An environmentalist who chained himself to a ship to protest against dredging in Gladstone Harbour says he does not regret his actions despite having to appear in court.

But Mark ‘‘Potts’’ Driscoll, 48, will have to keep any further protests within the confines of the law after he was issued with a $2000 good behaviour bond in the Brisbane Magistrates Court today.

Driscoll, a former real estate agent, was arrested on March 14 after he boarded and then chained himself to a dredging ship working to prepare Gladstone Harbour for the city’s liquefied natural gas (LNG) boom.

Dredging in the harbour, which is in the Great Barrier Reef World Heritage Area, has been criticised by several environmental groups after fish in Gladstone began developing red eyes and lesions.

His lawyer James Dillon told the court Driscoll had planned to unchain himself after he had unfurled a protest banner and made his point.

However, he had dropped his bag, with his keys inside, into the water while boarding the vessel, Mr Dillon said.

Driscoll told reporters outside court he knew after he lost the keys there was no turning back.

He said despite water police having to hacksaw the chain away from him and needing firefighters to break open the lock around his neck, he did not regret the protest.

"When I walked out of court, the people who had been in the courtroom came over and said, ’Thank you for doing what you did'," he said.

"It’s our Great Barrier Reef.

"It's of global significance and that's why it has world heritage (status)."

Driscoll said he would not stop protesting, but the good behaviour bond meant he would have to "modify" his approach.

The sentence means he is not allowed to commit any further offences for two years or he will lose $2000.

AAP