What is an Estuary? An Estuary is a partially enclosed body of water formed by freshwater mixing with saltwater Estuaries and the land surrounding them are transitions from land to sea, and from fresh water to salt water They are influenced by the tides, however they are protected from the force of the ocean waves, winds and storms by the reefs, islands, and pieces of land, mud, or sand. They come in all shapes and sizes

What is an Estuary Continued… Estuaries are frequently known as bays, lagoons, harbors, inlets and sounds, however not all of these are estuaries They are equipped to shelter communities of plants and animals, who are specially adapted to life at the edge of the sea Species which live in estuaries are known to be some of the most productive species around

What is an Estuary Continued… Estuaries are home to many different habitats such as open waters, freshwater and salt marshes, sandy beaches, mud and sand flats, rocky shores, oyster reefs and mangrove forests. There are also many different forms of wildlife including shore birds, sea birds, fish, lobsters, marine mammals and clams They are very important to the thousands of animals and plants which depend on the habitat Estuaries are common places for migrating birds to stop and rest at

What is an Estuary Continued… They are nicknamed the “Nurseries of the Sea”, this is due to the sheltered waters that protect the organisms Some of the most well known estuaries are the San Francisco Bay, Puget Sound, Chesapeake Bay and Boston Harbor.

Pictures of Estuaries

Predator/Prey Relationships Starfish/Shellfish- Starfish are extremely destructive to shellfish populations. Starfish are able to pry the shells of a shellfish off with their five arms. Starfish are dangerous to shellfish farmers because they can regenerate limbs and are difficult to kill. Crab/Fanworm- The crab has been shown to greatly lower the population of fanworms in estuaries. The crabs prefer to occupy shallow water and the fanworms prefer to occupy deep water. Fanworms are usually hunted on mudflats.

Crab Fanworm Starfish

Mutualism One example of mutualism in estuaries is of the oysters and the eelgrass. Beds of oysters can aid in the growth of eelgrass. The eelgrass can provide sanctuary for fish and attract crab and other species to the area. Oysters in estuaries can filter as much as fifty-five gallons of water a day. This clears the water and allows light to penetrate the surface allowing sea plants to grow.

Parasitism One parasite in estuaries is the nematode, Philonema agubernaculum. It infests the coelomic cavity (body cavity) of a wide variety of fish, one example being salmon. The nematode can increase the probability of the host being eaten. The host is forced to use excess energy to fight the parasite instead of using its energy to avoid predators. When the host gets eaten, the parasite will be able to infest the other organism through its digestive system.

Salmon Nematode Fish with a nematode

Commercial Products Food- Healthy estuaries produce more food per acre than the richest Midwestern farmland because of the fertile mix of nutrients from land and sea. Seafood from estuaries such as fish and oysters are sold in food markets around the world. Other products- During the process of dredging, or cleaning, of estuaries, organic chemicals are collected that can be used for manufactured cement, glass and ceramic tiles, bricks, and topsoil.

Ecological Issues Eutrophication- Eutrophication threatens water quality in many estuaries. It is the process where excessive plant growth on the water’s surface lowers oxygen levels and prevents sunlight from penetrating the water. This threatens fishery populations and their habitat. It is caused by an excess of phosphorous and nitrogen which stimulates excessive plant growth. Altered Freshwater Inflows- Diverting freshwater from an estuary to provide public drinking water and maintain water supplies for irrigation, wastewater treatment plants, and industrial facilities can alter the water’s salinity. If salinity rises above certain levels, aquatic populations that once lived in estuaries may no longer able to survive in the saltier water.

Ecological Issues Continued… Oil Pollution- In an estuary, even small oil spills can wipe out whole populations of certain species. This in turn disrupts the food chain, killing off other animals. Oil can pollute estuaries in a number of ways, including major spills from freighters, tankers, barges, and other ships going aground or colliding with other objects, and minor spills from small recreational and commercial craft. The currents in an estuary make spills difficult to contain. Oil gets quickly spread to other areas.

Eutrophication An Oil Spill

Estuaries by, Christian Caballero Hannah Loxley Lauren Portnoi Justin Quaglia Nick Schumacher