Why Study Continental Aquatic Systems

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Types of Aquatic Organisms

• The species concept
• Major taxonomic groups
• Classification of organisms by functional
  significance
• Organisms found in freshwater systems

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The Species Concept

• How do you define species?
• How do taxonomists usually define species?

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Major Taxonomic Groups

• Archaea
• Bacteria
• Eukarya
• Using rRNA for taxonomic identification of
  organisms

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rna.ucsc.edu/rnacenter/ribosome_images.html
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Classification of Organisms by Functional
Significance

• Autotrophic versus heterotrophic
• Chemoautotrophic versus photoautotrophic
• Detritivory versus predation
• Functional feeding groups shredders- shred
  leaves grazers- eat algae or plants collectors-
  collect particles carnivores- eat other animals

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Classification by Direct Interaction Type

• Competition -/-
• Mutualism /
• Exploitation /-
• Commensalism /0
• Amensalism -/0
• Neutralism 0/0

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Classification by Habitat

• Memorize all terms on Table 7.3

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Microbes and Plants

• Viruses
• Archaea
• Bacteria
• Protoctista
• Fungi
• Plantae

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Viruses

• All organisms have viruses
• RNA or DNA, capsid (covering) also important
• Prions little understood

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Virus-Like Particles Common in Lakes
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Archaea

• As different from bacteria as eukarya
• Morphologically similar to bacteria
• Originally thought to be mainly extremophiles
  (hyperthermic, halophilic, anaerobic)
• Now known to occur in all habitats
• Essential in nutrient cycling

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Bacteria

• Most important organisms in nutrient cycling on
  earth
• Can only culture lt 1 of all species
• Most species only have few morphologies
• Most identification based on metabolic or
  chemical characteristics
• Cyanobacteria are included in this group

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Bacterial Morphologies
10 µm
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Cyanobacteria

• Produce O2, photosynthetic
• Fix nitrogen with heterocysts
• Float by gas vesicles
• Produce objectionable odors, tastes, and toxins
• Unique light-harvesting pigments

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Cyanobacterial Morphologies
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Cyanobacterial Toxins

• Produce hepatotoxins and neurotoxins
• Neurotoxins are highly toxic
• Hepatotoxins damage liver. Low, chronic exposures
  may cause liver cancer
• Toxins can be bioconcentrated by some organisms,
  and influence many different types of animals
• Toxins evolved as protection against zooplankton
  grazing
• Other algae make toxins, red-tide, Prymnesium
  parvum responsible for a massive fish kill in
  summer 2002 in NE Colorado. Coming to a
  reservoir near you soon! Also important in fish
  culture ponds

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Google algal blooms fish kill.any summer

• Second fish kill found--nearly 4 million reported
  in Pamlico River
• August 6, 2008 - 856PM
• Sun Journal
• Nearly 4 million fish were found dead Wednesday
  in the Pamlico River just east of Washington.
• It was the second large fish kill reported this
  week in Eastern North Carolina rivers. On
  Tuesday, an estimated 750,000 dead fish were
  found in the Neuse River between Otter Creek and
  Carolina Pines.

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Protoctista

• Eukaryotic Algae
• Protozoa

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Eukaryotic Algae

• Chrysophyceae- flagellated, and ingest particles
• Bacillariophyceae- diatoms, have silicon frustule
  that is useful in paleolimnology, abundant in
  many types of freshwaters
• Dinophyceae- dinoflagellates, flagellates, some
  toxic and cause fish kills
• Euglenophyceae- Euglena
• Chlorophyceae and Charophyceae- green algae

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Protozoa

• Important consumers of bacteria
• Mastigophora- flagellates
• Phytomastigophora- green
• Zomastigophora- colorless
• Sarcodina- amoeboid protozoa
• Cilipophora- ciliates

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Protozoa
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Fungi

• Aquatic Fungi
• saprophytic
• some predatory
• Aquatic Lichens
• symbiosis between fungi and alga
• can be very important in some wetlands

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Plantae

• Nonvascular plants
• Vascular plants
• Large algae and plants called macrophytes, often
  classified by growth habit

