A coral reef near the Caribbean island of Bonaire teems with plant and animal life. Rising water temperatures and increasing ocean acidity pose enormous threats to this wondrous but vulnerable ecosystem. Mark Vermeij hide caption

itoggle caption Mark Vermeij

Glassy sweepers are small nervous fish that can cluster in groups of over a hundred. When they're young, their bodies are nearly transparent, allowing an observer to see what these fish just ate. Mark Vermeij hide caption

itoggle caption Mark Vermeij

A longfin damselfish patrols its algae garden off the coast of Bonaire. Damselfish kill a section of the coral, and then wait for algae to grow in the dead spot. On this coral, only a few live sections remain. Henry DeBey hide caption

itoggle caption Henry DeBey

Passengers on a whale-watching ship in Massachusetts Bay. Whale watching is one of many recreational activities that draw people to the waters off the coast of Massachusetts. Kerry Crisley/The Nature Conservancy hide caption

itoggle caption Kerry Crisley/The Nature Conservancy