Biology 612 Freshwater Ecology
Exam 1
Fall 2008
Name______________________________
1. List five distinct properties of freshwater systems that provide economic
value to humanity and mention why a purely economic argument for
conserving freshwater systems might miss an important reason for
protection our aquatic resources (7)
2. In contrast to large organisms such as fish, small aquatic organisms such
as rotifers lack circulatory systems for two overall reasons. 1) it costs
substantial energy to circulate fluids in a small organism and 2) they are
less likely to be diffusion limited. What is it about Reynolds numbers that
leads to point 1 and what is it about diffusion and size that leads to point
2? (5)
3. Fill in the blank. Small organisms generally do not streamline their body
shape because there is no evolutionary reason to avoid turbulence
because ___________ is high at small scales. A bacterium would glide
hardly at all relative to a whale because _____________ is low at small
Reynolds numbers. The low turbulence also means that ___________
diffusion predominates whereas at larger scales _____________ diffusion
dominates and rates are substantially greater. In streams the turbulence
effects on diffusion are important because water velocity is ___________
close to objects especially in pits. Lower water velocity leads to a thicker
____________ boundary layer, and inhibits diffusion. Thus, invertebrates
living in rapid water can have reduced _______________ because
diffusion rates are greater with more turbulence. This diffusion rate is
slower at _____________ temperatures, but metabolic rates are lower as
well, leading to overall reduced rate of invertebrate activity. Viscosity is
_______________ at lower temperatures, leading to greater energy to
move through water. (9)
4. Fill in the table (9) that indicates the apparent color of a fish lure with a
white stripe, a red stripe, and a blue stripe at 3 m depth in lakes of various
trophic states.
Lake
Oligotrophic
Oligotrophic
Oligotrophic
Stripe color at
surface
White
Red
Blue
Mesotrophic
Oligotrophic
Oligotrophic
White
Red
Blue
Eutrophic
Oligotrophic
Oligotrophic
White
Red
Blue
3 meters deep strip
color
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5. Rainfall patterns in the central U.S. are predicted to change due to altered
climate. Rainfall total amounts are not expected to vary much, but more
intense rain events, with longer periods between rains are expected. How
will this affect the variability of stream discharge and how might processes
happening on land magnify this variability (10)?
6. How can Langmuir spirals and internal seiches increase productivity in
lake surface waters? Where specifically would these areas of higher
productivity be located (6)?
7. Why is rRNA used to study the evolutionary relationships among
organism? Would conservative genetic sequences in rRNA be more
useful to differentiate (bacteria from archeae) or (calonoid from cyclopid
copepods) (5).
8. Define monomictic and polymictic in terms of lake stratification. Why can
both terms be used to describe Tuttle Creek reservoir stratification (8)?
9. List three types of lakes formed by glaciers (3).
10. What effect does watershed urbanization have on stream discharge?
How can this change in discharge regime alter biotic communities within
this stream (8)?
11. What two groups of aquatic organisms discussed in class are often used
as indicators of water quality? How do differences in their generation time
affect their usefulness in assessing pollution (6)?
12. In the diagram below, draw in the thalweg, areas of erosion and
deposition, and one place each where gravel and fine sediments will likely
be located. (8)
13. Areas of algal growth in this pond are marked by letters. Match each
letter with its correct habitat classification terminology. (6)
epilithic
epipelic
epiphytic
episammic
epizooic
pelagic
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14. Matching. (10)
comensalism _____
a) +/- interaction
dinoflagellate_____
b) -/0 interaction
photoautotroph_____
c) +/+ interaction
cnidaria_____
d) +/0 interaction
mutualism_____
e) CO2 carbon source
arthropoda_____
f) organic C carbon source
cyanobacteria_____
g) fix nitrogen with heterocysts
chemoautotroph_____
h) armor covered body, one flagella wraps around
body, one trails behind
exploitation_____
i) used in forensic science
diatoms_____
j) cart-wheeling hydra
amensalism_____
k) includes insects, daphnia, crayfish, and isopods
Biology 612 Freshwater Ecology test 2 Fall 2008
Name_______________________
1. Circle with or against to indicate which of the following chemical reactions go
with or against potential energy (10)
reaction
Photosynthesis
Nitrification
Nitrogen fixation
Biotic sulfur oxidation (from sulfide to
sulfate)
From reduced to oxidized iron
Anoxygenic photosynthesis (sulfide as
electron donor with sulfate as end product)
Respiration
Fermentation
Nitrate uptake (assimilation)
Denitrification
Environment
Oxic
Oxic
Anoxic
Oxic
With or against ?
