Seasonal and interannual variation in vegetation composition: Implications for survey design and data interpretation

Understanding how vegetation composition varies with season and interannual climate variability is important for any ecological research that uses vegetation data derived from surveys for the basis of inference. Misunderstanding this variation can influence land management and planning decisions, leading to poor implementation of biodiversity offsetting mechanisms, for example. We monitored plots (400 m²) grazed by livestock paired with adjacent ungrazed plots in derived native pastures four times a year over 2.5 years on the North‐West Slopes of New South Wales. Species density in plots varied greatly with season and interannual rainfall. Highest species density was recorded in spring, though species density in summer was not significantly lower, nor was a spring–summer peak in species density evident in the 2009 drought. Surveys in spring 2008 had the highest species density, and recorded only 60–72% of the total species recorded at each site over 2.5 years. Variation in the proportion of total site diversity represented in combinations of two or three surveys was large, though the best combinations comprised surveys from spring and summer in years of above‐average rainfall, either from the same spring‐summer, or from different years. Compositional differences among sites were much greater than within sites, showing that differences among sites related to broad environmental gradients were not overwhelmed by seasonal and interannual variability in site composition. When grazing was excluded, there was no evidence of competitive exclusion by the dominant grasses, and no directional shift in composition. The implications of these findings for ecological research depend on the question being addressed: if capturing a large proportion of site diversity is important, then surveys must be carefully timed, or repeat surveys must be conducted. Single surveys did not effectively capture site diversity for use in biodiversity offsetting, and the timing of repeat surveys was critical.     

Passive acoustic monitoring as a potential tool to survey animal and ecosystem processes in freshwater environments

1. Biodiversity in freshwater habitats is decreasing faster than in any other type of environment, mostly as a result of human activities. Monitoring these losses can help guide mitigation efforts. In most studies, sampling strategies predominantly rely on collecting animal and vegetal specimens. Although these techniques produce valuable data, they are invasive, time-consuming and typically permit only limited spatial and temporal replication. There is need for the development of complementary methods.
2. As observed in other ecosystems, freshwater environments host animals that emit sounds, either to communicate or as a by-product of their activity. The main freshwater soniferous groups are amphibians, fish, and macroinvertebrates (mainly Coleoptera and Hemiptera, but also some Decapoda, Odonata, and Trichoptera). Biophysical processes such as flow or sediment transport also produce sounds, as well as human activities within aquatic ecosystems.
3. Such animals and processes can be recorded, remotely and autonomously, and provide information on local diversity and ecosystem health. Passive acoustic monitoring (PAM) is an emerging method already deployed in terrestrial environments that uses sounds to survey environments. Key advantages of PAM are its non-invasive nature, as well as its ability to record autonomously and over long timescales. All these research topics are the main aims of ecoacoustics, a new scientific discipline investigating the ecological role of sounds.
4. In this paper, we review the sources of sounds present in freshwater environments. We then underline areas of research in which PAM may be helpful emphasising the role of PAM for the development of ecoacoustics. Finally, we present methods used to record and analyse sounds in those environments.
5. Passive acoustics represents a potentially revolutionary development in freshwater ecology, enabling continuous monitoring of dynamic bio-physical processes to inform conservation practitioners and managers.

     

