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Fig. 3. Bottom sediments play an important role in recycling nutrients and as nutrient sinks, depending on the availability of dissolved oxygen. Positive feedbacks worsen eutrophication as coastal ecosystems degrade because more nutrients are recycled to the water column under anoxic conditions. The feedbacks work in the opposite direction as ecosystems are restored, by reducing nutrient loadings as more phosphorus is buried and more nitrogen is lost to the atmosphere
