Marine pollution is a primary cause of eutrophication of surface waters, in which excess nutrients, usually nitrates or phosphates, stimulate algae growth. Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton and benthic animals, most of which are either deposit feeders or filter feeders. In this way, the toxins are concentrated upward within ocean food chains. Many particles combine chemically in a manner highly depletive of oxygen, causing estuaries to become anoxic. When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs. Once in the food webs, these pesticides can
Short food supply chains proximate, extended. Face to face are characterized by physical encounters between producers and consumers (as in the case of farmers' markets). In the proximate short food supply chains producers are not necessarily managing product distribution (as in the case of consumers' cooperatives). In the extended short food supply chains, although geographical distances between producers and consumers may be long, consumers are aware of the identity of the producers and of the products (such as in the case of fair trade and protected denominations of origin). An action plan developed in 2009 at the Ministry of Agriculture, Agrifood, and Forestry of