Plastic Pollution in Aquatic Environments: Connecting Water and Wastewater, Hydrology, Groundwater and Its Impacts on Sustainable Aquaculture and Fisheries

Plastic pollution is commonly investigated within separate compartments, although particles and plastic-associated materials move through wastewater infrastructure, stormwater networks, rivers, sediments, aquifers, aquaculture facilities and fishing grounds. This disciplinary separation impedes source attribution, comparison of exposure estimates and evaluation of controls. This critical narrative review integrates evidence published from 2008 to 31 August 2026, drawing on verified experimental, observational, modelling and synthesis studies. It examines how material properties, hydrological connectivity and treatment processes jointly shape plastic transport, retention and biological exposure, with particular attention to sustainable aquaculture and fisheries. Conventional wastewater treatment captures substantial fractions of the particles measured in plant influent, but retained material is frequently transferred to sludge, and residual discharge remains relevant where effluent volumes are large. River emissions are strongly influenced by episodic runoff, floodplain retention and remobilisation; consequently, instantaneous concentrations poorly approximate catchment-scale delivery. Groundwater contamination is documented in karst, shallow and other vulnerable aquifers, yet filtration, preferential flow, sampling artefacts and limited temporal coverage restrict the estimation of subsurface fluxes. Aquaculture systems receive plastics through source water, equipment, feed and atmospheric inputs, while fishing activity generates additional macroplastic hazards through lost gear. Laboratory studies demonstrate organism-level responses under some exposure conditions, including oxidative stress and reproductive effects, but these findings cannot automatically be translated into population-level losses or human health risks. A source-to-receptor framework is proposed that separates particle abundance from mass flux, identifies changes in particle characteristics across compartments, and links biological evidence to environmentally plausible exposure. Priorities include harmonised size-resolved measurements, paired surface-water–groundwater monitoring, event-based mass balances, realistic chronic exposure designs and intervention evaluation across the entire material lifecycle. Sustainable management requires upstream plastic prevention alongside independently assessed treatment and gear-retention measures, rather than reliance on end-of-pipe removal alone.