Measuring Waterbird Response to Salinity, Depth, and Foraging...
Transcript of Measuring Waterbird Response to Salinity, Depth, and Foraging...
Measuring Waterbird Response to Salinity, Depth, and Foraging Area Manipulation: An Experiment to Inform
Adaptive Management
John KrauseCalifornia Department of Fish and Wildlife, Eden Landing Ecological Reserve
Susan De La CruzU.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary
Field Station
E12/13 Project Location
Before: Seasonal Ponds, dry in summer
2008 EIR/S Design (no reservoir, cells larger, island locations not optimized, no “mounds”)
Berms Re-aligned, Cells Smaller; New Forebay with Pump
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SNPL Nest Buffer Size: Island Location Optimized re: Disturbance
Islands Located Based on Trail Buffer max.(600 feet)
Constructed Berms with Finished Grade, Varied Slopes (5:1 to 10:1) for Enhanced Foraging/Roosting
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Excavated Channels, Built Mounds (< 12” high, 25:1 side slopes) for Topo Variation (Bird Roosting/Foraging)
5 Test Islands, to Address Cracking: Varied Surface Treatments, incl. Lime, Gravel, Oyster Shells, Lower Top Elevation
Test Islands: Gravel, Oyster Shell, Lime-treated Excavated Mud, Imported Dirt Fill
Islands Constructed
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Swales & Mounds: Excavated Mud
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E12-E13: Flooded, Operated 2014-16; Reached targets
Waterbird and Invertebrate Response
Research Questions
1. Was a salinity gradient established and maintained?
2. How are invertebrate community composition and abundance responding to variations in salinity level and water depth?
3. Are waterbirds responding to habitat characteristics?
E13
Methods - Habitat characteristics
• Real-time kinematics GPS elevation survey• Continuous water quality measurements in each cell with Odyssey salinity
loggers and Hach Hydrolab mini-sondes and data-sondes
Methods - Invertebrate SamplingOctober – May Benthic Invertebrates• Monthly cores (60cc, 2.6cm)*• Sampled 6 elevation zones/mound • 24 mounds
Aquatic Invertebrate Sweeps• Monthly within channels
Analyses• Generalized Linear Mixed Model with negative binomial
distribution
• Response variable: Total Benthic Invertebrate Abundance
• Fixed effects: Dissolved Oxygen, Percent Exposure, Month, Temperature, Salinity, pH, Elevation (Mound Zone); Random effects: Season Year, Pond, and Mound nested in Pond
*Sutherland et al. 2000. Marine Bio. Pomeroy & Butler. 2005. Waterbirds.
Methods - Waterbird Counts Whole Pond Counts• Monthly
• Birds assigned to 125 x 125 m grids
Foraging Mound Counts• Weekly
• Birds assigned to elevation zones
Analyses• Generalized linear mixed models with a zero-inflated
negative binomial distribution
• Response variables: Foraging and roosting small and medium shorebird abundance (mound counts)
• Fixed effects: Salinity, percent mound exposed, invertebrate density, distance to the nearest levee; Random effects: Month nested in Year, Mound nested in Pond
Average Salinity (ppt)
Targets: C1 = 20 – 50 ppt; C2 = 50 – 80 ppt; C3 = 80 - 140
Average DO (mg/L)
Benthic Invertebrate Densities
C1 C2 C3
Invertebrate Abundance Model Benthic Invertebrates
Fixed Effect Estimate Standard
Error Z Value p
Intercept 2.780 1.347 2.064 0.039
Salinity -0.008 0.008 -1.020 0.308
Temperature -0.010 0.024 -0.426 0.670pH -0.164 0.150 -1.094 0.274Dissolved Oxygen -0.065 0.024 -2.688 0.007
Mean Percent Exposure -0.004 0.001 -3.421 0.001Zone3 -0.048 0.103 -0.464 0.643Zone5 -0.086 0.104 -0.825 0.409October -0.051 0.244 -2.08 0.445November 0.286 0.202 1.42 0.157December 0.533 0.202 2.64 0.014February 0.492 0.163 3.01 0.003March 0.634 0.160 3.98 <0.001April 0.997 0.158 6.3 <0.001May 0.874 0.172 5.09 <0.001
