This species of dinoflagellate is a rare visitor to the Rhode River area. The salinity of the mid-Chesapeake Bay is usually too low to support D. accuminata. It has been known to cause toxic shellfish poisoning. The cells average 48u in length and 16u wide with an average total volume of 3.2x103 cubic microns. During late winter and early spring of 2002,
D. accuminata grew to bloom proportions in the Potomac River causing oysters beds to be closed. A few wandering cells were found in main bay and near the mouth of the Rhode River.