ImplementationofFloatingAquaticVegetativeTillingTechnologyintheCaloosahatcheeRiverWatershed
Deliverable#19:FinalReport
Site1
Preparedfor:FloridaDepartmentofAgricultureandConsumerService
(FDACS)
Contract#022563
Preparedby:Water&SoilSolutions,LLC
Loxahatchee,FL
September9,2016
RevisedSeptember14,2016
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TableofContents
ListofFigures.................................................................................................................................ii
ListofTables...................................................................................................................................v
Executivesummary......................................................................................................................1
Introduction....................................................................................................................................4
FAVTSystemUnitProcesses...............................................................................................6
Optimization&MonitoringResults......................................................................................7
WaterChemistryintheFAVTsystem..............................................................................7
Characterizationofinflowandoutflowwaterchemistry...................................9
TPandpHmonitoringatcellinflowsandoutflows...........................................17
FloatingandSubmergedAquaticVegetationSurveys...........................................24
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ListofFiguresFigure 1. Project location within the watershed (Source – Caloosahatchee River Watershed
Protection Plan January 2009). ................................................................................................. 5
Figure 2. Water quality sampling locations in the FAVT facility for sampling performed July 2015 through June 2016. ........................................................................................................... 9
Figure 3. TP concentrations in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016. ............... 13
Figure 4. SRP concentrations in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016. ............... 13
Figure 5. DOP concentrations in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016. ............... 14
Figure 6. PP concentrations in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016. ............... 14
Figure 7. TN concentrations in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016. ............... 15
Figure 8. Nitrate+nitrite (NOx) concentrations in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016......................................................................................................................................... 15
Figure 9. Ammonia-N concentrations in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016. . 16
Figure 10. Alkalinity in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016. ............... 16
Figure 11. pH in the Caloosahatchee FAVT system inflow and outflow streams. Monitoring was conducted on a weekly basis from July 2015 through June 2016. .......................................... 17
Figure 12. Surface water TP concentration and pH at the inflow and outflow of Cell 1 of the Caloosahatchee FAVT system. Monitoring was conducted on a weekly basis from July 2015 through June 2016. .................................................................................................................. 20
Figure 13. Surface water TP concentration and pH at the inflow and outflow of Cell 2 of the Caloosahatchee FAVT system. Monitoring was conducted on a weekly basis from July 2015 through June 2016. .................................................................................................................. 21
Figure 14. Surface water TP concentration and pH at the inflow and outflow of Cell 3 of the Caloosahatchee FAVT system. Monitoring was conducted on a weekly basis from July 2015 through June 2016. .................................................................................................................. 22
Figure 15. Mean surface water TP concentration (±1 standard deviation) at the system inflow (=Cell 1 inflow), Cell 1 outflow (=Cell 2 inflow), Cell 2 outflow (=Cell 3 inflow), and system outflow (=Cell 3 outflow) of the Caloosahatchee FAVT system. Values were calculated from data collected during 34 weekly monitoring events from July 2015 through June 2016. ............................................................................................................................... 23
Figure 16. Mean surface water pH (±1 standard deviation) at the system inflow (=Cell 1 inflow), Cell 1 outflow (=Cell 2 inflow), Cell 2 outflow (=Cell 3 inflow), and system outflow (=Cell 3
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outflow) of the Caloosahatchee FAVT system. Values were calculated from data collected during 34 weekly monitoring events from July 2015 through June 2016. ............................. 23
Figure 17. Very dense mat of Eichhornia crassipes (water hyacinth) and Pistia stratiotes (water lettuce) in Cell 1 ...................................................................................................................... 27
Figure 18. Time-series for FAV species within Cells 1 and 2 depicting the percent of stations that was moderately dense or greater for each species. ................................................................. 28
Figure 19. Time-series for FAV species within Cells 1 and 2 depicting the percent of stations that each species present. ............................................................................................................... 29
Figure 20. Mixed species mat with Eichhornia crassipes (water hyacinth) and Pistia stratiotes (water lettuce) in Cell 1. .......................................................................................................... 30
Figure 21. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during July 2015. ...................................................... 31
Figure 22. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during August 2015. ................................................. 31
Figure 23. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during September 2015. ........................................... 32
Figure 24. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during October 2015. ............................................... 32