Monthly Invertebrate Densities
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Waterbird Total AbundanceMound Scale
C1 C2 C3
Small Shorebird Distribution and Abundance on Mounds
11 Dec 201526 Dec 20159 Jan 201613 Jan 2016
Waterbird Monthly Abundance Pond Scale
Small Shorebird ModelForaging
Fixed Effect Estimate Standard error Z value pIntercept 3.796 0.797 4.766 <0.001Salinity -0.026 0.012 -2.211 0.027Benthic Invertebrate Density 0.007 0.014 1.597 0.110Distance To Levee (m) 0.005 0.006 0.917 0.359Percent Exposed (0 – 14%) 0.533 0.235 2.274 0.023Percent Exposed (15 -29 %) -0.265 0.326 -0.813 0.416Percent Exposed (30 – 44 %) 0.773 0.326 2.371 0.018Percent Exposed (45 – 59 %) -0.039 0.350 - 0.112 0.911Percent Exposed (60 – 74%) 1.011 0.259 3.900 0.173Percent Exposed (75 – 89 %) 0.280 0.617 0.454 0.154Percent Exposed 100% N/A N/A N/A NA
Small Shorebird ModelRoosting
Fixed Effect Estimate Standard error Z value pIntercept 4.859 1.008 4.822 <0.001Salinity - 0.040 0.018 1.948 0.028Benthic Invertebrate Density 0.007 0.014 0.436 0.663Distance To Levee (m) 0.001 0.003 0.483 0.029Percent Exposed (0 – 14%) 0.096 0.296 0.323 0.747Percent Exposed (15 -29 %) -0.118 0.443 -0.265 0.791PercentExposed (30 – 44 %) 0.830 0.463 1.793 0.073PercentExposed (45 – 59 %) 0.129 0.569 0.227 0.820PercentExposed (60 – 74%) 0.890 0.630 1.413 0.158Percent Exposed (75 – 89 %) N/A N/A N/A N/APercent Exposed 100% -0.626 1.022 -1.383 0.167
Medium Shorebird Model
Medium ShorebirdFixed Effect Estimate Standard error Z value p
Intercept -0.656 0.729 -0.899 0.368Salinity -0.020 0.014 -1.419 0.156Benthic Invertebrate Density 0.029 0.021 1.369 0.171Distance To Levee (m) 0.001 0.005 0.269 0.788Percent Exposed (0 – 14%) 0.021 0.257 0.081 0.935Percent Exposed (15 -29 %) 0.212 0.432 0.490 0.624Percent Exposed (30 – 44 %) 0.340 0.429 0.794 0.427Percent Exposed (45 – 59 %) -0.013 0.503 -0.027 0.979Percent Exposed (60 – 74%) -0.811 1.035 -0.783 0.434Percent Exposed (75 – 89 %) 0.788 1.099 0.717 0.473Percent Exposed 100% -19.690 29891.000 -0.001 0.999
Summary and Lessons Learned So Far….. Water Quality
• Salinities differentiate among cells, especially in drier months • Target salinities in C3 often difficult to reach • DO increases in early winter, but then drops – less circulation and macroalgae
influence?
Invertebrates• Communities highly differentiated among cells• Highest densities and diversity in C1. What about biomass?• Total abundance driven by DO and percent of mound exposed, not related to salinity
Waterbirds on mounds• Primary use was by small shorebirds• Highest abundances in C2 • Foraging small shorebirds associated with lower salinity cells and mounds that were
more inundated • Roosting small shorebirds associated with lower salinities and on mounds that were
greater distance to surrounding levees
On-going Work• Use true elevation (RTK) and staff gauge data to
calculate water depths for inclusion in models• Model response of individual dominant invertebrate
taxa to habitat variables• Evaluate invertebrate community composition
• Multi-dimensional modeling – canonical correspondence analyses, Permanova
• Model invertebrate biomass effect on shorebird abundance
• Evaluate waterbird use of pond bottom and associated habitat features
• Goals: • User-friendly model to
achieve and maintain differentiated salinity across cells; minimize pump use
• Develop niches or habitat "envelopes" for the major invertebrate species found in the South Bay Salt Pond restoration
• Collaborative effort• DU engineering and
model design• Model informed by USGS
water quality and invertebrate field data
E12/13 Hydrologic Model
Thanks to All of our Project Partners!
~ rJMlTED