Reading Assignment:

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Reading Assignment
2006

• Chapter 13--Evolution

coelacanth
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Semester Projects

• 100 point project
• usually library research leading to a written
  paper
• do some preliminary research to define topic
• have topics approved by September 24
• Project due at end of semester
• Purposes synthesis lit. search sci. writing

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Project Topics

• Select a fish-related topic that is in an area of
  interest to you--ecology, behavior, physiology
• Topic should be sufficiently narrow for an
  in-depth treatment (10-12 pages)
• sea lamprey--too broad
• behavioral responses of fish to sea lamprey
  attack--better

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• Try to do some synthesis rather than a report
• develop an hypothesis or competing hypotheses
  find studies that support or refute them
• or present and evaluate competing hypotheses
• learn enough about the subject to make your own
  contribution

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• Access the primary literature--journals
• Do a subject search using
• Biological Abstracts (now avail. In e form
  http//www.library.und.edu/research/articleindexes
  .php )
• Zoological Record
• Fisheries Review
• Aquatic Sciences and Fisheries Abstracts
• Current Contents http//www.und.edu/dept/library/

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Develop specific objectives

• The objectives of this study are to
• describe modes of sea lamprey attack
• describe behavioral responses of hosts to
  parasitism by sea lampreys
• use existing literature to test the hypothesis
  that lampreys select hosts of sufficient size to
  minimize host mortality

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Develop an Outline

• Introduction
• Methods
• Results and Discussion
• Literature Cited

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Physical Aspects of Aquatic Environments
Water
covalent bond
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Water is a polar molecule

• dissolves polar substances--salts, etc
• doesnt dissolve non-polar substances--fats,
  oils, waxes.

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Soap molecule
polar
carboxyl group
hydrocarbon
Does this remind you of anything?
non-polar
cell membranephospholipid bi-layer
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Ionization of water
2H2O
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How much does water ionize?

• Hint pH -log H
• 10log
• 10-7 g-ions/l
• 0.0000001 g-ions/l

Note inverse log scale
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Many other substances ionize in water
Salts NaCl
Acids H2CO3
carbonic acid
bicarbonate
Bases NH3 H2O
ammonium
ammonia
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Density of water
Ice
Covalent bond-share electrons
Hydrogen bond-electrostatic
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As temp of ice increases
Density g/ml

• Molecules vibrate more rapidly
• hydrogen bonds begin to break
• free molecules fill voids
• water becomes densest
• vibrations increase in amplitude intermolecular
  distances increase

Ice 0.917
water 0.9999
1.000
0.996
Significance with respect to life?
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Thermal Stratification
epilimnion
less dense
hypolimnion
more dense
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Density of water increases slightly with salinity
Density
102.9
100
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0
Salinity 0/00
(sea water)
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Viscosity

• Viscosity - tendency for a fluid to resist motion
  within itself due to attraction among molecules.
• Salinity - little effect on viscosity (slight inc)

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Comparative Viscosities
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Temperature vs Viscosity
Viscosity doubles as temp. decreases from 25 to 0
C/
Viscosity of water offers approx. 100 x the
resistance to movement as air.
Viscosity 10-3 kg/m/s
Temperature C
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Surface Tension

• Defn--inward adhesion of molecules at surface due
  to attraction of molecules
• surface tension of water is higher than any other
  liquid except mercury
• increases slightly with salinity
• decreases with temp

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spider jumping
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water strider
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Specific heat

• Defn--amount of energy (in calories) required to
  raise temperature of 1 g of substance 1degree C
• water is standard with value of 1 (varies with
  temp but close to 1).

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Comparison of specific heat
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Effects of Properties of Water on Living Organisms

• Density Buoyancy
• Archimedes Principle--when an object is immersed
  in a fluid, an upward force acts on it, equal to
  the weight of the fluid it displaces

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air
Archimedes Principle
positive buoyancy
positive buoyancy
positive buoyancy
neutral buoyancy
water
neutral buoyancy
density
Fish?
negative buoyancy
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Densities of Biological Substances
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• Slight negative buoyancy--densities of most
  aquatic organisms are close to that of water
  (usually slightly more dense)
• fish densities--1.06-1.09 g/cm3.

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Support

• Aquatic organisms are well supported due to
  density similarities between water and aquatic
  organisms
• Effects--reduced energy expenditure
• reduction or lack of support
  tissues.

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Streamlined shapes

• Active fish tend to be streamlined due to high
  energy required for locomotion in water

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Ecological Groupings of Fishes

• Body shape--6 general categories
• habitat
• body shape
• general life style

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Rover Predators--moving hunters

• Terminal mouth
• Fins evenly placed (maneuverability)
• stream-lined

brassy minnow
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Ex Salmonidae
brook trout
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Ex Percidae
walleye
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Ex Centrarchidae (basses only)
largemouth bass
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Lie-in-Wait predator (piscivores)

• Terminal mouth large w needle-like teeth
• stream-lined often elongated and thin
• head flattened

northern pike
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Lie-in-Wait predator (continued)

• Caudal fin large
• Dorsal and anal fins placed posteriorly
• Cryptic coloration

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Esocidae-pikes, pickerel, muskie
muskellunge
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Lepisosteidae - gars
longnose gar
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needlefish
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Sphraenidae -- barracuda
longnose gar
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Surface-Oriented fishes

• Often small
• Upward tending mouth (superior or superterminal
• Dorsoventrally flattened head
• Adapted to surface

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