Pelagic habitat is the largest habitat on earth made up of 330 million cubic miles of water. It encompasses both the shallower well-lit coastal waters out to the continental shelf, and the much deeper oceanic water beyond.
The habitat is defined by the lack of boundaries or structure that excludes the shore and seafloor, it is the open-water environment with a 36-thousand-foot vertical range. The inhabitants are found throughout the water column with the density of life decreasing as the depth increases. The pelagic water column is structured vertically by zones: Photic sunlight zone (epipelagic 0-200m) and the aphotic without light (mesopelagic 200 - 1000m, bathypelagic 1000 - 4000m, abyssopelagic 4000 - 10,000m). These zones aren’t simply formed by depth but a combination of nutrients, dissolved oxygen, sunlight, temperature, salinity, pressure, continental or submarine topographic barriers.
The pelagic habitat has a huge ecological role in providing a multitude of ecosystem services to humans and the planet. The ocean is responsible for half of the planet’s overall primary production (Field et al., 1998) while aiding in climate regulation through carbon sequestration as oxygen is produced using CO2 during photosynthesis (Russo et al., 2025). While providing a food source for a large portion of the world with huge contributions to the economy, tourism, and cultural aspects.
The pelagic zone supports a biodiverse environment containing multiple trophic levels who all rely on each other to create an ever-changing balance. From the smallest phytoplankton relying on the sun to photosynthesize creating the base of the food chain. To the zooplankton who rely on mainly water currents for transportation such as crustacean copepods and euphausiids. And Nektons who are free swimmers like the bony and cartilaginous fishes, molluscans, decapods, mammals, and reptiles.
Fish like Atlantic mahi mahi and wahoo use our pelagic waters. Some tracking of these species lets us know where and how they use our pelagic environments: https://dolphintagging.com/caribbean-sea/
Many seabirds such as Roseate Terns, Tropicbirds, and Sargasso Shearwaters use our pelagic waters for foraging and migration as they stopover or breed in the USVI: https://atlanticflywayshorebirds.org/
The pelagic habitat is threatened by many factors but mainly anthropogenic sources as a main cause or indirectly aid in the degradation. With the two main sources being overfishing and the exploitation and removal of marine resources and climate change. The changing climate and warming of our world’s oceans originate from many sources but it shifts resource availability and livable habitats within the ocean. While overfishing comes in many damaging forms of directly removing species but also through indirect pressures such as destructive fishing gear and pollution of plastic and oil origin. It has been found overfishing has had negative impacts on species potential to adapt and manage the changing climates (Sumaila 2020)
Of the USVI SGCN, 35 rely on pelagic habitat including 28 marine fish, six marine mammals, and one sea turtle. See table below for the list of these species: