Chapter 8

• Table of Contents


  • Zooplankton
  • Benthic Macroinvertebrates
  • Composition and richness of plankton species and abundance of organisms in pelagic and litoral regions of lakes and reservoirs
  • Fish
  • Food webs and Food Chains
  • Bioindicators: Organisms as indicators of pollution in natural waters
• Zooplankton


  • Measure 0.3-0.5 mm in length
  • Important link in the food chain in all freshwater ecosystems, estuaries, oceans, and coastal waters
  • Feed on phytoplankton or bacterioplankton
• Types of zooplankton


  • Micro-zooplankton (protozoa & rotifers)
  • Meso-zooplankton (crustaceans, cladocerans, cycloploid & calanoid copepods)
  • Macro-zooplankton
• Zooplankton life cycle and reproduction

  • Depend on environmental factors such as water temp, food availability, levels of DO, and general conditions of water quality in aquatic ecosystems
  • Parthenogenesis - a reproductive strategy that involves development of a female (rarely a male) gamete (sex cell) without fertilization
  • Cyclomorphosis - phenomenon that occurs in zooplankton to change their morphology at different phases of seasonal cycle
• Spatial distribution and Seasonal cycle of zooplankton

  • Spatial variation and distribution depend on various physical, chemical and biological factors
  • Abiotic factors key factor: Current velocity, suspended organic particulate matter, the presence of pollutants and contaminants
  • Seasonal cycle: Biotic factors and abiotic factors
• Vertical Migration of zooplankton

  1. Zooplankton generally spends the day towards the bottom of the lakes and reservoirs and migrating the at night in the surface

  2. Reverse migration may occur to some species of zooplankton (Argyrodiaptomus furcatus and S. corderoi)

  3. Vertical distribution varies with the intensity of thermal stratification and circulation
• Latitudinal distribution of zooplankton


  • Cosmopolitan species such as calanoids
  • A small difference in tolerance to temperature, pH, and conductivity is probably enough to isolate species
• Interrelationships between phytoplankton and zooplankton

  • Succession in phytoplankton and zooplankton in temperate region lakes was expressed in PEG model
  • Tropical systems affected by hydrological cycles, high temperature and accelerated biogeochemical process are more dynamic and complex than temperate-region systems
• Diapause


  The period of arrested growth or development in the life cycle of the species during which the physiological processes like differentiation and reproduction are suspended
• Benthic Macroinvertebrates


  • Factors affecting composition, structure, and functioning: Substratum type, Current velocity, transportation of sediments, water temperature and DO levels
• Factors affecting fishery production of inland ecosystems

  • Introduction of exotic species, which alter food web
  • Eutrophication
  • Acute chronic water toxicity
  • Effects of morphological changes on aquatic ecosystems
  • Heat pollution
  • Reforestation of riparian forest
  • Changes in the fish species' reproductive areas
• Feeding groups of aquatic organisms

  • Herbivores
  • Carnivores
  • Detritivores
  • Omnivores
• Feeding-system types of aquatic organisms

  • Filter feeders
  • Collectors
  • Scrapers
  • Sediment collectors
• Bioindicators of pollution in natural waters

  • Macrophytes
  • Benthic macroinvertebrates
  • Planktonic organisms
  • Crustaceans
  • Periphyton
• Objectives of biological monitoring

  • Early assessment of the deterioration
  • Determining the impacts of episodic events
  • Detecting tendencies or cycles
  • Determining the effects from the introduction of GMOs