Ocean science news, explainers, and statistics covering marine environments, currents, climate, coasts, seafloor research, and the changing global ocean.
A mesophotic coral ecosystem is a tropical or subtropical reef community living in dim, middle-depth water where some sunlight still reaches the seafloor. It typically begins around 30 meters deep and can extend beyond 150 meters, depending on water clarity. Light-dependent corals, algae, sponges and fishes form the community. NOAA’s mesophotic reef overview places these…
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An anchialine pool is a landlocked coastal pond with a hidden connection to the sea. Fresh groundwater enters from the land while seawater moves through porous rock or cave passages below ground. The result is usually a small body of brackish water whose level may rise and fall with distant ocean tides, even though no…
Salt fingers are narrow sinking and rising motions that can develop where warm, salty seawater lies above cooler, fresher water. The overall density arrangement can remain stable, with lighter water over denser water, yet small disturbances grow because heat moves between water parcels much faster than dissolved salt does. Oceanographers call the process double-diffusive instability.…
Estuarine circulation is the repeated exchange of river water and seawater where a river meets the coast. Fresh water tends to move seaward near the surface, while denser saltwater can move landward below. Tides reverse the instantaneous current, yet the average flow over many tidal cycles often preserves this two-layer pattern. The real motion is…
