Preliminary indoor evidences of microplastic effects on freshwater benthic macroinvertebrates

Abstract

Plastics are to date considered one of the main detrimental drivers for the health of aquatic ecosystems, both in marine and inland waters. Regarding the latter habitat, it seems surprising how the plastic effects on benthic invertebrates are neglected since macroinvertebrates have a long tradition in the water quality assessment activities. In this context, we propose timely indoor observations on the exposure of caddisfly Odontocerum albicorne and mayfly Ephemera danica to various microplastic polymers (ABS, PET, PP, PS, PVDF). Three different experimental designs were performed on caddisflies and mayflies by exposing their larvae to natural and microplastic substrates. Our findings highlighted how microplastics affected both caddisflies in rebuilding its own case (after having removed the natural one) and mayflies burrowing. Particularly, all caddisflies rebuilt cases using the microplastic polymers provided instead of natural items only. Moreover, we provide the first evidence that mayflies burrow mainly in microplastic substrates rather than in natural ones. Our research highlights that macroinvertebrate larvae would use naturally occurring microplastics and this could be of particular concern in freshwaters with high contamination by plastics. Indeed, larvae appear to not necessarily perceive microplastics as a direct stressor. Further studies ought to be conducted to understand the chronic perturbation on larvae fitness and for example, on drift behaviour. Also, further investigations are needed to understand the potentialities of using plastics by benthic macroinvertebrates.

Field evidence for microplastic interactions in marine benthic invertebrates

“…Ingestion can take place directly, accidentally assimilating throughout filter-feeding or deposit-feeding or confusing for food, indirectly, by ingesting prey of lower trophic levels which contain microplastics 17 . This event can bring to different biological and ecological effect, as internal physical and chemical damage, trophic transfer and biomagnification, absorption to microplastics surfaces of other contaminants such as heavy metal, antibiotics, polycyclic aromatic hydrocarbons and polychlorinated bisphenols, transport of pathogens and alien species that colonize microplastic surface 18 .…”

First record of mayfly Povilla (Languidipes) taprobanes Hubbard from Karnataka

“…It is presumed that the damage could have been caused due to larvae burrowing in the fold, and chewing or clawing through the plastic lining to build earthen cases. It is also possible that the larvae used the folds as an 'enemy free space' to hide from their natural predators in the aquatic habitat (Gallitelli et al, 2021). The loss appears to be though less, considering that large number of farmers following this system of water conservation, where plastic sheets are laid on the dug pits of different sizes and water is stored the damage can be critical.…”

Lethal and Sublethal Responses of Hydropsyche pellucidula (Insecta, Trichoptera) to Commercial Polypropylene Microplastics after Different Preconditioning Treatments

“…Based on such an assumption, significant negative effects on organisms occur only when the microplastics dose with which organisms are challenged exceeds organism-specific toxicological thresholds [ 76 ]. Furthermore, a recent study highlighted how caddisflies and mayflies seem to use mainly microplastics over natural construction materials or substrates [ 78 ], threatening caddisflies by destabilizing their cases [ 79 ].…”