LAUSR

Stormwater runoff from roadways is a global threat to water quality, aquatic organisms, and ecosystems. Tire tread wear particles (TWP) from roadway runoff may lead to urban runoff mortality syndrome (URMS) in some aquatic organisms. We tested the hypothesis that urban runoff from roadways can kill zooplankton. Both roadway runoff and TWP leachate were acutely lethal to a model species, the water flea Daphnia pulex. Life table experiments further revealed the lowered survival rates, intrinsic rate of increase, average life span, and net productive rate of D. pulex when exposed to roadway runoff and TWP leachate. The tire rubber antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) mainly contributed to the TWP toxicity. The toxicity of TWP and 6PPD extracted varied with time in nature. Cladocerans and rotifers were more sensitive to TWP and 6PPD than copepods. These results demonstrate the presence of URMS in zooplankton, which may cascade through food webs and affect aquatic ecosystems.