National Institute of Aquatic Resources, Technical University of Denmark, Kemitorvet, Kongens Lyngby, Denmark.
National Institute of Aquatic Resources, Technical University of Denmark, Kemitorvet, Kongens Lyngby, Denmark; Marine Ecophysiology Group (EOMAR), IU- ECOAQUA, University of Las Palmas de Gran Canaria, Canary Islands, Spain.
Aquat Toxicol. 2020 Nov;228:105631. doi: 10.1016/j.aquatox.2020.105631. Epub 2020 Sep 19.
Microplastics (MPs) are contaminants of emerging concern in the Arctic, but knowledge of their potential effects on Arctic plankton food webs remains scarce. We experimentally investigated ingestion and effects of MPs (20 μm polyethylene spheres) on the arctic copepods Calanus finmarchicus, C. glacialis and C. hyperboreus. These species dominate arctic zooplankton biomass and are relevant target species to investigate the potential impacts of MPs on the Arctic marine ecosystem. Females of each species were exposed to two concentrations of MPs (200 and 20,000 MPs L) in combination with different food (diatom) concentrations, reflecting high (3000-5000 cells mL, spring phytoplankton bloom) and low (50-500 cells mL, pre/post bloom) food conditions. MPs did not affect negatively fecal pellet production rates in any of the species at the studied exposure concentrations. However, egg production rates of copepods exposed to MPs were 8 times higher compared with the controls, which suggests that MP exposure can cause stress-induced spawning in arctic copepods. Microscopic examination of the fecal pellets confirmed ingested MPs in the three species (up to aprox. 1000 MPs cop d). The number of MPs per pellet decreased exponentially with increasing food concentration. The daily ingestion of MPs per copepod was higher at low- food concentrations (250-500 cells mL). At our exposure conditions, the presence of MPs inside C. hyperboreus fecal pellets did not affect their sinking rates. Overall, our experimental research show that 1) acute exposure to virgin polyethylene MPs has a low impact on arctic Calanus species at environmentally relevant MP concentrations, independent of food availability, and 2) arctic copepods influence the environmental fate of plankton-sized MPs by exporting buoyant MPs from the surface layer to the sea floor via fecal pellets.
微塑料（MPs）是北极地区新兴的关注污染物，但它们对北极浮游生物食物网的潜在影响知之甚少。我们通过实验研究了 MPs（20μm 聚乙烯球）对北极桡足类 Calanus finmarchicus、C. glacialis 和 C. hyperboreus 的摄食和影响。这些物种在北极浮游动物生物量中占主导地位，是研究 MPs 对北极海洋生态系统潜在影响的相关目标物种。每个物种的雌性暴露于两种浓度的 MPs（200 和 20,000 MPs L），同时结合不同的食物（硅藻）浓度，反映了高（3000-5000 个细胞 mL，春季浮游植物爆发）和低（50-500 个细胞 mL，爆发前/后）食物条件。在所研究的暴露浓度下，MPs 没有对任何一种物种的粪便颗粒产生率产生负面影响。然而，暴露于 MPs 的桡足类动物的产卵率比对照组高 8 倍，这表明 MPs 暴露会导致北极桡足类动物产生应激性产卵。对粪便颗粒的显微镜检查证实了三种物种都摄入了 MPs（多达约 1000 个 MPs cop d）。随着食物浓度的增加，每个颗粒中的 MPs 数量呈指数减少。在低食物浓度（250-500 个细胞 mL）下，每只桡足类动物每天摄入的 MPs 数量较高。在我们的暴露条件下，C. hyperboreus 粪便颗粒内存在 MPs 不会影响它们的沉降速率。总的来说，我们的实验研究表明：1）在环境相关的 MPs 浓度下，急性暴露于原始聚乙烯 MPs 对北极 Calanus 物种的影响较小，与食物供应无关；2）北极桡足类动物通过粪便颗粒将浮在表面层的浮游生物大小的 MPs 输出到海底，从而影响 MPs 的环境归宿。
