Agostinho C S
Núcleo de Estudos Ambientais (Neamb), Fundação Universidade do Tocantins, Setor Jardim dos Ipês, CEP 77500-000, Porto Nacional, Tocantins, Brazil.
Braz J Biol. 2003 Feb;63(1):1-6. doi: 10.1590/s1519-69842003000100002. Epub 2003 Aug 14.
Construction of the Itaipu Dam, 150 km downstream from Sete Quedas Falls, resulted in the drowning of that natural geographic barrier, with consequent invasion of Serrasalmus marginatus in the upper stream. This event was followed by the reduction in the abundance of the native species, S. spilopleura. Analyzes of reproductive activity these species revealed that in lotic waters S. marginatus had a very intense reproductive activity while activity of S. spilopleura was nil. This, probably made it possible for the invading species to occupy new environments into the Upper Paraná River, using the river as an entry port. In the 1987-1988 period there was a marked decline in reproductive activity of S. spilopleura reflecting the negative effects of its interaction with the invading species, S. marginatus. The assertiveness of S. marginatus in caring for its offspring and aggressiveness in establishing its feeding territory may be the determining factor for its competitive superiority over S. spilopleura, and consequently its success in colonizing the Upper Paraná River. In addition to the negative interference of S. marginatus, a possible recruitment failure of S. spilopleura could have benefited the colonization of the floodplain by the invader species.
伊泰普大坝建于塞特克达斯瀑布下游150公里处，导致该天然地理屏障被淹没，缘锯脂鲤随之侵入上游。这一事件之后，本土物种斯氏锯脂鲤的数量减少。对这些物种繁殖活动的分析表明，在流水水域中，缘锯脂鲤的繁殖活动非常强烈，而斯氏锯脂鲤则没有繁殖活动。这可能使入侵物种得以以上巴拉那河为入口，占据新的环境。1987 - 1988年期间，斯氏锯脂鲤的繁殖活动显著下降，反映出其与入侵物种缘锯脂鲤相互作用的负面影响。缘锯脂鲤在照顾后代方面的坚定性以及在建立觅食领地方面的攻击性，可能是其比斯氏锯脂鲤具有竞争优势的决定性因素，从而也是其成功在上巴拉那河殖民的原因。除了缘锯脂鲤的负面干扰外，斯氏锯脂鲤可能的补充失败可能有利于入侵物种在洪泛区的殖民。
