Dr. Brad Austin
University of Arkansas
Exam 3 Study Guide
River Continuum Concept: In a river, from headwaters to mouth, the physical variables in a stream (width, depth, velocity, stream order) create a gradient of physical conditions, creating a continuum of biological features in the river, such as energy input, organic matter transport, and macroinvertebrate functional feeding groups.
Shredders: tear and eat coarse particulate organic matter (CPOM) for nutrition from microbial colonizers.
∙ Example: Crayfish
∙ Analogy: “Peanut butter on a cracker”
o Peanut butter = microbial biofilms
o Cracker = leaf
o The shredders get more of their nutrition from the microbial biofilm (PB) than from the leaf (cracker)
Scrapers: “Grazers” of biofilms and benthic algae
Collectors: Filter fine particulate organic matter (FPOM) from water flowing by ∙ Example: Simulidae (Black fly)
∙ Some collectors use nets, others use webs
∙ Collectors produce feces which is also FPOM, and is sometimes bigger than the FROM they consume
Predators: Eat other invertebrates We also discuss several other topics like How does the nervous system operate?
∙ Predators are common throughout almost every food web
Shredders, scrapers, collectors, and predators all produce FROM in the form of feces! Richness: the total number of different species per area
Evenness: how well the total number of organisms are spread between the total number of species (how equally represented)
Evenness = H′/lnS
It is ideal for both the species richness and species evenness to be high in an ecosystem.
Shannon-Weaver Diversity: a quantitative measure of diversity in a community which takes into account richness and evenness of species. Theoretically, the diversity index can be used to compare diversity between ecosystems
Don't forget about the age old question of What does premise mean?
Alpha Diversity: within-habitat diversity (example: riffle in a stream) Don't forget about the age old question of What is octet rule in chemistry?
Beta Diversity: between-habitat diversity (example: between 2 riffles)
Gamma Diversity: entire landscape diversity (whole stream)
A-D and E-H have the same overall diversity (gamma diversity).
E-H has greater alpha diversity (within ponds).
A-D has greater beta diversity (between ponds).
Playa: Round hollows in the ground created by wind scour that are filled with water (relatively small ) If you want to learn more check out What was the libor scandal?
Maar: Low relief volcanic crater created by the explosion of groundwater when it comes in contact with lava
Graben: parallel faults which caused the displacement of a block of land downward. This can sometimes form a lake (examples: Lake Tahoe and Lake George)
Oxbow: Occurs when a river cuts a channel and leaves behind a cut off meander
Reservoir: Mostly man-made impoundments of rivers We also discuss several other topics like What is meant by production possibility frontier?
∙ Some are natural
∙ Quake Lake is a natural reservoir (formed by a land slide)
If you want to learn more check out What is the structure and function of proteins?
Biodiversity: total variety of organisms found within a defined area
∙ High diversity = good condition
∙ Low diversity = poor condition
Biological indicator: a species whose population can reveal the condition of the community ∙ Good Indicators: taxa with narrow and specific tolerances
∙ Poor Indicators: taxa with wide tolerances to disturbances
% EPT = % of Ephemeroptero (may flies), Plecoptera (stone flies), and Trichoptera (Caddisflies) which are present out of the entire community sampled
o E = Ephemeroptero (may flies)
o P = Plecoptera (stone flies)
o T = Trichoptera (Caddisflies)
These taxa are the most likely to be impacted by changes in water quality because these species are sensitive to decreases in DO, fluctuating pH, and high temperature.
The greater the percentage the better the quality of water; the %EPT is used to compare impacted sites versus un-impacted sites
Example: Calculate the %EPT for this community
# of individuals within each family
25 + 50 + 15 = 90
(90/403) = 22.3%
Invasive Species: plants, animals, or pathogens that are non-native to the ecosystem and whose introduction to the ecosystem causes or is likely to cause harm
Stock: the abundance of a species of fish
Yield: the total amount of fish captured
Maximum Sustainable Yield: the largest yield, or catch, which can be taken from a species stock over an indefinite period. In most fisheries this is around 30% of the population size. However, this approach ignores the size, age, and reproductive status of the fish which are taken, which has led to the collapse of many fisheries
Functional Bio-indicators: consists of a systems capacity to process organic matter or cycle nutrients ∙ Decomposition rates
∙ Primary production and respiration (whole-stream/lake metabolism)
∙ Nutrient cycling
∙ Nutrient spiraling (a stream or reservoir concept): the water is moving downstream and taking nutrients with it
o Uptake and turnover velocities
Structural Bio-indicators: consists of identity and enumerating organisms in a system ∙ Macroinvertebrate community composition
∙ Algal community composition
∙ Individual organisms
o E. Coli
Pathogen: infectious agents that can cause disease
Total Maximum Daily Load: load of a contaminant that can enter a waterbody and the waterbody still meet WQ standards to protect designated uses
1. What is the River Continuum Concept? Be able to describe concisely the changes that occur in a river network as you move from headwater (low order streams) to large river (high order streams) with respect to abiotic conditions, basal food resources and macroinvertebrate communities.
