Practice question

The neritic zone is the shallow marine water extending from the low-tide margin to the edge of the continental shelf. Its exact offshore width varies because continental shelves may be narrow or hundreds of kilometres broad, but depth commonly remains below about 200 metres. Sunlight can reach much or all of this water column, while rivers, coastal runoff, sediment resuspension, and upwelling often supply nutrients. These conditions support phytoplankton, seaweeds, seagrasses, benthic invertebrates, fishes, and many commercial fisheries. The neritic zone is not simply the shoreline: the intertidal region is periodically exposed, whereas neritic water remains marine and overlies the shelf. Beyond the shelf break lies the oceanic zone over deep open ocean. “Deep ocean” therefore describes neither its position nor typical depth, and “open sea” is too broad. By linking a horizontal marine region to the underlying continental shelf, the definition also explains its generally high productivity: shallow illumination and land-derived or mixed nutrients are more available than in many offshore surface waters.