State and Suffolk County officials have warned residents not to swim or wade in Roth Pond in Stony Brook because of an outbreak of blue-green algae.

Children and pets should be kept away from the pond, the Suffolk County Health Department said in a statement released late Monday. The advisory remained in effect on Tuesday, spokeswoman Grace Kelly-McGovern said.

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The state Department of Environmental Conservation issued the advisory after samples collected by Stony Brook State University researchers found cyanobacteria blooms, also known as blue–green algae.

Contact with the algae, which appears as floating scum on the surface of the water, may cause nausea, vomiting or diarrhea; skin, eye or throat irritation; or allergic reactions or breathing difficulties, county health officials said.