Insufficient knowledge about ecology of weed macrophytes from a large-scale perspective narrows the necessary decision-making for biodiversity conservation. The present study aimed to assess the occurrence frequency of Egeria densa in lotic and lentic/semi-lotic environments from a Brazilian dammed river, as well as to quantify the attributed explanation (pure or combined) by limnological and spatial variables on species occurrence frequency. Between 2006 and 2010, we repeatedly visited sample points classified as lotic (45) or lentic/semi-lotic environments (23) to collect data on species occurrence and limnological variables. We also generated spatial variables derived from latitude and longitude of sample points. E. densa showed a recurrent occurrence in the sample points classified as lentic/semi-lotic. Both spatial variables (16) and limnological variables (total phosphorus, nitrate, nitrite, transparency and turbidity) significantly contributed to explaining the species occurrence frequency. Forty-nine percent of the occurrence frequency variation was accounted purely by spatial variables. However, less than five percent of occurrence frequency variation was accounted purely by limnological variables. The several dams placed along the river determined the lentic/semi-lotic environments formation and regulated the dispersion processes of individuals of E. densa, consequently causing a recurrent occurrence of this species in particular environmental classes.

从大规模的角度对杂草大型植物的生态学知识不足，限制了生物多样性保护的必要决策。本研究旨在评估巴西大坝河在抽水和lentic / semi-lotic环境中Egeria densa的发生频率，并通过对物种发生频率的语言和空间变量量化归因（纯或组合）。在2006年至2010年之间，我们反复访问了分类为抽水（45）或透镜/半湿润环境（23）的采样点，以收集有关物种发生和气候学变量的数据。我们还生成了从采样点的经度和纬度得出的空间变量。Ë。登莎显示出在分类为片状/半片状的样本点中反复出现。空间变量（16）和植物学变量（总磷，硝酸盐，亚硝酸盐，透明度和浊度）都对解释该物种的发生频率做出了重要贡献。发生频率变化的百分之四十九完全由空间变量解释。但是，少于发生频率变化的百分之五是纯粹由语言学变量解释的。沿河放置的数个水坝决定了lentic / semi-lotic环境的形成，并调节了E. densa个体的扩散过程，因此导致该物种在特定环境类别中反复出现。