Marine environment. Benthos. Abiotic factors (irradiance, temperature, nutrients, moisture and salinity) and biotic (predation, competition and symbiosis) influencing the distribution of bentic communities. Models by Paine & Menge and Sutherland. Macroalgae of hard and soft bottoms. Introduced species of the Med. Causes and consequences of their introduction. The genus Caulerpa. Caulerpa taxifolia and Caulerpa racemosa. Seagrasses and thier importance. Monoic and dioci plants. The trophic cascade. Benthic microalgae. Lagoon systems. Eutrophication. Coral reefs. Conservation of the marine envrironment.