The competitive edge of an invading specialist
The competitive edge of an invading specialist
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DOI：
10.2307/2680222
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发表时间：
2001-08-01
期刊：
影响因子：
4.8
通讯作者：
Amundsen, PA
中科院分区：
文献类型：
--
作者：
Bohn, T;Amundsen, PA
引进物种是对本地和自然生物多样性的主要威胁。另一方面，生物学家可以通过在外来物种建立过程中跟踪群落来增加对生态相互作用的理解。因此，在挪威北部和俄罗斯的亚北极帕斯维克河水系内相距50公里的两个湖泊地区，研究了本地白鱼(Coregonus Lavaretus)和最近入侵的白鱼(C.alBula)的摄食生态和栖息地利用。白鱼最初在这两个湖的原生鱼类群落中占主导地位。最近的入侵和相继向下游扩张的venaces使两个地点可以进行比较：一个地点新的潜在竞争者对本地鱼类物种的影响较弱，而另一个地点的影响很强。在本研究进行时，在下游湖泊首次记录到金枪鱼，而且数量很少，而在上游湖泊，金枪鱼建立了很高的种群密度，是中上层区域的优势鱼种。在这两个湖中的两种鱼之间没有发现在中上层栖息地使用的垂直隔离。在下游的湖中，白鱼和银鱼都只以浮游动物为食，饮食几乎相同。在上游的湖里。相比之下，白鱼主要以底栖动物和表层昆虫为食，而白鱼主要以浮游动物为食。因此。作为一种专门的浮游生物，venace的强烈存在减少了浮游动物作为更通用的白鱼的猎物的可获得性。这两种鱼在上游湖泊中的食物分离明显是相互作用的，是由于对浮游动物的强烈不对称竞争造成的，文迪亚斯是优势物种。即使在几年后，浮游动物入侵帕斯维克水道的生态后果(包括浮游动物规模和物种多样性的减少，中上层食物网的改变，以及可能对初级生产产生的级联效应的富营养化)也是相当大的。而且很可能会在未来继续并加剧。
Introduced species represent major threats to native and natural biodiversity. On the other hand, biologists may increase the understanding of ecological interactions by following communities during establishment of exotic species. Accordingly, feeding ecology and habitat use were studied in native whitefish (Coregonus lavaretus) and recently invading vendace (C. albula) in two lake localities situated 50 km apart within the subarctic Pasvik River system, northern Norway and Russia. Whitefish originally dominated the native fish communities of both lakes. The recent invasion and successive downstream expansion of vendace allowed comparisons between two sites: one in which the influence of the new potential competitor on the native fish species was weak, and one in which the influence was strong. In the downstream lake vendace was recorded for the first time at the time of the study, and only in small numbers, whereas in the upstream lake vendace had established a high population density and was the dominant fish species in the pelagic zone. No vertical segregation in pelagic habitat use was found between the two fish species in either lake. In the downstream lake both whitefish and vendace fed exclusively on zooplankton and had almost identical diets. In the upstream lake. in contrast, whitefish fed predominantly on zoobenthos and surface insects, while vendace fed mainly on zooplankton. Thus. the strong presence of vendace as a specialized planktivore reduced the availability of zooplankton as prey for the more generalist whitefish. The food segregation between the two fish species in the upstream lake was apparently interactive and caused by a strong asymmetrical competition for zooplankton, vendace being the superior species. The ecological consequences (including reduced zooplankton size and species diversity, alteration of the pelagic food web, and eutrofication as a possible cascading effect on the primary production) of the vendace invasion in the Pasvik watercourse are considerable, even after a few years. and are likely to proceed and intensify in the future.