AUTOTROPHS

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AUTOTROPHS

• Periphyton (Aufwuchs)
• Phytoplankton
• Macrophytes
• Vascular plants (aquatic angiosperms)
• Non-vascular plants
• Large periphyton
• Green algae
• Chara

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Periphyton

• Virtually all surfaces receiving light in rivers
  streams can sustain a periphyton community
• Epilithon (rocks)
• Epidendron (wood)
• Epipelon (fine sediments)
• Epipsammon (sand)
• Epiphyton (other plants)
• Epizoon (aquatic animals)

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Dominant Periphyton Taxa
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After 1 month in the dark
Cleaned stone at start
After 2 months in the light
After 3 months in the dark
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Cladophora (Chlorophyta)
Cladophora crispita
Courtesy Protist Information Server
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Cladophora filaments may reach one meter in
length and thick mats may form on benthic surfaces
http//www.owwrc.com/AA.htm
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Seasonal Progression of Periphyton Species
Winter Dominants Spring Dominants Summer Dominants Fall Dominants
Achnanthes Hydrurus Cymbella Diatoma
Meridion Ulothrix Melosira Synedra
Gomphonema Phormidium Chamaesiphon Cocconeis
Navicula Oscillatoria Navicula
Diatoma Ulvilla Melosira
Synedra Cladophora
Cocconeis
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Diatoms (Bacillariophyta)

• Silica shell (frustule) composed of two lid-like
  valves
• Golden brown color that colors stream rocks
• Very old (400 million years)
• gt7,500 N.A. species
• Primarily vegetative reproduction until cells
  reach a minimum critical size
• Species are specific to the habitats in which
  they grow

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Diatom Structure
Pennate (bilateral symmetry)
Striae arranged linearly
Valve view Girdle View
Centric (radial symmetry)
Striae arranged radially
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Factors Affecting Distribution of Periphyton

• Temperature
• Hard to separate from effects of light, which is
  also low in winter
• Occurrence cold water hot springs
• Diatoms are more abundant in cold water
• Light
• Can be a limiting factor in small streams with
  dense canopy cover

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headwater tributaries, Deschutes River, WA
From Bilby and Bisson (1991)
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Primary production as a function of light
intensity
(after McIntire and Phinney, 1965)
Shade-adapted community (- - -) developed at 2500
lux the light- adapted community ( ) at 6000
lux.
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Rate of O2 production by algal communities In lab
streams at different temp. light
Light Intensity (lux) Net O2 Evolved (8-10 oC) (mg/m2-hr) (18-18.5 oC)
25,500 226 361
16,700 200 331
11,400 180 439
7,400 201 182
4,300 121 208
2,150 133 58
1,180 42 59
620 44 -62
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Factors (continued)

• Current
• - Affects
• Particle distribution attachment sites
• Nutrient availability physiological richness
• Force on organisms
• - Can select for certain species
• - Can select for attachment strategies within the
  same species (e.g., erect vs. prostrate position)

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Mean monthly chlorophyll declines with discharge
in a New Zealand stream
Chl a
R2 0.711 P lt 0.001
Flood frequency

• Chl a lowest at sites with frequent floods (gt15
  per year)
• Chlorophyll variation F(frequency of floods,
  catchment
• in intense agriculture, alkaline rocks in
  catchment

From Biggs (1995)
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Force exerted by the Current

• d
  
• Flow Index ? Fi
• 
  i 1 i
• where Fi max. daily Q i days prior to
• sampling
• d days in sampling
  interval
• example 100cfs/1 day ago vs. 100cfs/20
  days ago

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Flow Index and periphyton accumulation rate
Carnation Creek, Vancouver Island
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Effect of Current on Algal Growth in Lab
Species Current (15-30 cm/sec) Aerated Still Water
Tetraspora lubrica
Microspora stagnorum
Stigeoclonium tenue O
Oedogonium kurzii O
Spirogira sp.
Pinnularia sp. O
Batrachospermum sp. O
Lemanea australis O
Mougeotia sp.
good growth growth o no growth or
death
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Current effects may also lead to vertical zonation
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Factors (continued)

• Grazing
• Gastropods, insect larvae (water pennies riffle
  beetles), crustaceans herbivorous fish
• Can be locally important
• Elimination of grazers can result in rapid
  increase in periphyton biomass

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Invertebrate grazers affect periphyton biomass
Mean algal biomass in the grazing experiment. 0
initial stone samples -1N non-insecticide-treat
ed stones 1N insecticide-treated stones.
In lowland Danish streams From Kjeldsen (1996)
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Factors (continued)

• Nutrient Availability

R2 0.561 Plt0.05
R2 0.948 Plt0.001
Cellular N
Cellular N
catchment in hard rock
catchment in agriculture
In 16 New Zealand stream sites
From Biggs (1995)
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Autotrophy/Heterotrophy

• Headwaters
• turbulent
• shaded
• cool
• Orders 4-6
• wider stream
• less turbulence
• periphyton become more important

Heterotrophic
Respiration
P/R 1
Autotrophic
Photosynthesis
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Autotrophic Index (AI)

• Means for determining the trophic state of the
  periphyton community
• AI Biomass (AFDM) (mg/m2)
• chlorophyll a (mg/m2)
• Normal values 50-200 gt200
  heterotrophic conditions or poor water quality

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Study of Periphyton

• Units individuals/area or biomass/area
• Glass slides placed in stream
• Some species dont grow well
• Ceramic tiles
• Sampling directly from stones

Artificial substrates
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Bryophytes

• Have no lignin usually
• Are small, low-lying, (generally) moisture-loving
  plants
• Have no roots, only filamentous rhizoids
• Occurrence can be particularly dense in spring
  regions rich in CO2
• Favor turbulent flow

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Macrophytes

• Characteristics of lotic macrophytes compared to
  lentic macrophytes
• Smaller leaves
• Shorter petioles
• Shorter internodes
• Rarely produce floating leaves
• Often produce no (or few) flowers
• w/o seed production, reproduction is largely
  vegetative

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Chara and Nitella

• Macro-algae
• Very dense mats on slow moving water
• Chara has garlic odor when crushed

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Lotic macrophyte functions(angiosperms
Chara/Nitella)

• Provide habitat
• Supply labile organic matter
• Trap organic matter washed from upstream
• Remove NO3 from the water (0.56 1.14
• g N/m2-day)

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• South Saskatchewan River (Carr Chambers, 1998)
• biomass gt downstream of
• WWTF (no P removal)

• enrichment
• experiments suggest
• P-limitation
• used Potamogeton
• pectinatus in troughs
• installed on stream
• bottom

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Habitat partitioning occurs in stream
macrophytes (French Chambers, 1996)
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Rooted plants create their own instability
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Phytoplankton

• Not very important in low order streams
• Are washed out of the reach quickly
• Inverse relationship between Q and phytoplankton
• Lower river reaches have more phytoplankton
  however, even in large rivers phytoplankton
  productivity is several times lower than that in
  a lake.

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Autotrophic Production Rates
Periphyton 0.01-0.1 gC/m2-day (shade) 0.25-2.0 gC/m2-day (sun)
Submersed Macrophytes 3 gC/m2-day
Emergents 10-20 gC/m2-day