Limno Lec 2

  1. River Continuum
    • headwater vegetation is the source of energy for the stream
    • insects are divided into four functional feeding groups called shredders, grazers, collectors, predators
    • fallen leaves CPOM are consumed and smaller particles FPOM are released down the river
    • FPOM is consumed by collectors, grazers eat periphyton, predators eat other insects
  2. allocthonous
    • refers to external sources of organic material in rivers and streams transported in a dead or decaying state
    • primary productin is outside the system
  3. autochtonous
    • refers to the internal souces of organic material in rivers and streams through the photosynthesis of algae, macrophytes, and periphyton
    • primary production is inside the system
  4. headwaters
    • oligotrophic, cold, clear, low stream order (narrow width), steep gradient, V-shaped valley, shaded by riparian vegetation
    • PR<1 due to low levels of photosynthesis
    • zone of erosion of sediment
    • heterotrophic community
    • allochtonous energy souce
    • mostly riffles
    • 100-250 invertebrate species with shredders and collectors abundant
  5. shredders
    feed on CPOM produced from riparian vegetation
  6. collectors
    • feed on FPOM produced by shredders
    • filter-feeders, gatherers, and suspension-feeders
  7. midreach
    • zone of storage and transport of sediment
    • carry water from several tributarie
    • higher stream order so wider than headwaters
    • no overhanging vegetation leads to higher primary production
    • PR>1 so autotropic and autochtonous
    • channel becomes braided (small channels separated by small and often temporary islands)
    • moderate gradient
    • most species rich sectin of the river with 200-500 species with mostly collectors and grazers, but no shredders because no CPOM
  8. collectors
    feed on FPOM at the headwaters and at the midreaches where FPOM descended from headwaters
  9. large river
    • murky from a lot of FPOM and dissolved organic matter so not a lot of light can penetrate the water, leading to reduced primary production
    • heterotrophic community and homogenous habitat
    • mostly collectors, no grazers or shredders, and phytoplankton is the primary producer
  10. predators
    • founds in equal proportions throughout all sections
    • are carnivores who attack prey and pierce tissues ans suck suck fluids
    • at headwaters, mostly invertebrates
    • at midreaches, trout and bottom-grazing fish
    • at large river setting, aquatic beetles and bottom-feeding fish
  11. ultimate base level
    • where all stream erode towards
    • also called sea level
  12. acquatic insects
    • evolved in land, moved into headwater streams, and spread down to lower warmer settings
    • sorted into niches based on temperature
    • aquatic insects that metamorphose into flying forms represent a net loss of aquatic productivity
  13. grazers
    • eat periphyton
    • are either herbivores (graze surfaces for algae) or eat living cell and tissue fluid of filamentous algal cell fluids
  14. species richness in oligotrophic vs eutrophic lakes
    • oligotrophic lakes have little riparian vegetation and little or no periphyton; about 25-100 species
    • eutrophic lakes have limited insects and plants in the limnetic zone; about 10-50 species
  15. nutrient spiraling
    • refers to the use and re-use of energy as it descends a watershed
    • shredders eat CPOM then die, disintegrating to FPOM or DOM (dissolved OM); likewise predators can eat them
    • predators die and produce FPOM that in turn is taken up by collecters
    • same recycling occurs in all functional feeding groups
Card Set
Limno Lec 2
Lecture 2 Review