Microplastic Toxicity and Trophic Transfer in Freshwater Organisms: Ecotoxicological and Genotoxic Assessment in Spirodela polyrhiza (L.) Schleid. and Echinogammarus veneris (Heller, 1865) Treated with Polyethylene Microparticles

Abstract

The widespread occurrence of microplastics (MPs) has resulted in their interaction with biological processes. Thus, there is a great concern about the potential toxicity of MPs on animal and plant cells and on the possibility that MPs reach humans through the food web. In order to shed light on both issues, laboratory assays were performed for evaluating the effects of polyethylene (PE) microparticles on the aquatic plant Spirodela polyrhiza (L.) Schleid. and the gammarid Echinogammarus veneris (Heller, 1865). Moreover, a stock of MP-treated Spirodela plants was used to feed gammarid individuals, and the presence of MP particles in their digestive tracts was analyzed. Results evidenced the lack of toxic effects of MPs on plants, evaluated at growth and physiological level by biometric parameters, pigment content, and photosynthetic performance estimated by chlorophyll fluorescence imaging through the ETPT (EcoTox Photosystem Tool). Only a slight reduction in pigment-related indices in MP-treated plants was observed. A remarkable genotoxic effect was instead highlighted by Comet assay in the hemocytes of gammarid individuals exposed to MPs, with three times more DNA damage (expressed as Tail Moment) in MP-treated individuals compared to control ones. Finally, the gut content of the gammarids fed with MP-treated plants revealed the presence of 7.6 MP particles/individual, highlighting the occurrence of trophic transfer of MPs among freshwater ecosystem organisms. Novel indications about the potential impact of the PE microparticles in the aquatic compartment are provided. Notably, the transfer of MP particles between primary producer and primary consumer organisms of the freshwater trophic chain and the genotoxic effects associated with the ingestion of such particles by gammarids are issues of concern for the aquatic ecosystem and the food web leading to the human diet.

Uncovering the Hidden Dangers of Microplastic Pollution in Lake Ecosystems: Effects of Ingestion on Talitrid Amphipods

“…Furthermore, Hyalella azteca individuals were found to ingest MPs during 10-day exposures to PE particles (10-27 µm in diameter) and PP fibres (20 µm-75 µm in length and 20 µm in diameter). Recent research by Iannilli et al [8] demonstrated the ingestion of MPs by Echinogammarus veneris in laboratory conditions when the organisms were exposed to Spirodela polyrhiza plants contaminated with PE microparticles measuring approximately 50 µm.…”

“…MPs may contain toxic compounds that can disrupt the amphipods' endocrine system [50], affecting hormone production and altering energy metabolism, leading to a reduction in energy reserves. Additionally, the presence of MPs in the gastrointestinal tract can cause physical and physiological stress, resulting in irritation, inflammation [8], and the need for increased energy expenditure to repair damaged tissues. Environmental stress caused by the presence of MPs can have a significant impact on an organism's energy balance, as it requires additional energy to recover and maintain homeostasis.…”

“…for food and ingest them [4][5][6][7]. Such ingestion can have detrimental effects on individual organisms and can enter the food chain, impacting entire associated food webs [8].…”

Small Microplastics: A yet Unknown Threat in the Svalbard (Norway) Region

“…This characteristic, and their trophic role (primary consumers, detritivores, and polyphages) in aquatic environments, make them particularly suitable as bioindicators in toxicity tests [55]. MPs ingestion was documented in several marine species [56][57][58], and studies tested the MPs toxicity and genotoxicity on them at a lab scale [59][60][61][62].…”

Preliminary Report of Microplastic (MPs) Presence on East Java Freshwater Sponges at Brantas Porong River

“…These organisms ingest this microplastic debris while ingesting their food as well [18]. There have been many studies on the ingestion of microplastics by freshwater organisms, both vertebrates and invertebrates, with fish being the most studied group of aquatic organisms [19] and followed by other freshwater organisms, such as zooplankton (Daphnia magna) [20], arthropods (Chironomus riparius), gastropods (Physella acuta), annelids (Lumbricus variegatus) [21], crustaceans (Echinogammarus veneris) [22], diatoms (Cyclotella meneghiniana) [23], etc. However, sponges (Porifera) themselves are still very poorly studied in microplastic research [24], especially in Indonesia.…”