Stream Ecology II
1. Nutrients
2. Bioassessment
3. “Big Picture”
1. Nutrients
• Heterotrophs—obtain nutrients from food and
ingesting/absorbing water; usually limited by
C
• Autotrophs—often limited by macronutrients
(N & P, plus K, Ca, S, Mg)
• Often, N & P demand > availability, so nutrient
supply limits biological activity
Nutrients (2)
Nutrients (3)
Nutrients (4)
• Nitrogen
– ~1 mg/L, as influenced by humans
– ~0.1 mg/L, natural
– 40 to 90% is DON
• Phosphorus
– ~0.01 mg/L for PO4-3 (SRP)
– ~0.025 mg/L for TDP
Nutrients (5)
N-cycle
Nutrients (6) N-cycle
Nutrients (6): N Budget
Nitrogen budget for agricultural fields and riparian zones associated with the
Rhode River, Maryland (Peterjohn and Correll 1984). Units are kg/ha/yr.
Nutrients (7) P-cycle
Nutrients (8): P Budget
Phosphorus budget for agricultural fields and riparian zones associated with
the Rhode River, Maryland (Peterjohn and Correll 1984). Units are kg/ha/yr.
Nutrients (9)
• Transport and solute dynamics closely coupled with physical
movement of water
• For non-reactive solutes (ignoring subsurface exchange):
C
t
ΔC
with t
 u
C
x
ΔC
DS
 C
2
D
x
2
  C s  C 
mixing in
water mass
storage
C=concentration, t=time, x=distance, u=downstream velocity,
D=dispersion coefficient, Cs=storage zone, =storage coefficient
Nutrients (10)
• For reactive solutes (uptake and mineralization):
C
t
ΔC
with t
 u
C
x
ΔC
DS
 C
2
D
x
2
 cC 
1
z
bC b
mixing in uptake mineral.
water mass
C=concentration, t=time, x=distance, u=downstream velocity,
D=dispersion coefficient, c=dynamic uptake rate, z=depth,
b=mineralization rate, Cb=mass per unit area of immobilized
nutrient in streambed
Nutrients (11): N
Pristine:
~1 kg/ha-yr
Human-affected:
~9.4 kg/ha-yr, with 67% as
nitrate
80% of world’s variation due
to fertilizers
Nutrients (12): P
Pristine:
~1 kg/ha-yr
Agricultural:
~2 kg/ha-yr (row crops)
~2 kg/ha-yr for MSAtchafalaya River Basin
Inputs: fertilizers, manure,
and sewage sludge
Importance of Nutrients in Stream
Restoration
• Essential to ecologic function and integrity
• Typically nutrient-limited
• Pathways, budgets, and loadings are affected
by human activity and corridor condition
2. Bioassessment
•
To assess the biological integrity and composition of stream
points in relation to reference site (as defined here for use
in Ohio*)
•
To measure river condition relative to a “reference stream”
•
“River health” in the very broad sense that a healthy river is
one in good condition
Select examples
1. Index of Biotic Integrity (IBI)—fish
2. Invertebrate Community Index (ICI)
3. Qualitative Habitat Evaluation Index (QHEI)—physical
characteristics
*Dufour, K., M. Meehan, A. Van Kley, B. Weber, R. Will, I.Y. Yeo, with S.I. Gordon and M.M. Conroy, 2001,
Development and Change in the Big Darby Watershed, City and Regional Planning Regional Planning Studio.
Bioassessment (2)
Index of Biotic Integrity (IBI; 1)
• At a stream location, a score is given for each metric if it closely (5),
somewhat (3), or fails (1) to approximate the “reference site”
• With 12 metric scores, 60 is the maximum and 12 is the minimum
1. Total Number Species: direct diversity measure and general indicator of
environmental quality
2. Number of Darter Species/Percent Round-Bodied Suckers: site specific
species requiring clean water found in headwater or wading stream and
represented by round-bodied suckers in boating sites
3. Number of Sunfish Species/Number of Headwater Species: favor quiet
pools and in-stream cover; indicate degree of preservation of original
pools and riffles and channel components
4. Number of Sucker Species/Number of Minnow Species: relatively longlived and favor high environmental quality; serve as long-term indicators
of surrounding conditions
5. Number of Intolerant Species/Number of Sensitive Species: serve as
indicators of degradation; greater proportion of intolerant species
indicates less degradation
6. Percent Tolerant Species: serves as indicator of degradation; greater
proportion of tolerant species signifies a greater degree of degradation
Index of Biotic Integrity (IBI; 2)
7. Percent Omnivores: represents degree of disruption to the food base;
greater proportion of omnivores indicates greater environmental
degradation
8. Percent Insectivores: measures community integrity in the middle of the
food chain; fewer insectivores suggest depletion of insect food base and
therefore a greater degree of environmental degradation
9. Percent Top Carnivores/Percent Pioneering Species: measures fish species
at the top of the food chain; more carnivores suggest a greater food base
and therefore a relatively good community structure
10.Number of Individuals: excluding tolerant species, serves as a measure of
toxic sensitivity and total degradation
