Bioturbation and the resuspension of plastic pollutants by spawning common carp degrades lake water quality

Here, findings from a before-after-control-impact (BACI) field experiment are presented that tested the hypothesis that bioturbation (i.e., sediment disturbance through animal activities) from an invasive population of common carp (Cyprinus carpio) degrades water quality by resuspending microplastics and microfibers in lake surface waters during the spawning season. Concentrations of total suspended solids (TSS), microplastics (MP/L), and microfibers (MF/L) were compared before, during, and after a carp spawning event to assess the magnitude and duration of disturbance effects. Concentrations of total suspended solids, microplastics, and microfibers were all similar across sampling sites prior to spawning. As spawning commenced, carp bioturbation increased concentrations of TSS, microplastics, and microfibers by 2-3 times relative to control sites. After spawning ended, TSS and microplastic fragments each returned to ambient concentrations whereas microfiber concentrations remained higher than control sites for multiple weeks. Findings from this study expand the harmful environmental effects of invasive carp to the resuspension of microplastic pollutants and the degradation of lake water quality. Given the widespread distribution of common carp and their propensity for disturbing habitats and eroding water quality, the phenomena described in this study likely extends to many other lakes, floodplain and backwater habitats, ponds, and rivers polluted with plastics and other contaminants.