环境DNA技术在鱼类生态学中的应用研究进展

全球渔业衰退是21世纪人类面临的重要挑战之一。为了有效地遏制鱼类资源的衰退,精确的鱼类生态调查是其首要任务。传统的鱼类监测以渔获物采集与形态学鉴定为主,往往耗时耗力且效果不佳,已无法满足现阶段大尺度上的精确调查。环境DNA （eDNA）技术作为一种近年来新兴的鱼类生态调查方法,其与传统方法相比具有灵敏度高、经济高效、采样受限小且对生态系统无干扰的优势,目前其已被广泛地应用于鱼类物种监测、多样性调查、生物量评估以及繁殖活动监测等方面的研究。然而,eDNA技术在鱼类生态学研究的具体应用中暴露出的一些问题将会影响其监测结果的精确性,诸如操作流程的不规范、基因数据库的不完善以及eDNA在环境中生态学过程的不明确等。鉴于上述原因,首先对eDNA技术的发展历程、分析流程以及eDNA技术在鱼类生态学研究领域中的研究进展进行了综述,而后着重分析了eDNA技术的发展当前所面临的困难与挑战,并提出了相应的解决方案,最后对eDNA技术未来在鱼类生态学研究领域中的发展趋势做出了展望。通过本研究,以期能够为eDNA技术在鱼类生态学领域中的准确应用提供理论基础。     

Drivers of reef fish assemblages in an upwelling region from the Eastern Tropical Pacific Ocean

Reef fish assemblages are exposed to a wide range of anthropogenic threats as well as chronic natural disturbances. In upwelling regions, for example, there is a seasonal influx of cool nutrient-rich waters that may shape the structure and composition of reef fish assemblages. Given that climate change may disrupt the natural oceanographic processes by altering the frequency and strength of natural disturbances, understanding how fish assemblages respond to upwelling events is essential to effectively manage reef ecosystems under changing ocean conditions. This study used the baited remote underwater video stations (BRUVS) and the traditional underwater visual census (UVC) to investigate the spatiotemporal patterns of reef fish assemblages in an upwelling region in the North Pacific of Costa Rica. A total of 183 reef fish species from 60 families were recorded, of which 166 species were detected using BRUVS and 122 using UVC. Only 66% of all species were detected using both methods. This study showed that the upwelling had an important role in shaping reef fish assemblages in this region, but there was also a significant interaction between upwelling and location. In addition, other drivers such as habitat complexity and habitat composition had an effect on reef fish abundances and species. To authors’ knowledge, this is the first study in the Eastern Tropical Pacific that combines BRUVS and UVC to monitor reef fish assemblages in an upwelling region, which provides more detailed information to assess the state of reef ecosystems in response to multiple threats and changing ocean conditions.     

Things We Like: Human Preferences among Similar Organisms and Implications for Conservation

Human preferences will increasingly determine many species’ prospects for survival. However, aside from a small number of survey-based studies of preference among disparate taxa, human species preferences have received little attention. I determined human aesthetic preferences among a relatively homogenous group, the penguins, from representation in all recently published, comprehensive, popular books of photographs of penguins (n = 4 books; 304 photographs). Representation of visually distinguishable types of penguins, measured by total photograph area, was highly skewed and rankings were highly concordant across books, suggesting large and commonly held differences in aesthetic appeal. Multiple regression analysis indicated that amount of warm color was the only significant determinant of representation, and warm color was highly correlated (r ² = 0.96) with mean representation of the penguin types. Body size and neotenic form, traits found to influence human preferences among other animals, were not significant, suggesting that the bases of human species preferences differ by species type. The results of this study indicate that human aesthetic preferences discriminate finely among species and may be based on minor features. Conservationists must be vigilant to the potential for aesthetic responses to influence conservation efforts.     

Comparing iDNA from mosquitoes and flies to survey mammals in a semi-controlled Neotropical area

