Estuary and Coastal Questions?

Question

What causes the temperature and salinity in a estuary to change? And why does it cause this change?

How are coastlands ecologically important?

Answer 1

We are a nation fascinated by the water that surrounds our country and in awe of its tremendous system of inland freshwater lakes. However, despite the beauty — spectacular sunrises and sunsets, expansive sandy beaches and dunes, and a diverse wildlife population — we often fail to recognize our dependence on coastal resources to satisfy our increasing appetite for energy, goods, and services.

The U.S. coastal zone supports valuable coastal and ocean resources, including fisheries, marine mammals, minerals, oil and gas, and other energy resources. The ocean is also valued for such uses as marine transportation, tourism and recreation, and military operations.

Management of our coastal areas to balance environmental, economic, human health, and human activities is a relatively new concept, initiated less than four decades ago by Congress. Since that time, NOAA has worked with U.S. coastal and Great Lakes states to manage our nation’s coastlines. This article traces the history of coastal zone management, beginning with the passage of the Coastal Zone Management Act in 1972.

Estuaries are coastal zones where fresh water from mountains and planes meets the salty water of the ocean. Estuaries are rich and complex ecosystems that serve as nurseries to ocean life and they act as buffers to protect coastal areas from excessive storm damage.

Estuaries are the transition zone between rivers and the sea and provide habitat for a unique collection of plants and animals, which have both aesthetic and commercial value.

It is here that freshwater, draining from the land mixes with salt water from the ocean. This combination of seawater diluted with nutrient-laden freshwater from the land allows estuaries to support the vast sea grass meadows, mangrove fringes and many kinds of fish and shellfish that live in these systems.

Estuaries are valuable to society for many reasons. Because they provide a sheltered access to the open sea, many cities are located on estuaries to take advantage of commercial shipping and recreational boating opportunities.

Estuaries not only support local fish and shellfish populations that are harvested commercially and recreationally, but these waters also serve as spawning and nursery grounds for populations that are harvested offshore.

Also, because of their proximity to the ocean, estuaries have been traditionally used as convenient disposal sites for urban storm water runoff and sewage. Because the rivers that feed them are often used for this same purpose, estuaries can become severely impacted by municipal and industrial waste. Because an estuary is part fresh and part salty, the sheltered waters of an estuary are home to a variety of plants, trees, birds, fish, mammals and other wildlife.

Estuaries are coastal regions where salt water from the ocean mixes with fresh water from rivers, rainfall, and upland runoff. This dynamic combination of physical and biological factors produces an ecosystem unrivaled in productivity and a focal point for oceanic and inland commerce.

Such characteristics are often cited to describe estuaries as the “cradles of civilization.” Indeed, for thousands of years great civilizations have emerged and flourished in estuaries such as those of the Tigris-Euphrates, Nile, and Yangtze River deltas. Today estuaries are the foundation for many modern cities, such as London, Cairo, Calcutta, and Shanghai.

However, one of the most expansive and productive estuaries in the world is located in the United States at the interface of the Mississippi River and the Gulf of Mexico. This document inventories the functions and values of this estuary and chronicles the serious plight of landscape deterioration facing its inhabitants.

We also need better communication among coastal managers responsible for estuaries. The Coastal CRC hosts a network of estuary managers and researchers. It assisted the National Land and Water Resources Audit to determine the ‘state of health’ for each estuary and how estuaries function under pressure.