Coevolution Mechanisms in the Estuaries

Camouflage- Small fish are common pray in the estuaries. In order to not be eaten, some fish have avoided being meals by the use of camouflage. This rock goby, (Gobius paganellus) has the advantage of its skin being similar color to the rocks in shallow water, making it less detectable by the eye of predators. 



Mimicry- Some animals may use mimicry to avoid being eaten, or to drag in pray. mimic octopus are a type of octopus that use there tentacles to mimic the actions of another animal, tricking their opponent. It is common for a mimic octopus to mimic a banded sea snake to scare off a damselfish, which is a predator of the octopus.

The phosphorus cycle in estuaries

The carbon cycle in estuaries

Water Cycle in Estuaries

Nitrogen cycle in Estuaries

Oyster Drills as introduced species

While aquaculture species such as the Japanese oyster, Crassostrea gigas, were introduced intentionally, they also brought with them many undesirable hitchhikers, including oyster drills. Oyster drills are small predatory snails that use there drill to bore in small shellfish. These shelfsih are then destroyed, and Oyster drills are most prevelently taking out the american oyster. Not only does this hurt the food web, but also the local economy.

Predators of Estuaries

Bull Sharks are a common predator of hardhead (Arius felis) and gafftopsail (Barge marinus) catfish.



The Bonnethead Shark is a common predator of Swimming crabs, octopuses, squid, fishes, and shrimp



The Great Blue Heron is a common predator of estuaries, eating mostly small fish and amphibians like frogs.

Competitive

Many types of snails and oysters are only able to survive on hard surfaces like rocks. This is a stable area where they can be safe and have available food. The snails and oysters compete food available space, and when one dies many others compete for the new area. 

Parasitism

oysters are very common in Estuaries. Boring spongers, a type of sponges found in estuaries, are a parasite. They will drill trough the shell of the oyster, but will not actually eat the oyster. However, this process is known to kill the oyster.

Commensalism

Sharks are very fast swimming creatures. Sometimes, small fish are able to attach to the otter for a short period of time. This doesn't affect the shark, however the fish is able to get a quick ride to somewhere whereas normally it would take longer and it would have no protection.

Mutualism

In estuaries, sea anemones and clown fish are able to help each other. The sea anemones providers shelter for the clown fish, as most fish are prone the the sting of sea anemones. When the sea anemone stings a fish, the clown fish is able to eat the remains, providing food for the clown fish and cleaning the area of the sea anemone. Clown fish can even attract food to the sea anemone by having other fish notices its bright coloration. 

Biotic and Abiotic Features

Some biotic features would be Bristle Grass (Setaria megaphylla) or Irrawaddy Dolphins (Orcaella brevirostris).  Abiotic Features would be the Precipitation, that can vary between 100mm and 1000m. Another abiotic feature is temperature. Like precipitation, estuaries are incredibly varied in temperatures. The Amazon estuary in the summer can reach 100 degrees Fahrenheit while an Alaskan estuary in the winter may be -30 degrees Fahrenheit.

Estuary Soil Types

Peat/Salt Crust

• The top soil layer found in an estuary or salt marsh is composed mostly of peat or salt crust. In dense areas with higher concentrations of organic material, this layer will contain undecomposed plants and sea animals. Invertebrates are an integral part of this type of soil creation, helping to break down the peat ingredients into plant nutrients.

Clay

• Clay is an interesting and ever-changing soil. On an atomic level, the negatively charged particles that make up clay tend to repel each other. Yet, it is these negative charges that allow the soil to attract positive particles such as the nutrients of potassium and magnesium. Upon drying, the soil cracks and breaks apart, providing habitat for flora and fauna.

Yellow Earth

• Yellow soils, ranging from sand to clay loams, are produced by high concentrations of sulfur. The existing sulfur oxidizes, producing a butter-yellow appearance. These soil types are extremely acidic in pH. Sometimes the soil can become too acidic, due to water table depth and water salinity, providing additional challenges to plant life proliferation.

Alluvial

• Alluvial soils are found in floodplain areas. These soils are quite rich in nutrients. They exist due to the erosion of small particles washed down from higher areas and deposited into an estuary or delta. These fine particles, a compilation of sand, clay and silt, are called alluvium. Alluvium contains potash, lime and phosphoric acid, all which are beneficial to plant life.

Endangered Species of Estuaries: Light-Footed Clapper Rail

Light-Footed Clapper Rails

• The light-footed clapper rail was placed on the Endangered Species List in 1973. This brown bird about the size of a chicken lives along the coasts of southern California and northern Baja, Mexico. Human development is this bird's main threat. Housing developments and marina dredging have reduced its habitat, and the runoff from development continues to impact what habitat is left.

Average Monthly Precipitation and Temperature for Estuaries around Tokyo and Nagasaki

Estuary Food Web

Bristle Grass

Setaria megaphylla

Cordgrass

Spartina

Estuary Mangrove

Rhizophora mangle

Estuary Saltwort

Batis maritima

Estuary Sea Grass

Posidonia australis 

Estuary Sea Otters

Enhydra lutris

Estuary Bowhead Whale

Balaena mysticetus

Estuary Giant Brazilian Otter

Pteronura brasiliensis 

Estuary Irrawaddy Dolphins

Orcaella brevirostris

Estuary Dugongs

Dugong dugon

Estuaries Video