11.Percent Hybrids/Number of Simple Lithophilic Species: indicate levels of
stress and disturbance in stream reach; lithophilic spawners require clean
gravel or cobble and are a good indicator in non-headwater streams
12.Percent DELT Abnormalities: measures Deformities, Eroded fins, lesions or
tumors and usually indicate overcrowding, disease, or high levels of
toxicity
Invertebrate Community Index (ICI; 1)
• At a stream location, a score is given for each metric if it closely (6),
somewhat (4), less somewhat (2), or fails (0) to approximate the
“reference site”
• With 10 metric scores, 60 is the maximum and 0 is the minimum
1. Total Number of Taxa: species richness and diversity increases with warm
water stream quality; inverse relationship with drainage area
2. Number of Mayfly Taxa: pollution sensitive species; greater proportion of
taxa indicates higher environmental quality
3. Number of Caddisfly Taxa: main component in larger, unimpacted
waterways; wide range of pollution tolerances within taxa
4. Number of Fly Taxa: have wide range of tolerances to pollution; often only
organism collected under heavily polluted conditions - greater proportion
suggests lower stream quality
5. Percent Mayfly Composition: easily affected by even minor disturbances;
serves as measure of overall levels of stress and disturbance
Invertebrate Community Index (ICI; 2)
6. Percent Caddisfly Distribution: quickly absent under environmental stress;
serves as a measure of stream stress
7. Percent Tribe Tanytarsini Midge Composition: often predominant group at
minimally impacted sites; pollution tolerances are intermediate
8. Percent Other Fly and Non-insect Composition: includes non-insect
invertebrates such as worms, isopods, snails, etc.; main community
component in poor water quality conditions - greater abundance indicates
lower environmental quality
9. Percent Tolerant Organisms: tolerant to toxic and organic pollution;
greater proportion of organisms indicates lower overall environmental
quality
10.Number of Qualitative EPT Taxa: qualitative measure of habitat diversity
and water quality; measures richness of mayfly, stonefly, and caddisfly
taxa
Qualitative Habitat Evaluation
Index (QHEI; 1)
1. Substrate: measures substrate type and quality; takes into account
variables like parent material, embeddeness of cobble, gravel and
boulders and silt cover. The maximum score is 20
2. Instream Cover: measures instream cover type and amount. The
maximum score is 20
3. Channel Morphology: includes channel sinuosity, development, stability
and channelization; indicates the quality of the stream channel in relation
to creation and stability of the macrohabitat. The maximum score is 20
4. Riparian Zone and Bank Erosion: measures floodplain quality, extent of
bank erosion and the width of the riparian zone; serves as indication of
the quality of the riparian buffer and floodplain vegetation. The maximum
score is 10
Qualitative Habitat Evaluation
Index (QHEI; 2)
5. Pool and Riffle Quality: component measures include overall diversity of
current velocities, pool depth and morphology and riffle-run depth,
substrate and substrate quality; serves as indication of the quality of the
pool and riffle habitats. The maximum score is a combined 20 (12 for
pool, 8 for riffle)
6. Map Gradient: calculation of elevation drop through sampling area;
accounts for varying influence of gradient with respect to stream size. The
maximum score is 10
IBI, ICI, and QHEI
Application
Big Darby Watershed, Ohio
Comparison of Indices
Stream Visual Assessment Protocol
Version 2 (USDA-NRCS),
Qualitative Habitat Evaluation Index
(OH EPA), Rapid Bioassessment
Protocol (USEPA), and Qualitative
Physical Habitat Index (USEPA);
Hughes et al. (2010, JAWRA)
Biological Condition and Stress
Importance of Bioassessment in
Stream Restoration
• Rather than focus on specific taxa, relatively
rapid semi-quantitative protocols have been
developed to comprehensively characterize
the physical habitat structure of streams
(Reference, and various levels of impairment)
• Balance information content of candidate
indicators against the costs of acquiring the
information
3. “Big Picture”
“Big Picture” (2):
Hierarchical Organization
“Big Picture”
(3):
River Continua
“Big Picture”
(4):
River
Continua
“Big Picture” (5): Spatial Scales
(Minshall, JNABS, 1988)
“Big Picture” (6): Temporal Scales
(Minshall, JNABS, 1988)
“Big Picture” (7):
Hyporheic Zone
“Big Picture” (8): Urban Streams
“Big Picture” (9): Urban Streams
(Meyer et al., JNABS, 1988)
“Big Picture” (10): Urban Stream Syndrome
(Walsh, JNABS, 1988)
Importance of “Big Picture” in
Stream Restoration
• Appreciate connectivity and scale
• Hyporheic zone
• Special needs and opportunities of urban
streams