Figure 25. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during early November 2015. .................................. 33
Figure 26. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during late November 2015. ..................................... 33
Figure 27. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during December 2015. ............................................ 34
Figure 28. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during January 2016. ................................................ 34
Figure 29. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during February 2016. .............................................. 35
Figure 30. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during March 2016. .................................................. 35
Figure 31. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during April 2016. .................................................... 36
Figure 32. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during May 2016. ..................................................... 36
Figure 33. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during June 2016. ..................................................... 37
Figure 34. Hydrilla verticillata, an invasive SAV species, at the Cell 2 culvert. ......................... 39
Figure 35. Time-series for SAV species within Cell 3 depicting the percent of stations that stations that was moderately dense or greater for each species. ............................................. 40
Figure 36. Time-series for SAV species within Cell 3 depicting the percent of stations that each species is present. .................................................................................................................... 41
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Figure 37. Mixed SAV assemblage containing Utricularia sp. (bladderwort) and other species in Cell 3. ...................................................................................................................................... 42
Figure 38. Najas guadalupensis (southern naiad) growing near the outflow of Cell 3. ................ 42
Figure 39. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the July 2015 vegetation survey.................................................................................................... 43
Figure 40. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the August 2015 vegetation survey. .............................................................................................. 44
Figure 41. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the September 2015 vegetation survey. ........................................................................................ 45
Figure 42. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the October 2015 vegetation survey. ............................................................................................ 46
Figure 43. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the early November 2015 vegetation survey. ............................................................................... 47
Figure 44. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the late November 2015 vegetation survey. ........................................................................................ 48
Figure 45. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the December 2015 vegetation survey. ......................................................................................... 49
Figure 46. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the January 2016 vegetation survey. ............................................................................................. 50
Figure 47. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the February 2016 vegetation survey. ........................................................................................... 51
Figure 48. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the March 2016 vegetation survey. ............................................................................................... 52
Figure 49. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the April 2016 vegetation survey. ................................................................................................. 53
Figure 50. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the May 2016 vegetation survey. .................................................................................................. 54
Figure 51. Relative cover of SAV species in Cell 3 of the Caloosahatchee wetland during the June 2016 vegetation survey. .................................................................................................. 55
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ListofTables Table 1. Analytical methods used for laboratory analysis of surface water sampled for the
Caloosahatchee FAVT project. Method detection limits (MDL) are shown for each chemical parameter analyzed. .................................................................................................................. 8
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ExecutivesummaryWater& Soil Solutions, LLC (WSSLLC) has deployed an approximately 523‐acre Floating
AquaticVegetativeTilling(FAVT)wetlandtreatmentfacilityintheHendry‐HilliardWater
ControlDistrict (HHWCD) in theEastCaloosahatcheeRiver Sub‐Watershed southwestof
LakeOkeechobee.Thepurposeoftheprojectistocost‐effectivelyremovephosphorus(P)
and nitrogen (N) from regional canals, including surface waters of the HHWCD and the
Caloosahatchee River (C‐43 Canal), using the patented FAVT technology in aman‐made
flow‐throughtreatmentmarsh.
FAVTsystemsutilizeanovelapproachtoenhanceNandPremoval fromsurfacewaters.
Thetechnologyusesthedirectassimilationofnutrientsfromthewatercolumnthroughthe
use of floating plant roots (as compared to plants rooted in the soil) and, rather than
periodically harvesting the plants (which is costly and inefficient due to the highwater
contentof thevegetation),allof thebiomass israpidly incorporateddirectly intothesoil
via tilling during the dry season. FAVT systems therefore operate similarly to a
conventional treatmentwetland by storing P in the soil, but they accomplish P removal
moreefficientlyandatasignificantlyfasterrate. Atthissite,FAVspeciescommontothe
adjacentcanals,namelyEichhorniacrassipes (waterhyacinth)andPistiastratiotes (water
lettuce),areutilizedinthefronttwocells,whileNajasguadalupensis,Utriculariaspp.,and
otherspeciesofsubmergedaquaticvegetation(SAV)dominatethebackend(Cell3)asa
final,“polishing”,componentoftheFAVTsystem.
