Ecology and Environment Notes Part 2 – Ecosystem and Wetlands

  • Post category:Environment

Energy Flow in Ecosystem

  • Ecosystem obtains energy from the sun, which, is trapped by producers via photosynthesis and is converted into chemical energy.
  • The chemical energy is converted into mechanical and heats energy in cellular activities.
  • Energy enters is the ecosystem as light and exits as heat.
  • Energy flows in a one-way direction through ecosystem i.e. not recycled
  • Herbivores are primary consumers and can store only 10% of producers’ energy in their biomass and they use the remaining 90% in life activities.
  • In the same way carnivores store only 10% of the stored energy of herbivore.

Types of Ecosystem

Ecosystems are classified based on climate, habitat and plant communities.

  • Aquatic ecosystem: The aquatic ecosystem has been classified in several ecological ways. Based on salt content in water they are further divided into the freshwater, estuarine and marine ecosystem.
  • Terrestrial ecosystem: It is further divided into Forest, Grassland, Desert ecosystem and artificial ecosystems such as crop fields, gardens etc.

Aquatic Ecosystem

Based on salt content in water they are further divided into:

  • Wetlands
  • Estuarine and
  • Marine ecosystem

Wetlands

  • Wetlands are lands which, due to geological or ecological factors, have a natural supply of water – either from tidal flows, flooding rivers, connections with groundwater, or because they are perched above aquifers.
  • Wetlands are covered or soaked for at least a part, and often all, of the year and thus are intermediaries between terrestrial and aquatic ecosystems.
  • The periodicity of water level fluctuations is termed as hydroperiod and it is the key factor that determines the productivity and species composition of the wetland community. Generally, low-lying areas covered by shallow water and have characteristic soils and water-tolerant vegetation.
  • Wetlands occupy only 2 percent of the surface area of earth and they are estimated to contain 10 to 14 percent of carbon.
  • They may be either freshwater or saltwater (coastal).
  • Manmade wetlands: paddy fields, fishery ponds, Trapa & Euryale cultivation ponds and other aquaculture habitats.

Significance of Wetlands

  • Nutrient-rich and have high primary productivity.
  • Since they have both aquatic and semi-aquatic environmental conditions so support specialized vegetation and fauna. Often a prime breeding habitat for waterfowl, many migratory birds and other aquatic or semi-aquatic vertebrates.
  • Helps in controlling flood by holding excess water, and the flood water stored in wetlands then drains slowly back into the rivers, providing a steady flow of water throughout the year.
  • Serve as groundwater recharging areas.
  • Provide important commercial products, including wild rice and several types of berries (such as blackberries, blueberries etc.).
  • Hold sediments and accumulate soil slung the shoreline.
  • National Wetland Conservation Programme(NWCP) has been initiated for identified wetland which are at present 66 covering 21 states. Estuaries
  • An estuary (from Latin aestus, “tide”) is a semi-enclosed coastal body of water, which has a free connection with the open sea.
  • Nutrients from the river enrich estuarine waters, making estuaries one of the most biologically productive environments on earth and thus have more biodiversity in the unit area.
  • It is strongly affected by the tidal action which is an important physical regulator and an energy subsidy.

Estuaries

  • An estuary (from Latin aestus, “tide”) is a semi-enclosed coastal body of water, which has a free connection with the open sea.
  • Nutrients from the river enrich estuarine waters, making estuaries one of the most biologically productive environments on earth and thus have more biodiversity in the unit
  • It is strongly affected by a tidal action which is an important physical regulator and an energy subsidy.
  • Variability is a key characteristic of most of the estuaries. Since temperature and salinity vary spatially within estuaries, from nearly that of fresh water to that of the ocean and also on a daily cycle with the rise and fall of the tides so that organisms inhabiting such habitats are eurythermal and euryhaline.
  • They are transitional zones/ ecotones between the freshwater and marine habitats.
  • Examples include river mouths, coastal bays tidal marshes and bodies of water behind barrier beaches and extensive intertidal mudflats or salt marshes often border them.
  • They are considered in a “youthful” stage with regard to their productivity and often generate more fertility than they can use (P exceeds R), resulting in the export of nutrients and organic detritus into the ocean.
  • Outwelling: Movement of nutrient-rich estuarine water out to the sea.
  • Estuary provides the “nursery grounds” for most coastal shellfish and other fishes. e. g. Several kinds of commercially important shrimp live and spawn as adults offshore and come into the estuaries as larvae.
  • Fishes such as salmon and eels also depend on estuaries where they may reside for considerable lengths of time during their migrations from salt to fresh water.
  • Estuaries are also crucial feeding areas for many semiaquatic vertebrates, particularly waterfowl.

Mangroves

  • Found in tropical and sub-tropical land – sea ecotones.
  • They are potential “land builders” that help to form islands and to extend seashores.
  • Based on salinity, five zones of mangrove distribution are considered, namely euhaline, polyhaline, mesohaline, oligohaline and limnetic zones.
  • Indian coastline covers about 7500km and it accounts for 8% of the world’s mangrove area which is approximately 700,000 ha.
  • The Gulf of Kachchh & the Gulf of Khambhat constitute the major mangrove zones of the Gujarat Coast.

The significance of Mangroves:

  • Mangroves perform a variety of products as well as protective functions. The resilient mangroves protect the hinterland against cyclonic storms during cyclones, super cyclones, and ingress of seawater during tidal surges and other natural catastrophes acting as an effective shelterbelt.
  • Are considered as “land builders”. It is believed that the roots of mangroves secrete a substance, which modifies the coarse particles into fine ones and help in soil formation. The tangles of stilt roots also trap the sediments.
  • Support a range of interconnected food webs, which directly sustain the fisheries. Algae and detritus sustain shrimps and prawns, which provide a food source for fishes and prawns.
  • They are repositories of immense biological diversity. • The mangrove conservation programme was launched in 1987 and so far, 35 mangrove areas have been identified for intensive conservation and management in our county.
  • Sundarbans has been included in the world list of Biosphere Reserves by UNESCO.
  • A mangrove genetic resource centre is established in the Pichavaram mangrove area, Chidambaram, India where the endangered mangrove species are being conserved.

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