Aquatic sill
An aquatic sill is a sea floor barrier of relatively shallow depth restricting water movement between oceanic basins. A similar barrier can also exist on a lake floor.Aquatic sills as barriers
An aquatic sill can be a biogeographic barrier for species located in deep basins on either side. On top of an aquatic sill, water is often warmer than deeper water.
An aquatic sill can restrict movement of water masses in the bottom, and also results in their isolation, which can be partial, and is sometimes near total.Examples
