Department of Physics, University of Girona, 17003, Girona, Spain.
Department of Physics, University of Girona, 17003, Girona, Spain.
Environ Pollut. 2019 Aug;251:434-441. doi: 10.1016/j.envpol.2019.05.034. Epub 2019 May 9.
There is consensus on the need to study the potential impact microplastics (MP) have on freshwater planktonic organisms. It is not yet fully understood how MP enter the aquatic food web or the effect they have on all the trophic levels. As a result of the potential for MP to accumulate throughout food webs, there is increasing interest in evaluating their fate in a variety of environmental conditions. This study investigated the variability in the ingestion of MP to food ratios and the exposed time of MP to Daphnia magna in non-sheared and sheared conditions. The sheared environment provided Daphnia magna with the conditions for optimal filtering capacity. Regardless of the ratios of MP concentration to food concentration (MP:Food), the filtration capacity of the Daphnia magna was enhanced in the sheared experiments. In both the sheared and non-sheared experiments, filtration capacity decreased when the ratios of MP to food concentration and the exposure times to MP were increased. Mortality was mainly enhanced in the non-sheared conditions at higher MP concentrations and exposure times to MP. No mortality was found in the sheared conditions for the exposure times studied. Therefore, in aquatic systems that undergo constant low sheared conditions, Daphnia magna can survive longer when exposed to MP than in calm conditions, provided food concentrations do not limit their capacity to filter.
人们普遍认为需要研究微塑料（MP）对淡水浮游生物的潜在影响。目前还不完全清楚 MP 是如何进入水生生食物网的，以及它们对所有营养级别的影响。由于 MP 有可能在整个食物网中积累，因此人们越来越关注在各种环境条件下评估它们的命运。本研究调查了在非剪切和剪切条件下，MP 与食物的摄入量比和 MP 暴露于大型溞的时间的可变性。剪切环境为大型溞提供了最佳过滤能力的条件。无论 MP 浓度与食物浓度之比（MP：Food）如何，在剪切实验中，大型溞的过滤能力都得到了增强。在剪切和非剪切实验中，当 MP 与食物浓度之比和 MP 暴露时间增加时，过滤能力都会下降。在较高的 MP 浓度和 MP 暴露时间下，非剪切条件下的死亡率主要增加。在研究的暴露时间内，剪切条件下未发现死亡率。因此，在经常处于低剪切条件的水生系统中，如果食物浓度不限制其过滤能力，那么与在平静条件下相比，大型溞在暴露于 MP 时可以存活更长时间。
