The New Jersey Department of Environmental Protection has sent out a warning to swimmers in Monmouth and Ocean Counties after clinging jellyfish have begun to populate in the Metedeconk, Shrewsbury and Manasquan rivers.

These stinging jellyfish are very small and hard to spot in the water but a sting can put you in a lot of pain and bring on other possible symptoms that could lead to hospitalization in some cases.

Montclair researchers this week confirmed the presence of about 15 clinging jellyfish of varying sizes off a private dock in the Metedeconk.

Genetic testing is being conducted for final verification.

DEP officials add that this type of jellyfish is not known to live in the ocean beaches or other sandy areas but typically will cling to "submerged aquatic vegetation and algae in back bays and estuaries, areas not heavily used for swimming."

They encourage you to use common sense and caution during recreation in areas where these jellyfish are suspected.

The clinging jellyfish was first confirmed in New Jersey in 2016 in the Manasquan River at the Point Pleasant Canal.

The DEP has been working with Montclair University in studying the possible distribution of clinging jellyfish in New Jersey.

Previous surveys in 2016 and 2017 found a single clinging jellyfish from the Manasquan River and did not detect the jellyfish outside isolated populations in the Shrewsbury River.

Here is what the NJ DEP says to do if you're stung by a clinging jellyfish:

  • Apply white vinegar to the affected area to immobilize any remaining stinging cells.
  • Rinse the area with salt water and remove any remaining tentacle materials using gloves or a thick towel.
  • A hot compress or cold pack can then be applied to alleviate pain.
  • If symptoms persist or pain increases instead of subsiding, seek prompt medical attention.

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