Fish invasions in the world's river systems: when natural processes are blurred by human activities.
Fish invasions in the world's river systems: when natural processes are blurred by human activities.
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DOI：
10.1371/journal.pbio.0060028
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发表时间：
2008-02
期刊：
影响因子：
9.8
通讯作者：
Brosse S
中科院分区：
文献类型：
--
作者：
Leprieur F;Beauchard O;Blanchet S;Oberdorff T;Brosse S
由于物种入侵是人类引起的生物多样性危机的主要驱动因素，确定全球入侵的主要决定因素是采取健全的保护政策的先决条件。为解释非本地物种的建立，提出了三个不一定相互排斥的主要假说：“人类活动”假说，认为人类活动通过扰乱自然景观和增加繁殖压力，促进了非本地物种的建立;“生物抵抗力”假说，预测物种丰富的社区很容易阻碍非本地物种的建立;以及“生物接受”假说，预测环境上适合本地物种的生境也适合非本地物种。我们测试了这些假设，并在这里报告了鱼类入侵的全球地图（即，该数据库使用了全球淡水鱼出现、环境变量和人类活动指标的原始数据集，涵盖了地球表面80%以上的1，055个河流流域。首先，我们确定了六个主要的入侵热点，其中非本地物种占物种总数的四分之一以上。根据世界自然保护联盟的数据，这些地区的特点是受威胁鱼类的比例最高。其次，我们发现，人类活动指标占全球变化的大部分非本地物种丰富度，这是高度一致的“人类活动”的假设。相比之下，我们的研究结果不支持“生物接受”或“生物抗性”假说。我们发现，鱼类入侵的地理学与全球范围内人类影响的地理学相匹配，这意味着人类活动在世界河流系统中推动鱼类入侵的自然过程是模糊的。鉴于我们的调查结果，我们担心经济不断增长的发展中国家会发生大规模入侵，发达国家已经经历过这种情况。因此，预测这种潜在的生物多样性威胁应成为优先事项。作为生物多样性的主要威胁之一，生物入侵的有害后果已被广泛认识。尽管如此，在水生生态系统中仍然缺乏对入侵模式及其决定因素的全球观点，这降低了我们采取实际行动的能力。在这里，我们报告了全球淡水鱼入侵的模式，在1,055个河流流域，覆盖了地球80%以上的大陆表面。这使我们能够确定六个主要的入侵热点，其中非本地物种占物种总数的四分之一以上。根据世界自然保护联盟的数据，这些地区的特点是受威胁鱼类的比例最高。我们还表明，控制全球生物多样性的自然因素并不影响在一个给定的河流流域的非本地物种的数量。相反，与人类活动有关的因素，特别是经济活动，解释了为什么一些河流流域拥有更多的非本地物种。鉴于我们的调查结果，我们担心经济不断增长的发展中国家会发生大规模入侵，发达国家已经经历过这种情况。这对全球生物多样性构成了严重威胁。绘制世界范围内淡水鱼入侵的地图可以确定主要的入侵热点，并表明经济活动是全球范围内淡水鱼入侵的主要决定因素。
Because species invasions are a principal driver of the human-induced biodiversity crisis, the identification of the major determinants of global invasions is a prerequisite for adopting sound conservation policies. Three major hypotheses, which are not necessarily mutually exclusive, have been proposed to explain the establishment of non-native species: the “human activity” hypothesis, which argues that human activities facilitate the establishment of non-native species by disturbing natural landscapes and by increasing propagule pressure; the “biotic resistance” hypothesis, predicting that species-rich communities will readily impede the establishment of non-native species; and the “biotic acceptance” hypothesis, predicting that environmentally suitable habitats for native species are also suitable for non-native species. We tested these hypotheses and report here a global map of fish invasions (i.e., the number of non-native fish species established per river basin) using an original worldwide dataset of freshwater fish occurrences, environmental variables, and human activity indicators for 1,055 river basins covering more than 80% of Earth's surface. First, we identified six major invasion hotspots where non-native species represent more than a quarter of the total number of species. According to the World Conservation Union, these areas are also characterised by the highest proportion of threatened fish species. Second, we show that the human activity indicators account for most of the global variation in non-native species richness, which is highly consistent with the “human activity” hypothesis. In contrast, our results do not provide support for either the “biotic acceptance” or the “biotic resistance” hypothesis. We show that the biogeography of fish invasions matches the geography of human impact at the global scale, which means that natural processes are blurred by human activities in driving fish invasions in the world's river systems. In view of our findings, we fear massive invasions in developing countries with a growing economy as already experienced in developed countries. Anticipating such potential biodiversity threats should therefore be a priority. As one of the major threats to biodiversity, the detrimental consequences of biological invasions are widely recognised. Despite this, a global view of invasion patterns and their determinants is still lacking in aquatic ecosystems, reducing our ability to initiate practical actions. Here we report the global patterns of freshwater fish invasion in 1,055 river basins covering more than 80% of Earth's continental surface. This allows us to identify six major invasion hotspots where non-native species represent more than a quarter of the total number of species. According to the World Conservation Union, these areas are also characterised by the highest proportion of threatened fish species. We also show that the natural factors controlling global biodiversity do not influence the number of non-native species in a given river basin. Instead, human activity–related factors, and particularly economic activity, explain why some river basins host more non-native species. In view of our findings, we fear massive invasions in developing countries with a growing economy as already experienced in developed countries. This constitutes a serious threat to global biodiversity. Mapping worldwide freshwater fish invasions allowed the identification of major invasion hot spots and demonstrated that economic activity is the main determinant of freshwater fish invasions at the global scale.