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Growth Habit of Macrophytes
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Non-Vascular Plants

• Bryophytes- mosses and liverworts
• Sphagnum globally important in carbon deposition
  in peat bogs
• Some aquatic mosses can be found very deep in
  oligotrophic lakes
• Some streams can be dominated by bryophytes

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Vascular Plants

• Dominant producers in many wetlands, shallow
  lakes and ponds
• Many wetlands classified based on the vegetation
  that they contain
• A wide variety of forms

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Diversity of Aquatic Plants- Emergent
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Diversity of Aquatic Plants-Submerged and Floating
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Multicellular Freshwater Animals, Invertebrates

• Porifera- sponges
• Cnidaria- include hydra
• Platyhelminthes- include planarians (Turbellaria)
  and some important parasites
• Gastrotricha- can be abundant, benthic
• Rotifera- rotifers some sexual, others asexual
• Nematoda- important predators and bactivores
• Mollusca- Gastropoda (snails and limpets) and
  Bivalva (clams and mussels)
• Annelida- segmented worms
• Bryozoa- sessile ciliated invertebrates
• Arthropoda- includes insects, Crustacea, etc.

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Invasion by Zebra Mussels

• Entered Great Lakes in 1986 from European ships
  dumping bilge water
• Can produce 1,000,000 eggs each reproductive
  cycle, giving rise to easily transported veliger
  larvae
• Attach to solid substrates and rapidly cover
  other organisms
• Filter feed and remove substantial amount of
  materials from water, improve water clarity and
  outcompete other filterers
• Will spread through United States eventually,
  just made it into Missouri River
• Recently entered Kansas waters Cheney, Marion,
  Afton reservoirs

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Zebra Mussel Expansion
2008
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Arthropoda

• Class Arichnida- spiders and mites
• Subphylum Insecta
• Collembola
• Ephemeroptera- mayflies
• Odonata- dragonflies
• Plecoptera- stoneflies
• Tricoptera- caddisflies
• Megaloptera and Neuroptera- fissflies,
  alderflies, and spongillaflies
• Hemitera- true bugs
• Lepidoptera- aquatic caterpillars
• Coleoptera- water beetles
• Diptera- flies and midges

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Arthropoda, continued

• Suphylum Crustacea
• Ostracoda- seed shrimp
• Copepoda- copepods
• Branchiopoda
• Cladocera- water fleas (Daphnia)
• fairy, tadpole, brine, and clam shrimps (e.g.
  Artemia)
• Decapoda- crayfish, crabs, shrimps
• Isopoda- isopods
• Amphipoda- scuds and sideswimmers

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Phylum Chordata, Subphylum Vertebrata

• Fishes
• Tetrapods
• Amphibians
• Urodela or Caudata- salamanders
• Anura- frogs
• Birds, Reptiles, Mammals

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Biodiversity of Freshwaters

• Measures of diversity
• Temporal and spatial factors influencing
  evolution of freshwater organisms
• Short-term factors influencing local distribution
  of species
• Invasions of nonnative species
• Extinction
• What is the value of freshwater species diversity?

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Measures of Diversity

• Species richness- the number of species
• Eveness- how well represented each species is
• Shannon-Weiner diversity measure includes both
  richness and evenness.
• ?- within habitat, and ?- between habitat
  diversity

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? and ? Diversity
B
A
C
D
F
E
G
H
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Temporal and Spatial Factors Influencing
Evolution of Freshwater Organisms

• Time- ancient lakes and watersheds have many
  unique species and high diversity
• Lake Baikal has 377 endemic crustacea, 86
  Turbellaria, 98 mollusks, 29 fish, and a
  freshwater seal
• Geographic isolation
• unique groundwater fauna related to isolation
• dispersal ability linked to degree of isolation
• temporary pools can have many endemic species

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Short-Term Factors Influencing Local
Distribution of Species

• Colonization
• Habitat type
• Disturbance
• Productivity
• Species interactions
• Species introductions