Ingested-derived DNA (iDNA) from insects represents a powerful tool for assessing vertebrate diversity because insects are easy to sample, have a diverse diet and are widely distributed. Because of these advantages, the use of iDNA for detecting mammals has gained increasing attention. Here we aimed to compare the effectiveness of mosquitoes and flies to detect mammals with a small sampling effort in a semi-controlled area, a zoo that houses native and non-native species. We compared mosquitoes and flies regarding the number of mammal species detected, the amount of mammal sequence reads recovered, and the flight distance range for detecting mammals. We also verified if the combination of two mini-barcodes (12SrRNA and 16SrRNA) would perform better than either mini-barcode alone to inform local mammal biodiversity from iDNA. To capture mosquitoes and flies, we distributed insect traps in eight sampling points during 5 days. We identified 43 Operational Taxonomic Units from 10 orders, from the iDNA of 17 mosquitoes and 46 flies. There was no difference in the number of species recovered per individual insect between mosquitoes and flies, but the number of flies captured was higher, resulting in more mammal species recovered by flies. Eight species were recorded exclusively by mosquitoes and 20 by flies, suggesting that using both samplers would allow a more comprehensive screening of the biodiversity. The maximum distance recorded was 337 m for flies and 289 m for mosquitoes, but the average range distance did not differ between insect groups. Our assay proved to be efficient for mammal detection, considering the high number of species detected with a reduced sampling effort.     

Assessment of fish communities using environmental DNA: Effect of spatial sampling design in lentic systems of different sizes

Freshwater fish biodiversity is quickly decreasing and requires effective monitoring and conservation. Environmental DNA (eDNA)‐based methods have been shown to be highly sensitive and cost‐efficient for aquatic biodiversity surveys, but few studies have systematically investigated how spatial sampling design affects eDNA‐detected fish communities across lentic systems of different sizes. We compared the spatial patterns of fish diversity determined using eDNA in three lakes of small (SL; 3 ha), medium (ML; 122 ha) and large (LL; 4,343 ha) size using a spatially explicit grid sampling method. A total of 100 water samples (including nine, 17 and 18 shoreline samples and six, 14 and 36 interior samples from SL, ML and LL, respectively) were collected, and fish communities were analysed using eDNA metabarcoding of the mitochondrial 12S region. Together, 30, 35 and 41 fish taxa were detected in samples from SL, ML, and LL, respectively. We observed that eDNA from shoreline samples effectively captured the majority of the fish diversity of entire waterbodies, and pooled samples recovered fewer species than individually processed samples. Significant spatial autocorrelations between fish communities within 250 m and 2 km of each other were detected in ML and LL, respectively. Additionally, the relative sequence abundances of many fish species exhibited spatial distribution patterns that correlated with their typical habitat occupation. Overall, our results support the validity of a shoreline sampling strategy for eDNA‐based fish community surveys in lentic systems but also suggest that a spatially comprehensive sampling design can reveal finer distribution patterns of individual species.     

Bias in freshwater biodiversity sampling: the case of Iberian water beetles

Extensive distributional data bases are key tools in ecological research, and good-quality data are required to provide reliable conservation strategies and an understanding of biodiversity patterns and processes. Although the evaluation of data bases requires the incorporation of estimates of sampling effort and bias, no studies have focused on these aspects for freshwater biodiversity data. We used here a comprehensive data base of water beetles from the Iberian Peninsula and the Balearic Islands, and examine whether these data provide an unbiased, reliable picture of their diversity and distribution in the study area. Based on theoretical estimates using the Clench function on the accumulated number of records as a surrogate of sampling effort, about a quarter of the Iberian and Balearic 50 × 50 km Universal Transverse Mercator grid cells can be considered well prospected, with more than 70% of the theoretical species richness actually recorded. These well-surveyed cells are not evenly distributed across biogeographical and physicoclimatic subregions, reflecting some geographical bias in the distribution of sampling effort. Our results suggest that recording was skewed by relatively simple variables affecting collector activity, such as the perceived 'attractiveness' of mountainous landscapes and protected areas with recently described species, and accessibility of sampling sites (distance from main research centres). We emphasize the importance of these evaluation exercises, which are useful to locate areas needed of further sampling as well as to identify potential biases in the distribution of current biodiversity patterns.     

淡水生态系统中的TOP—DOWN效应与生物多样性保护

淡水生态系统中高营养级类群可以对低营养级类群产生强烈的影响,最终导致整个生态环境的改变,这一现象被称作下行（ｔｏｐｄｏｗｎ）效应。本文对ｔｏｐｄｏｗｎ的含义特别是鱼类所产生ｔｏｐｄｏｗｎ效应的结果进行了阐述,提出了ｔｏｐｄｏｗｎ效应还表现在当原来生态系统中的高营养级类群缺少时,也会造成生态系统结构与功能发生变化的观点。最后,根据淡水生态系统ｔｏｐｄｏｗｎ效应的特点,认为在淡水生态系统的生物多样性保护中,应注意高营养级类群的保护和谨慎地对待引种问题     

Diurnal variation in the abundance of juvenile parasitic gnathiid isopods on coral reef fish: implications for parasite-cleaner fish interactions

 The dynamics of parasitic gnathiid isopod infestation on the fish Hemigymnus melapterus were examined at Heron Island, Great Barrier Reef, by measuring the abundance and feeding state of gnathiids on fish collected between dawn and sunset and by estimating the time required for gnathiids to become engorged on host fluids. A model was developed to estimate gnathiid abundance on fish for any given time of day and host size. Fish at dawn had 2.4 times as many gnathiids compared with fish at sunset, indicating that some gnathiids infest fish overnight. Most gnathiids had engorged guts (72–86%); the proportion of empty guts and engorged guts did not differ in three time periods of collection (<0800 h, 0800 to 1100 h, and >1100 h). In the laboratory, gnathiids fed quickly with 75% of gnathiids exposed to fish for 4 h having engorged guts. The short time required for gnathiids to become engorged and the presence of gnathiids with empty guts throughout the day suggests that gnathiids also infest fish during the day. Thus gnathiids eaten by cleaner fish during the day may be replaced by other gnathiids during the day or night suggesting that interactions between gnathiids and cleaner fish are highly dynamic. Accepted: 15 April 1999     

中国香港淡水鱼类的生物多样性与保护

Hong Kong Special Administrative Region,China,has an area of1095km2and is located at the edge of thenorthern tropical zone.The landscape is dominated byhills and ravines withflat landrestrictedtothe lowflood-plains and coastal regions.Inthis hilly domain,the smallrocky streams are typically fast flowing at their uplandsources,and graduallyreduceinspeed asthey wind alonghill cuttings to reach the lowlands.While streams arecommonlyfound,rivers are very limited in number.Thefewlong and meanderi…     

Geographical gradients in the biodiversity of Chinese freshwater molluscs: Implications for conservation

Aim

Large ‐ scale diversity patterns are generated by different but not mutually exclusive mechanisms. However, understanding of multiple facets of diversity and their determinants in the freshwater realm remains limited. Here, we characterized the geographical gradients, hotspots and spatial congruence of three facets of freshwater molluscan diversity and evaluated the relative importance of three different underlying mechanisms related to the energy, area/environmental heterogeneity and dispersal/historical hypotheses.

Location

China.

Methods

Species richness (SR), functional richness (FR) and taxonomic distinctness (TD, a proxy of phylogenetic diversity) were calculated for 212 drainage basins with a total of 313 molluscan species. Spatial congruence between the diversity facets was evaluated with Pearson correlation coefficient and overlap among hotspots. Multiple linear regression models and variation partitioning were used to assess the relative importance of different mechanisms.

Results

Hotspots of SR and FR were mainly concentrated in the Yangtze River and Huai River basins, while high TD values were patchily distributed across China. We found extremely low spatial congruence between TD and both SR and FR, while there was relatively high concordance between SR and FR. All diversity facets were best explained by the dispersal/historical hypothesis with strong unique effects, followed by the factors related to the energy hypothesis. The area/ environmental heterogeneity hypothesis was only weakly supported.

Main conclusions

We found a potentially strong influence of dispersal limitation and evolutionary history on the geographical diversity gradients of Chinese molluscs. This finding contrasts with the general finding that energy‐related factors are the strongest correlates of diversity patterns at large spatial scales. Moreover, our results do not support the idea that using any one diversity component as a surrogate of the others in developing conservation strategies. Instead, an integrative approach embracing multiple facets of diversity should be adopted in the conservation of freshwater biodiversity.

