Autumn

The nutrient cycle

In the summer, the rugged bird islets were stained white by bird droppings. Now the autumn rains and the waves raised by storms wash some of these nutrients back into the waters of Airisto. However, these are simply the same nutrients that the birds temporarily removed from the water by eating the fish, invertebrates and plants growing in the sea. In other words, the nutrients follow a cycle. Eutrophication, on the other hand, is increased by external loading caused by humans, i.e. new nutrients transported to the sea from fields, means of transport and waste waters.