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Aquatic environments

Aquatic environments are diverse and include stratification of energy levels.

Freshwater

  • Lentic - still water ecosystems
  • Lotic - moving water ecosystems
  • Grazing food chain
  • Detrital food chain
Ecosystem
Stream ecosystem showing the multitude of organisms at all levels

Important Abiotic Factors

  • temperature
  • pH (acidity: low = more acidic, 7 = neutral, high = more alkaline)
  • DO = dissolved oxygen (related to BOD - biochemical oxygen demand, but a direct measurement of the amount of oxygen in water)
  • flow rate
  • substrate (bottom of the stream or river: hard or soft?)
  • nutrient availability

Evolution Review

The set of characteristics that enable an organism to succeed uder one set of environmental conditions limits ability to do equally well under differing conditions. e.g. organism in slow stream may not be successful in a fast flowing stream

As a result, areas that have similar environmental conditions should have a similar assemblage (community) of species. (see super-organism concept of succession as opposed to the individualistic concept of succession)

Exercise:

Choose one of the following organisms: learn the general facts about the organism, food source, common habitat, life cycle, etc.

Stonefly larvae
Stonefly larvae
Stonefly
Stonefly

Mayfly nymph
Mayfly nymph
Mayfly
Mayfly

Caddisfly larva
Caddisfly
Caddisfly larva
Caddisfly larva

Dragonfly larvae
Dragonfly larvae
Dragonfly
Dragonfly

Horsefly larvae
Horsefly larvae
Horsefly
Horsefly

Freshwater shrimp
Freshwater shrimp
Freshwater shrimp
Freshwater shrimp (female)

Characteristics of a water body: these need to be measured and recorded with each field trip

  • flow rate
  • depth
  • width
  • temperature
  • DO: dissolved oxygen
  • nutrients
River ecology
River ecology is a favourite activity in schools

Other considerations include biotic factors, vegetation type and abundance, and any zonation that is present.

Content © Andrew Bone. All rights reserved. Created : February 18, 2014 Last updated :August 21, 2015

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