Aquaculture has the lightest environmental effects of any form of large-scale food production. These effects are limited largely to the ocean floor in the immediate vicinity of salmon farms, are short-term, and fully reversible. Salmon waste and uneaten food on the ocean floor can cause temporary oxygen reduction and other chemical changes as they decompose. For this reason, salmon farms are situated in deep waters over sand and silt sea bottoms with low fauna diversity. Some of the organisms that live in these soft sediments in fact thrive under salmon farms because the wastes are a source of food for them.