Some of the creatures that live in estuaries are fish, birds, otters, seals, clams, crabs, jellyfish, scallops and eelgrass. An estuary forms when fresh and saltwater mix together. Within the estuary, there are multiple habitats, such as coral reefs, marshes and mangroves.
Some of the fish that reside in estuaries are salmon, perch, flounder and trout. Bird species that call the estuary home include the peregrine falcon, bald eagle, great-blue heron and Canada goose.
Estuaries are easily threatened by human activities, such as industrial pollution and overfishing. Chemical runoff can create zones unsuitable for marine life. If fish populations are too low, larger fish and the waterfowl do not have enough food.