intertidal

The intertidal zone is the coastal region that lies between the high tide line and the low tide line. It is alternately exposed to air and submerged by seawater with the tides, making it a highly dynamic and stressful environment. The zone experiences rapid changes in temperature, salinity, moisture, wave exposure, and oxygen availability.

Intertidal habitats occur on rocky shores, sandy and mud flats, and in shell middens and tide pools. Distinct vertical zones are often observed: the upper intertidal is exposed most of the time and hosts desiccation-tolerant organisms such as barnacles, limpets, and some algae; the middle intertidal supports more sessile and mobile organisms including mussels, barnacles, and various seaweeds; the lower intertidal is submerged longer and contains species adapted to longer immersion, such as sea anemones, sea urchins, and larger brown algae. Tide pools within the intertidal zone create localized microhabitats with unique communities.

Ecology in the intertidal emphasizes zonation, competition for space, predation, and stress tolerance. Organisms employ adaptations such as strong shells, suction and clinging mechanisms, mucus to reduce desiccation, and behaviors that minimize water loss or overheating. Reproduction often involves planktonic larvae that disperse with currents, influencing community composition over time.

Humans interact with intertidal zones through fishing, tourism, and coastal management. These areas are important for biodiversity, research, and education, but are vulnerable to pollution, trampling, and climate-related changes such as ocean warming and acidification, which can alter community structure and species distributions.