A no swim advisory has been issued for this Sarasota beach

A no swim advisory has been issued for Longboat Key Beach, according to Sarasota County.

Sarasota County health officials issued the advisory after high levels of enterococcus bacteria were found during a water quality test on Tuesday.

Enterococcus bacteria can come from a variety of sources, including pet waste, livestock, birds, wildlife, human sewage and sewage spills.

No sewage spills have been reported within a mile of the beach in the past two weeks, and health officials say the high bacteria levels are likely due to natural sources. A rapid response team observed decaying algae and dead and decaying fish associated with red tide among the rocks and along the shoreline at the beach. Runoff caused by recent rainfall may also be a contributing factor.

The beach will remain open, but wading, swimming and water recreation are not advised.

“When these bacteria are found at high levels in recreational waters, there is a risk that some people may become ill. ... Those who are very young, elderly or who have a weak immune system who swallow water while swimming can get stomach or intestinal illnesses. If water comes in contact with a cut or sore, people can get infections or rashes,” Sarasota environmental administrator Tom Higginbotham said.

Bacteria levels were within acceptable limits at all other test sites. The next round of testing is scheduled for Friday.