The Behavior of Planktonic Copepods Minimizes the Entry of Microplastics in Marine Food Webs

Abstract

The entry of microplastics (MPs) into marine food webs is a major environmental concern. We investigated how the behavior of planktonic copepods influences the risk of MPs to enter marine food webs by applying a trait-based approach and by combining experiments (bottle incubations and video observations) with biogeographical analyses. We aimed to evaluate which type of feeding behavior is most risky in terms of MP ingestion and which marine geographical areas are more susceptible to MP ingestion by planktonic copepods. We used different species as models of the main foraging behaviors in planktonic copepods: feeding-current, cruising, ambush, and mixed behavior feeding. All behaviors showed a similarly low risk of MP ingestion, up to 1 order of magnitude lower than for similar-sized microalgae. We did not observe any influence of the prey type or MP size (8 and 20 μm) on MP ingestion for any of the behaviors. By mapping the global distribution of feeding behaviors, we showed that feeding-current feeding is the most common behavior, but the risk of MP ingestion remains equally low across the global ocean, independently of the predominant behavior. Overall, our results suggest a low risk of MP ingestion by planktonic copepods and therefore a minimal risk of trophic transfer of MPs via marine pelagic copepods in marine ecosystems.

Is Zooplankton an Entry Point of Microplastics into the Marine Food Web?

“…In the case of ambush zooplankton (e.g., cyclopoid copepods Oithona sp. ), clearance rates on nonmotile prey or particles like MPs are very low, , reducing the risk of MPs ingestion. Besides copepods, chaetognaths were a dominant component of the zooplankton community at stations 13 and 14 (Figure A).…”

Tracking Nano- and Microplastics Accumulation and Egestion in a Marine Copepod by Novel Fluorescent AIEgens: Kinetic Modeling of the Rhythm Behavior

“…C. sinicus could distinguish NMPs from food by mechanical or chemical recognition and actively rejected the plastic microbeads, although they were similar in size and shape. ,,, NPs were consumed by C. sinicus despite of their small sizes, presumably because they were mistakenly ingested together with the microalgae by surface adhesion. − …”

Feeding Behavior Responses of the Small Copepod, Paracalanus parvus, to Toxic Algae at Different Concentrations

“…Kiørboe et al classified the feeding behaviors of copepods into three categories, namely, ambush, cruising, and feeding-current types, and provided a theoretical framework for further elucidation of their feeding mechanisms [10,11]. The method used by Kiørboe et al has been applied for studying the escape velocity [12] and ingestion of microplastics by copepods [13,14]. Xu et al investigated the effects of toxic algae on copepods using a high-speed camera and directly observed the feeding behaviors of copepods.…”