Florida wildlife officials announced Wednesday they are temporarily closing all state waters along Pasco County south of the Hernando county line to recreational scallop harvesting after water quality tests found unsafe toxins produced by harmful algal blooms.

Officials said they detected potentially harmful levels of an algal bloom called Pyrodinium bahamense and the toxins it creates. The so-called saxitoxin can build up in shellfish and lead to human illness if a contaminated scallop is consumed, according to the Florida Fish and Wildlife Conservation Commission.

The closed waters, which include north of the Anclote Key Lighthouse in northern Pinellas County, won’t reopen until water tests return to safe levels established by the National Shellfish Sanitation Program, according to FWC.