Riverine%20Ecosystems

1
Riverine Ecosystems

• Energy sources allochthonous autochthonous
• Interrelated
• Utilized by different functional groups of
  organisms
• How do the relationships change from headwaters
  to mouth?

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X-section of a typical stream
Photosynthesis
Geology Temperature Nutrients Current
Photosynthesis
Detritus CPOM
Plants Algae
FPOM
1o Production
Grazers Collectors Shredders Predators
2o Production
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River continuum Concept (RCC)

• Vannote, R.L., G.W. Minshall, K.W. Cummings, J.R.
  Sedell, and C.E. Cushing. 1980. The River
  Continuum Concept. Can. J. Fish. Aquat. Sci.
  37130-137
• General outline of how a river changes along its
  length
• Physical dimensions
• Changing energy inputs
• Changes in community of organisms

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River Continuum Concept
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Shaded headwater stream, Ohio
www.epa.state.oh.us/dsw/wqs/headwaters/A-P6280010.
jpg
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Outlet to Crescent Lake, Pocono Watershed, Monroe
Co., PA
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What are some features of headwater streams?
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Hypothetical headwater stream conditions

• Typical of Eastern deciduous forest
• Flows through heavily shaded forest riparian
  canopy
• Narrow
• Stream bottom rocky or sandy depends upon
  geological characteristics of drainage

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Where does the energy come from?
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Hypothetical headwater stream conditions

• Low light low nutrients
• Low algal and macrophyte growth
• Mosses 1o primary producers
• CPOM from terrestrial environment enters strea
• Leaves (1o autumn), twigs branches
• Respiration exceeds primary production
• Heterotrophic stream reach
• Energy from terrestrial sources

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Which Guilds Should We See?
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Which Guilds do we see?

• Diversity of functional groups
• Shredders 35
• Collectors 45
• Grazers few to 5
• Predators 15
• Diversity pattern?
• large CPOM supports shredders
• FPOM generated by shredders and mechanical
  breakdown supports collectors
• No plants no grazers

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Headwaters fishes
Brown trout

• Minnows
• Trout
• Sculpins
• Other fishes tolerant of seasonal and daily cold
  temperature regimes

Sculpin
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Mid-reach streams Salmon and Lemhi in Idaho
www.lewisandclarkpictures.com/
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How should conditions change in the mid reaches?
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Mid-reach Conditions Structure

• Stream wider, bottom well lit, temperatures and
  nutrients increased
• Stream bottom rubble, rocks, pebbles with sand
  and silt in low current areas

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Where does the energy come from?
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Mid-reach Conditions Energy

• Bottom algae proliferate (filamentous greens or
  diatoms)
• Where protected -gt sediment accumulates and
  rooted aquatics grow
• Primary production gt respiration autotrophic
  reach

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What FFGs do you expect to find?
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Mid-reach functional groups

• Collectors 50 export of FPOM from headwaters
  that generated in mid-reach
• Shredders 5 low input of CPOM
• Grazers 30 more algae on stream bottom
• Predators 15
• Export of FPOM to lower reach

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Mid-reach fishes

• Typically tolerate wider fluctuations in daily
  and seasonal temperature
• Overlap with some headwater species
• Examples
• Trout
• Suckers
• Minnows

Blue suckerfish
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Lower reach river Confluence of Snake
Columbia River at Oregon/Washington Border
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What physical features do you expect in lower
reaches?
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Lower Reach Conditions Physical

• Slow-flowing, deeper, lake-like
• Increased turbidity fine-grained, shifting
  bottom

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Where does the energy come from in the lower
reaches?
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Lower Reach Conditions Energy

• No sunlight on bottom no algal growth
• Autochthonous production from phytoplankton
  macrophytes along the margins
• Terrestrial input of CPOM small
• Water column has high FPOM from mid-reach
• Respiration gt primary production -gt heterotrophic
  reach

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Which FFGs do you expect in lower reaches?
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Lower Reach Functional Groups

• Collectors (filterers gatherers) 85
• Sediment dwellers mollusks or dipteran larvae
• Shredders and grazers absent lack of CPOM and
  periphyton
• Predators 15

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Lower Reach Fishes

• Adapted to environments where temperatures
  fluctuate widely
• Suckers
• Carp
• Chubs

Exotic
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Problems with RCC

• Different geomorphologies
• Shorter streams in New Zealand CPOM flushed by
  floods, few shredders in many streams
• Western US streams in dry areas often less
  shaded, even in headwaters
• Anthropogenic changes to streams interrupt
  continuum
• Logging or removal of riparian vegetation
• Damming change in temperature depending whether
  water release is surface (warm) or bottom (cold)

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Reset mechanisms

• Changes in a river below a confluence
• Makes receiving stream more like a stream higher
  in the continuum
• FFGs closer to that of tributary
• Will revert below the inlet of the tributary
• Removal of riparian buffer in headwater
• Change to pattern of mid-reach

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Hyporheic community

• Organisms occurring in the interstitial spaces
  between rocks and stones on bottom
• Examples insect larvae
• Stoneflies (Plecoptera)
• Midges (Chironomidae)

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Water on the Web

• This presentation includes material from Water on
  the Web (WoW)
• WOW. 2004. Water on the Web - Monitoring
  Minnesota Lakes on the Internet and Training
  Water Science Technicians for the Future - A
  National On-line Curriculum using Advanced
  Technologies and Real-Time Data.
• http//WaterOntheWeb.org).
• University of Minnesota-Duluth, Duluth, MN 55812.
• Authors Munson, BH, Axler, R, Hagley C, Host G,
  Merrick G, Richards C.
• I would also like to thank Dr. Jewett-Smith for
  her contributions to this presentation