BEACHGOERS were back in the water yesterday afternoon, the day after a tourist was flown to hospital for an irukandji sting and more jellyfish were netted at Trinity Beach.

A 40-year-old man was treated at Cairns Base Hospital after being stung on the lip by an irukandji jellyfish while snorkelling at Green Island on Thursday, and hours later researchers caught more than a dozen irukandjis near Trinity Beach's stinger net.

Jellyfish expert Lisa-ann Gershwin said most had been juveniles.

Surf lifesavers still closed swimming enclosures from Trinity to Ellis Beach at 1.30pm, and only reopened them after drag-netting yesterday afternoon.

Green Island's beaches remained closed after six irukandji nettings yesterday afternoon.

Lifesaving Services North Queensland co-ordinator Ebeny Keating said the tourist who was stung on the island spent a night in hospital as a precautionary measure but was discharged yesterday morning.

New research into irukandji jellyfish venom and how to best treat patients stepped up this week as two separate teams made Cairns their base for specimen netting.

James Cook University stinger expert Jamie Seymour said research was indicating the venom’s effect varied depending on the age of an irukandji and its location in the Far North.

"The effect is worse in the older animals but the venom also changes depending on whether an animal is caught at Lizard Island, Cairns or Townsville," Dr Seymour said.

"And that has consequences on treatments."

The Australian Venom Research Unit’s researcher in Melbourne, Ran Li, is collecting specimens with Dr Gershwin to study the effectiveness of different drugs in treating stings from Far North Queensland and West Australian jellyfish.

Mr Li said animal tissue would be used to test the effect of stings and effectiveness of particular drugs including those used to combat high blood pressure.