Feeding type and development drive the ingestion of microplastics by freshwater invertebrates

Christian Scherer,Georg Reifferscheid,Nicole Brennholt,Martin Wagner

doi:10.1038/s41598-017-17191-7

Abstract

Microscopic plastic items (microplastics) are ubiquitously present in aquatic ecosystems. With decreasing size their availability and potential to accumulate throughout food webs increase. However, little is known on the uptake of microplastics by freshwater invertebrates. To address this, we exposed species with different feeding strategies to 1, 10 and 90 µm fluorescent polystyrene spheres (3–3 000 particles mL−1). Additionally, we investigated how developmental stages and a co-exposure to natural particles (e.g., food) modulate microplastic ingestion. All species ingested microplastics in a concentration-dependent manner with Daphnia magna consuming up to 6 180 particles h−1, followed by Chironomus riparius (226 particles h−1), Physella acuta (118 particles h−1), Gammarus pulex (10 particles h−1) and Lumbriculus variegatus (8 particles h−1). D. magna did not ingest 90 µm microplastics whereas the other species preferred larger microplastics over 1 µm in size. In C. riparius and D. magna, size preference depended on the life stage with larger specimens ingesting more and larger microplastics. The presence of natural particles generally reduced the microplastics uptake. Our results demonstrate that freshwater invertebrates have the capacity to ingest microplastics. However, the quantity of uptake depends on their feeding type and morphology as well as on the availability of microplastics.

Highlights

Since the 1950s plastic materials have basically permeated everyday life
To include more realistic parameters, we investigated the co-exposure to additional natural particles as well as different developmental stages of C. riparius and D. magna
To evaluate how the developmental stage affects the microplastics ingestion, we investigated the feeding on polystyrene spheres by different sizes and ages of the benthic feeder C. riparius and the pelagic feeder D. magna

Summary

Introduction

Since the 1950s plastic materials have basically permeated everyday life. Besides massive economic and social benefits of synthetic polymers, unsustainable resource management has resulted in plastic materials entering the environment. Focused on marine systems, an increasing number of recent studies demonstrate that freshwater compartments are contaminated to a comparable degree[4,5,6]. Owing to their small size, microplastics are potentially available for a broad range of aquatic species. Ecologists have frequently used polymer beads to investigate the feeding behavior of pelagic freshwater zooplankton In their attempt to categorize filtering capacities of different species and their ability to feed on bacteria and algae, they collected essential data for a better understanding of community assemblages in various habitats[10,11]. Documented adverse effects on freshwater organisms by microplastic exposure including the waterflea Daphnia magna[22,23,24], the amphipod Hyalella azteka[25] and the fish Danio rerio[26], whereas the freshwater snail Potamopyrgus antipodarum was not affected throughout their development[27]

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