Thesystembecamefullyoperational inSeptember2014,receivingregionalsourcewater
anddischargingthroughtheoutflowculvertsbeginning9/15/14.Subsequentmonitoring
of system inflow and outflow water chemistry was conducted on a weekly basis.
Monitoring results through June 2016 show that system outflow total phosphorus (TP)
concentrations were consistently lower than inflow TP concentrations, despite highly
variable inflow TP concentrations ranging from 33 µg/L to 147 µg/L. Outflow TP
concentrations ranged from 12 to 41 µg/L. There was a generally declining trend in
outflow TP concentration over the period July 2015 – June 2016. Overall mean TP
concentrations in the inflowandoutflow streamswere73 and23µg/L.Mean inflowTP
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was nearly the same as the mean inflow TP during the previous sampling period
(September 2014 – June 2015), yetmean outflow concentration has decreased by 30%.
Thismayreflectsystemmaturationandadecliningreleaseof legacysoilTPtothewater
column.SolublereactiveP(SRP)concentrationswereconsiderablyreducedintheoutflow
stream,fromanaverageof30µg/Lattheinflowto3µg/Lattheoutflow.Onaverage,SRP
accounted for41percentofTP in the inflowstreamand11percentofTP in theoutflow
stream.ThereductioninSRPconcentrationisassumedtobe largelyduetoplantuptake.
Inflow SRP concentration was consistently higher during the current (2015 – 2016)
monitoringperiod,comparedtothepreviousperiod,yetmeanoutflowSRPconcentration
was nearly identical during both periods, and close to the lower limit of detection.
Dissolved organic P (DOP) and particulate P (PP) concentrations were also effectively
reducedbytheFAVTsystem.
TPmonitoringattheinflowandoutflowofeachofCells1,2and3indicatedthatmostof
theP removalhasoccurredacrossCells1and2, a finding thatwasalsoobserved in the
previous year. Nearly all Cell 1 outflow samples were lower in TP concentration than
inflows.Thisisinsharpcontrasttotheprevioussamplingperiod,whereonlyinthelater
portionoftheperiodwasthereacleardifferenceininflowandoutflowTP.Cell1outflow
TPconcentrationwasrelativelystable,withanaveragevalueof28µg/Lduringthe2015–
2016period.TotalPwasfurtherreducedinCell2,fromaninflowmeanconcentrationof
28µg/L,to18µg/Lattheoutflow.AverageTPconcentrationincreasedslightlyacrossCell
3, from18µg/Latthe inflowto23µg/Lattheoutflow.Asobservedinpreviousreports,
lackof reduction inTPacrossCell3 couldbedue toanumberof factors, includingslow
releaseofphosphorusthathasaccumulatedduringpreviouslandmanagementpractices.
Aswasthecaseforthepreviousmonitoringperiod,TotalN(TN)concentrationswerenot
effectivelyreducedduringthecurrentperiod.TheoverallmeanoutflowTNconcentration
wasslightlyhigherthanmeaninflowTN(1.50versus1.42mg/L,respectively)andthese
valuesarenearlyidenticaltothoseobservedduringthepreviousperiod.Nearlyallofthe
TNloadtothesystemwasinorganicform,representingasubstantialpoolofNthatisnot
readily bioavailable. Both ammonia‐N andNOx‐Nwere reduced in the FAVT, from0.073
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mg/Lto0.047mg/Lforammonia‐N,and0.047mg/Lto0.017mg/LforNOx‐N.Thesumof
these two (dissolved inorganic N) represented approximately 8% of total N, thus
considerable organic N (about 92% of TN) probably passes through the system and is
unavailableforplantuptake.
