Biological Stream Functions

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Biological Stream Functions
Eve Brantley, Alabama Cooperative Extension System
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Stream Functions

• Transport water
• Transport sediment
• Transport energy
• Aquatic organism habitat
• Terrestrial organism habitat

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• General stream characteristics
• River Continuum Concept
• Stream biology basics
• Floodplain functions values
• Importance of Restoration

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Restoration

• Projects need an interdisciplinary team stream
  restoration is more than just altering the size
  and shape of the channel.

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• Change in energy as streams flow from
• headwaters to mouths

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Stream Gradient

• Headwater streams are typically small with
  greater velocity and a steeper gradient

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Stream Gradient

• As these streams flow downhill, they meet up with
  other streams becoming a bigger slower moving
  body of water with less gradient

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Stream Order

• Streams within watersheds are often classified
  hierarchically
• Segments can be categorized by their order in the
  system

A stream to one person may be considered a river
by another, good communication tool
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• The smallest headwater streams are first order

Stream Corridor Restoration Principles,
Processes, and Practices, 10/98, by the Federal
Interagency Stream Restoration Working Group
(FISRWG)."
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• The union of two first order streams creates a
  second order stream

Stream Corridor Restoration Principles,
Processes, and Practices, 10/98, by the Federal
Interagency Stream Restoration Working Group
(FISRWG)."
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• The union of two second order streams creates a
  third order stream

The union of two streams of order n creates a
stream of order n1
Stream Corridor Restoration Principles,
Processes, and Practices, 10/98, by the Federal
Interagency Stream Restoration Working Group
(FISRWG)."
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• Headwater streams are orders 1 3
• Mid-sized rivers are orders 4 6
• Large rivers are orders 7 12
• About 85 of all stream miles in the U.S. are
  first to third order streams close to 3 million
  miles.
• The Mississippi River is 12th order at its mouth.

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Stream Gradient

• The decrease in stream gradient and energy along
  a streams route to its mouth is accompanied with
  changes in habitat and ecological communities.

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The Concept of Connectivity
Headwater streams are especially susceptible to
watershed impacts
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River Continuum Concept

• Describes general changes in stream ecosystems
  from headwaters to the mouth
• Identifies connections between the watershed,
  floodplain, and stream systems
• Places site in context within a watershed,
  helping define and focus restoration goals

Stream Corridor Restoration Principles,
Processes, and Practices, 10/98, by the Federal
Interagency Stream Restoration Working Group
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River Continuum Concept
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In Stream Habitats
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Riffles

• Characterized by rapid flow carrying small
  particles in suspension, coarse sediments on
  stream bed, and removal of finer sediments

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Importance of Riffles

• Areas of oxygenation
• Highly diverse substrate and habitat
• Diverse macroinvertebrate population

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Pools

• Regions of slower water current characterized by
  the deposition of finer sediments

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Importance of Pools

• Refuge for fish during low flow, drought periods
• Rest stop and food area for fish
• Predator refuge for young fish

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What is living in the stream?

• Biological diversity abundance depends
• on diversity of available habitats

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Benthic Macroinvertebrates

• Benthic bottom dwelling organisms that live in,
  crawl upon, or attach themselves to the substrate
• Macroinvertebrate can be seen without a
  microscope, no backbone

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• Common benthic macroinvertebrates include
• insects (stonefly, dragonfly)
• annelids (aquatic earthworms, leeches)
• crustaceans (amphipods, crayfish shrimps)
• mollusks (clams and snails)
• 4 Functional Feeding Groups
• Shredders
• Grazers
• Collectors
• Predators

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Shredders

• Commonly found in leaf packs

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Collectors Filter Feeders

• Filter organic matter from water column

Caddisfly nets (philopotamids) in the current.
Common below dams.
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Grazers

• Feeds on periphyton attached to rocks, large
  woody debris

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Predators

• Feed on other organisms

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System changes with stream order

• Orders 1 - 3
• Riffles with intermittent pools
• Large substrate sediment size
• Riparian vegetation shades stream, minimizes
  growth of algae and other aquatic plants
• Coarse particulate organic matter from
  surrounding watershed important for stream
  ecosystem energy inputs

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• Cool water fish community
• Darters
• Shiners
• Macroinvertebrate community
• Shredders in leaf packs
• Collectors (filter feeders and gatherers)

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System changes with stream order

• Orders 4 6
• Ratio of riffles to pools decreases
• there are greater stretches of depositional areas
  in the river
• Substrate materials consist of more muds and
  lighter sediments
• Increased sunlight with wider channels, primary
  productivity increases
• Ecosystem shift to dependence on materials
  produced inside the channel upstream

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• Shift in fish community
• Greenbreast darter
• Banded Sculpin
• Macroinvertebrate community
• Collectors (filter feeders)
• Grazers

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System changes with stream order

• Orders 7 12
• Few riffles areas are present
• Bottom sediments consist of loose muds, silt, and
  organic detritus.
• Bordered by marshes and swamps
• Increased dependence on primary productivity
• Continue receiving heavy inputs of dissolved and
  ultra-fine organic particles from upstream

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• Warm water fish community
• Catfish
• Sunfish
• Macroinvertebrate community
• Increase in plankton
• Decrease in macroinvertebrate diversity

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What can cause a loss of aquatic habitat stream
function?

