marine Sedimente

Marine sediments – a poorly understood habitat

Hidden biodiversity at the bottom of our oceans

Marine sediments cover most of the ocean’s seafloor, ranging from gravel to fine mud this complex habitat represents one of the richest species pools in the oceans and on Earth. Despite their global importance, marine sediments are among the least understood environments. This is due partly to the difficulty of sampling, especially in the deep sea, as well as the complexity of its inhabiting communities. Invertebrates represent the largest taxa associated with marine sediments, living in (infauna) or on (epifauna) the sediments. These invertebrates include larger animals (megafauna), such as sea stars, scallops, and crabs; however, the great majority of species are represented by small-size organisms known as macrofauna (5cm-1 mm: e.g. polychaetes, crustaceans, molluscs, cnidarians) and meiofauna (1 mm-40µm: e.g. copepods, ostracods, nematodes, flatworms).

Although the diversity of marine sediments in certain areas is well-known, there are still several places on Earth −particularly the deep sea− where almost every single species found is new to science. Thus, the significance of biodiversity in marine sediments to ecosystem processes is still poorly understood. Despite of that, we know that marine sediment fauna activity impacts global carbon, nitrogen and sulphur cycling, transport, burial, and metabolism of pollutants, secondary production including commercial species, and transport of sediment, thus such communities play a key role in the ecosystem functioning and provide several ecosystem services to humans.