Ingestion of bivalve droppings by benthic invertebrates may lead to the transfer of nanomaterials in the aquatic food chain

Abstract

Background Manufactured nanomaterials (MNMs) are released into the environment in increasing quantities. Consequently, MNMs also reach the aquatic environment, where they can interact with different organisms. Previous studies have already shown that filter-feeding bivalves can ingest nanomaterials from the surrounding water leading to higher concentration of the material. Furthermore, they have been shown to be vectors for environmental chemicals and pathogens to other organisms, as their feces/pseudofeces (F/pF) play a crucial role as a food source for other species. We exposed bivalves (Corbicula sp.) to MNMs and performed experiments to investigate the possible transport of MNMs by their feces to the benthic amphipod Hyalella azteca. Silver (Ag) and gold (Au) nanoparticles (NPs) as well as fluorescent polystyrene nanoparticles were used in this study. They allowed the investigation of the metal content of the bivalves’ feces and the amphipods feeding on it, as well as the localization of the fluorescent particles in the body of the animals. Results Examination of the feces by fluorescence microscope and determination of the total metal content by inductively coupled plasma mass spectrometry (ICP-MS) showed a high accumulation of the exposed MNMs in the F/pF. The examination of fecal matter, using transmission electron microscopy confirmed the nanoparticulate character of the metals in the examined fecal matter. After exposure of amphipods to the MNMs containing fecal matter, the fluorescent MNMs were localized in the animals gut. The chronic exposure of juvenile amphipods over 21 days to feces enriched with Au MNMs caused significant effects on the growth of the amphipods. The transfer of both metals (Ag and Au) from the fecal matter to the amphipods was confirmed after total metal measurements. Conclusion Probably, for the first time, it has been shown that when exposed to MNMs bivalves can transfer these particles to other benthic species. Transfer is via released F/pF upon which the benthic species feed and thus could ingest the particles. The high concentrations of MNMs in the fecal matter raises concerns about the potential accumulation and transfer of the materials and associated ecotoxicological effects in invertebrates such as benthic amphipods.

Invertebrate Species for the Bioavailability and Accumulation Assessment of Manufactured Polymer‐Based Nano‐ and Microplastics

“…The strong accumulation of ingested nano‐polystyrene in the feces confirms the observations recently described by Kuehr, Diehle, et al (2021) for the same nano‐polystyrene. The fact that only viscera showed a strong decrease in measurable polystyrene concentrations during the respective depuration phases underlines the idea that the decrease of body burden/loss of previously ingested material in the viscera seems to be caused by the release of F/pF with high polystyrene burdens.…”

“…The stock suspensions were handled as described by Kuehr, Diehle, et al (2021), including sonication for 1 min using an ultrasonic homogenizer (Bandelin Sonoplus HD2200 ultrasonic homogenizer, 200 W, Bandelin Cup Horn BB6).…”

Are Fragrance Encapsulates Taken Up by Aquatic and Terrestrial Invertebrate Species?

“…A subset of dissected tissue samples obtained from the exposure study with freshwater bivalves was further digested using Proteinase K to extract the test item with fluorophores. The fluorescence measurements were carried out using a microplate reader (Synergy H1; Biotek) as described by Kuehr et al (2021). The digestion method was carried out as described by Kuehr, Meisterjahn, et al (2020).…”

“…To avoid copper contamination, plastic water pipes were used in the test facilities. Further characteristics of the water used can be found in Sebastian Kuehr, Diehle, et al (2021) where the same water was used at the same time as the aquatic studies of this work.…”

“…During the chronic exposure of C. fluminea to 5 mg AuNPs/L by Kuehr, Diehle, et al (2021) an increased mortality was observed which was explained by the high energy demand required for the increased filtration activity and the loss of nutrients and energy by the continuous excretion of pseudo-feces.…”