Avelar W E P, Neves F F, Lavrador M A S
Department of Biology, Faculty of Philosophy, Sciences and Languages of Ribeirão Preto ? FFCLRP, University of São Paulo ? USP, Ribeirão Preto, SP, Brazil.
Department of Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirão Preto ? FCFRP, University of São Paulo ? USP, Ribeirão Preto, SP, Brazil.
Braz J Biol. 2014 May;74(2):509-14. doi: 10.1590/1519-6984.21612.
The provision of sediment in rivers, due to erosion processes that occur in the environment, consists of a major source of pollution and alteration of the physicochemical conditions of water resources. In addition, the increase in water turbidity may cause siltation, dramatically impacting aquatic communities. Specifically considering the bivalve Corbicula fluminea (Müller, 1774), the aim of this study was to analyse the effect of exposure to different turbidity conditions of sediments, as a risk factor for the animals. For this purpose, a docking device was designed to ensure water circulation in a closed system and to maintain the desired levels of turbidity. Although C. fluminea can generally tolerate environmental changes in aquatic systems, an intolerance to high turbidity levels was experimentally observed, expressed by the mortality rate of the animals when exposed to conditions above 150 nephelometric turbidity units (NTU). This value was similar to the one recorded at study sites in the rivers Pardo (Serrana-SP-Brazil) and Mogi Guaçu (Porto Ferreira-SP-Brazil) during the rainy season. Using a logistic regression model, the experimental results were analysed and the observed mortality rates indicate that the exposure of the animals to turbidity levels above 150 nephelometric turbidity units (NTU), for periods longer than 120 hours, may be considered a probable cause of mortality for the species.
由于环境中发生的侵蚀过程，河流中的沉积物供应构成了主要的污染源，并改变了水资源的物理化学条件。此外，水体浊度的增加可能导致淤积，对水生生物群落产生重大影响。具体针对双壳类河蚬（Corbicula fluminea，穆勒，1774年），本研究的目的是分析暴露于不同浊度条件的沉积物对这些动物的影响，将其作为一个风险因素。为此，设计了一种对接装置，以确保在封闭系统中的水循环，并维持所需的浊度水平。尽管河蚬通常能够耐受水生系统中的环境变化，但通过实验观察到其对高浊度水平不耐受，表现为当暴露于高于150散射浊度单位（NTU）的条件时动物的死亡率。该值与雨季期间在巴西圣保罗州塞拉纳的帕尔杜河以及巴西圣保罗州费雷拉港的莫吉瓜苏河研究地点记录的值相似。使用逻辑回归模型对实验结果进行分析，观察到的死亡率表明，动物暴露于高于150散射浊度单位（NTU）的浊度水平且持续时间超过120小时，可能被视为该物种死亡的一个可能原因。
