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Chapter 23 Primary Producer Consumer Interactions

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Title: Chapter 23 Primary Producer Consumer Interactions


1
Chapter 23 Primary Producer Consumer Interactions
  • Christopher Eisler
  • Tennessee Tech University

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2
Ecosystem Processes
  • Benthic environments are zones of high
    bioactivity. Processes include
  • 1. Primary Production
  • 2. Consumption
  • 3. Nutrient Cycling
  • 4. Decomposition

3
Primary Producers
  • Primary Producers are the physical-chemical
    interface in streams.
  • Producers include bacteria, benthic algae,
    bryophytes, and vascular plants.
  • Bio-films found in a variety of habitats.

4
Production With Time
  • Stable conditions are required for mature algal
    community structure.
  • Disturbances such as floods can impair this.
  • Algal growth typically follows a pattern which
    grazers can affect.

5
Primary Production With Time
6
Producers and Consumers
  • Producers provide energy for consumers (Grazers).
  • Grazing is the consumption of
  • living producers or their parts by primary
    consumers.
  • Consumption can be either the main
  • energy intake or variable depending on the
    species and stream.

7
Producers and Consumers
  • Consumers can affect primary producers and vise
    versa.
  • Grazers can affect algal community biomass.
  • Algal biomass and species composition may be
    positively or negatively affected.

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Producers and Consumers
  • Primary producers play an important role in many
    stream organisms life cycles.
  • Consumers include Fish, Invertebrates, Insects,
    Mollusks, Crustations, and Larval Amphibians.
  • Consumers can increase species richness or
    decrease species richness depending on how they
    graze and on mouth structure of the consumer.
  • The same applies to biomass.

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11
Autochthonous Production
  • Synthesis of organic matter by primary producers.
  • Large portion of the food web in most streams.
  • Stream orders 3-6 usually rely this since light
    is high, water is shallow clear, temperature
    and nutrients are favorable for growth of benthic
    algae.

12
Autochthonous Production
  • In higher orders phytoplankton dominate due to
    light reduction, however shallow regions can
    yield high benthic algae production.
  • Small shaded streams with low algal biomass can
    yield high grazer numbers due to rapid turnover
    and high nutrient value thus affecting food web
    structure.

13
Few Rules Many Exceptions
  • Grazers affects on primary producers arent
    applicable to a wide range of streams. Much is
    yet to know.
  • The best way is to determine the primary
    production and consumer interactions for your
    stream. This may be done by a variety of methods
  • Factors affecting producer consumer interactions
    are tied to season, successional stage, size,
    nutrients, pathogens, habitat disturbances,
    light, depth, types and numbers of species
    present.

14
Platform Exclusion
  • Tiles are raised and at substrate level to
    determine consumer affects.
  • Most invertebrates will be absent in the short
    term.
  • Allows comparison between grazed and un-grazed
    tiles.

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16
Cage Method
  • Effects by species.
  • Very Controlled

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Electric Shock Exclusion
  • Uses electric fence chargers to exclude
    invertebrates.
  • Not effective on some types.

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References
  • Biggs, B.F., 1996 Patterns in Benthic Algae of
    Streams. Pages 31-56 in R. J. Stevenson, et al.
    (Eds.) Algal Ecology Freshwater Benthic
    Ecosystems. Academic Press, San Diego, C.A.
  • Haur, F. R., and G.A. Lamberti, 2006 Methods in
    Stream Ecology 2nd edition. New York, New York
    Academic Press.
  • Steinman, A.D., 1996 Patterns in Benthic Algae of
    Streams. Pages 31-56 in R. J. Stevenson, et al.
    (Eds.) Algal Ecology Freshwater Benthic
    Ecosystems. Academic Press, San Diego, C.A.

21
Questions
22
Chapter Questions
  • 1. This question can not be answered without
    field data.
  • 3. Grazing decreases algal biomass. You cant
    extend this to all the stream bed or watershed
    since nutrients along with light will very with
    time and space.
  • 5. This question cant be fully answered but
    variables exist with light, nutrients or
    consumers present.
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