pelagiska

Pelagiska, or pelagic, describes the environmental realm of the open ocean away from the coast and the seabed. It refers to the water column and the organisms that inhabit it, as distinct from benthic communities on the ocean floor and demersal life living near the bottom. The pelagic zone is typically divided into subzones by depth and light: epipelagic (the sunlit layer at the surface to about 200 meters), mesopelagic (twilight zone to about 1000 meters), and the deeper bathypelagic and abyssopelagic zones. Some schemes also recognize hadopelagic waters in deep trenches.

Organisms in the pelagic realm include plankton that drift with currents and nekton—swimming animals such as most fish (for example tunas, mackerels, swordfish), squids, marine mammals, and seabirds that rely on open-water prey. Many pelagic species undertake vertical or horizontal migrations, notably diel vertical migration where zooplankton rise to the surface at night and descend by day, feeding into the surface food web.

Pelagic ecosystems support major commercial fisheries and play a key role in the global carbon cycle, as carbon-rich organisms and fecal pellets transport carbon from surface waters to deeper layers. Climate change and overfishing pose threats by altering distribution, abundance, and the timing of migrations.

In sum, the pelagic zone encompasses the open-ocean environments and their unique communities, functioning as a central component of marine biodiversity and biogeochemical processes.