Macroinvertebrate responses to nickel in multisystem exposures.

Metals introduced to sediments undergo a variety of complexation and partitioning changes that affect metal bioavailability. Using simultaneously extracted metal (SEM)/acid volatile sulfide (AVS) and organic carbon (f(OC)) models, the authors examined nickel (Ni) toxicity and bioavailability in 2 field studies (using streamside mesocosm and in situ colonization) and 1 laboratory study. The streamside mesocosm experiments indicated that benthic communities (Ephemeroptera, abundance, and taxa richness) responded negatively to increasing SEM(Ni) /AVS and (SEM(Ni) -AVS)/f(OC) models.