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Habitat as Template for Evolution-Habitats from a
Small Lake
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Species Area Relationships

• S Caz
• Holds from diatoms to fish

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Invasions of Nonnative Species

• Most permanent form of pollution
• Conceptual model of why species invade
  successfully
• most invaders fail to establish
• most successful invaders have no significant
  effects
• all aquatic systems can be invaded
• major community effects occur most often in
  low-diversity systems
• top predators are more likely to have strong
  effects
• species must have appropriate physiological and
  morphological adaptations to invade successfully
• invaders are more likely to become established in
  disturbed systems
• environmental variability can play a role in
  establishment
• very stable systems may be vulnerable to invasion
• the greater the number of invaders and the number
  of invasions, the greater the probability of
  successful invasions
• species that have a history of prior invasions
  are likely to invade successfully again

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Invaders of the Great Lakes
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Extinction

• Extinction rates are about 1 million times
  greater than naturally
• Aquatic systems are very vulnerable
• Lake Victoria- 300 species evolved in last 12,000
  years, 200 extinct in last decade from
  introduction of Nile Perch and pollution
• In U.S. there are 73 fish, 69 bivalves, 28
  snails, 17 amphibians, and 20 crustaceans listed
  as threatened or endangered
• Over half of the freshwater unionid mussel
  species are endangered
• Extinction is forever

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What is the Value of Freshwater Species Diversity?

• What do you think?

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Aquatic Chemistry Controlling Nutrient Cycling
Redox and O2

• Chemicals in freshwaters
• Redox potential, potential energy, and chemical
  transformations
• Oxygen- forms and transformations
• Photosynthesis
• Distribution of dissolved oxygen in the
  environment

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Chemicals in Freshwaters

• Dissolved versus particulate
• Colloidal versus gravitoidal
• Total dissolved solids
• Salinity
• Conductivity
• pH
• Turbidity
• Alkalinity

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Spatial Scale and Chemicals in Water
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Correct Version of Fig. 11.3
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Frequency Distribution of Dissolved Chemicals
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Redox Potential, Potential Energy, and Chemical
Transformations

• Redox is a measure of free electron availability
• Chemicals have potential energy if they are at a
  different redox state than the solution that they
  are in

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Potential Energy and Redox
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Redox of Biologically Important Molecules
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Iron and Redox
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Oxygen- Forms and Transformations

• 21 of atmosphere is O2
• Aerobic/anaerobic- oxic/anoxic
• Oxygen drives redox
• Saturation concentration of dissolved O2 depends
  on atmospheric pressure and temperature
• Photosynthesis produces O2 , respiration consumes
  it. Memorize the equations in the book

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Photosynthesis

• Net photosynthetic rate gross photosynthetic
  rate - respiration
• Factors that influence photosynthesis include
  light, temperature, water velocity, and chemicals
  (e.g. herbicides)
• Relationship between photosynthesis and light
  referred to as P-I relationship

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P-I Relationship
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Photosynthesis and Temperature
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Photosynthesis and Water Velocity
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Spatial Variation in O2
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Temporal Variation in O2
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Carbon

• Forms of carbon
• Transformations of carbon
• A general introduction to nutrient cycling and
  the carbon cycle

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Forms of Carbon

• Inorganic carbon-bicarbonate equilibrium
• carbon dioxide CO2
• carbonic acid H2CO3
• bicarbonate HCO3-
• carbonate CO32-
• CO2 H2O? H2CO3 ?HCO3- H ?CO32- 2H
• Organic carbon

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pH and Bicarbonate Equilibrium
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Lake Nyos Disaster

• 1700 people and many livestock died near Lake
  Nyos in Cameroon in 1986
• A survivor reported a 25m high water surge and
  odor of rotten eggs
• Caused by catastrophic release of supersaturated
  CO2 from the hypolimnion
• CO2 probably came from volcanic activity
• Landslide or cool weather released the gas
• Building up again, using pipes to release
  pressurized water

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Photo Bernard Canet, March 1995
http//perso.wanadoo.fr/mhalb/nyos/index.htm
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Organic Carbon

