NEW YORK (AP) — Two generations after Jacques Cousteau introduced television viewers to an undersea world, his grandson is becoming a go-to environmentalist for TV producers on some of the same topics.

Philippe Cousteau hosts a series of documentaries with his sister Alexandra this month for what the Planet Green network calls its "Blue August". The centrepiece is a six-part series, "Oceans Blue", where Cousteau and other marine explorers tell stories about secrets of the ocean.

Cousteau was a frequent guest on news programs to discuss the Gulf oil spill, particularly on CNN. He dived into the Gulf of Mexico for ABC's "Good Morning America" for a story on how oil was spreading away from the surface.

Cousteau, 30, hopes to use his burgeoning celebrity status to make sure the Gulf story isn't forgotten, even as cameras move away with the gushing underwater well capped and the oil slick on the water's surface starting to shrink.

"We are so eager to make declarative statements and to wrap things up in an easy box," he said. "It's so easy to do that, and we can't allow that to happen."

Cousteau's grandfather became a celebrity through his nature documentaries, most focused on bodies of water and how they are affected by humans. "The Undersea World of Jacques Cousteau" captivated audiences on ABC from the late 1960s to mid-1970s. Cousteau's son, Philippe, was a frequent traveller on the research ship The Calypso.

The elder Philippe died in a plane crash six months before the young Philippe was born, so he knew him only through the images caught in the documentaries. Young Philippe visited his grandfather a few times a year; he credited his mother for keeping the family legacy alive.

A decade ago Philippe started a foundation aimed at empowering youngsters to take action on keeping oceans clean and healthy. It was initially named for his grandfather, but after losing a legal battle with his grandfather's widow, the name was changed to EarthEcho International.

Cousteau speaks to youth groups, he blogs and is an energetic networker in the environmental community — a modern-day mash-up of citizen, celebrity and politician in the Bono mould. He recognises what his grandfather did, that television is a hugely powerful medium for getting his message across.

He's also cognisant of the power his last name holds in the environmental and media worlds.

"It's such an honour to be part of that legacy and a responsibility," he said. "It opens doors. I've always found those doors are very fast to close in your face because there are big expectations. You've got to perform."

Cousteau was with ABC's Sam Champion at the time of the explosion that set off this summer's Gulf disaster. They were doing a story on manatees, a particular interest of Champion's that dates back to when he saw a Jacques Cousteau documentary about them.

Champion said he found Cousteau "hugely impressive". Cousteau could probably have coasted on his name, but he's very knowledgeable about the oceans and is able to put what he knows in terms that average people can understand, he said.

"He's got a great personality and he's easy on TV, and that's not something that comes easily," he said. "He's a natural on camera."

It also doesn't hurt that Cousteau is slim, blond and handsome, maintaining a "cool" stubble of a beard. There's always a buzz among the women of "Good Morning America" when Cousteau is on the set, Champion said.

Although Cousteau was frequently on CNN, visiting with Larry King and others, he's been reluctant to sign any exclusivity agreement with a news network. He finds it limits his options; Cousteau has also been booked on MSNBC's "Morning Joe" programme.

The Gulf spill also found Planet Green scrambling to put together some programming that addressed the topic. "Black Wave: Legacy of the Exxon Valdez" is a previously recorded documentary that takes on new resonance now. Cousteau said the 1989 Alaskan oil spill had long-lasting effects on the fishing industry and environment that could not have initially been predicted.

"History is not going to judge us by the mistakes we made but by what we learned from them," Cousteau said. "I'm very concerned that that is not happening."