One barometer of ocean health is the penguin, whose Southern Hemisphere range extends from the tropical Galapagos Islands near the equator to the ice shelf of Antarctica.
Penguins Barometer for Ocean Health

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Chinstrap penguin prancing on Prasiola crispa, a terrestrial green algae. (Ron Naveen/ OCEANITES)

2
Adélie penguin wing spread. (Ron Naveen/ OCEANITES)

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Nesting Adélie penguins, Admiralty Bay. (Ron Naveen/ OCEANITES)

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Penguin swimming, Antarctica. (John B. Weller)