Rainwater picks up dissolved minerals, chemicals and materials from the land and this material eventually enters the estua ry. This constant mixing of nutrients from both the land and the ocean, creates a murky brown mixture of fresh and salt water along with nutrients that makes the estuarine waters so productive. P lants and animals flourish in the blend of brackish water. E stuaries are important as the nursery of the sea. Seventy to ninety percent of recreational and commercially valuable fish, shrimp, crabs, and shellfish depend on and live in estuaries for at least part of their life cycle.
Estuaries have important commercial and recreational value.
They also provide breeding and nesting grounds for coastal birds, reptiles and mammals. Acting like a big sponge, the estuarine salt marsh controls flooding naturally and somewhat filters out pollutants. T he estuarine ecosystems are very susceptible to the impact of human population. All of these situations can have a profound impact on the variety of food chains and the web of life. Sadly, many of our world's estuaries are being destroyed.