Benthos

[1] This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.

Burrowing animals can find protection and food in soft, loose sediments such as mud, clay and sand.

[7] Macrobenthos, prefix from Ancient Greek makrós 'long', comprises the larger, visible to the naked eye, benthic organisms greater than about 1 mm in size.

In shallow waters, seagrass meadows, coral reefs and kelp forests provide particularly rich habitats for macrobenthos.

Microbenthos, prefix from the Greek mikrós 'small', comprises microscopic benthic organisms that are less than about 0.1 mm in size.

Both foraminifera and diatoms have planktonic and benthic forms, that is, they can drift in the water column or live on sediment at the bottom of the ocean.

In 2020 it was reported that researchers have examined the chemical composition of thousands of samples of these benthic forams and used their findings to build the most detailed climate record of Earth ever.

Phytobenthos, prefix from Ancient Greek phutón 'plant', plants belonging to the benthos, mainly benthic diatoms and macroalgae (seaweed).

Endobenthos (or endobenthic), prefix from Ancient Greek éndon 'inner, internal', lives buried, or burrowing in the sediment, often in the oxygenated top layer, e.g., a sea pen or a sand dollar.

[18] Meiofauna and bacteria consume and recycle organic matter in the sediments, playing an important role in returning nitrate and phosphate to the pelagic.

[19] The depth of water, temperature and salinity, and type of local substrate all affect what benthos is present.

In coastal waters and other places where light reaches the bottom, benthic photosynthesizing diatoms can proliferate.

Fish, such as dragonets, as well as sea stars, snails, cephalopods, and crustaceans are important predators and scavengers.

Some water contaminants—such as nutrients, chemicals from surface runoff, and metals[20]—settle in the sediment of river beds, where many benthos reside.

[22] In biomarker assessments, quantitative data can be collected on the amount of and direct effect of specific pollutants in a waterbody.