If you’re a reef manta, there are few better places to be than northeastern Indonesia.

In the clear blue seas of the Raja Ampat archipelago, these marine giants — up to 4 meters, or 14 feet, in wingspan — are thriving. In fact, it’s the only place on Earth where their populations are growing , thanks to strong marine protections dating back more than a decade.

Now, research from Conservation International and its local partner, Konservasi Indonesia, is renewing concerns about a threat to these pristine waters: nickel mining.

Experts worry that rising prices for the precious metal, spurred by growing demand for electric vehicles, could imperil a critical habitat just outside of Raja Ampat’s vast marine protected areas, which span 6.7 million hectares (16.5 million acres) — an area twice the size of Taiwan.

© Shawn Heinrichs

Mining could smother coral reefs, critical habitat for reef mantas and other marine life in Raja Ampat.

Using data from more than 30 acoustic sensors, researchers tracked the…