VPE 511: Environment and Environmental Hygiene (2+1)

AQUATIC ECOSYSTEM

• Aquatic ecosystem deals with water bodies and the biotic communities. It is either freshwater or marine.
• A pond ecosystem is a self regulating and self sufficient fresh water ecosystem. Here fresh water is stagnant, receiving water during rainy season.

• There are three region in this ecosystem
  • Littoral (surface of water with sunlight)
  • Limnetic (sunlight penerates into less deep water)
  • Profundal ( No sunlight with deep region)
• The various components of the ecosystem are as follow:
• Abiotic factors
  • The biotic components are temperature, light, water, organic and inorganic compounds like C,H,O,N,P, Ca, S and carbohydrates, proteins and lipids. The amount of minerals present at any time in the pond is called standing state.
• Biotic factors
  • Producers
    • They include phytoplankton (Ulothrix, Spriogyra, Oedogonium, Diatom and Zygnenna). There are larger plants like Marsilia, Vallisneria, Azolla, Eichhornia, Salvinia, Wolffia and Pistia.
  • Consumers
    • Primary consumers: They include Zooplankton, worms, protozoan and crabs (Herbivores).
    • Secondary consumers: They include insects, small fish which feed on herbivores.
    • Tertiary consumers: These are some fish, crane and hawks.
  •  Decomposers ( or) Micro consumers: These include Bacteria, fungi like Aspergillus and Pythium.

Ocean Ecosystem

• The Ocean ecosystem is larger than the other ecosystems on earth. Oceangraphy is the study of the oceans. There are two environments in the ocean. The open sea environment (pelagic -40 -50 feet from the surface) and deep sea environment) (Benthic).
• Two thirds of earth’s surface is marine water. In sea water, more salt and metals are present. Oceans are major sinks of CO₂, regulating biogeochemical cycles, hydrological cycles thereby earth’s climate.
• These are two major life zones-coastal zone and open sea. The coastal zone will be warm with nutrient rich shallow water. There is high primary productivity due to more nutrients and light. The open is the deeper part of the ocean.
• Abiotic factors
  • They include salt, organic and inorganic compounds O₂, light, temperature, tides and waves.
• Biotic factors
  • Producers: They include phytoplanktons, algae, angiosperms, grasses mangrove plants like Rhizophora, Avicennia and Sonneratia.
  • Consumers: There are three types of consumers:
  • Primary consumers: They include small fish, crabs, protozoans and prawns.
  • Secondary consumers: They include big fishes like herring, saat and markerel.
  • Tertiary consumers: They include very big fishes like cod, hedak, and whales.
  • Decomposers: They include Bacteria and Fungi.

Estuaries or Estuarine Ecosystem

• At the mouth of a river where fresh water and sea water meet, estuary is present. The estuary is always affected by tides of the sea. Mixing of fresh water and salt water helps the producers in the ecosystem to get more nutrients and energy. The organisms show wide range of tolerance to salinity and temperature because there are variations in the stream flow and tidal currents (eg. Tidal marshes and coastal bays).
• The abiotic factors are salt and organic and inorganic compounds. The biotic factors include macrophytes , microphytes and phytoplanktons. There are many endemic species. The consumers resemble marine ecosystem. There are migratory species of fishes eg., cels and salmons, These migratory fishes spend half of their life in salt water and half in freshwater. They get a lot of food in estuaries which are highly productive ecosystems.
• Since the estuaries provide more food for man and other animals, we have to protect the estuary ecosystems by all means.