In order to evaluate vegetation growth and health, visual assessments of speciation and
areal coverage (i.e., relative abundance) of FAV (Cells 1 and 2) and SAV (Cell 3) were
performedonaroutinebasisatstations locatedonapre‐determinedgridpatternacross
Cells 1 (21 stations), 2 (33 stations) and 3 (53 stations). These surveyswere conducted
monthly from July 2015 through June 2016. Results of the surveys indicated that dense
growthofwaterhyacinthhascontinuedtoincreaseincoverage,from86%to100%inCell
1.DensehyacinthcoveragehasdeclinedinCell2,withdensegrowthofhyacinthobserved
at67%ofsamplingstations inJuly2015,decliningto49%ofstationsbyJuly2016.Both
densityandpresenceofhyacinthhavedeclinedinCell2comparedtothepreviousperiod.
Spatiotemporal analysis showed persistent regions of open water appearing along the
western and southern regions of Cell 2, and in the outflow region. As observed in the
previousannualreport,totalPattheinflowtoCell2declinedsteadilyovertheNovember
2014toJune2015period.ThisdeclinemayhaveimpactedproductivityofhyacinthinCell
2.PistiaiscurrentlyarelativelyminorthoughstablecomponentoftheFAVcommunityin
bothcells.Atboththebeginningandendofthesamplingperiod,nodensestandsofPistia
wereobservedatanysamplingstationinCell1.Conversely,from3%to15%ofsampling
stationsreporteddensePistiainCell2overthecourseofthesamplingperiod.
Themost commonSAVspecies inCell3wereUtricularia,Najas,andHydrillaverticillata.
Themoststriking findingof thesubmergedaquaticvegetation(SAV)surveys for the July
2015 – June 2016 period is the increasing extent and density ofHydrilla. For example,
duringFebruary2015,Hydrillawasfoundatonly5%ofthemonitoringstations,andatno
stationwasitfoundtobeevenmoderatelydense.ByJune2016,Hydrillawasfoundtobeat
leastmoderatelydenseat50%ofthestationsandwaspresentat80%ofthestations.This
has been accompanied by large declines in Utricularia. During the previous period,
Utricularia densitywas relatively stable,with40‐70%of stationshavingdense standsof
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Utricularia. By November 2015, this had declined to 2% of stations reporting dense
Utricularia.Thus,Hydrilla seems tohavemostly replacedUtricularia inCell3.Continued
monitoringofbothSAVandFAVwillbeperformedinFY2016,inordertoenhancesystem
operations andmanagement practices, and to facilitate our understanding of spatial and
temporalpatternsinTPremovalperformance.
IntroductionWater&SoilSolutions,LLC(WSSLLC)hascompletedthefirst fullyearofoperationofan
approximately 523‐acre Floating Aquatic Vegetative Tilling (FAVT) wetland treatment
facilityintheHendry‐HilliardWaterControlDistrict(HHWCD)intheEastCaloosahatchee
River Sub‐Watershed southwest of Lake Okeechobee. The watershed is located in the
NorthernEvergladeswestofLakeOkeechobee.Theprojectsiteispartofalargeparcelof
privateland(Sections18&19/Township44South/Range32East)onthesouthernside
of the Caloosahatchee River (Figure 1). The purpose of the project is to cost effectively
removephosphorus(P)andnitrogen(N)fromregionalcanals,includingsurfacewatersof
the HHWCD and the Caloosahatchee River (C‐43 Canal), using the patented FAVT
technology in aman‐made flow‐through treatmentmarsh. This document encompasses
theFinalReportfortheprojectperiodJuly1,2015throughJune30,2016.
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ProjectSite
Figure1.Projectlocationwithinthewatershed(Source–CaloosahatcheeRiverWatershedProtectionPlanJanuary2009).
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FAVTSystemUnitProcesses
FAVTsystemsutilizeanovelapproachtoenhanceNandPremoval fromsurfacewaters.
