Intertidal Zone

Intertidal zone

The area between the mean low tide and mean high tide.

Subtidal zone

The area that is always submerged, bordering the intertidal zone.

Substrate

The type of bottom or seafloor present in a marine community.

Epifauna

Organisms that live on the surface of the substrate, such as snails or barnacles.

Infauna

Organisms that live within the substrate, such as burrowed clams.

Meiofauna

Organisms so small that they live between the grains of soft substrate.

Intertidal zone challenges

Desiccation, extreme temperature and salinity changes, interrupted feeding, wave action, limited oxygen, and limited space.

Desiccation

Potential water loss experienced by intertidal organisms when exposed during low tide.

Euryhaline organisms

Organisms that can tolerate a wide range of salinities, common in the intertidal zone.

Wave shock

The physical dislodgement of organisms from their habitat caused by wave action.

Keystone predators

Top carnivores that have the ability to change community composition significantly.

Vertical zonation limits

Upper limits are generally set by physical drivers, while lower limits are set by biological drivers like competition.

Middle intertidal zone upper boundary

Usually marked by acorn barnacles.

Intermediate Disturbance Hypothesis

The concept that moderate levels of disturbance increase biodiversity by preventing competitive exclusion.

Anoxic zone in soft bottoms

The layer below the oxygenated zone with few macro-organisms, where anaerobic bacteria produce hydrogen sulfide.

Bioturbators

Organisms like stingrays and crabs that actively disturb top sediment layers, allowing oxygen to penetrate deeper.

Mudflat biofilms

Aggregations of microbes in a polysaccharide matrix that provide energy-dense food for migratory birds.