NEW ORLEANS — Images of oil-coated birds and testimony about “widespread socio-cultural harm” opened the third phase of a trial to establish environmental penalties BP must pay for spilling millions of barrels of crude into the Gulf of Mexico in 2010.

The government wants the oil giant to pay another $13.7 billion for harming not just the birds and fish, but the business climate and social fabric of coastal communities.

The pollution caused by the Deepwater Horizon explosion not only killed wildlife, but disrupted human societies as well, disrupting livelihoods exacerbating economic inequality across the Gulf states, anthropologist Diane Austin testified Tuesday.

She based her findings on interviews with more than 1,300 people – not only fishermen who derive their living from the Gulf, but bankers and business owners of all kinds. Even florists described a sudden drop in orders after the spill, she said.

Harm was widespread because so much of life along the coast depends on both fishing and energy production, both of which were upended while BP struggled for 87 days to cap the crude gushing from the undersea Macondo well.

“People who work offshore often times also fish,” she said. “Grocery stores that provide food to commercial fishing vessels also provide to the offshore oil and gas industry … . When all of these economic sectors went down at the same time, it had a huge effect.”

Austin’s work was done for the federal Bureau of Ocean Energy Management.