河流域典型县域生境质量的时空分异特征及影响因素研究

通过探索黄河流域山东段县域生境质量时空分异特征与影响因素,以便从县域尺度为地方生态环境保护与社会经济高质量发展提供政策建议。基于2000、2010和2020年3期土地利用数据,采用InVEST模型解析生境质量的时空分布格局与演变特征,结合空间自相关模型对其空间分异特征进行探测,并采用地理加权回归(GWR)模型分析社会、经济与自然影响因素在空间维度上对生境质量的影响。结果表明:(1)2000—2020年,黄河流域山东段平均生境质量指数为0.448,空间上表现出中段、上段低和下段高的分布格局,生境质量整体呈先快速下降后缓慢下降趋势,中段生境质量下降趋势最为显著;(2)生境质量变化在空间分布上呈显著集聚性特征,会受到邻近区域的影响,且总体集聚态势不断增强,高-高型集聚区面积明显大于低-低型集聚区,在流域下段范围连片分布;(3)土地开发强度是影响生境质量时空分布的首要因素,城市化水平、人口密度和NDVI对生境质量有重要影响,社会、经济和自然因素共同影响生境质量时空变化,GWR回归分析结果表明生境质量具有空间差异性。识别这些时空差异对推动该区域生态高质量发展具有重要意义。

北江丁坝群对鲫鱼栖息地适宜度的影响

为了探究北江丁坝群对鱼类栖息地的影响,以北江干流英德段为研究区域,采用非结构化网格有限体积法(FVCOM),计算了不同流量条件下鲫鱼栖息地加权可利用面积(WUA),得到鱼类最适生态流量值。基于鱼类最适生态流量值开展了丁坝群对流速、水深、鱼类栖息地适宜性指数和水力生境多样性变化的影响。结果表明:当上游为最适生态流量350 m 3/s时,丁坝群使得WUA由7.142 km 2降低至5.692 km 2;丁坝群会显著改变河道中心和近岸的流速,导致流速适宜度指数下降,进而降低整个研究区域的栖息地适宜度指数;丁坝群的水位壅高作用有限,最大壅高水深为0.38 m,对水深适宜度指数分布影响较小;在丁坝群作用下,栖息地可接受性高的面积占比由52.151%降至32.271%,降低了鱼类栖息地质量;丁坝群造成水力生境多样性辛普森指数由0.547降至0.529,使得研究区域内的水力生境多样性略微减少。研究成果可为北江鱼类栖息地保护和生态恢复提供参考。