THE COMPOSITION OF INVASIVE FISH SPECIES AND ECOLOGICAL RISK ASSESSMENT IN LONGYANGXIA RESERVOIR

To understand the current composition, ecological risks, and potential distribution areas of high-risk invasive fish species in the Longyangxia Reservoir, and to develop targeted prevention and control measures, this study conducted systematic field investigations in the Longyangxia Reservoir and the surrounding Yellow River Basin in May, September, and December of 2023, as well as May and July 2024. These were complemented by a literature review to systematically summarize the current fish composition and ecological types of invasive fish in the reservoir. The AS-ISK tool was used to assess the risk level of each invasive species, and the MaxEnt model was used to predict its potential distribution of one typical invasive species, Pseudorasbora parva, across the Longyangxia Reservoir Basin. The results showed that: (1) A total of 21 fish species belonging to 4 orders, 6 families, and 16 genera were collected, including 11 invasive species. Based on the index of relative importance (IRI), 6 dominant species were identified, 4 of which were invasive: Carassius auratus, Pseudorasbora parva, Oncorhynchus mykiss, and Hypomesus olidus; (2) Ecological matrix factors revealed that invasive fish species were predominantly characterized by terminal mouth positions (R=0.64), adhesive egg production (R=0.91), omnivorous feeding habits (R=0.72), and benthic lifestyles (R=0.45), with most being resident species (R=0.73) adapted to calm water environments (R=0.91); (3) According to the AS-ISK assessment, there were 5 high-risk, 2 medium-risk, and 4 low-risk species, with the top 5 highest-risk species being Hypomesus olidus, Pseudorasbora parva, Cyprinus carpio, Oncorhynchus mykiss, and Carassius auratus. Compared with historical data and incorporating weather predictions, the number of invasive species is expected to continue increasing; (4) The MaxEnt model prediction indicated that high-risk area of H. olidus is mainly concentrated in the Longyangxia Reservoir, Liujiaxia Reservoir, and the Yellow River Basin between the two reservoirs, while the reservoir tail and upstream areas represent low-risk zones. The study highlight H. olidus as the key species for prevention, with the Longyangxia Reservoir tail being the primary focal zone. These findings provide data support and theoretical references for the supporting green and sustainable fisheries development in the Yellow River Basin.

为明晰龙羊峡水库内高风险外来入侵鱼类的当前群落组成、生态风险及潜在分布区域，并制定针对性防控措施，本研究于2023年5月、9月、12月及2024年5月、7月，针对龙羊峡水库及其周边黄河流域开展了系统性野外调查。本研究辅以文献综述，系统梳理了该水库内现有鱼类群落组成及外来入侵鱼类的生态类型。采用AS-ISK风险评估工具（AS-ISK）对各入侵鱼类的风险等级进行评估，并利用MaxEnt模型针对典型入侵物种麦穗鱼（Pseudorasbora parva）预测其在龙羊峡水库流域的潜在分布范围。研究结果显示：（1）共采集到鱼类21种，隶属于4目6科16属，其中入侵鱼类11种。以相对重要性指数（IRI）为依据，共鉴定出6个优势种，其中4种为入侵鱼类：鲫（Carassius auratus）、麦穗鱼（Pseudorasbora parva）、虹鳟（Oncorhynchus mykiss）及胡瓜鱼（Hypomesus olidus）；（2）生态矩阵因子分析结果表明，入侵鱼类主要具有以下特征：口端位（R=0.64）、产粘性卵（R=0.91）、杂食性食性（R=0.72）及底栖生活方式（R=0.45），且多数为定居性物种（R=0.73），适应静水环境（R=0.91）；（3）经AS-ISK风险评估，该区域入侵鱼类中高风险物种5种、中风险物种2种、低风险物种4种，风险等级排名前五的物种依次为胡瓜鱼（Hypomesus olidus）、麦穗鱼（Pseudorasbora parva）、鲤（Cyprinus carpio）、虹鳟（Oncorhynchus mykiss）及鲫（Carassius auratus）。结合历史数据与气象预测结果，预计该区域入侵鱼类的种类数量将持续增加；（4）MaxEnt模型预测结果显示，胡瓜鱼的高风险分布区主要集中于龙羊峡水库、刘家峡水库以及两库之间的黄河流域，而水库尾部及上游区域为低风险分布区。本研究明确胡瓜鱼为核心防控物种，龙羊峡水库尾部为重点防控区域。本研究结果可为黄河流域绿色可持续渔业发展提供数据支撑与理论参考。