Rapid, detrimental response of estuarine benthic macrofauna communities to pollution by littered cigarette filters and e-liquid

Cigarette butts are amongst the most littered single-use plastics on coasts, yet their impacts on marine ecosystems, especially on a community level, are not well understood. Recently, e-cigarettes have become popular and are a novel litter item in marine habitats. Preliminary research indicates that e-liquid can harm individual organisms, but few studies have been done and none on a community level. In a mesocosm experiment, we tested the impacts of cigarette butts (0.25, 1 butt L⁻¹) or e-liquid (1 mL L⁻¹) on infaunal invertebrate communities using intact sediment cores. After two weeks, the abundance of polychaetes, bivalves, and gastropods was significantly reduced in mesocosms with 1 cigarette butt L⁻¹ compared with controls. Exposure to e-liquid resulted in severe oxygen depletion (<1 mg L⁻¹) and almost complete mortality of sediment infauna after just four days. As litter, cigarette butts and disposable e-cigarettes both pose a threat to estuarine biodiversity.