Stream Fishes

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Stream Fishes
Source Bonar (2004)
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Native riverine fishes of North America
native spp. at risk
Source Karr et al. (2000)
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Spatial and Temporal Scales Important to Fishes
Gamma diversity
Beta diversity
Alpha diversity
Bailey and Li (1992)
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Riverine Habitat Constraints

• Headwaters
• small habitat size
• cooler
• gt O2
• high gradient
• gt hydraulic power variability
• Less kinetic energy for pool formation
• formed by scouring during bankfull flow
• important as refugia

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Fish Attributes - Headwaters

• Small body size
• less available cover
• demand for acceleration agility
• Body shape optimizes fitness ratio
• Body length/depth 4.5
• Streamlined round in cross-section
• Is correlation between cross-section shape of
  body and ability of fish to resist current

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Fitness Ratio is optimized in these riverine fish
species
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Riverine fish need ability to attain higher
maximum swimming speeds than do primarily lentic
species
Source Mackie (2001)
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Not all riverine fish are strong swimmers
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Benthic riverine fish may possess unique
adaptations
enlarged pectorals suction-like mouth
friction pad
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Headwater Fish Attributes (cont.)

• High metabolic rates
• Due to gt muscles
• High hemoglobin delivers gtO2
• Accumulate lactic acid 3-8x faster than mammals
• Higher Production/Biomass (P/B) ratio
• ( turnover )

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Source Schlosser (1990)
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Which is more important in structuring fish
communities?

• Physical (environmental) Factors?
• Ecological Factors?
• Community processes
• Trophic level interactions

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Environmental Factors Affecting River Fishes

• Oxygen
• since metabolism gtw/temp
• since O2 ltw/temp
• Temperature
• are temperature preferences
• distribution temperature
• tolerance temperatures
• rapid ?T can displace fish (normal safe magnitude
  6-8 oC)

Short-term problems
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Environmental Factors (cont)
Current Effects - Stream fish spend most of their
time positioned against the current. - maintain
position - easier respiration - Fish maintain
position in river by reference to fixed objects
on bank. - most downstream drift occurs at night
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Trout oriented upstream in a Black Hills, SD
headwaters stream
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Environmental Factors (cont)

• Instability of Flow
• Flow reduction isolated pools
• can expose fish to gtT, ltO2, predation by land
  animals
• fish adapted to this include creek chub, white
  crappie, bluegill, longear sunfish

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Environmental Factors (cont)

• Substrate
• important in most species only during breeding
• current velocity depth are more important
• Turbidity
• Some species cannot tolerate continuously turbid
  water

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Fish Diversity and Habitat Condition
Fish Species Diversity
Gorman Karr (1978)
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Black River, IN Fish community changes with
downstream habitat change
Gorman Karr (1978)
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Can you predict biotic (fish) distribution
according to physical gradients?

• Headwaters erosional substrate, few macrophytes,
  cool water
• Feeding Guilds benthivores, piscivores
• Downstream slow current, deposition, warm water,
  turbid
• Feeding Guilds detritivores, omnivores,
  piscivores, surface feeders

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Slope Rule
In a given bio-geographical area, rivers or
stretches of rivers of like breadth, depth and
slope have nearly identical biological
characteristics and very similar fish
populations - Huet
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Ecological Factors

• Predation Competition
• Resource partitioning
• ex. Vertical segregation of shiners (Notropis)
  in pools appear to be based on morphological
  behaviorial adaptations
• ex. Darters subdivide riffles horizontally on
  the basis of current substrate
• ex. Coho salmon force other salmonids to less
  desirable locations

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Fish Trophic Guilds N. America
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1. Predation Competition (cont.)
b) Longitutidal Pattern (from headwaters) Periphy
ton grazers Invert. Predators Piscivores Mud
eaters

• c) Body Size
• places limits on trophic specialization, life
  span reproductive capacity
• mean food particle size is 0.07 of fish length
  (higher in obligate piscivores)

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Ecological Factors (cont)

• Territoriality
• in calm water - - exhibited only during breeding
• in flowing water - - may occur at any time
• largest fish usually wins
• Most territoriality is intraspecific although
  some is interspecific
• ex. Sculpins will not share same stone with a
  loach

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Ecological Factors (cont)

• Trophic Level Interactions

(Power 1990)
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no piscivorous fish
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Fish Production Rivers vs. Lakes
Which is higher??
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Fish Production Rivers vs. Lakes
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