River Continuum Concept: In a river, from headwaters to mouth, the physical variables in a stream (width, depth, velocity, stream order) create a gradient of physical conditions, creating a continuum of biological features in the river, such as energy input, organic matter transport, and use by macroinvertebrate functional feeding groups.
As the river network moves from lower order streams to higher order streams, the stream channel becomes wider and deeper, and the canopy cover decreases.
In first through third order streams there is high amounts of allochthonous organic matter (organic matter from outside the stream order), and shredders and collectors dominate while there are few predators and grazers.
In fourth through sixth stream orders, there is greater amounts of autochthonous organic matter (organic matter from inside the system – generally algal biomass), and grazers and collectors dominate while there are few shredders and predators.
In seventh order streams and larger, there is both autochthonous and allochthonous organic matter, and collectors dominate with few predators.
2. Be able to calculate alpha diversity using the Shannon-Weaver equation for a data set.
Pi = Number of a particular species/ total number of organisms (10/33=0.303)
H′ = 1.157
3. Compare and contrast the Riverine zone, Transitional zone and lacustrine zones for reservoirs. Be able to compare how water clarity, basal food resources, sediment type, and flushing rates change between zones.
Narrow, channelized basin
Broader and deeper than the riverine zone
Broad and deep (lake-like) basin
Relatively high flow and flushing rate
Decreasing flow and
Little flow and low flushing rate
High suspended sediments:
solids and turbidity
Low suspended solids (clear)
low light availability at depth
light availability at depth
high light availability at depth
High nutrients (nutrient supply by advection)
Advective nutrient supply is decreasing
Diffusive nutrient supply (nutrient supply is from
internal cycling); low nutrients
growth < flushing rate
light limited primary
phytoplankton primary production
growth > flushing rate
(nutrient-limited primary productivity)
Higher DO over sediments (cell losses primarily by
Cell losses by grazing and sedimentation
Fine benthic organic sediments (cell losses primarily by
Primary organic matter source is allochthonous
Organic matter comprised of both autochthonous and allochthonous matter
Primary organic matter source is autochthonous
Stratification does not occur in this zone
Stratification occurs in this zone
Stratification occurs in this zone
Allochthonous Organic Matter: from the watershed
Autochthonous Organic Matter: from within the lake or river
4. Briefly describe the different stages in the life and death of a reservoir.
1. Impound a river and the valley fills with water
2. Influx of inorganic sediments, and this begins to fill the lake. Nutrient loading from the watershed results in an upsurge period
a. Increased primary productivity
b. Increased primary consumers (zooplankton)
3. As a result, there is:
a. Increased planktivorous fish
b. Decreased zooplankton
c. Decreased DO due to greater biomass (greater swings between day and night DO)
d. Culminated in a stable period
4. Lake Decline
a. High biomass and low DO (results in decreased decomposition and benthos filling up with organic matter)
5. River valley continues to fill with inorganic and organic sediments and the lake transitions into a bog
6. Eventually the lake will fill completely with sediments.
5. Be able to calculate and determine stream impairment based on Coliforms and E. coli.
GM (cfu/100 ml)
STV (cfu/100 ml)
STV = Statistical Threshold Value (based on 36/1,000 probability of sickness)
Recommendation 36/1000 will become sick if exposed to GM concentrations
GM = Geometric mean (the nth root of a product of numbers). The geometric mean normalizes the range of data so that extreme values do not dominate the average
Can be calculated as (x1, x2, x3… xn)1/n
The GM should not be above the standard for a 30-day period.
STV cannot be exceeded in more than 10% of observations over a 30-day period
Example: Calculate the GM and STV values for this stream to determine if it is impaired.
