Types of Aquatic Ecosystem: There are two types of Aquatic Ecosystem.
Freshwater Ecosystems: Freshwater ecosystems cover 0.8% of the Earth's surface and contain 0.009% of its total water. Freshwater ecosystems contain 41% of the world's known fish species. Aquatic ecosystems perform many important environmental functions. For example: They recycle nutrients, purify water, attenuate floods, recharge ground water and provide habitats for wildlife.
Aquatic ecosystems are also used for human recreation, and are very important to the tourism industry, especially in coastal region.
There are three basic types of freshwater ecosystems:
Lentic:slow-moving water, including Pools, Ponds, and Lakes.
Lotic: rapidly-moving water, for example Streams and Rivers.
Lakes & pond Ecosystem: A pond is a place where living organisms not only live but interact with biotic & abiotic components.Ponds are often exposed to tremendous anthropogenic pressure which significantly affects the system.Lakes are usually big standing freshwater bodies.They have a shallow water zone called Littoral zone; an open water zone where effective penetration of solar light takes place, called limnetic zone and a deep water zone where light penetration is negligible, called Profoundal zone. Lands: areas where the soil is saturated with water or inundated for at least part of the time.
1. Producer Organisms: It includes submerged, free floating and amphibious macrophytes (like; Hydrilla, Utricularia, Wolfia, Azolla, Typha etc.) and minute floating and suspended lower phytoplanktons (like; Ulothrix, Spirogyra, Oedogonium etc.)
2. Consumer Organisms:
A. Primary consumers: These are zooplanktons (ciliates, flagellates, other protozoan, small crustaceans) and benthos.
B. Secondary consumers: These are carnivores like insects and fishes feeding on herbivores
C. Tertiary consumers: These are the large fishes feeding on small fishes.
3. Decomposers Micro – organisms like bacteria, fungi and actinomyctes.
Abiotic component: These are the inorganic as well as organic substances present in the bottom soil or dissolved in water. In addition, to the minerals, some dead organic matter is also present.
Lentic: Lake ecosystems can be divided into zones. One common system divides lakes into three zones (see figure). The first, the littoral zone, is the shallow zone near the shore. This is where rooted wetland plants occur. The offshore is divided into two further zones, an open water zone and a deep water zone. In the open water zone (or photic zone) sunlight supports photosynthetic algae, and the species that feed upon them. In the deep water zone, sunlight is not available and the food web is based on detritus entering from the littoral and photic zones. Some systems use other names. The off shore areas may be called the pelagic zone, and the aphotic zone may be called the profundal zone. Inland from the littoral zone one can also frequently identify a riparian zone which has plants still affected by the presence of the lake—this can include effects from windfalls, spring flooding, and winter ice damage. The production of the lake as a whole is the result of production from plants growing in the littoral zone, combined with production from plankton growing in the open water.
Wetlands can be part of the lentic system, as they form naturally along most lakeshores, the width of the wetland and littoral zone being dependent upon the slope of the shoreline and the amount of natural change in water levels, within and among years. Often dead trees accumulate in this zone, either from windfalls on the shore or logs transported to the site during floods. This woody debris provides important habitat for fish and nesting birds, as well as protecting shorelines from erosion.
Ponds:Ponds are small pools with shallow water, marsh, and aquatic plants. They can be further divided into four zones: vegetation zone, open water, bottom mud and surface film. The size and depth of ponds often varies greatly with the time of year; many ponds are produced by spring flooding from rivers. Food webs are based both on free-floating algae and upon aquatic plants. There is usually a diverse array of aquatic life, with a few examples including algae, snails, fish, beetles, water bugs, frogs, turtles, otters and muskrats. Top predators may include large fish, herons, or alligators. Since fish are a major predator upon amphibian larvae, ponds that dry up each year, thereby killing resident fish, provide important refugia for amphibian breeding. Ponds that dry up completely each year are often known as vernal pools. Some ponds are produced by animal activity, including alligator holes and beaver ponds, and these add important diversity to landscapes.
Wetlands:Wetlands are dominated by vascular plants that have adapted to saturated soil. There are four main types of wetlands: swamp, marsh, fen and bog. Wetlands are the most productive natural ecosystems in the world because of the proximity of water and soil. Hence they support large numbers of plant and animal species. Due to their productivity, wetlands are often converted into dry land with dykes and drains and used for agricultural purposes. The construction of dykes, and dams, has negative consequences for individual wetlands and entire watersheds.Their closeness to lakes and rivers means that they are often developed for human settlement.Once settlements are constructed and protected by dykes, the settlements then become vulnerable to land subsidence and ever increasing risk of flooding. The Louisiana coast around New Orleans is a well known example;the Danube Delta in Europe is another.