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This estuarine food web shows how nutrients are transferred through ecosystems. For example, plants are consumed by invertebrates such as snails and cockles, which are then eaten by small fish, which in turn may be hunted by larger fish like snapper.

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-One-third of all United States estuaries have disappeared
-70 percent of California estuaries have been eliminated
-Estuaries around the globe are being converted into harbors or ports
-Dammed rivers, garbage dumps, boat usage, and urban development all have a negative impact on estuaries
-Mangrove forests are eliminated for human benefit (roads, crops, dumps, urban development)

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Some mangroves develop pneumatophores, which are unbranched shallow roots that grow upward from low-oxygen mud to help aerate the plant tissue.

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Estuaries and Bays: Texas Aquatic Science- Chapter 11

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-Mangroves are flowering land plants adapted to live in the intertidal zone.
Mangals- dense forests formed by mangroves

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The sharing of a resource by two or more species to avoid competition.

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Estuaries act as important feeding and breeding grounds.
For example, Salmon are one of the most well known organisms that migrate. They migrate into the estuaries from the ocean
Another, Organism that migrates is a sea trout, they do a very similar migration to salmon

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Estuaries and their surrounding wetlands are bodies of water usually found where rivers meet the sea. Estuaries are home to unique plant and animal communities that have adapted to brackish water-a mixture of fresh water draining from the land and salty seawater.

However, there are also several types of entirely freshwater ecosystems that have many similar characteristics to the traditional brackish estuaries. For example, along the Great Lakes, river water with very different chemical and physical characteristics mixes with lake water in coastal wetlands that are affected by tides and storms just like estuaries along the oceanic coasts. These freshwater estuaries also provide many of the ecosystem services and functions that brackish estuaries do, such as serving as natural filters for runoff and providing nursery grounds for many species of birds, fish, and other animals.

Estuaries are among the most productive ecosystems in the world. Many animals rely on estuaries for food, places to breed, and migration stopovers.

Estuaries are delicate ecosystems. Congress created the National Estuarine Research Reserve System to protect more than one million acres of estuarine land and water. These estuarine reserves provide essential habitat for wildlife, offer educational opportunities for students, and serve as living laboratories for scientists.

Video Transcript

Estuaries: Where the River Meets the Sea. Estuaries. Where freshwater rivers meet the salty open sea. There is a lot to love in an estuary. A popular destination for fishing, boating, birding and hiking, estuaries are a beautiful place to be. Miles of beaches, flowing grasses, marshes, creeks, and streams. This salty freshwater mix is where life begins and is the nursing grounds for 75% of the fish we catch. Estuaries are lined with marshes and sea grasses that filter water flowing to the ocean and act as a buffer protecting us from coastal storms. NOAA works closely with coastal states to manage the National Estuarine Research Reserve System of 28 protected areas along the nation's coasts. These valuable reserves are living laboratories for scientists and exciting, hands-on classrooms for students and teachers. At the reserves, scientists study sea level rise, water pollution, erosion, and impacts of human development. These studies provide strong scientific knowledge to help us create healthy, productive estuaries. The Chesapeake Bay, the ACE Basin in South Carolina, and San Francisco Bay in California, are just a few of the 28 reserves that can be found near you . So visit an estuary and experience firsthand the beauty and wildlife where the river meets the sea.

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national oceanic and atmospheric administration

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Estuaries and their surrounding wetlands are bodies of water usually found where rivers meet the sea.

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-Stenohaline species can tolerate only a narrow range of salinities
-They only reside in the upper or lower ends of the estuary.

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-Euryhaline species can tolerate a wide range of salinities.
-Most species in estuaries are euryhaline species.

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-Large amounts of suspended sediments which greatly reduce water clarity.
-Very little light penetrates through the water column
-The material can clog feeding surfaces of some filter feeders and can even cause the death of some animals.

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When the salinity of the water is lower than the salinity of an organism's blood, they get rid of excess water and absorb surrounding solutes through active transport (the gills and kidneys help aid active transport).

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(Fish, crabs, molluscs)- the salt concentration in their bodies remains mostly constant despite the salinity of the water.

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Soft-bodied estuary animals (molluscs, worms)- maintain their osmotic (salinity equilibrium) balance by allowing their body fluids to change in reaction to changing salinity of the water.

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Fish, shellfish, and migratory birds are a few of the animals that can live in an estuary.
Manatees are also a key species due to them being one of the main consumers of producers for these areas
but the keystone species of the estuary is the oyster, a filter feeder due to them controlling the amount of toxins in the water
-Blue crabs
-Oyster reefs

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Many estuaries are shallow and very wide (large surface area), causing them to have a high temperature, especially during low tide.

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Glaciers cut deep valleys along the coast. When sea levels rose, sea water would flow through them. Now rivers run through the valleys.

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-Rivers carry large amounts of sediment and other materials, including pollutants, into most estuaries.
-Fine muddy particles are carried down the estuary.
-The substrate of most estuaries is sand or soft mud.
-Mud is rich in organic material
- Respiration by decay bacteria uses up oxygen in the interstitial water(water between sediments)
-Sediments are often devoid of oxygen or are anoxic below first few centimeters.
-Estuaries with unimpeded tidal flow, most shallow ones have plenty of oxygen dissolved in water.
- Some deep water estuaries (fjords) have a shallow sill that restricts water circulation .
-The sill prevents seawater from flowing along the bottom.
-The stagnant deep water may become depleted in oxygen because of bacterial respiration and decomposition of organic matter.

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Land subsides because of the movement of the crust.

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Sediments accumulate and act as a wall between the ocean and fresh water.

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tide pool animals and plants are well adapted to the zones. Some adaptations include the ochre sea star can tolerate a longer time period exposed to air than many other sea stars. Limiting factor is space and food but the main limiting factor is space.

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the producers have a very high number due to the unique water system that brings producers from the ocean and the freshwater, that means that the amount of invertebrates and fish, also many shellfish and shrimps/crabs
but many animals have their adolescents in these estuaries

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Coastal plain estuaries (drowned river valleys)

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Coastal plain estuaries (drowned river valleys)

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Most common type of estuary- formed when ice from the last ice age melted and the rising sea water invaded freshwater.

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where the freshwater, rivers meet the salt water, sea
the mixing of the salt water and the freshwater occur due to tides and sometimes even strong winds

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Coastal plain estuaries (drowned river valleys), bar-built estuaries, tectonic estuaries, and fjords.

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Estuaries can be subdivided into further habitats types such as: shallow subtidal, tidal sand, or mud flaps salt march, tidal creeks, and the upland transition zone. The shallow subtidal habitats are submerged but are rarely deeper.

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-Salinity fluctuates dramatically from place to place and from time to time.
-Salinity also varies with depth, salty seawater is more dense and sinks to the bottom forming a salt wedge.
-Salt wedge moves back and forth with rhythm of tides.
- Seasonal variations in freshwater runoff from rivers as a result of rainfall or snowmelt.
-High-salinity estuaries are called negative estuaries.
-The average salinity for estuaries is about 35 ppt (parts per thousand)