The marine life that lives near the ocean bottom becomes smaller and the diversity becomes limited. Without animals living in the sediment, the sediment is not mixed. When this mixing doesn't occur, the nutrient (nitrogen and phosphorus) cycles are altered. The degradation of bottom habitats effects all sorts of marine life.16
Dead zones occur around the world, but primarily around areas where there is heavy agricultural and industrial activity. Companies, plants, and farms spill nutrients into the water which affects the oxygen levels. Organisms, mainly in the benthic zone of the ocean, have to adapt to oxygen depleted sediments where the diversity of life is much higher, making it difficult.16