Estuaries

An estuary is a coastal area where fresh water from rivers and streams mixes with

salt water from the ocean. Many bays, sounds, and lagoons along coasts are estuaries.

Portions of rivers and streams connected to estuaries are also considered part of the

estuary. The land area from which fresh water drains into the estuary is its watershed.

Estuaries come in all shapes and sizes, each unique to their location and climate. Bays,

sounds, marshes, swamps, inlets, and sloughs are all examples of estuaries.

An estuary is a fascinating place from the largest landscape features to the smallest

microscopic organisms. When viewing an estuary from the air on is practically amazed by

dramatic river bends as freshwater finds its way back to the sea. The vast expanse of

marsh grasses or mudflats extend into calm waters that then follow the curve of an

expansive barrier beach. Wherever there are estuaries, there is a unique beauty.

Česky: Pitná voda - kohoutek Español: Agua pota...

English: Water fountain found in a small Swiss vil...

English: Estuary mouth of Sandy Creek at low tide....

As rivers

meet the sea, both ocean and land contribute to an ecosystem of specialized plants and

animals.

At high tide, seawater changes estuaries, submerging the plants and flooding creeks,

marshes, panes, mudflats or mangroves, until what once was land is now water.

Throughout the tides, the days and the years, an estuary is cradled between outreaching

headlands and is buttressed on its vulnerable seaward side by fingers of sand or mud.

Estuaries transform with the tides, the incoming waters seemingly bringing back to

life organisms that have sought shelter from their temporary exposure to the non-aquatic

world. As the tides decline, organisms return to their protective postures, receding into

sediments and adjusting to changing temperatures.

The community of life found on the land and in the water includes mammals, birds,

fish, reptiles, shellfish, and plants all interacting within complex food webs. Flocks of

shore birds stilt through the shallows, lunging long bills at their abundant prey of fish,

worms, crabs or clams. Within the sediments, whether mud, sand or rocks, live billions of

microscopic bacteria, a lower level of the food web based largely on decaying plants.

Estuaries are tidally-influenced ecological systems where rivers meet the sea and

fresh water mixes with salt water. Estuaries provide habitat;tens of thousands of birds,

mammals, fish, and other wildlife depend on estuaries. They provide marine organisms,

most commercially valuable fish species included, depend on estuaries at some point

during their development. Where productivity is concerned, a healthy, untended estuary

produces from four to ten times the weight of organic matter produced by a cultivated

corn field of the same size. Estuaries provide water filtration;water draining off the

uplands carries a load of sediments and nutrients. As water flows through salt marsh peat

and the dense mesh of marsh grass blades, much of the sediment and nutrient load is

filtered out. This filtration process creates cleaner and clearer water. Estuaries also

provide flood control. Porous, resilient salt marsh soils and grasses absorb flood waters

and diffuse storm surges. Salt marsh dominated estuaries provide natural buffers between

the land and the ocean. They protect upland organisms as well as billions of dollars of

human real estate.

Estuaries are crucial transition zones between land and water that provide an

environment for lessons in biology, geology, chemistry, physics, history, and social issues.

Estuaries are significant to both marine life and people. They are critical for the survival

of fish, birds, and other wildlife because they provide safe spawning grounds and

nurseries. Marshes and other vegetation in the estuaries protect marine life and water

quality by filtering sediment and pollution. They also provide barriers against damaging

storm waves and floods.

Estuaries also have economic, recreational, and aesthetic value. People love water

sports and visit estuaries to boat, fish, swim, and just enjoy their beauty. As a result, the

economy of many coastal areas is based primarily on the natural beauty and bounty of

their estuaries. Estuaries often have ports serving shipping, transportation, and industry.

Healthy estuaries support profitable, commercial fisheries. In fact, almost 31 percent of

the Gross National Product (GNP) is produced in coastal counties. This relationship

between plants, animals, and humans makes up and estuary's ecosystem. When its

components are in balance, plant and animal life flourishes.

Humans have long been attracted to estuaries. Indian mittens consisting of shellfish

and fish bones are reminders of how ancient cultures lived. Since Colonial times we have

used estuaries and their connecting network of rivers for transporting agricultural goods

for manufacturing and trade. Not only do commercially important fish and shellfish

spawn, nurse, or feed in estuaries, estuaries also feed our hears and minds. Scientists and

even poets and painters are inspired by the beauty and diversity found in an estuary.

Human activity also seriously threatens the vulnerable ecosystems found in the

estuaries. Long considered to be wastelands, estuaries have had their channels dredged,

marshes and tidal flats filled, waters populated, and shorelines reconstructed to

accommodate our housing, transportation, and agriculture needs. As our population

grows and the demands imposed on our natural resources increase, so too does the

importance of protecting these resources for their natural and aesthetic values.

In recognition to these threats, Congress, in 1987, established the National Estuary

Program (NEP) as part of the Clean Water Act. The NEP's mission is to protect and

restore the health of estuaries while supporting economic and recreational activities. To

achieve this, the Environmental Protection Agency (EPA) helps create local NEPs by

developing partnerships between government agencies that oversee estuarine resources

and the people who depend on the estuaries for their livelihood and quality of life. These

groups plan and implement programs according to the needs of their own areas. Local

NEPs are demonstrating practical and innovative ways to revitalize and protect their

estuaries. The benefit of this program is that it brings communities together to decide the

future of their own estuaries.

One specific estuary is the San Francisco Estuary. Human activities in the 1600

square mile Bay/Delta watershed region have drastically altered natural habitats and

impaired the functions of the estuary's ecosystem. Poor cattle grazing practices contribute

to soil erosion and water quality problems. In model public or private partnership, this

NEP is assisting a private rancher in developing a grazing management strategy for a 500

acre parcel of public land within Wildcat Creek Regional Park. Strategies already being

implemented include building barriers to prevent livestock from trampling sensitive

habitats, installing pens to improvelivestock management, and selecting cattle grazing

period to retard the growth of alien and nuisance plants. These measures encourage the

regrowth of native bunchgrasses and fords that provide not only better habitat for wild

life, but also more desirable forage for the cattle. In addition, soil erosion and pollutant

loading should decrease.

Another interesting and problematic estuary is New York-New Jersey Harbor

Estuary. Trash and other foldable marine debris washing up on area beaches had been

chronic problem for the New York-New Jersey Harbor Estuary, but unusual episodes in

1987 and 1988 shocked the public and closed many beaches. The New York-New Jersey

Harbor GNP developed a short-term plan using helicopters and vessels for surveillance

and capture of the foldable debris. Along-term plan to address the floatables problem was

subsequently developed. This included the purchase of additional skimmer vessels to

collect debris, a pollution decrease strategy, and an Operation Clean Shores program in

New Jersey that has already removed 10,000 tons of debris.

There are many estuaries in the United States that are in the NEP. There are also

small estuaries. Such resources include the Mississippi and Alabama estuaries. The

GNP, National Estuary Program's basic purpose is to bring new life to present-day

estuaries.