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X2 reflects many ecosystem factors

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Massive change in food web had little impact on relationships ... Isohaline position as a habitat indicator for estuarine populations. ... – PowerPoint PPT presentation

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Title: X2 reflects many ecosystem factors


1
X2 reflects many ecosystem factors
Physical Habitat changes Water Quality Contaminant
effects Larval dispersal Adult migration and
spawning
X2
2
X2
X22
X12
X32
3
Fish- X2 Relationships From Kimmerer 2002
1967-87 1988-2000 1982-2000 (DS) All Years
4
X2 observations
  • FishX2 Relationships maintained across 35 years
    of data
  • Massive change in food web had little impact on
    relationships
  • Mechanisms remain unclear and probably diverse

5
Future Directions
  • Research strategy under development (CBDA grant
    to Kimmerer and Bennett)
  • Limited ability to test mechanisms
  • Reduced funding likely to restrict studies
  • Discussion with local biologists suggest that,
    for many possible mechanisms, variability is
    likely important (Estuarine Ecology Team July
    2004)

6
Conclusions
  • X2 seems to be working to protect aquatic
    resources from reductions in estuarine habitat
    quality
  • Protecting both mean and variance of X2 seem
    important
  • Unlikely that more effective ways to protect
    resources will be found soon
  • Continued data collection is vital for meaningful
    review

7
Main references
  • Kimmerer, W.J. 2002.  Physical, biological, and
    management responses to variable freshwater flow
    into the San Francisco estuary. Estuaries
    251275-1290
  • Jassby, A.D., W. J. Kimmerer, S.G. Monismith, C.
    Armor, J.E. Cloern, T.M. Powell, J.R. Schubel,
    and T.J. Vendlinski. 1995. Isohaline position as
    a habitat indicator for estuarine populations.
    Ecological Applications 5272-289
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