With or Against
With or Against
With or Against
With or Against
Oxic
Anoxic
With or Against
With or Against
Oxic
Anoxic
Oxic
Anoxic
With or Against
With or Against
With or Against
With or Against
2. Why are the oldest lakes the most speciose (3)?
3. There was a oligotrophic lake, and by chemical treatment, all the sulfate was
removed. What would you expect to happen to the rate of pyrite formation in
anoxic sediments and to the levels of dissolved P in the water column (explain
why you think this will happen) (5).
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4. Diagram the sulfur cycle as presented in class with all pools and major fluxes
labeled (15)
5. What are the major adaptations to very hot environments for proteins, lipids, and
DNA and RNA (6)?
6. Why are lake depths of saline lakes often widely varying over time (3)?
7. Why are wetlands major sources of atmospheric methane, and have much greater
rates of methane emission per unit area than lakes, even though the lakes have
sediments with conditions suitable to methanogenesis (5)?
8. Describe the annual cycles of diatoms (Asterionella) and silica in the epilimnion
of Lake Windermere (6)
9. Why are anoxic oxic interfaces, such as those that occur in sediments, hostspots
of biogeochemical cycling (5)?
10. How do cyanobacteria protect the nitrogenase in heterocysts from O2, list at least
3 adaptations (6)?
11. Match the following (10)
Feature
Rachel Carson
bioremediation
Chronic exposure
LD50
Match
a. deadly gas release
b. concentration of toxins from the
environment
c. oligotrophic bogs, N limited
d. simple chemoautotrophic
communities
e. decreased pH
f. long term exposure
g. Silent spring
ecoestorgen
bioconcentration
Tropical amictic lake with CO2
supersaturated hypolimnion
Decreased degradation of recalcitrant h. hormone mimic
carbon compounds
Pitcher plants
i. dose at which half the population
dies
Deep subsurface groundwater
j. biological breakdown of toxins
12. Why is there worry that tropical mosquito-borne diseases will spread with global
warming (5)?
13. High altitude snow and neustonic habits have one extreme feature in common,
what is it (4)?
14. What form of inorganic carbon is dominant at a pH of:
pH 4: _______________
pH 8: _______________
4
250
200
Net Production (mg O
2
L-1 d-1)
pH 12: _______________ (3)
15. Why are snails in the Kansas Flint Hills more resistant to negative effect of acid
rain than snails in the northeastern U.S where limestone is less abundant in the
watershed (5)?
16. Draw two hypothetical curves for photosynthesis versus irradiance on the
following plot for a high and low light acclimated phytoplankton assemblage.
Label alpha, Pmax, respiration, compensation point and if it is the high light or
low light species for each curve (9)
150
100
50
0
0
500
1000
1500
2000
2500
-50
Light (umol quanta m -2 s-1)
Biology 612 Freshwater Ecology, Test 3 Fall 2008 Name_______________________
1. Matching: (10)
Feature
Match
Experimental Lakes Area
a. determined that P can limit primary
production
Droop model
b. warm epilimnion, cold hypolimnion
Omnivory
c. can confound the concept of food chains
Lake Washington
d. Primary succession
Monod model
e. cell growth rates
Daphnia vertical migration
f. predatory avoidance behavior
Two story fishery
g. W. Thomas Edmondson
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Sprit Lake
Virus
Nostoc
h. more concentrated phytoplankton more
vulnerable to infection
i. cell nutrient content
j. midge endosymbiont (mutualist)
2. What is the paradox of the plankton? Give 3 proposed reasons why complete
competitive exclusion is not observed in lakes. (8)
3. What is the Redfield ratio and how can it be used as an index of nutrient
limitation in algae? Give an example of a ratio for one nitrogen limited algal cell,
and one carbon limited algal cell. (6)
4. List 2 processes that we discussed in class that can lead to nutrient
remineralization from organisms back into the water. (2)
5. How did Lehman and Scavia demonstrate that phytoplankton can exploit nutrient
pulses by zooplankton? (5)
6. Why do heterotrophs typically excrete more nitrogen and phosphorus than
carbon? (4)
7. What is trophic state and why is it more difficult to assign a trophic status to
streams than to lakes? Some lakes do not follow typical classification schemes.
Why does Tuttle Creek Reservoir not follow the typical nutrient/productivity
classification? (8)
8. Name 4 problems that algal blooms can cause in lakes. In class, we emphasized
one crucial method to mitigate algal blooms and eutrophication in lakes, what was
it? (5)
9. Why should eutrophication be controlled in a lake before the hypolimnion goes
anoxic? (5)
10. What is being removed from wastewater during each of the following wastewater
treatment processes? (4)
A. Primary treatment
B. Secondary treatment
C. Tertiary treatment
Which treatment method (A, B, or C) is not implemented by Manhattan’s
treatment plant (but is being added soon)?
