Fish Nutrient Recycling

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Fish Nutrient Recycling

• Dana Nguyen
• Biology 402
• Nov 23/06

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Overview

• Fish Nutrient Recycling (Introduction)
• History of Fish Nutrient Recycling Research
• Main Questions and Observations
• Specific Papers
• Nutrient recycling by fish versus zooplankton
  grazing as drivers of the trophic cascade in
  alpine lakes. By Sarnelle O. Knapp R.A. (2005)
  Limnology and Oceanography, 50, 2032-2042
• Marine-derived nutrients, commercial fisheries,
  and production of salmon and lake algae in
  Alaska. By Schindler, D. E., Leavitt, P. R.,
  Brock, C. S., Johnson, S. P., Quay, P. D. (2005)
  Ecology, 86, 3225-3231
• Conclusion
• How are these papers connected
• What are future lines of inquiry

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Fish Nutrient Recycling
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History of Nutrient Recycling in Fish

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History of Fish Nutrient Recycling

• Alteration of nutrient cycles and algal
  production resulting from fish introductions into
  mountain lakes
• Schindler, D. E., Knapp, R. A., Leavitt, P. R.
  Ecosystems June, (2001) 4 (4) 308-321
• Questions
• Does introduction of fish affect nutrient cycling
  of lakes?
• Observations
• Modeling and Paleolimnological analysis show that
  introduction of fish change nutrient cycling by
  accessing benthic P sources usually inaccessible
  by other lake organisms
• Significance
• Shows that nutrients such as phosphorous is
  significantly affect by fish
• Fish aids in translocation of nutrients
  throughout the water column

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History of Fish Nutrient Recycling

• Resilience and Resistance of a Lake Phosphorus
  Cycle Before and After Food Web Manipulation
• Carpenter, S.R. Kraft, C.E Wright, R He, X
  Soranno. P Hodgson J.R.The American Naturalist,
  Vol. 140, No. 5. (Nov., 1992), pp. 781-798.
• Question
• What are the parameters for phosphorous cycling
  models of a planktivore dominated configuration
  and a piscivore dominated configuration
• Observations
• littoral fish deposit similar amounts of P as
  physical processes
• Phosphorus cycling and ecosystem resilience are
  positively related
• Significance
• suggests that fish are important sources of P and
  may affect ecosystem turnover

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History of Fish Nutrient Recycling

• Nutrient Recycling and Herbivory as Mechanisms in
  the "Top-Down" Effect of Fish on Algae in Lakes
• Vanni M.J. Layne, C. D. Ecology, Vol. 78, No. 1.
  (Jan., 1997), pp. 21-40.
• Question
• Is phytoplankton biomass affected by decreased
  zooplankton grazing in the presence of fish, fish
  nutrient recycling or changes in nutrient cycling
  rates of zooplankton in accordance with fish
  biomass variation?
• Observations
• High fish biomass as well as indirect and direct
  nutrient recycling by fish all increased
  phytoplankton biomass
• Significance
• Successfully separated grazing affects and
  nutrient recycling affects of fish on
  phytoplankton by using enclosures

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Nutrient Recycling WebVanni et al. 1997
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History of Fish Nutrient Recycling

• Pacific salmon and the ecology of coastal
  ecosystems
• Schindler, D. E., M. D. Scheuerell, J. W. Moore,
  S. M. Gende, T. B. Francis, and W. J.
  Palen.Frontiers in Ecology and Environment (2003)
  1 3137.
• Question
• Does salmon have an influence in other
  ecosystems
• Observations
• Salmon carcasses during spawning are deposited
  throughout aquatic and terrestrial ecosystems and
  consumed.
• Digging and Nesting changes ecosystem physically
• Significance
• Explored how salmon physically and chemically
  affect ecosystems around streams and lakes.
  Explored the affects of over fishing salmon on
  these ecosystem

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History of Fish Nutrient Recycling

• Pacific salmon, nutrients, and the dynamics of
  freshwater and riparian ecosystems.
• Naiman, R. J., R. E. Bilby, D. E. Schindler,
  and J. M. Helfield Ecosystems(2002) 5 399417.
• Question
• Reviews current understanding of marine derived
  nutrients and their affects on freshwater
  ecosystems
• Observations
• Suggests that salmon production is important in
  linking nutrients from the oceans to freshwater
  ecosystems and sustaining this system will
  require a holistic approach
• Significance
• Summarizes and validates current discoveries
  regarding Marine derived nutrients

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Main Question

• How and to what extent does Fish contribute to
  their ecosystems through nutrient recycling?

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• Specific Papers

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Nutrient Recycling by Fish versus Zooplankton
Grazing as Drivers of the Trophic Cascade in
Alpine Lakes by Sarnelle O. Knapp R.A

• Question
• What is the influence of Fish Nutrient Recycling
  relative to Zooplankton Grazing on Phytoplankton
  Biomass in Trophic Cascade Experiments?

