GenØk Centre for Biosafety, Tromsø, Norway.
Institute of Marine Research, PB 6404, N-9294 Tromsø, Norway.
Environ Pollut. 2019 Nov;254(Pt A):112919. doi: 10.1016/j.envpol.2019.07.087. Epub 2019 Jul 22.
We investigate the distribution and effects of polystyrene microplastic (MP) particles in exposure experiments with the ecotoxicology model organism Daphnia magna. The aim was to investigate the short and long-term toxicity of MP at different concentrations. To achieve this goal, the effects of 6 μm commercially available polystyrene beads on two different life-stages of D. magna: < 24 h old juveniles and 9 days old adults was assessed. The following end points in test animals were measured: (1) survival, (2) growth, (3) individual and population fecundity, (4) age at maturation and (5) body size of newborn offspring. These response variables were followed in two acute and two chronic experiments. The acute experiments showed that MP is not acutely toxic to D. magna within 48 h, but cause added mortality within 120 h. The juveniles were about 50% more sensitive than the adults tested. In life-cycle experiments testing chronic exposure to MP, again, animals exposed as juveniles at relatively high concentrations, i.e. > 30 μg ml showed higher sensitivity. We observed slightly increased mortality, reduced growth and stimulation of early reproduction at the cost of later reproduction. Animals exposed after reaching adulthood did not show increased mortality and showed a stimulation response with higher reproductive rates than the control group. However, both the growth rate of mother animals and the body size of newborn declined with increasing dose of MP. We conclude that these effects indicate a role of MP in mechanical interaction/interference with the animal on the level of feeding (clogging filtering functions), digestion (gut filled with plastic particles), and/or other animal behavior. The study also illustrates how MP with slow break-down rates may accumulate in the environment and enter the food-chain as obstructing non-food particles in filter-feeding organisms.
我们研究了聚苯乙烯微塑料（MP）颗粒在水蚤（Daphnia magna）生态毒理学模型暴露实验中的分布和影响。目的是研究不同浓度的 MP 的短期和长期毒性。为了实现这一目标，评估了 6μm 市售聚苯乙烯珠对水蚤的两个不同生命阶段的影响：<24 小时的幼体和 9 天的成虫。在试验动物中测量了以下终点：（1）存活率，（2）生长，（3）个体和种群繁殖力，（4）成熟年龄和（5）新生后代的体型。这些响应变量在两个急性和两个慢性实验中进行了跟踪。急性实验表明，在 48 小时内，MP 对水蚤没有急性毒性，但在 120 小时内会导致额外的死亡率。与成年水蚤相比，幼体的敏感性约高 50%。在测试慢性暴露于 MP 的生命周期实验中，再次发现，在相对较高浓度下暴露于幼体的动物，即>30μg/ml 表现出更高的敏感性。我们观察到死亡率略有增加，生长速度降低，早期繁殖受到刺激，而后期繁殖减少。暴露于成年后再繁殖的动物没有增加死亡率，表现出更高的繁殖率刺激反应，高于对照组。然而，母体动物的生长率和新生后代的体型都随着 MP 剂量的增加而下降。我们得出结论，这些影响表明 MP 在动物的摄食（过滤功能堵塞）、消化（肠道充满塑料颗粒）和/或其他动物行为层面上通过机械相互作用/干扰发挥作用。该研究还说明了具有缓慢降解率的 MP 如何在环境中积累，并作为滤食性生物体内的非食物颗粒进入食物链。
