Effects of Microplastic Contamination on the Aquatic Plant Lemna minuta (Least Duckweed)

Abstract

Microplastics are widely spread in aquatic environments. Although they are considered among the most alarming contaminants, toxic effects on organisms are unclear, particularly on freshwater plants. In this study, the duckweed Lemna minuta was grown on different concentrations (50, 100 mg/L) of poly(styrene-co-methyl methacrylate) microplastics (MP) and exposure times (T0, T7, T14, T28 days). The phytotoxic effects of MP were investigated by analyzing several plant morphological and biochemical parameters (frond and root size, plant growth, chlorophyll, and malondialdehyde content). Observations by scanning electron microscope revealed MP adsorption on plant surfaces. Exposition to MP adversely affected plant growth and chlorophyll content with respect to both MP concentrations and exposure times. Conversely, malondialdehyde measurements did not indicate an alteration of oxidative lipid damage in plant tissue. The presence of MP induced root elongation when compared to the control plants. The effects of MP on L. minuta plants were more evident at T28. These results contribute to a better understanding of MP’s impact on aquatic plants and highlight that MP contamination manifests with chronic-type effects, which are thus detectable at longer exposure times of 7 days than those traditionally used in phytotoxicology tests on duckweeds.

Dye-Doped Polymeric Microplastics: Light Tools for Bioimaging in Test Organisms

“…Organisms for bioimaging tests were chosen from those used as model organisms in studies on the trophic transfer of MPs from producers (plants) to primary consumers (herbivores): the aquatic plant Lemna minuta and aquatic larvae of the insect Cataclysta lemnata [ 38 , 39 ]. These organisms were exposed to tap water contaminated with RITC-MPs (100 mL of suspension of RITC-MPs 100 mg/L), in the same conditions discussed in our previous works (28 days for L. minuta and 21 days for C. lemnata , grown in the presence of L. minuta fronds contaminated with RITC-MPs) [ 38 , 39 ]. After these exposures, specimens of the two organisms were observed under a macroscope (Axiozoom v16, Zeiss) equipped with a HXP 200C metal halide lamp, PlanNeoFluor Z 1x objective, and a color photocamera (Axiocam 503, Zeiss).…”

Emerging contaminants: A One Health perspective

“… 400 Microplastics can also negatively affect the physiology of aquatic plants, affecting processes such as photosynthesis and nutrient uptake. 401 , 402 This can lead to reduced growth rates, altered reproductive patterns, and diminished aquatic plant health. 401 , 402 Moreover, microplastics are often mistaken for food by aquatic organisms, leading to ingestion at various trophic levels.…”

“… 401 , 402 This can lead to reduced growth rates, altered reproductive patterns, and diminished aquatic plant health. 401 , 402 Moreover, microplastics are often mistaken for food by aquatic organisms, leading to ingestion at various trophic levels. 403 This ingestion can cause physical harm, including internal injuries, blockages, and interference with digestive processes.…”

Duckweed: Research Meets Applications

“…Two studies aimed to fill this knowledge gap: Rozman and Kalčíková [ 48 ] tested if duckweeds could be used in monitoring microplastic contamination of freshwaters by adsorbing these particles on their surface. Ceschin et al [ 49 ] focused on the morphological and biochemical responses of these plants to microplastics, comparing acute effects to the chronic ones over an extended exposure period. Two further studies addressed methodological aspects of working with duckweeds: Oláh et al [ 50 ] reviewed the vast diversity of various chlorophyll fluorescence-derived phytotoxicity endpoints that were reported in the literature on the application of the chlorophyll fluorescence imaging method on duckweeds and compared the responsivity of some widely used parameters to different toxicants.…”