WELLINGTON, New Zealand — A remnant of the largest iceberg ever recorded is blocking Antarctica's McMurdo Sound, threatening tens of thousands of penguin chicks with starvation and cutting off a supply route for three science stations, a New Zealand official said Tuesday.

The iceberg, known as B15A, measures about 1,200 square miles, said Lou Sanson, chief executive of the government scientific agency Antarctica New Zealand.

He called it "the largest floating thing on the planet right now" and said U.S. researchers estimate it contains enough water to supply Egypt's Nile River complex for 80 years.

It is so big it has blocked wind and water currents that break up ice floes in McMurdo Sound during the Antarctic summer, which begins later this month. The U.S. McMurdo Station and New Zealand's Scott Base are located on the sound. Italy's Terra Nova base is nearby.

The iceberg is in the path of four ships due to arrive in Antarctica in a month with fuel and food for the three stations. Scientists are looking into solutions, including breaking an 80-mile path through the ice.

While the situation is a growing concern, the bases are not immediately in danger of running out of supplies, Sanson said.

The same cannot be said for the newborn Adele penguins.

Tens of thousands of the chicks could starve in coming weeks because the ice buildup in the sound has cut off their parents' access to waters where they catch their fish, Sanson said.

Currently there is "more fast (blocked) ice in McMurdo Sound than we've ever recorded in living history for this time of year," Sanson said.

The penguins are important to scientists as markers of environmental change, such as global warming. The iceberg is threatening two of four colonies in the area that scientists have been studying for 25 years.

One is on Cape Royds, where 3,000 breeding pairs of Adele penguins now face a 112-mile round trip to bring food to chicks at their nesting grounds. The parents cannot survive such a long journey without eating much of the food they have gathered for their young, Sanson said.

Penguins carry the food for their young in a pouch in their necks and will eat it themselves if they are hungry enough.

"Penguin researchers are predicting that the annual hatching is pretty certain to fail," Sanson said, meaning most chicks will die.

Likewise, scientists fear that only about 10 percent of the 50,000 breeding pairs of Adele penguins at nearby Cape Bird will rear a chick this season, Sanson said. Adult penguins there face a 60-mile round trip across the ice to reach open water and food.

New Zealand research scientist Peter Wilson said the ice blockage "is a very serious event for these colonies." Penguins breed for the first time at three years of age.