• Dissolved versus particulate (DOC vs POC)
• CPOM and FPOM
• Biochemical Oxygen Demand (BOD)
• Tannins, lignins, cellulose
• Humic materials
• humic acids (soluble in alkaline precip in acid)
• fulvic acids (soluble in acid)
• humins (not extractable by acid or base)

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Transformations of Carbon

• Oxidation of organic carbon with inorganic
  electron acceptors other than O2
• Fermentation
• Methanotrophy
• Methanogenesis
• Autotrophy (photoautotrophy includes oxygenic and
  anoxygenic photosynthesis)
• Respiration

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Aerobic Carbon Breakdown
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Anaerobic Carbon Transformations
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Methanotrophy and Methanogenesis

• Methanotrophs are aerobic organisms that eat
  methane and carbon monoxide. Very important in
  global carbon cycle
• Methanogens make methane from CO2 and H2 at very
  low redox. Also can use acetate. Important in
  global methane cycle

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Wetlands and the Global Methane Budget
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A General Introduction to Nutrient Cycling and
the Carbon Cycle

• A general method for diagramming nutrient cycles
• The carbon cycle

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Nitrogen, Sulfur, Phosphorus, and Other Nutrients

• Nitrogen
• Sulfur
• Phosphorus
• Silicon, Iron, and other trace nutrient cycles
• Gradients of redox and nutrient cycles and
  interactions among the cycles

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Nitrogen

• Nitrogen Forms
• N2 gas, N2O nitrous oxide, NH4 ammonium, NO2-
  nitrite, NO3- nitrate
• Nitrogen Fluxes
• uptake, remineralization, denitrification,
  nitrification, dissimilatory nitrate reduction,
  nitrogen fixation
• Nitrogen Cycle

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Nitrogen Fixation

• N2 gas to ammonium, very expensive energetically
• Only bacteria known to fix nitrogen
• Nitrogenase sensitive to O2, and a variety of
  adaptations protect it
• Lightning also fixes N2 to NO3- in the atmosphere
• Nitrogen-fixing cyanobacteria can be very
  important in lake N cycles

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Cyanobacterial Heterocysts
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N Cycling

• Nitrification- oxidation of ammonium to nitrite
  (Azotobacter) and nitrite to nitrate
  (Nitrobacter)
• Denitrification- using NO3- as an electron
  acceptor for oxidation of carbon, yields N2O and
  N2. Drives N loss from environment. Under very
  low redox, can go to ammonium
• Remineralization (ammonification)

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Nitrate Contamination

• Nitrate not allowed in drinking water in U.S.
  over 10 mg/L
• Can lead to methhemoglobinemia, blue baby
  syndrome
• Can be converted to carcinogenic nitrosamines in
  the stomach

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N Distribution in a Lake
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N Distribution in a Stream
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Be Able to Draw the N Cycle from Scratch
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Sulfur

• Forms (only some listed)
• S2-, sulfide S0, elemental sulfur S2O32-,
  thiosulfate SO42-, organic S, dimethyl sulfide
• Sulfur Transformations
• Abiotic oxidization (spontaneous conversion to
  sulfate, slow)
• Biotic oxidation (chemoautotrophic bacteria)

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More Sulfur Transformation

• Dissimilatory sulfur reduction
• sulfate and successively reduced sulfur compounds
  used as electron acceptors for carbon oxidation
• Disproportionation
• two sulfurs in thiosulfate, one used to oxidize
  the other and energy is produced
• S2O32-? S2- SO42- H energy
• Precipitation of metal sulfides
• Anoxygenic photosynthesis- uses sulfide as an
  electron donor for photosynthesis and produces
  sulfate

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Be Able to Draw Complete Sulfur Cycle From Scratch
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Phosphorus

• Forms
• organic P phosphate, PO43-
• Transformations
• uptake
• remineralization (phosphatases)
• precipitation with oxidized iron

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Silicon, Iron, and Other Trace Nutrient Cycles

