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Chapter 4 part 2 - Classifications of Aquatic organisms on the basis of their zone and occurrence
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Classifications of Aquatic organisms on the basis of their zone and occurrence

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Aartee Mishra
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  1. uatic Organisms 4 major types of organisms Plankton (zoo- and phyto) Nekton (fish, turtles, whales) Benthos (bottom-dwellers such as oysters) Decomposers (mostly bacteria) (microscopic) microscopic) Nekton Plankton Epifora Epifauna Infauna BENTHOS

  2. zooplankton and phytoplankton neuston nekton periphyton benthos

  3. 2 Littoral Zone Open-water Zone (Photic Zone) Deep-water Zone (Aphotic Zone)

  4. Abiotic Factors affecting Aquatic Ecosystems Light Solubility of gases varies w/ depth, particulate matter Co2 oceans as carbon sink, leads to acidificatiorn Photosynthetic organisms. Temperature Important component of carbonate shells varies w/ depth and season Convection Food for autotrophs O2 Solubility of solids/liquids Acidity Salinity pollutants Lower pH results in more metals soluble in water Certain level for which organisms adapted



  7. AQUATIC ECOSYSTEMS Aquatic ecosystems are classified based on their salt content. i) Fresh water ecosystems- The salt content of fresh bodies is very low, always less than 5 ppt (parts per thousand). E.g lakes, ponds, pools, springs, streams, and rivers ii) Marine ecosystems the water bodies containing salt concentration equal to or above that of sea water (i.e., 35 ppt or above). E.g shallow seas and open ocean iii) Brackish water ecosystems these water bodies have salt content in between 5 to 35 ppt. e.g. estuaries, salt marshes, mangrove swamp and forests. AQUATIC ORGANISMS .The aquatic organisms are classified on the basis of their zone of occurrence and their ability to cross these zones.

  8. i) Neuston: . These are unattached organisms which live at the air-water interface such as floating plants, etc. . E.g., beetles and back-swimmers ii) Periphyton: . These are organisms which remain attached to stems and leaves of rooted plants or substances emerging above the bottom mud such as sessile algae and their associated group of animals iii) Plankton: . This group includes both microscopic plants like algae (phytoplankton) arid animals like crustaceans and protozoans (zooplankton) found in all aquatic ecosystems,. except certain swift moving waters.

  9. iv) Nekton: This group contains animals which are swimmers. The nektons are relatively large and powerful as they have to overcome the water currents. cts (a The animals range in size- from the swimming insects (about 2 mm long to the largest animals, the blue whale. v) Benthos: . The benthic organisms are those found living in the bottom of the water mass. Practically every aquatic ecosystem contains well developed benthos. Factors Limiting . The Productivity of Aquatic Habitats Sunlight and oxygen are most important limiting factors of the aquatic ecosystems whereas moisture and temperature are the main limiting factors of terrestrial ecosystem