benthos

Benthos refers to the organisms that inhabit the bottom surfaces of a body of water, including the seabed, riverbeds, and lake floors, and to the communities that reside there. The term encompasses epibenthos (organisms on the surface of the substrate), infauna (within sediments), and demersal or benthic species that live near the bottom. Benthic habitats occur from shallow littoral zones to the deep ocean and from freshwater shores to abyssal plains, with community composition shaped by depth, substrate type, energy regime, and oxygen availability.

Ecology and adaptations: Benthos includes a wide range of taxa such as polychaete worms, mollusks, crustaceans, echinoderms, sponges, and microbes. Many benthic organisms are adapted to low light, high pressure, and variable oxygen levels; some are sessile, others burrow or crawl, and feeding modes include detritivory, deposit feeding, suspension feeding, and predation. The benthic realm participates in nutrient cycling, bioturbation (reworking of sediments), and provides habitat and food for pelagic species, creating important benthic–pelagic linkages.

Research and methods: Scientists study benthos through grab and core sampling, dredging, bottom trawling, as well as photographic and video surveys, ROVs, and underwater imagery. Data inform biodiversity assessments, productivity estimates, and ecosystem health evaluations.

Human impacts and management: Bottom-dwelling communities are vulnerable to disturbances such as pelagic and highly mobile bottom-towed gear, sedimentation, pollution, and climate-driven changes in oxygen and temperature. Conservation and management approaches include protected areas, sustainable fisheries, and practices that minimize seabed disturbance and enhance ecosystem resilience.

Etymology: The term derives from Greek benthos, meaning depth.