     

Biodiversity pattern of fish assemblages in Poyang Lake Basin: Threat and conservation

Poyang Lake Basin is of great importance to maintain regional ecological balance. However, fish biodiversity in this basin has rapidly declined as the result of anthropogenic habitat alteration, such as dam construction, sand mining, and water pollution. Here, we aimed to analyze the temporal and spatial changes in biodiversity patterns of fish in Poyang Lake Basin over the last 37 years. The number of fish species underwent a significant decrease in the current period. In particular, 36.7% of the migration of fish was extirpated. Twenty‐seven fish species have been formally assessed using the Chinese Red List were currently listed as Critically Endangered (9), Endangered (3), Vulnerable (10), and Near Threatened (5). Alpha and gamma diversity revealed that fish diversity had also decreased, and beta diversity showed significant composition dissimilarity in two periods. PCoA showed that the historical fish composition dissimilarity was significantly different from that of the current period. We found a significant effect of the geographical distance on the spatial turnover component for the historical and current periods. In addition, the nestedness component was the main contributor to beta diversity, which indicated one large protected area should be established in Poyang Lake and the Ganjiang River Basin with higher species richness. These results indicated that fish biodiversity declined in the current period likely caused by anthropogenic habitat alteration and other threatened factors. Therefore, we suggest that the habitat reconstruction and biodiversity conservation for fish have become imperative in this basin, and a complete management plan should be carried out.     

Declining freshwater mussel diversity in the middle and lower reaches of the Xin River Basin: Threat and conservation

Freshwater mussels provide important functions and services for aquatic ecosystems, but populations of many species have been extirpated. Information on biodiversity plays an important role in the conservation and management of freshwater mussels. The Xin River Basin is a biodiversity hotspot for freshwater mussels in China, with more than 43 species known, but populations of which are decreasing. Here, we quantify the diversity of freshwater mussels in the middle and lower reaches of the Xin River Basin and study the correlation of habitat characteristics and freshwater mussel diversity. Compared to the historical period, the number of species, density, and biomass of freshwater mussels decreased 33%, 83%, and 82% in the current period, respectively. Fifty two percent of recorded species were empty shells, and 14 native freshwater mussels were not found in the study area. Four species are currently listed as vulnerable species using IUCN criteria and their global status. The assemblage structure of freshwater mussels exhibits significant spatial differences, and there was a correlation with substrate and physicochemical parameters. The main tributary of the Xin River with higher freshwater mussel diversity should be established as one large protected area because the nestedness component was the main pattern of beta diversity. These results indicated freshwater mussel diversity was declining rapidly, which can help focus conservation effort for freshwater mussel biodiversity.     

Determinants of fine‐scale homogenization and differentiation of native freshwater fish faunas in a Mediterranean Basin: implications for conservation

Aim Increasing threats to freshwater biodiversity are rapidly changing the distinctiveness of regional species pools and local assemblages. Biotic homogenization/differentiation processes are threatening the integrity and persistence of native biodiversity patterns at a range of spatial scales and pose a challenge for effective conservation planning. Here, we evaluate the extent and determinants of fine‐scale alteration in native freshwater fish assemblages among stream reaches throughout a large river basin and consider the implications of these changes for the long‐term conservation of native fishes. Location Guadiana River basin (South‐Western Iberian Peninsula). Methods We quantified the magnitude of change in compositional similarity between observed and reference assemblages and its potential effect on natural patterns of compositional distinctiveness. Reference assemblages were defined as the native species expected to occur naturally (in absence of anthropogenic alterations) and were reconstructed using a multivariate adaptive regression splines predictive model. We also evaluated the role of habitat degradation and introduced species as determinants of biotic homogenization/differentiation. Results We found a significant trend towards homogenization for native fish assemblages. Changes in native fish distributions led to the loss of distinctiveness patterns along natural environmental gradients. Introduced species were the most important factor explaining the homogenization process. Homogenization of native assemblages was stronger in areas close to reservoirs and in lowland reaches where introduced species were more abundant. Main conclusions The implementation of efficient conservation for the maintenance of native fish diversity is seriously threatened by the homogenization processes. The identification of priority areas for conservation is hindered by the fact that the most diverse communities are vanishing, which would require the selection of broader areas to adequately protect all the species. Given the principal role that introduced species play in the homogenization process and their relation with reservoirs, special attention must be paid to mitigating or preventing these threats.     