11. Draw and explain an example of the Random Walk Model in flowing water. (5)
12. Explain this predator functional response curve (i.e. what is happening to predator
consumption of prey at low, medium, and high prey densities?). (6)
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13. Explain why a manger might remove large fish (that eat smaller fish) from a lake
when their goal is to increase water clarity. (5)
14. Draw the relationship between particle concentration (on x axis) and filtering rate
(on Y axis) as well as consumption rate (on second Y axis) for Daphnia being fed
a unicellular algal culture. (8)
15. Describe why resource ratio theory can predict coexistence of two algal species in
spite of Leibig’s Law of the Minimum. (5)
16. How can stable isotopes of N and C be used to trace foodweb dynamics and what
information does this add over analyses of gut contents? (5)
17. Describe seasonal succession in lakes with respect to Si concentration, and
populations of diatoms, grazing resistant phytoplankton, cyanobacteria,
zooplankton, and larval fishes., and how they are all related. (11)
Biol 612 Final Fall 2008
Name _____________________________
1. List 3 ways humans can alter stream hydrology and list 5 negative effects of this
altered flow on aquatic biota. (8)
2. Lake stratification matching: (8)
stratification
type
# times
mixes
per year
Example :
fill in letter
polymictic
a) subtropical lake that does not freeze in winter
monomictic
amictic
b) cold-temperate lake
c) tropical lake with salt intrusion into the
hypolimnion
dimictic
d) shallow lake with a long fetch
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3. Fill in the 3 blanks and explain this graph. How is this equilibrium important for
organisms that get energy through photosynthesis? (6)
CO2 (H2CO3)
HCO3CO32-
4. Why are dissolved concentrations of inorganic nitrogen and phosphorus in the
water column of a lake relatively stable over short time periods (that is, what two
processes stabilize concentrations)? What does this mean for using dissolved
inorganic N and P ratio to determine nutrient limitation of algae? (5)
5. List 6 specific actions that can be taken to reduce causes or symptoms of
eutrophication in lakes (for example, instead of saying reduce nutrient input,
state a method to reduce nutrient input). (6)
6. A large quantity of a toxic chemical that kills aquatic microorganisms is dumped
into the city of Manhattan’s sewer and makes its way into the wastewater
treatment plant. (10)
a. Which treatment process within the plant will be the most effected
(primary, secondary, or tertiary) and why?
b. How will this change the chemical makeup of the effluent discharged from
the plant?
c. How will this affect the Kansas River downstream of the effluent outfall?
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7. Describe the primary carbon sources in lakes, streams and wetlands and the
organisms responsible for those sources. (9)
8. What did Alyssa talk about in her Wednesday lecture the week before finals? (5)
9. Why are the goals of having lakes that are crystal clear and blue, with no
macrophytes but lots of big fish, at odds with reality? (5)
10. Fill in the blanks (38)
Suspended microscopic algae are called _________________________.
The number that characterizes viscosity and inertia as a function of scale is called
_______________ number.
A bacterium experiences ____________ viscosity and _____________ inertia relative to
a fish.
Light is attenuated by a __________________ shaped function when intensity is plotted
against depth.
The equation for photosynthesis is ________ + __________+ light -> _________
+___________.
The equation for respiration is ________ + __________ -> _________ +___________+
energy.
Anaerobic respiration can use oxidized inorganic molecules such as ____________ or
_____________ for an electron acceptor .
Sulfur oxidization and nitrification are examples of ___________________, obtaining
energy from inorganic chemicals (as opposed to light).
Three forms of inorganic nitrogen are __________, ___________, and ______________.
The enzyme that cleaves organic phosphorus compounds is called _________________.
Iron binds with _____________ in anoxic conditions and _____________ in oxic
conditions. This makes it important to stop eutrophication before ____________
disappears from the hypolimnion.
Extinction rates are currently __________ times greater than rates of evolution.
Silicon is required for the frustules of ____________.
Cyanobacteria that fix nitrogen use a specialized cell called a ___________________.
The ________________ is where photosynthesis equals respiration on a photosynthesisirradiance curve.
Standing stocks of materials in ecosystems are called __________ , whereas movement
of material between these are called ______________.
The fastest portion of a river is called a __________________ and the area inside a
meander where materials are deposited is called a ________ _________.
The entire land area above any point in a stream is called the __________________.
Water flows more slowly next to solid objects and this leads to formation of a
___________ boundary layer, and in this layer movement of dissolved materials is
retarded leading existence of a _______________ boundary layer.
The world’s largest wetland is in South America and is called the ________________
and it is threatened by _______________.
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Lake Nyos was a disaster because of rapid release of ________________ that suffocated
1700 people.
Deep groundwaters are generally ultra-oligotrophic because of limited rates of input of
____________.
A linear view of feeding relationships among organisms is called food __________,
whereas more reticulated diagrams of feeding relationships are called food __________.
11. Extra credit (5) What do you think the most significant environmental threat to
freshwater is and why?
... have a nice break
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