Photo credit: Dr. Vera Trainer and Brian Bill, NOAA
Dinophysis acuminata are smaller sized (38-50µm long and 30-35 µm wide) armored dinoflagellates. The top of the cell (epitheca) is low and either flat or weakly convex while the bottom (hypotheca) is rounded and sometimes has small protuberances (bumbs) along the bottom edge. The side wing (left sulcal list) of the cell is supported by three ribs and extends down slightly over half of the cell length. Their chloroplasts are reddish-brown in color.
Their distribution is neritic in cold to warm temperate waters worldwide and are often present in late spring to summer. They produce dinophysis toxins and okadaic acid causing Diarrhetic Shellfish Poisoning in humans.
For more information see:
A Taxonomic Guide to Some Common Marine Phytoplankton, by Rita Horner (Biopress Ltd. 2002)
SoundToxins, a diverse partnership of Washington state shellfish and finfish growers, environmental learning centers, Native American tribes, and Puget Sound volunteers, is a monitoring program designed to provide early warning of harmful algal bloom events in order to minimize both human health risks and economic losses to Puget Sound fisheries.