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The Sun and Inorganic Nutrients
Allochthonous Input
Autochthonous Input
Role Players (Functional Feeding Groups)
Aquatic Insects
Other Role Players
Hyporheic Zone
The Good Stream
The Fish: Bring it Full Cycle

The Hyporheic Zone
Indian River Gravel in Stream Channel

Unseen World Under The Gravel

  • The Hyporheic Zone: The area below the streambed where water percolates through spaces between the rocks and cobbles (Interstitial Space).
  • Home of Meiofuana (Animals smaller the 0.5 mm): Includes copepods, aquatic earthworms, rotifers, water bears, cladocerans, ostracods, midges, and early instars of other aquatic insects.
  • Mostly collector-gatherers or predators in this zone.
  • Many stoneflies live their entire aquatic life in the Hyporheic Zone.
  • Refuge for organisms during flood and drought. Can replenish a dewatered or scoured streambed with macroinvertebrates.
Insects and other Invertebrates drift in the current. This Drift varies in intensity but occurs continuously in rivers and streams.

Invertebrate Drift

  • All invertebrate groups represented in Drift.
  • It is a way for Invertebrates to Disperse Downstream: To repopulate areas, relieve population pressure, find other food sources, or get away from predators
  • Much of it may be Unintentional from accidental dislodgement or high river flows from storms.
  • Heaviest at Night; Peak around Sunset and Sunrise when Sight Feeding Predators (e.g., Fish) would have the hardest time seeing their Prey.
  • Juvenile Salmonids feed primarily on Drifting Invertebrates belonging mainly to the Scraper-grazer and Collector-gatherer Functional Feeding Groups.

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