Which is an ecosystem with very shallow saltwater found where rivers empty into oceans?
saltwater marsh I do believe ^_^
Otters are found on every single continent in the world except for Australia and Antarctica. They enjoy the freshwater but they are also known to live in the saltwater of the oceans as well. Other places you will find there dens include around rivers, streams, and lakes. They tend to stick to the shallow waters so that they can easily reach land when they are ready to.