There are fewer and fewer natural water purifiers. Toxic substances, which fish take from water, are deposited in them, and most of them are used by humans in their diet. Changes in the temperature and amount of oxygen in the oceans lead to changes in the behavior of fish. This is primarily about a changed diet.
In the Mediterranean, seagrass is crucial to sustaining life. It emits 20 liters of oxygen per square meter – thus cleaning the sea. However, it is also decreasing.