Aquatic ecology and Biodiversity

Unit 7- Biotic communities

7.1.1. Benthic communities
Benthos are those animals and plants that are attached to, crawl over, or that burrow into the bottom in aquatic ecosystems. Benthic organisms are always associated with benthic floor from litter zone to the deep sea system. They live in the marine sediments distributing from tidal pools along the foreshore to the abyssal depths. The term benthos comes from the Greek word meaning depths of the sea. Benthos also lives in freshwater bodies of water, such as lakes, rivers and streams.
The distribution occurrence and structure of most benthic organisms are determined by depth of water, temperature dissolved oxygen, salinity soil texture, availability of food and their biological interactions. Filter feeders, such as sponges and bivalves dominate the hard sandy bottoms. Deposit feeders such as polychaetes populate in softer bottoms. Fish, sea stars, snails, cephalopods, and crustaceans are important predators and scavengers. Benthic organisms such as sea stars, oysters, clams, sea cucumbers, brittle stars and sea anemones play an important role as a food source for fish and humans.