Tide pool
A pool of seawater left among shore rocks as the tide recedes. Its organisms endure changing exposure, temperature, salinity, and wave action.
Intertidal zone: The coastal area alternately covered and uncovered by seawater as tides rise and fall. Tide pools occur within this zone, where organisms regularly shift between immersion and exposure.
Rocky shore: A coastal habitat where bedrock or large rocks form the shoreline. Rock surfaces and depressions provide the setting and basins that hold tide pools.
Rocky intertidal ecology: The study of organisms and ecological interactions on rocky shores between high and low tide. Tide pools are accessible sites for studying intertidal communities and environmental change.
Giant green anemone: A large intertidal sea anemone, Anthopleura xanthogrammica, found along the Pacific coast of North America. It occupies tide pools and can close its tentacles as water levels fall.
Keystone species: A species whose ecological effects are unusually large relative to its abundance. Predators such as sea stars can shape which organisms dominate nearby pools and rocks.
Tide: The periodic rise and fall of sea level, driven mainly by the Moon’s and Sun’s gravity. Falling tides isolate pools; rising tides reconnect them to the sea.
Salinity: The concentration of dissolved salts in water. Pool salinity rises with evaporation and falls with rainfall or freshwater runoff.
Biodiversity monitoring: The repeated measurement of species presence, abundance, or diversity over time. Repeated pool surveys can track changes in coastal species and habitat conditions.
Ochre sea star: A common northeastern Pacific sea star, Pisaster ochraceus, with purple, orange, or brown coloration. Its feeding on mussels can influence the composition of rocky-shore communities.
Ecological succession: The change in a community’s species composition over time. Disturbance can clear pool surfaces, after which organisms recolonize in changing sequences.