Species and hybrid richness in spined loaches of the genus Cobitis (Teleostei: Cobitidae), with a checklist of European forms and suggestions for conservation

Until recently, one widespread species of the genus Cobitis was thought to be present in Europe, the common spined loach Cobitis taenia . Recent studies have shown that the diversity of spined loaches is considerably higher due to (1) presence of several species as well as C. taenia and (2) presence of hybrid biotypes, living together with species. Here knowledge about distribution and diversity of spined loaches in Europe is summarized by combining original with published data. In Southern Europe, a number of distinct species occur allopatrically, while in Central and Eastern Europe a few species have wide distribution areas. Hybrid biotypes were found exclusively in Central and Eastern Europe. They were not restricted to the contact areas between the parental species, but occur in almost the entire area. In total, 15 hybrid biotypes with different genomic compositions were recorded. In the most diverse complex, four hybrid biotypes were associated with one species. In general, a syntopic occurrence of different species of Cobitis can be considered as exceptional, while the association of species with hybrid biotypes is the rule in Central and Eastern Europe. The composition of complexes seems to be most strongly influenced by the kind of associated species and by local history. Implications for conservation are (1) not to disturb the natural patterns of diversity, (2) to consider the known richness in legislation, and (3) to consider the evolutionary significance of hybrid biotypes.     

生物多样性保护优先区抽样调查策略研究——以武陵山地区为例

生物多样性保护优先区是我国为加强生物多样性保护和监管划定的重要区域,目前部分优先区已陆续开展生物本底资料的调查评估工作,但受限于经费、时间等条件,对区内所有县域或网格全覆盖式科考,既不现实也无必要,因而区域尺度的抽样设计是一个亟需解决的关键问题。以武陵山生物多样性保护优先区为例,结合层次聚类和系统抽样方法,同时考虑历史调查资料的系统完整程度和空间保护属性,提出了一个科学可行的抽样方案。首先将研究区域内的所有县域聚为5类,每类挑选出2个重点县域,共获得6个历史上进行过系统科学考察的县域和4个本底资料相对缺乏的县域,进而挑选出76个重点调查网格（10 km×10 km）,其中生物多样性富集网格36个,保护区外的人类干扰网格40个,抽样比例为11.09%,每个网格平均调查经费为2.52万元。该抽样策略区分了调查层次并突出重点区域,使调查和评估更有针对性,进一步完善了保护优先区基础调查系统,也强化了项目管理能力,对其他保护优先区项目开展具有一定参考价值。     

The conservation value of elevation data accuracy and model sophistication in reserve design under sea‐level rise

