Ingestion and impact of microplastics on arctic Calanus copepods

Abstract

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 − 1 ) in combination with different food (diatom) concentrations, reflecting high (3000-5000 cells mL − 1 , spring phytoplankton bloom) and low (50-500 cells mL − 1 , 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 − 1 d − 1 ). 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 − 1 ). 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.

A Critical Review of the Availability, Reliability, and Ecological Relevance of Arctic Species Toxicity Tests for Use in Environmental Risk Assessment

“…The vast majority of our knowledge thus far is related to oil spills and oil spill–remediation methods. There have been no studies assessing the effect of multiple stressors on Arctic organisms or other emerging contaminants besides a single study on microplastics (Rodríguez‐Torres et al, 2020 ). For example, the impact of contaminants found in wastewater has not been determined via first‐tier toxicity tests (e.g., pharmaceuticals and personal care products), nor has that of persistent organic pollutants (e.g., pesticides and industrial chemicals).…”

Microplastics in Arctic invertebrates: status on occurrence and recommendations for future monitoring

“…The ability of zooplankton to ingest MP has been demonstrated in several laboratory experiments (reviewed in Galloway et al, 2017 andVillarrubia-Gómez et al, 2018There are three main calanoid copepod species, C. finmarchicus, C. glacialis and C. hyperboreus (Berge et al, 2012). The effects of 20 µm polyethylene (PE spheres on these three species were investigated by Rodríguez-Torres et al (2020), showing a low impact at environmentally relevant concentration (200 MPs L -1 ), while observing increased egg production rates at higher concentrations (20,000 MPs L -1 ). Cole et al (2019) found that nylon fibres (10x30 µm) can affect prey selectivity in C. finmarchicus and that both nylon fibres and granules (10-30 µm) caused earlier moulting (50,000 MPs L -1 ).…”

Nanoplastics in Aquatic Environments: Impacts on Aquatic Species and Interactions with Environmental Factors and Pollutants

“…Food availability has no impact on MP ingestion in daphnids [139] Food availability PE-MP (20 µm) Food availability does not affect food ingestion in copepods [140] * Surface group functionalization is represented by COOH, NH 2 , or HSO 3 . # The nominal value from a commercial source, or the value measured using electron microscopy or dynamic zeta potential (hydrodynamic diameter).…”

“…MPs exhibited a strong detrimental influence on algae intake (particularly secondary PE-MPs), reducing the growth rate and producing other negative consequences on reproduction, regardless of algal abundance [139]. Another study investigated the effect of PE-MPs (20 µm) on arctic copepods, including Calanus finmarchicus, C. glacialis, and C. hyperboreus [140], as a factor of food availability. The study used various combinations of MPs and diets and found no effect on food availability, as PE-MP intake increased with increasing concentrations of MPs, independent of food content.…”