November 2013 Caloosahatchee Science Workshop



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Utilization of Benthic Invertebrates as Salinity Indicators in South Florida Rivers, Lessons from the Peace and Alafia Rivers

  • November 2013

  • Caloosahatchee Science Workshop


Objectives

  • Peace & Alafia River Projects, Large & Intensive

  • Determine benthic components that will have greatest utility for a possible long-term monitoring program.

  • Evaluate relationships between the distribution and abundance of important benthic components and salinity.

  • Conclusions Transferrable to Caloosahatchee River?



When

  • Peace River

  • November 1998 end of wet season,

  • January 1999 winter dry season,

  • March 1999 spring dry season,

  • April 1999 spring very dry season

  • June 1999 end of dry season.

  • Alafia River

  • May 1999 very low flow

  • September 2001 end normal wet season



Level of Effort

  • Peace River – “Healthy River”

    • Mollusk survey – 61 sites, 2 visits
      • 17,000 specimens
    • Infauna – 12 defined areas, 1,450 samples
      • 4 zones intertidal / subtidal + 3 creeks + 1 SAV site
      • 5 visits – 1 wet season, 4 dry season
      • Each area – 10 cores, 10 sweep nets, 1AS/km
      • + 120 sediment samples for granulometry
      • 60,936 benthic specimens
      • 314 species


Level of Effort

  • Alafia River – “Impaired River”

    • Molluscs – 37 sites, 2 visits, 20 species
    • Infauna – 17 defined areas, 298 samples
      • 2 Hillsborough Bay locations, 15 River locations
      • 2 visits – 1 wet season, 1 dry season
      • Each area – 7 grabs & 2 sweep nets per season
      • 120 sediment samples for granulometry
      • 16,266 benthic specimens
      • 222 species dry season, 132 species wet season


Level of Effort – 1994-1995

  • Caloosahatchee River – “Impaired River”

    • Infauna – 4 locations, 12 sample periods
    • 192 samples
    • 219 species identified from 26,269 organisms


Biologically Relevant Salinity Zones (NOAA) used for strata for Peace River study

  • Zone I ≤ 0.5 PSU freshwater

  • Zone II > 0.5 to ≤ 8.0

  • Zone III > 8.0 to ≤ 16.0

  • Zone IV > 16.0 PSU estuarine



Peace River Zone Characteristics



Alafia River



Alafia River



Alafia River



Alafia River Taxa ranked by abundance vs. weighted center of salinity.



Alafia River



Caloosahatchee River Substrate Dial Cordy and Associates, Inc. 2012











Observations

  • Benthic fauna – species rich & abundant

  • Life history details for most species sparse

  • Epifaunal transients very important to fisheries

  • Seasonal movement upstream important



Observations, continued.

  • Intertidal river habitat is important

  • Rare taxa important? But not useful…

  • Abundant taxa too plastic?

  • High spatial and sample variance

    • Large sample numbers needed to detect differences
  • Molluscs (other than oysters)

    • Point in time collection ≠ species spatial domain.
    • 70% more species in Peace than Alafia*.


Observations, continued.

  • Molluscs (other than oysters)

    • Point in time collection ≠ species domain
    • 70% more species in Peace than Alafia*
  • Crustaceans – mobile species “keystone”

  • Sedentary species worms etc. record of recent past conditions

  • It’s Complicated – few simple effective tools



End



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