The invasion success of non-native species depends on a variety of factors, and abiotic characteristics of invasive ranges and their native populations can offer resistance to non-native species establishment. Reservoirs, compared to natural lakes, can facilitate submerged macrophyte invasion because they provide favorable abiotic conditions to macrophyte establishment and development. However, previous colonization of native species can hamper the development of invasive ones through priority effects. In this investigation we used large data-set obtained in the Itaipu Reservoir (Brazil/Paraguay) to assess the relationship between the abundance of the native submerged macrophyte Egeria najas and of the invasive Hydrilla verticillata and water level, littoral slope and Secchi disk depth. We also investigated how the concomitant and previous abundance of both macrophytes correlates. A Bayesian modeling was applied, controlling the effect of spatial-temporal autocorrelation. Our results indicate an important role of water transparency, littoral slope and water level oscillations in a short period of time (30 days) for the temporal dynamics of these species’ abundances. Fluctuations of water levels and littoral slope affected H. verticillata to a greater extent than E. najas. In addition, the abundance of each species was related with its own abundance in previous samplings, highlighting the possible importance of habitat suitability, vegetative propagule pressure and resistance structures for population recovery. In low abundances, there was a possible facilitation between both species, while high abundances probably increased competition. The great importance of water level oscillations on these species’ abundances indicate that this strategy can be used as management tool.

非本地物种的入侵成功取决于多种因素，入侵范围及其本地种群的非生物特征可以提供对非本地物种建立的抵抗力。与天然湖泊相比，水库可以促进沉水植物入侵，因为它们为大型植物的建立和发展提供了有利的非生物条件。然而，本地物种之前的殖民化可能会通过优先效应阻碍入侵物种的发展。在这项调查中，我们使用在伊泰普水库（巴西/巴拉圭）获得的大型数据集来评估本地沉水大型植物Egeria najas与侵入性Hydrilla verticillata丰度之间的关系和水位、沿岸坡度和 Secchi 盘深度。我们还研究了两种大型植物的伴随丰度和先前丰度之间的相关性。应用贝叶斯建模，控制时空自相关的影响。我们的研究结果表明，水透明度、沿岸坡度和水位波动在短时间内（30 天）对这些物种丰度的时间动态具有重要作用。水位和沿岸坡度的波动对轮叶螟的影响程度大于蝾螈. 此外，每个物种的丰度与其之前采样中的丰度有关，突出了栖息地适宜性、营养繁殖压力和抵抗结构对种群恢复的可能重要性。在低丰度下，两个物种之间可能存在促进作用，而高丰度可能会增加竞争。水位波动对这些物种丰度的重要性表明该策略可用作管理工具。