A large gas project off the Tiwi Islands could threaten a vulnerable turtle species and disrupt a thriving ecosystem of fish, a marine ranger has told the Federal Court.
Tiwi Islander Dennis Tipakalippa is challenging the decision to allow Santos to drill eight wells in the Barossa gas field, 265 kilometres northwest of Darwin.
The Munupi elder says he was not consulted over the company's environmental plan and fears the project could damage his people's sea-country.
The offshore gas project would cut into the migration path of the vulnerable olive ridley sea turtle, marine ranger James De Santis said in his evidence on Tuesday.
Mr De Santis, who has monitored the turtles for years, described to the Darwin courtroom how the species swim out in the Timor Sea and return to the Tiwi Islands to lay eggs.
"There's too much to lose out there if anything goes wrong," he said.
"It will be a great big loss for myself, my children and my grandchildren, right through generations of Tiwi people."
The drilling would disrupt the sea floor and a chemical spill would have a devastating effect on the thriving marine ecosystem, Mr De Santis said.
"If there is a spill, small fish can't break through so they die," he told the court.
"The big fish and birds will eat them and then be contaminated. It's a big cycle and everything ends up dead."
Mr De Santis did not recall having any contact with Santos about the drilling process.
Michael Marren, Santos' senior stakeholder engagement adviser, told the court the company did engage with Tiwi Islander groups including the Tiwi Land Council.
During his evidence on Tuesday afternoon, Mr Marren was taken to a number of emails he sent to the council and other stakeholders between 2018 and 2021.
He conceded he did not receive a response from the council on a number of occasions and he may have sent the messages to the wrong email address.
Santos was planning to meet in person with the Tiwi Islands clans in November last year but the company ultimately did not send any officials to the islands due to the rising COVID-19 risk, Mr Marren said.
The company instead held virtual meetings with most of the groups, he told the court, and issues around the environmental impact and potential oil spills were raised.
Santos, which is Australia's second-largest independent gas producer, has said it would "vigorously defend" the Barossa project, and that it had all necessary approvals following consultation with stakeholders.
The $US3.6 billion ($A5.2 billion) offshore natural gas development is expected to create up to 600 jobs and pipe gas 280km to the Darwin LNG facility, with first production expected in 2025.
The company says the project, which it purchased from ConocoPhillips in 2020, is 43 per cent complete and on schedule. The drilling that is the subject of the court case started in July.
The Federal Court judicial review of the National Offshore Petroleum Safety and Environmental Management Authority's decision started on Monday at a bush court on Melville Island.
The historic hearing - the first of its kind - was preceded by a smoking ceremony and evidence was given orally and in song and dance.
The hearing before Justice Mordecai Bromberg will continue on Wednesday.