E. Coli (cfu/100 ml)
Statistical Threshold Value
STV cannot be exceeded in more than 10% of observations over a 30-day period STV Maximum= 410 cfu/100 ml
1 observation exceeds the STV out of 13 observations
1/13 = 7.69%
This is less than 10% of all observations, so the stream is NOT impaired for STV
The GM should not be above the standard for a 30-day period
GM Maximum= 126 cfu/100 ml
(50 x 31 x 36 x 154 x 44 x 321 x 12,060 x 106 x 96 x 264 x 31 x 78 x 105)1/13 = 119.3 19.3 cfu/100 ml is less than 126 cfu/100 ml so the stream is NOT impaired for G
6. Be able to determine lake impairment based on chlorophyll and secchi measurements (In class assignment).
AA Secchi (m)
GM CHLA (ug/L)
Secchi disk depth must be greater than or equal to 1.1 meters
Growing season geometric CHLA concentrations must be less than or equal to 8 µg
The secchi disk depth and geometric mean for CHLA shall not exceed the standard in more than 1 out of 5 years (or 20% if there are more than 5 years of data)
7. Define relative weight. A higher value means what?
Relative weight indicates the body condition of the fish. Relative weight is based on the relationship between the length and the weight of the fish (the “fatter” the fish, the higher the relative weight). Relative weight is calculated by dividing the weight of the fish by the expected weight of what is considered a healthy fish based on that length.
8. Which of the following structures can be used to age a fish?
9. What is maximum sustainable yield? What are some problems with using MSY to manage a fishery?
Maximum Sustainable Yield is the largest yield, or catch, which can be taken from a species stock over an indefinite period. In most fisheries this is around 30% of the population size. However, this approach ignores the size, age, and reproductive status of the fish which are taken, which has led to the collapse of many fisheries
10. What are the three components of a fishery?
11. Be able to calculate TMDL from a hypothetical scenario (Homework #6)
lnSD = 2.04 – 0.68lnChla
SD = Secchi depth (m)
Chla = Chlorophyll-a (ug/L)
Log10Chla = 1.583log10TP – 1.134
Chla = Chlorophyll-a (ug/L)
TP = Total phosphorus (ug/L = mg/m3)
TP = L / (z(ρ + σ))
L = average annual TP (ug/L)
Z = average depth of the lake (m)
ρ = flushing rate (y—1)
σ = sedimentation rate (y—1)
TMDL = WLA + LA + MOS + BC
TMDL = Total Maximum Daily Load
WLA = Waste Load Allocation
LA = Load Allocation
MOS = Margin of Safety
Example: Assuming that Lake Fayetteville, an Ozark Highland lake, has average depth of 5 m, flushing rate of 0.5 year-1, and a sedimentation rate of 0.5 year-1, and a surface area of 600,000 m2, what is the maximum annual P loading rate (kg P year-1) that can enter the lake so that the average annual secchi depth does not fall below 1.5 m?
Convert the maximum annual P loading rate from the previous question into a Total Maximum Daily Load. Assuming that there is no waste load (WLA) to Lake Fayetteville, that the Margin of Safety (MOS) is 20% of the TMDL, and that the background load from the watershed is 120 g/day, how much load allocation (LA) can be assigned to human non-point P sources?
Steps to Solving the Problem
1. Plug SD into first equation and solve for Chla (answer is in ug/L)
2. Plug Chla into second equation and solve for TP (answer is in mg/m3)
3. Plug TP into the third equation to solve for L (answer is in mg m2y—1)
4. Convert L to KgP y—1 by multiplying by the area of the watershed and dividing by 106 5. Convert the L (KgP y—1) to gPday—1 by multiplying by 1,000 and diving by 365 6. Plug the TMDL into the fourth equation to calculate LA (answer is in gday—1)
ln(1.5) = 2.04 – 0.68Chla
0.405 = 2.04 – 0.68lnChla
-1.63 = - 0.68lnChla
2.4 = lnChla
Chla = 11.06 ug/L
Log10(11.06) = 1.583Log10TP – 1.134
1.04 = 1.583Log10TP – 1.134
2.178 = 1.583Log10TP
1.3757 = Log10TP
TP = 23.75 mg/m3
23.75 = L/(5(0.5+0.5)
L = 118.75 mg m2y—1
L = 118.75 mg m2y—1(600,000) / (106)
L = 71.25 KgPy—1
L = 71.25 KgPy—1
71.25 KgPy—1/365 = 0.195 KgPday—1
0.195 KgPday—1 (1,000 mg/Kg) = 195 gPday—1
MOS = 195 gPday—1(0.2) = 39
TMDL = WLA + LA + MOS + BC
195 = LA + 39 +120
LA = 36 gday—1