In this study, the effects of silver nanocolloids (SNCs) on the early life stages of the reef-building coral Acropora japonica were investigated. The tolerance of this species to SNC contamination was estimated by exposing gametes, larvae, and primary polyps to a range of SNC concentrations (0, 0.5, 5, 50, and 500 mu g l(-1)). Pure SNCs were immediately ionized to Ag+ in seawater and concentrations of >= 50 mu g l(-1) SNC had a significant detrimental effect on fertilization, larval metamorphosis, and primary polyp growth. Exposure to 50 mu g l(-1) SNC did not significantly affect larval survival; however, the larvae were deformed and lost their ability to metamorphose. At the highest concentration (500 mu g l(-1) SNC), all gametes, larvae, and primary polyps died. These experiments provide the first data on the effects of silver-nanomaterial-contaminated seawater on cnidarians, and suggest that silver nanomaterials can influence the early development of corals through anthropogenic waste-water inputs. (C) 2014 Elsevier Ltd. All rights reserved.