Short-term and full life cycle toxicity tests have been conducted with Ampelisca abdita as part of the joint COE-EPA field Verification Program (FVP). These studies comprised a portion of the effects assessment component of a risk analysis describing the hazards associated with aquatic disposal of dredged materials from Black Rock Harbor (BRH), Connecticut. The specific objective of these toxicity tests was to document the sensitivity of Ampelisca's chronic endpoints to a range of contaminated suspended particulate concentrations. In long-term exposures of 56 days, amphipod growth and intrinsic rate of population growth, r, were impaired at all BRH sediment exposures. In all cases, the reduction in population growth rate was a function of slower growth of females, causing a longer time to maturity, which was coupled with a reduced egg production at maturity because the females were smaller.