Question

1. What is the role of animals in Estuaries?

2. What types of animals are the most prevalent in estuaries?

3.What types of adaptations do these animals have that let them survive in estuaries ?

4. Do these animals have to compete for resources? How do they compete?

5. Do the animals provide any services to estuaries that help maintain it?

Answer 1

1.Estuaries are full of decaying plants and animals. This makes the soil of estuaries rich in nutrients. Because the soil is so rich, lots of different plants grow in estuaries. The plants attract lots of different animals to the estuary and those animals attract other animals to the estuary.

2.Plankton-A plankton technically is just an organism that lives in water and that cannot propel themselves.Two most commonly categories of plankton are zooplankton (animal)and phytoplankton (algae/plant-like protist).

Insects-Insects are also tiny creatures found in estuaries that act as a food source for many other animals.The dragonfly is one of the best-known estuary insects.

Fish (Vertebrates)-There are more than 200 species of fish that live in estuary waters. In the Pacific Northwest, salmon migrate through estuaries and upriver to breed and spawn.

Other bottomfish, like the starry flounder, spawn in estuaries near river mouths. It feeds on zooplankton, crustaceans, amphipods and copepods, and changes its color to blend in with the bottom to avoid other preying animals. You can find all types of rockfish, hiding out behind and under their favorite habitat... well, you guessed it, rocks.

Estuaries are also known for their abundance of forage fish, like herring and surf smelt, which other larger fish and mammals prey upon.

Echinoderms, Crustaceans and Shellfish (Invertebrates)-Unlike fish that have backbones, many invertebrates (think squishy creatures) live in estuaries. These include colorful nudibranchs (sea slugs), jellyfish, anemones, worms and even octopus.

Birds

Marshes and mangroves provide an essential food source for a variety of birds. They feed on fish, plants and snails as it is very easy to hunt and forage in the shallow waters of estuaries.Ducks hunt in the mud to find food, feeding on shellfish and insect larvae. The great blue heron is a common sight in marshes, agricultural areas and mud flats feeding on fish, small mammals, reptiles and even other birds.

Mammals-The river otter, a cousin to the mink, weasel, wolverine and badger, belongs to a group called Mustelids, which have special scent glands to mark their territory.

3.In almost all estuaries the salinity of the water changes constantly over the tidal cycle. To survive in these conditions, plants and animals living in estuaries must be able to respond quickly to drastic changes in salinity.They must find a way to breathe underwater and intake the salt water, so amimals have adapted and grown gills. Gills allow them to breathe in the ocean water. Most animals have sleek bodies to swim through the water, the sleek bodies help cut down friction on the animal.

4.Interspecific Competition- is individuals of multiple species fighting over the same limited resource.
One example of interspecific competition is between harbor seals and american wigeon's. Both of these two species compete over various mollusks in estuaries.  

5 . Estuaries help maintain biodiversity by providing a diverse range of habitats that are critical for the survival of many species. Thousands of birds, mammals, fish and other wildlife use estuaries as places to live, feed and reproduce. Migratory birds use estuaries to rest and gain food during their journeys

Many estuarine habitats filter pollutants such as herbicides, pesticides, and heavy metals out of the water flowing through them. ... Habitats associated with estuaries, such as salt marshes and mangrove forests, act like enormous filters.