• Silicon
• key element in diatom frustules
• can become limiting in lakes
• Iron
• ferric, Fe3, oxidized ferrous, Fe2 reduced
• iron oxidation by microorganisms important
  chemoautotrophic pathway, but also will happen
  abiotically, so must occur at oxic/anoxic
  interface
• oxidized iron precipitates with phosphate, but
  dissociates again in anoxic conditions
• Chelators can keep iron in oxic solutions

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Annual Cycle of Silicon in a Lake
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Sulfur-Iron Dynamics and Wetland Eutrophication

• Phosphorus pollution in peaty lowlands of
  Netherlands encouraged unwanted algal blooms and
  hurt macrophyte populations
• Put low P, high sulfate river water in
• Sulfate was reduced to sulfide, which
  precipitated iron and poisoned roots of
  macrophytes
• Iron was not present to bind to phosphates and
  phosphate concentrations actually increased

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Gradients of Redox and Nutrient Cycles and
Interactions Among the Cycles
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Effects of Toxic Chemicals and Other Pollutants
on Aquatic Ecosystems

• Basic toxicology
• Bioassessment
• Acid precipitation
• Metals and other inorganic pollutants
• Organic pollutants
• Suspended solids
• Thermal pollution

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Basic Toxicology

• Acute vs. chronic exposure
• lethal/ sublethal/ cumulative
• LD50, EC50
• Additive versus multiplicative effects
• Effects of other factors on toxins
• Bioconcentration- moving into organisms
• Bioaccumulation- accumulation from food (lipid
  solubility)
• Biomagnification- increases as you move up the
  food web

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Bioassessment

• Use native assemblages to indicate chronic
  toxicity
• Useful because long term effects are difficult to
  document and acute episodes may be hard to sample
• EPT index is one common tool for assessment
• Index of Biotic Integrity (Karr) assesses
  habitats and fish species

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Relationship between Invertebrate Diversity and
some Environmental Parameters
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Acid Precipitation

• Sources and geography of acid precipitation
• Biological effects of acidification

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Sources and Distribution of the Problem in the
United States
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Influences of Decreased pH on Aquatic Organisms
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Influence of Decreased pH on Bacterial Activity
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Paleolimnology to Show Trends in Acidification
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Increased Aluminum with Lower pH
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Aluminum and Fish
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Metals and Other Inorganic Pollutants

• Lead toxicity and waterfowl
• Mercury contamination of fish. Atmospheric
  deposition followed by methylation
• Selenium concentrates in some areas as water
  evaporates. A cofactor at low concentrations but
  toxic at high
• Arsenic in groundwater

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Organic Pollutants

• More than 10,000 created and used by humans,
  several hundred new each year
• Petroleum products. Urban runoff. A 20hp 2
  stroke engine can make 11,000 m3 of water
  undrinkable in one hour
• Chlorinated hydrocarbons concentrate in sediments
• Atrazine common in agricultural areas. Poisons
  algae and macrophytes, may poison frogs

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Endocrine Disrupting Compounds

• Ecoestrogens mimic estrogen, many compounds
  including DDT
• Active at minute concentrations
• May cause disruption in sex determination in
  animals
• Can be bioconcentrated and passed to offspring
• Combinations of organic chemicals may interact
  with estrogen acceptors

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Bioremediation

• Using organisms to mediate pollution
• Usually bacteria
• Bacteria rapidly evolve the ability to withstand
  and utilize organic compounds (e.g. antibiotic
  resistance)
• Plasmids transfer genetic information readily
• In situ bioremediation is often the cheapest way
  to clean up organic pollution, particularly in
  groundwater

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Suspended Solids

• Can smother invertebrates
• Also serve as food source for filtering
  invertebrates
• Largest mass of any pollutant
• Can fill gravel and interfere with fish
  reproduction
• Can increase light extinction rates, and lower
  phytoplankton production

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Thermal Pollution

• Power plants need cooling water
• Increased temperatures can have adverse
  environmental impacts, including
• extend range of exotic invaders
• interfering with reproductive cycles and timing
• death of heat intolerant species
• This research now relevant to global warming