瓯江源头区龙泉溪底栖大型无脊椎动物多样性和群落特征

Diversity and Community Characteristics of Benthic Macroinvertebrates in Longquan River,the Source Area of the Oujiang River

源头区溪流是河流生态系统最脆弱的部分,也是淡水底栖大型无脊椎动物(简称底栖动物)集中分布的热点区域,在流域物种库的形成和生态系统的多样性维持过程中具有不可忽视的作用。然而,目前国内对源头区溪流底栖动物多样性的系统调查研究较少。笔者对位于浙江省丽水市瓯江源头区的龙泉溪进行了底栖动物多样性调查研究,分别于2021年丰水期和平水期在覆盖龙泉溪主要山溪河流的18个样点采样,共采集获得底栖动物标本3700余号。通过联合使用传统形态分类和DNA条形码技术,共鉴定出底栖动物165种,隶属5门、9纲、19目、68科、124属。联合使用DNA条形码可使底栖动物科、种水平的分辨力提升28.3%和34.1%。调查研究表明:龙泉溪底栖动物多样性丰富,物种组成以节肢动物为主(占比高达87.9%,145种),其中水生昆虫占绝大多数(共计8目、48科、140种,占84.8%),主要优势种为鞘翅目的狭溪泥甲属1种Stenelmis sp.1、毛翅目的纹石蛾属Hydorpsyche和短脉纹石蛾属Cheumatopsyche各1种;底栖动物群落多样性丰富,且在丰水期和平水期均维持在较高的水平;海拔和底质类型等微生境条件对底栖动物多样性分布的影响分析显示,底质类型对底栖动物分布密度的影响显著。对水生态状况的生物评估结果显示:Biotic Index污染生物指数更适合龙泉溪流域的水质健康状况评估,龙泉溪流域整体的水生态状况健康,水质属清洁或极清洁。该研究使用传统形态学和DNA条形码技术相结合的鉴定方式,提高了底栖动物物种鉴定的精度,所获得的多样性调查和水质评价结果为瓯江源头区溪流乃至整个流域的生态保护和长期监测提供了本底基础资料。

Headwater streams are the most vulnerable parts of the river ecosystems and the biodiversity hotspots of freshwater benthic macroinvertebrates(benthic fauna for short),which play important roles in the formation of the species pool and the maintenance of ecosystem diversity.However,to date,there are only few studies on the benthic fauna diversity of headwater streams in China.In this study,the benthic fauna diversity of Longquan River in the source area of the Oujiang River in Lishui City,Zhejiang Province,was investigated for the first time.A total of 18 sampling sites covering the main mountain streams and rivers of Longquan River were sampled during the high-flow period and normal-flow period in 2021.More than 3700 specimens were collected.By combining the morphological classification with the DNA barcoding,a total of 165 species of benthic fauna were identified,belonging to 124 genera,68 families,19 orders,9 classes,5 phyla.The usage of DNA barcoding has improved the identifications of benthic fauna at families and species levels by 28.3%and 34.1%.Our survey showed that the benthic fauna diversity in Longquan River was rich,and the species composition was mainly arthropods,accounting for 87.9%(145 species),among which aquatic insects accounted for the majority(140 species in 48 families,8 orders,accounting for 84.8%),with the main dominant species being Stenelmis sp.1,Hydorpsyche sp.1,and Cheumatopsyche sp.1.The diversity of benthic fauna was high and maintained at a high level in both high-flow period and normal-flow period.The analysis of the effects of microhabitat conditions,such as elevation and substrate type,on the distribution of benthic fauna diversity showed that substrate type had significant impact on the density of benthic fauna.The results of the bioassessment of the water ecological status showed that the Biotic Index is more suitable for assessing the water quality health of the Longquan River watershed,and the overall aquatic ecological condition of the Longquan River basin was healthy and the water quality was clean or extremely clean.The study provides support for the combination of traditional morphology and DNA barcoding technology for identification,and the results of the diversity survey and water quality evaluation provide background basic information for ecological protection and long-term monitoring of the streams in the source area of Oujiang River and even the whole watershed.