• Toxicity tests;
  • Spiked exposures;
  • Oil spill dispersants;
  • Early life stages


Spiked exposure, continuous flow toxicity tests using the oil dispersant Corexit 9527® were performed during the early life stages of four California marine species. Test chambers containing sensitive life stages of the giant kelp (Macrocystis pyrifera), the red abalone (Haliotis rufescens), a kelp forest mysid (Holmesimysis costata), and the topsmelt (Atherinops affinis) were inoculated with concentrated dispersant, then allowed to flush with clean, filtered seawater Spectrophotometric monitoring of tests showed dispersant levels diminishing to below detection limits within 5 to 6 h or less Results showed Hahotis to be the most sensitive species tested, with Atherinops being least sensitive in terms of no-observed effect concentration (NOEC) and Holmesimysis being least sensitive in terms of median effect concentration, Macrocystis was intermediate in both measures. When spiked exposure toxicity results were compared to those of previously reported constant-exposure tests, no consistent conversion factor that might relate spiked- and constant-exposure toxicity data was found.