Brackish water - Wikipedia
aquatic systems where water with a dissolved salt concentration of less than 1% by A habitat in which the fresh water of a river meets the salt water of the ocean . shelf separates the coastal zone from the vast volume of the ocean called the . Marine ecosystems are found in the saltwater of seas and oceans. Communities of plants and animals living in water are known as aquatic ecosystems. where a river meets the sea, such as San Francisco Bay, are part freshwater and part. LOCATION: Freshwater ecosystems include lakes, ponds, rivers, and streams. Lakes are large The place where fresh and salt-water meet is called an estuary .
The following sections describe the characteristics of these three freshwater zones. Ponds and Lakes These regions range in size from just a few square meters to thousands of square kilometers.
Scattered throughout the earth, several are remnants from the Pleistocene glaciation. Many ponds are seasonal, lasting just a couple of months such as sessile pools while lakes may exist for hundreds of years or more. Ponds and lakes may have limited species diversity since they are often isolated from one another and from other water sources like rivers and oceans. The topmost zone near the shore of a lake or pond is the littoral zone.
It sustains a fairly diverse community, which can include several species of algae like diatomsrooted and floating aquatic plants, grazing snails, clams, insects, crustaceans, fishes, and amphibians.
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In the case of the insects, such as dragonflies and midges, only the egg and larvae stages are found in this zone. The vegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks. The near-surface open water surrounded by the littoral zone is the limnetic zone.
The limnetic zone is well-lighted like the littoral zone and is dominated by plankton, both phytoplankton and zooplankton. Plankton are small organisms that play a crucial role in the food chain. Without aquatic plankton, there would be few living organisms in the world, and certainly no humans. A variety of freshwater fish also occupy this zone. This zone is much colder and denser than the other two. Little light penetrates all the way through the limnetic zone into the profundal zone.
The fauna are heterotrophs, meaning that they eat dead organisms and use oxygen for cellular respiration. Temperature varies in ponds and lakes seasonally. In between the two layers, there is a narrow zone called the thermocline where the temperature of the water changes rapidly.
This mixing also circulates oxygen throughout the lake. Of course there are many lakes and ponds that do not freeze during the winter, thus the top layer would be a little warmer. Streams and Rivers These are bodies of flowing water moving in one direction. The characteristics of a river or stream change during the journey from the source to the mouth.
The temperature is cooler at the source than it is at the mouth.
What is an Estuary? The Areas Where Fresh & Salt Water Meet Are Known As Estuaries
The water is also clearer, has higher oxygen levels, and freshwater fish such as trout and heterotrophs can be found there. Since there is less light, there is less diversity of flora, and because of the lower oxygen levels, fish that require less oxygen, such as catfish and carp, can be found. Wetlands Wetlands are areas of standing water that support aquatic plants. Marshes, swamps, and bogs are all considered wetlands.
Plant species adapted to the very moist and humid conditions are called hydrophytes. These include pond lilies, cattails, sedges, tamarack, and black spruce. Marsh flora also include such species as cypress and gum.
Wetlands have the highest species diversity of all ecosystems.
Many species of amphibians, reptiles, birds such as ducks and wadersand furbearers can be found in the wetlands.
Visit our gallery of wetlands imageswhich illustrate the amazing diversity of wetland ecosystems. The evaporation of the seawater provides rainwater for the land. Like ponds and lakes, the ocean regions are separated into separate zones: All four zones have a great diversity of species.
This causes ox bow lakes, caverns, and canyons. The place where fresh and salt-water meet is called an estuary. A unique place where two habitats come together is called an ecotone.
Because estuaries are usually shallow, sunlight can reach all levels of the water. Plants and algae are important to freshwater biomes because they provide oxygen through photosynthesis, and food for animals in this biome. In fact, that slimy scum you see on the surface of a pond or lake is lunch for many of your favorite aquatic animals, like turtles.
In fast streams and rivers many plants have special structures that keep them from being carried away by the water.
Some aquatic plants have strong roots that keep them anchored securely, while others have stems that bend easily with the movement of the water. Certain mosses are able to cling to rocks. Plants who live in still waters have different adaptations.
Aquatic Ecosystems | szsizu.info
Water lilies, algae, and duckweed float on the surface. Cattails and reeds grow along the shoreline of many freshwater ecosystems. Estuaries house plant life with the unique adaptation of being able to survive in fresh and salty environments. Mangroves and pickleweed are just some examples of estuarine plants. Many animals live in freshwater ecosystems.
Some need the movement of the stream or river water to survive. In fast moving waters animals that have to hold onto rocks and the bottom may have suction-cup like structures on their bodies. Others thrive in still water environments, like lakes. There are a variety of fish, birds, insects, amphibians, and crustaceans that make freshwater biomes their home. One important freshwater animal in the United States is the trout.
Many people love to fish for, and eat trout.Freshwater & Saltwater Dividing Line
Trout live in both streams and rivers. They eat fish and insects. Estuaries are rich in animal life and are often a protected area where juvenile creatures seek refuge. There are also a variety of animals who live in estuaries that people like to eat, for example clams, shrimp and lots of fish. Without freshwater biomes you and I would not be alive.