A new study reported that the area of Danish seas hit by low oxygen levels has doubled in a year. The area underwent from high levels of water from rivers at the start of the year, raising the amount of organic matter and nutrients. A large number of nutrients in the sea can lead to the extreme growth of plants like algae, which eventually leads to less oxygen in the water. This can have serious effects on the survival of plants, animals, and fish. As per IUCN, around 700 spots around the world undergo exhausted oxygen levels, compared with just 45 in the 1960s.