• Increase in sediment loads embeds substrate
• Increase in temperature, decrease in dissolved
  oxygen
• loss of riparian vegetation
• widening of channel / shallow water
• Loss of bed features (pools and riffles)
• straightening of channel
• pools and riffles fill in with increased sediment

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Water Quality Impairments - AL

• Draft 2002 Alabama 303(d) list
• 43 of Total Impaired Miles due to siltation
• Sources of impairment include pasture grazing,
  urban runoff storm sewers, agriculture, and
  unknown

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How do we know?

• Measure stream health through
• Visual Assessments
• Chemical / Physical monitoring
• Bioassessments

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Bioindicators

• Aquatic macroinvertebrates are used to assess the
  relative health of a stream system and its
  watershed
• relatively immobile -they will take a hit with
  water pollution
• are easy to capture, relatively abundant and easy
  to distinguish
• have diverse communities with varying levels of
  tolerance to pollution

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• Hanging Rock Creek, NC
• Feeding Type Upstream Downstream
• Shredders 17 1
• Collector/gatherer 21 20
• Scrapers/grazers 27 38
• Predators 14 18
• Filter-Feeders 21 23

Courtesy David Penrose
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Pollution Tolerance Levels

• Highly sensitive to pollution or stream habitat
  alteration

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Pollution Tolerance Levels

• Wide range of tolerance to pollution or stream
  habitat alteration

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Pollution Tolerance Levels

• Generally tolerant of pollution or stream habitat
  alteration

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EPT Index

• This measures the total number of species within
  the orders Ephemeroptera (mayfly), Plecoptera
  (stonefly), and Trichoptera (caddisfly)
• Mayflies, stoneflies, and caddisflies generally
  require high levels of dissolved oxygen
• A high EPT Index generally indicates a stream and
  watershed with low disturbance and pollution
  levels

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Adaptations to Living Underwater

• Oxygen Gradient
• Tube breathers (atmospheric O2)
• Cutaneous breathers (dissolved O2)

Rattailed maggot telescopic respiratory tube used
to obtain air from the surface
External gills of mayfly nymph obtain dissolved
oxygen from water
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Riffles

• Life in a riffle means special adaptations to
  keep from drifting downstream
• Clingers / Sprawlers
• Tarsal or anal claws
• (stonefly nymphs)
• Attachment discs
• (water penny / black fly)
• Streamlined bodies and orientation to flow

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Pools

• Adaptations to slow moving water (less dissolved
  oxygen)
• Dragonfly - anal gills ventilation by repeated
  intake and expulsion of water from the rectal
  chamber
• Midges - possess a form of hemoglobin that
  enables them to utilize small amounts of D.O.

Blood Worms
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Index of Biotic Integrity

• Comprised of fish community parameters or metrics
  divided into categories
• Species richness composition
• Trophic structure
• Indicator species
• Abundance and condition
• Assists in quantifying changes in ecosystem
  health resulting from habitat degradation, flow
  alteration, and poor water quality
• There are regional differences in IBI metrics

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Cahaba River
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Need for Restoration
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Suspended Sediment Effects

• Clay particles can coat biologically active
  surfaces of plants and animals
• Can abrade and suffocate periphyton and
  macrophytes
• Reduced light penetration
• Disrupt respiration and behaviors (feeding and
  reproduction)

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Suspended Sediment Effects

• Macroinvertebrates, fish eggs and fry in
  interstitial spaces may suffocate
• Migrating fish will avoid streams with high
  turbidity

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Suspended Sediment Effects

• Some states have turbidity limits of 5 to 25 NTU
  above background (Ala. 50 NTU) which translates
  into about 3-7 mg/L of suspended sediment
• 5 NTU has been shown to be deleterious to some
  aquatic organisms

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• Loss of riparian vegetation means loss of
  important 1-3 order habitat
• Increased sediment loads embeds substrates, loss
  of feeding and habitat area

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Restore Stream Functions

• Narrow stream channel
• Increase water velocity
• Deeper water depth
• Improved aeration
• Diversify bed features
• Diversity of substrate sizes
• Create pools and riffles
• Replant riparian corridor
• Energy source
• Stability for streambanks
• Shade

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Restore connection with floodplain
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Stream Functions

• Transport water
• Transport sediment
• Transport energy
• Aquatic organism habitat
• Terrestrial organism habitat

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Floodplain Functions

• Floodwater Storage

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Flood Hazards
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Floodplain Functions

• Floodwater Storage
• Sediment Storage

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Floodplain Functions

• Floodwater Storage
• Sediment Storage
• Channel Stability

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Floodplain Functions

• Floodwater Storage
• Sediment Storage
• Channel Stability
• Habitat

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Importance of Restoration

• With more pressure on streams from increased
  urbanization, functions and values are impaired
  or lost
• degraded water quality
• loss of habitat
• loss of water storage conveyance capacity
• decreased recreational aesthetic value

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Loss of Water Storage and Conveyance Capacity
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Loss of Habitat Decreased Recreational Value
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