Many studies have explored the value of using more sophisticated coastal impact models and higher resolution elevation data in sea‐level rise (SLR) adaptation planning. However, we know little about to what extent the improved models and data could actually lead to better conservation outcomes under SLR. This is important to know because high‐resolution data are likely to not be available in some data‐poor coastal areas in the world and running more complicated coastal impact models is relatively time‐consuming, expensive, and requires assistance by qualified experts and technicians. We address this research question in the context of identifying conservation priorities in response to SLR. Specifically, we investigated the conservation value of using more accurate light detection and ranging (Lidar)‐based digital elevation data and process‐based coastal land‐cover change models (Sea Level Affecting Marshes Model, SLAMM) to identify conservation priorities versus simple “bathtub” models based on the relatively coarse National Elevation Dataset (NED) in a coastal region of northeast Florida. We compared conservation outcomes identified by reserve design software (Zonation) using three different model dataset combinations (Bathtub–NED, Bathtub–Lidar, and SLAMM–Lidar). The comparisons show that the conservation priorities are significantly different with different combinations of coastal impact models and elevation dataset inputs. The research suggests that it is valuable to invest in more accurate coastal impact models and elevation datasets in SLR adaptive conservation planning because this model–dataset combination could improve conservation outcomes under SLR. Less accurate coastal impact models, including ones created using coarser Digital Elevation Model (DEM) data can still be useful when better data and models are not available or feasible, but results need to be appropriately assessed and communicated. A future research priority is to investigate how conservation priorities may vary among different SLR scenarios when different combinations of model‐data inputs are used.     

Valley‐scale hydrogeomorphology drives river fish assemblage variation in Mongolia

River hydrogeomorphology is a major driver shaping biodiversity and community composition. Here, we examine how hydrogeomorphic heterogeneity expressed by Functional Process Zones (FPZs) in river networks is associated with fish assemblage variation. We examined this association in two distinct ecoregions in Mongolia expected to display different gradients of river network hydrogeomorphic heterogeneity. We delineated FPZs by extracting valley‐scale hydrogeomorphic variables at 10 km sample intervals in forest steppe (FS) and in grassland (G) river networks. We sampled fish assemblages and examined variation associated with changes in gradients of hydrogeomorphology as expressed by the FPZs. Thus, we examined assemblage variation as patterns of occurrence‐ and abundance‐based beta diversities for the taxonomic composition of assemblages and as functional beta diversity. Overall, we delineated 5 and 6 FPZs in river networks of the FS and G, respectively. Eight fish species were found in the FS river network and seventeen in the G, four of them common to both ecoregions. Functional richness was correspondingly higher in the G river network. Variation in the taxonomic composition of assemblages was driven by species turnover and was only significant in the G river network. Abundance‐based taxonomic variation was significant in river networks of both ecoregions, while the functional beta diversity results were inconclusive. We show that valley‐scale hydrogeomorphology is a significant driver of variation in fish assemblages at a macrosystem scale. Both changes in the composition of fish assemblages and the carrying capacity of the river network were driven by valley‐scale hydrogeomorphic variables. River network hydrogeomorphology as accounted for in the study has, therefore, the potential to inform macrosystem scale community ecology research and conservation efforts.     

基于环境DNA技术的赤水河秋季鱼类多样性分布特征

赤水河是长江上游少有的仍保持自然流态的大型一级支流,是长江鱼类重要的繁衍场和珍稀物种的保护地,摸清其鱼类多样性现状及鱼类群落结构特征对赤水河水生态恢复评估极为重要。于2021年9月对赤水河流域开展了鱼类多样性、分布及其特征调查,全流域共设置52个采样点,采用环境DNA技术采集并研究了赤水河鱼类的组成及其分布。结果显示通过环境DNA方法共调查到鱼类6目18科62属77种,包含16种长江特有鱼类。以鲤形目为主,占总数的87.87%。赤水河鱼类食性以杂食性和肉食性鱼类为主,群落结构上,处于下层水环境鱼类较多;赤水河鱼类优势种为宽鳍鱲(Y=0.205)、西昌华吸鳅(Y=0.085)、麦穗鱼(Y=0.068)、乌苏拟鲿(Y=0.033)、云南光唇鱼(Y=0.027);赤水河上游和下游鱼类群落(P<0.01)和Shannon-Wiener指数差异均显著(P<0.05)。海拔、流速、pH、电导率和温度是影响赤水河鱼类多样性的主要环境因素。为环境DNA技术在赤水河鱼类多样性调查中的应用提供了探索性研究,将有助于赤水河生物多样性的保护。