Natural infochemical DMSP stimulates the transfer of microplastics from freshwater zooplankton to fish: An olfactory trap

Natural infochemicals may largely affect the trophic transfer of microplastics (MPs) in ecosystems but such infochemical effect and mechanisms are poorly understood. Here, a daphnids-zebrafish freshwater microcosm was designed to elucidate whether and how an algae-derived infochemical, dimethylsulfoniopropionate (DMSP), affects the ingestion and transfer of MPs. Daphnids fast accumulated DMSP and MPs from water, DMSP in daphnids was mainly enriched from the DMSP in water but not from MPs. DMSP did not change the MP ingestion by daphnids. A low concentration of DMSP (<5 nM) increased predation of daphnids by zebrafish, while a high concentration of DMSP (>50 nM) did not increase predation rates. The MP predation by zebrafish in the 0.5 and 5 nM DMSP treatments were 2.06 and 1.69 times that of the control, respectively. This suggest the DMSP at environmentally relevant concentrations may promote the trophic transfer of MPs in freshwater ecosystem via olfactory traps.