1. In freshwater ecosystems, an alternative name for the limnetic zone.

2. The sea-shore zone lying immediately below the littoral (intertidal) zone and extending to a depth of about 200 m or to the edge of the continental shelf. Red and brown algae are characteristic of this area. Typical animals include sea anemones and corals on rocky shores, and shrimps, crabs, and flounders on sandy shores. The zone may alternatively be called the subtidal zone. It is approximately equivalent to the circalittoral zone.