LYNN – The state ban on harvesting blue mussels and soft-shell and razor clams in several lower North Shore communities was lifted today, although restrictions on taking other species remain effective.Paul J. Diodati, director of the state Division of Marine Fisheries and Wildlife, last week notified local authorities or the shellfish wardens in Lynn, Nahant, Saugus, Swampscott, Revere, Boston, Danvers, Manchester-by-the-Sea, Beverly, Salem, Marblehead, Winthrop and Hull of the amended regulations.According to Diodati, state officials determined that soft-shell clams (Mya arenaria), razor clams (Ensis directus), and blue mussels (Mytilus edulis), no longer contain in excess of established standards the biotoxins known as Paralytic Shellfish Poison or (PSP), as contained in the phytoplankton Alexandrium.”These areas remain closed to the harvesting of all other shellfish and carnivorous snails, with the exception of the adductor of the sea scallop,” he said.Starting at sunrise today, the PSP-related closures of May 21-22 are amended, he said.The shellfish area at Devereaux Beach in Marblehead is classified as conditionally approved. The Pines River flats in Revere are classified as conditionally restricted and may be opened to harvesting of the soft-shell and razor clams as well as blue mussels, depending on the area management plan.Harvesting clams in the Pines River flats is also subject to the Shellfish Purification Plant digging schedule, said Diodati, explaining that only soft-shell clams may be harvested from this area at this time.The harvesting area under scrutiny includes “the waters, flats and all tributaries of those areas from the Gloucester/Manchester-by-the-Sea municipal line to the southern tip of Deer Island; to the eastern tips of Great Brewster and Little Brewster Islands; to Allerton Point; to the Hull/Cohasset municipal line and out to the state territorial waters line.”