Analysing spatio-temporal patterns of non-native fish in a biodiversity hotspot across decades

Aim: Analysing the spatio-temporal patterns and dynamics of non-native species is essential to understanding the mechanisms underlying successful invasions and developing effective management strategies. Yet, such analyses generally neglect the influence of receiving ecosystem types and non-native species sources (i.e. alien species, non-natives originating outside the concerned region; translocated species, nonnatives introduced to locations outside their historical range within the concerned region). Location: Yunnan, China. Methods: We analysed long-term (1950–2022) spatio-temporal patterns and potential underlying dynamics of non-native fishes in a biodiversity hotspot (Yunnan, China), paying special attention to waterbody types receiving non-native species and comparing alien and translocated species. We did this through compiling a highly comprehensive occurrence dataset of native and non-native fishes. Results: We recorded 783 native species and 94 non-native species (49 alien species and 45 translocated species), which mainly belonged to the order Cypriniformes (52 species) and were introduced via purposes for advancing aquaculture. Most frequently encountered non-native species were either intentionally introduced aquaculture species or small-bodied fish unintentionally introduced via aquaculture activities. The richness and spatial ranges of non-native fishes increased consistently since the 1950s and demonstrated a pronounced change after the 2000s, with densely populated areas and the middle to lower reaches of large rivers being more profoundly affected. The number of records of translocated species exceeded the number of records of alien species after the 2000s. Lakes and reservoirs are hotspots for both alien and translocated species introductions, and watersheds with large areas in Yunnan (e.g. the Jinsha-Yangtze and Lancang-Mekong basins) contained more non-native fish. Main Conclusions: Our study highlights the need to consider invasion sensitivities of receiving ecosystems and pay special attention to intra-regional species translocations when developing prevention and management strategies against invasions of alien species, particularly in important biodiversity hotspots around the world.

研究目的：解析外来物种的时空分布格局与动态，是阐明成功入侵内在机制、制定高效管理策略的核心前提。然而，现有相关分析普遍忽略了接纳生态系统类型与外来物种来源的影响：前者指外来种（alien species），即源自研究区域以外的非本土物种；后者指移殖种（translocated species），即被引入研究区域内其历史分布范围以外区域的非本土物种。
研究区域：中国云南省。
研究方法：本研究聚焦中国生物多样性热点区域（biodiversity hotspot）——云南省，对1950年至2022年的非本土鱼类开展长期时空分布格局与潜在内在动态分析，重点关注接纳非本土物种的水体类型，并对比外来种与移殖种的差异。为此，我们整合构建了一套覆盖本土与非本土鱼类的高完整性物种出现数据集。
研究结果：本次调查共记录783种本土鱼类与94种非本土鱼类（其中49种为外来种、45种为移殖种），非本土鱼类中以鲤形目（Cypriniformes）物种占比最高，共计52种，且多以水产养殖为目的被引入。最常被检出的非本土鱼类，要么是人为主动引种的养殖品种，要么是随水产养殖活动无意传入的小型鱼类。自1950年以来，非本土鱼类的物种丰富度与空间分布范围持续扩张，并在2000年后呈现显著变化：人口稠密区域以及大型河流中下游受影响程度更深。2000年后，移殖种的记录数量超过外来种。湖泊与水库是外来种与移殖种引入的热点区域，而云南省内流域面积较大的水系（如金沙江-长江流域、澜沧江-湄公河流域）的非本土鱼类资源更为丰富。
研究结论：本研究强调，在制定外来物种入侵防控与管理策略时，需充分考虑接纳生态系统的入侵敏感性，尤其应重视区域内的物种移殖活动，这一要点对于全球范围内的重要生物多样性热点区域而言尤为关键。