The clams and steamers served up as a summertime staple will not come from South Shore shellfish beds until further notice, the Patriot Ledger reported. A red tide bloom closed all the shellfish beds from Boston to Plymouth effective on Thursday afternoon, according to the state Division of Marine Fisheries.The state announced Thursday that shellfish from beds in Hull, Cohasset, Scituate, Marshfield, Duxbury and Plymouth tested positive for paralytic shellfish poison toxin, also known as red tide. Officials monitor the harmful algal blooms closely because it can be fatal if ingested through shellfish.Harvesting soft-shell clams, surf clams, mussels and carnivorous snails from beds in those communities is prohibited until further notice. Sea scallops are still safe to harvest and eat, according to the state.