Global Ocean Darkening Shrinks Photic Zones

SCIENCE

By Aniket Chakraborty May 29, 2025 Arrow

This “ocean darkening” shrinks the photic zone — where sunlight powers marine life.

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More than 75 million square km of ocean now sees reduced light penetration.

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In some areas, sunlight reaches 100 meters less than it did twenty years ago.

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Plankton, fish, and light-sensitive species are being forced into tighter zones.

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The biggest darkening hotspots? Gulf Stream, Arctic waters, and the Baltic Sea.

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Climate change, nutrient runoff, and algal bloom shifts are driving this trend.

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Researchers warn this could disrupt food webs and oxygen production globally.

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Even moonlight-sensitive species are being impacted by reduced night photic zones.

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Scientists call this a “wake-up call” for ocean conservation and global action.

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