Aswani Volety1, Peter Doering2, Patricia Sime2 and Patricia Goodman2

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• Aswani Volety1, Peter Doering2, Patricia Sime2
  and Patricia Goodman2
• 1. Coastal Watershed Institute, Florida Gulf
  Coast University
• 2. South Florida Water Management District

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Rationale

• SW Florida is one of the fastest growing areas in
  the United States
• Watershed development and water management
  practices to accommodate development in areas
  including the Caloosahatchee and Estero Bay
  watershed.
• Interruption of sheet flow, water releases
  regulated through weirs
• Altered regime flow and impacts to water quality
  and salinity.

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Rationale

• Watershed management (and seasonal rainfall)
  typified by large freshwater releases during wet
  (rainy) summer months and little or no releases
  during dry winter months
• Water runoff and freshwater releases typically
  occur during summer, followed by storm water
  runoff depressing the salinities for extended
  periods

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Rationale

• Information related to optimal timing, duration,
  frequency and quantity of FW releases into the SW
  Florida estuaries is lacking.
• Better communication between the resource
  managers and scientists in adjusting the FW flows
  to enhance and sustain oyster reefs in SW Florida
  estuaries is required.
• Higher temperatures and salinities result in the
  disease due to Perkinsus marinus and ultimately
  mortality.
• Ties in with the greater Everglades Restoration

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Historic Flow
Current Flow
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Objectives

• Establish the relation between freshwater inflows
  and salinities in the Caloosahatchee estuary.
• Examine the temporal and spatial relationships
  between salinities and oyster responses.
• Recommend target freshwater inflows that would
  sustain and enhance oyster populations in SW
  Florida estuaries.

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Caloosahatchee Estuary Sampling Locations
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Materials and Methods

• Temperature (oC), salinity (ppt), flow (cfs), D.
  O.
• Disease prevalence and intensity of the oyster
  pathogen, Perkinsus marinus (Ray 1954 Mackin
  1962)
• Spat recruitment oyster shells (Haven Fritz
  1985)
• Reproductive Potential (Fisher et al. 1996)
• Condition index (Lucas and Beninger 1985)

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Salinity Flow
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Flow vs. Salinity
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P. marinus intensity
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Condition Index
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Gonadal Index
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Gonadal Index
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Spat Recruitment
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Spat Recruitment
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Summary

• Significant relationship exists between flows
  from into the Caloosahatchee river and salinities
  at various locations(R2 54-75).
• Prevalence and intensity of P. marinus was
  influenced by salinity (freshwater inflow)
  Higher flows (lower salinities) decreased disease
  prevalence and intensity.
• Condition index varied over sampling months and
  may have been related to spawning.

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Summary

• Spat recruitment in all the rivers occurred
  continuously between May October.
• Flows between 500 and 3500 CFS in the
  Caloosahatchee River will result in salinities
  that are favorable to oysters.

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Summary

• Flows should be minimized between May October
  to prevent flushing of oyster larvae during
  spawning season. Freshwater inflows can be
  managed to minimize disease impacts to oysters.
• Shellfish responses and flow targets are being
  used in setting minimum and maximum flows of
  fresh water into the Caloosahatchee estuary and
  as an indicator of the success of the Everglades
  Restoration.

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Acknowledgments

• Sharon Thurston, Erin Dykes, Lesli Haynes, Amanda
  Booth, and numerous undergraduate students for
  technical and field help.
• Funding South Florida Water management District
  and U. S. Environmental Protection Agency.