Use of the Zebra Mussel Dreissena polymorpha (Mollusca, Bivalvia) as a Bioindicator of Microplastics Pollution in Freshwater Ecosystems: A Case Study from Lake Iseo (North Italy)

Paolo Pastorino,Serena Anselmi,Elisabetta Pizzul,Vasco Menconi,Monia Renzi,Marco Bertoli,Alessandro Dondo,Marino Prearo

doi:10.3390/w13040434

Abstract

The monitoring of microplastics pollution in freshwater environments trails behind its practice in marine ecosystems. We evaluated the use of the invasive zebra mussel (Dreissena polymorpha) as a potential bioindicator of microplastic litter in freshwater lakes. Samples were collected from three sites (Lovere, Costa Volpino, Castro) at the northern end of Lake Iseo (one of the major subalpine lakes in north Italy) and compared for water physicochemical parameters, biometrical features of zebra mussels, and microplastics items/specimens (color, shape, size, and chemical composition). We hypothesized that since a wastewater treatment plant (WWTP) on the Oglio River discharges into this area of the lake, the microplastics in D.polymorpha could be measured and compared in samples from the three sites at different distances from the WWTP. There was no difference in the physicochemical water parameters and biometric features between the samples from the three sites, whereas there was a significant difference in items/specimen between the sites in decreasing order (mean ± standard deviation): Costa Volpino (0.23 ± 0.43) > Lovere (0.07 ± 0.25) > Castro (0.03 ± 0.18). The chi-square test showed a significant difference in shape, color, and chemical composition frequency in the samples from the three sites. The chemical composition of the microplastics was polyethylene terephthalate (45%), nylon (20%), polypropylene (20%), polyamide resin (10%), and polyvinyl chloride (5%). Our data show that the amount of microplastics the zebra mussel accumulated was greater the closer the sampling site to the WWTP. Our findings suggest that the zebra mussel may provide a useful tool to monitor microplastics pollution in lakes.

Highlights

Microplastics of secondary origin derive from plastics of larger dimension dispersed in the environment and their subsequent fragmentation by atmospheric agents, mechanical erosion, UV radiation, or biological degradation [3]
Attention was largely focused on the possible physical effects of macroplastics (>5 mm), for example, obstruction of the respiratory or the digestive tract of aquatic fauna [5], while research into the possible environmental effects of microplastics is fairly recent by comparison [6]
The chemical composition was in line with the findings reported by Sighicelli et al [23] in which polyethylene terephthalate (PET) and PP

Summary

Introduction

Environment microplastics pollution is ubiquitous in water, soil, and organisms [1]. Microplastics of secondary origin derive from plastics of larger dimension (macroplastics) dispersed in the environment and their subsequent fragmentation by atmospheric agents, mechanical erosion, UV radiation, or biological degradation [3]. Environmental plastics pollution of marine ecosystems has been documented since the 1970s [4]. Even in countries with advanced environmental protection technologies, microplastics concentrations were found to be similar for freshwater and marine environments [7]. Monitoring the effects of microplastics pollution differs from macroplastics because of accumulation phenomena by which they can be more transmitted through the trophic chain, both directly and indirectly [8]. Other negative effects may depend on numerous variables, such as chemical composition and particle size, characteristics that become relevant for other undesirable properties such as the absorption potential of other pollutants (i.e., persistent organic contaminants) [9]

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Results

Conclusion