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Why Did They Ask This Question?

• They wanted to see the extent in which Nutrient
  Recycling by Fish through excretion affected
  phytoplankton biomass and P-limitation
• Significance
• Disentangle the influence of grazing on
  phytoplankton biomass
• Whole Lake scale
• Compared zooplankton grazing and nutrient
  recycling to that of fish

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Hypothesis

• If fish nutrient recycling is a major influence
  in the biomass of phytoplankton, we would see a
  decrease in phytoplankton biomass and a
  corresponding increase in P limitation

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Methods

• Multi-lake study!
• Experimental Lakes (Fish removed)
• Knob 1997
• No Good 2000
• Square 1997 Fish Removed (Daphnia added)
• Control Lakes
• Lower Desolation and Mesa Fish Restocked
  Continuously
• Measure Chlorophyll a, phosphatase activity,
  benthic invertebrates, zooplankton, fish
  excrement and zooplankton excrement

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Results (zooplankton)
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Unexpected ResultsSimilar Results were found in
No Good Lake
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Chlorophyll changes with Addition of Daphnia
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Phosphatase Activity with Addition of Daphnia
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Phosphorous Demand and Recycling
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Conclusions

• Knob and No good lakes no significant changes in
  chlorophyll a or phosphatase activity
• Fish Nutrient Recycling had little if any affect
  on phytoplankton biomass or P limitation but
  Daphnia establishment seemed to have a large
  affect
• In Knob lake, the timing of benthic growth did
  not compensate for P cycling lost by removal of
  fish
• Estimate of P excretion by fish were small in
  comparison with P demand by fish but zooplankton
  excrement did
• May have more success in smaller scale, higher
  variance pre-manipulation for whole lake

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MARINE-DERIVED NUTRIENTS, COMMERCIAL FISHERIES,
AND PRODUCTION OF SALMON AND LAKE ALGAE IN
ALASKAby Daniel E. Schindler, Peter R. Leavitt,
Curtis S. Brock, Susan P. Johnson, and Paul D.
Quay

• Main Question Does Marine Derived Nutrients
  (MDN) that are deposited in freshwater ecosystems
  by fish have an influence on fish and lake
  productivity?
• Marine Derived Nutrients 15N and 13C

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Why ask this question?

• It has been observed that as salmon spawn, the
  tend to take nutrients that they have obtained in
  the ocean and deposit them along their runs as
  they travel to the nursery ecosystem
• Circumstantial evidence shows that previous
  generations of salmon deposit MDN in freshwater
  and riparian ecosystems during spawning that may
  be beneficial to lake productivity as well as
  following generations of salmon

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Hypothesis

• Fishery interceptions of sockeye salmon have
  reduced MDN deposition by spawning salmon which
  in effect will reduce lake productivity and
  subsequent salmon populations

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Methods

• Paleolimnological Time Series was created and
  long term fishing records showed Salmon runs for
  past 300 years for Lake Nerka (with salmon) and
  Grant Lake (without salmon)
• Paleolimnological Time Series was created using
  sediments in the lakes. Measuring 210 Pb
  determined sediment chronology 15N found in
  sediment was used in conjunction with mixed model
  equation and Monte Carlos Simulation to determine
  abundance in salmon runs
• Fossil Algal Pigments were measured in order to
  determine Algae abundance (productivity)

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Results (Lead)

• Pb activity is
• continuous though the depths

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Nitrogen 15 level

• Mixed Model Equation

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Algal concentration in the past 300 years

• MDN has been intercepted by two-thirds since
  intense commercial fishing started (1900). This
  decrease has affected lake productivity

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Results

• Historical records show intercepted MDN levels of
  two thirds
• Algae has decreased three-fold since intense
  commercial fishing
• Fish stocks have decreased slightly but remain
  relatively equivalent to fish abundance 300 years
  ago

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Conclusions

• Salmon enhances algae deposits and MDN is
  important in increases in Lake productivity
• Salmon productivity is not affected by decreases
  in algae levels which suggest that other factors
  influences salmon stock
• Limited spawning areas may affect salmon
  productivity

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How are these paper connected?

• Nutrient recycling
• Translocation of nutrients
• Explore potential benefits of fish nutrient
  recycling
• Concluded that fish nutrient recycling had little
  affect on biomass

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Future Lines of Inquiry

• Determine to what extent and in what specific
  ways do MDN affect the productivity of lakes or
  streams
• Determine if fish nutrient recycling in lakes
  other than alpine lakes affects phytoplankton
  biomass
• Determine if fish nutrient recycling influences
  phytoplankton or zooplankton diversity