5.1. Introduction

A smelly tidal flat or saltwater marsh may seem unimportant but these areas provide food and shelter for many fish, shellfish, birds, plants, and small animals.

In addition, a large percentage of the world's people live close to an estuary or its river. Natural harbours, fertile river basins, and plentiful fish and animal life are some of the underlying reasons. In Nova Scotia, most people live in the Halifax-Dartmouth area and along our coasts, where rivers and streams empty at the sea. 		An estuary is where fresh water from a river mixes with salt water from the sea. Freshwater flowing out over the surface sets up a circulation pattern, drawing nutrient-rich water up from the bottom. The combination of nutrients and light produces plankton, a major food source for life in the estuary.
Many Nova Scotians have daily contact with an estuary or salt marsh. This makes it especially important to understand how human activity affects this ecosystem

Estuary ecosystems are extremely fragile and vulnerable to human interference. Any change in river flow or water quality can dramatically affect the health of the ecosystem.
Each estuary has its own unique ecosystem and there are many kinds. The Bedford Basin near Halifax, West Petpeswick and the Bras d'Or Lakes are examples of estuaries known as fjords. These were originally lake and river channels.
Over 70% of all commercial fish species use estuaries and coastal zones at the critical juvenile (youth) stage of their lives
 
It's estimated that Nova Scotia has 7,442 km (4,625 miles) of coastline!