ManyspeciesofFAV,suchaswaterhyacinth,areknowntorapidlyassimilateNandP,but
their high nutrient uptake rate can only be sustained if the plants aremaintained at an
optimaldensity.The ideal coverage is usually achievedbyperiodicharvesting; however,
since FAV are predominantly water, mechanical removal of the biomass is costly and
inefficient.FAVTovercomestheseconstraintsbyusingthefollowingoperationalapproach:
(1)theFAVwetlandisoperatedforaninitialgrowingseason,duringwhichtimetheFAV
assimilatenutrientsandgrowtoahighdensity;(2)thewetlandisdrainedduringthedry
season,therebystrandingtheFAVonthesoil;(3)afteranaturaldryingprocess,theplant
material is tilled into the soil togetherwith its associated nutrients; (4) thewetland is
reflooded;and(5)FAVthatarestoredindeeperzonesareusedtorepopulatethewetland
for the subsequent growth period. During this post‐tilling process, water is held in the
wetlandwithoutdischargeforseveralweekstoprovidetimeforthevegetationandwater
columnnutrient levels to equilibrate. It is anticipated that tillingwill beperformedon a
yearlybasis(approximately)attheProjectsite.ThisFAVTsystemalsocontainsanadded
component consisting of a variety of submerged aquatic vegetation (SAV) such asNajas
guadalupensis,Utriculariaspp.,andotherSAVspeciesatthebackendofthesystem(Cell3).
Thisprovidesafinal,“polishing”stepfortreatedwaterintheFAVTsystem.
FAVTsystemsthereforeoperatesimilarlytoaconventionaltreatmentwetlandbystoringP
inthesoil,buttheyaccomplishPremovalmoreefficientlyandatasignificantlyfasterrate.
Thetechnologyusesthedirectassimilationofnutrientsfromthewatercolumnthroughthe
useoffloatingplantroots(ascomparedtoplantsrootedinthesoil),andallofthebiomass
israpidlyincorporateddirectlyintothesoilthroughtilling.Theprocesstherebyresultsina
reductionofup to80%of landneeded for treatmentascomparedto traditionalwetland
treatment systems. It isexpected that theFAVTsystemswillprovideP reductions in the
rangeof3to15gP/m2‐yr,dependingonthegrowthrateoftheFAV,whichwillbelinkedto
factorssuchas theP loadingrate,speciationofP inthe inflowwaters,andavailabilityof
inorganic N and other macro‐ and micro‐nutrients in the inflow waters. Similarly, N
removalcanbeextremelyhighinFAVsystems(upto250gN/m2‐yr)whenthesupplyof
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inorganicNishighintheinflowwaters.AnefforttoestimatetotalPandNmassremoval
bytheEastCaloosahatcheeRiverProjecthasnotyetbeenmadeduetouncertaintiesofkey
underlyingvariables,suchaswateravailabilityandnutrientlevels.
At this site, FAV species common to the adjacent canals are being utilized, for example,
Eichhornia crassipes (water hyacinth). Maximum growth (and P uptake) rates of this
species occur in the summer, which coincides with the periods of highest runoff flows
availablefortreatment.
Asnotedabove,soilsaretheultimatestoragereservoirforPwithinalltreatmentwetlands.
In conventional, emergent plant based wetlands such as the front‐end cells of the
Everglades Stormwater Treatment Areas (STAs), most of the soil P is associated with
organicmatterwith lesseramounts associatedwithminerals suchas calcium, aluminum
andiron.AnimportantaspectoftheFAVTtillingapproachisthatitacceleratestherateof
transferringnotonlyP,butalsoorganicmatterand inorganicP‐sorbingcompounds into
permanent storage. The treatment process of this FAVT consists of two initial cells that
havebeenstockedwithhyacinthandwaterlettuce(Pistiastratiotes)(Figure2).Athirdand
largercellcontainsavarietyofsubmergedaquaticvegetation.Waterispumpedfromthe
OrangeGatecanalintoCell1,andthenflowssouththroughCell1andCell2.Itisgravity‐
discharged through three culverts to Cell 3, flows northward, and is then discharged
throughfourculvertstotheMcKinneycanalonthenorthendofthesystem.
Optimization&MonitoringResultsThegoalofthisoptimizationandmonitoringeffortistocollect,analyzeandreportwater
quality, water flow, vegetation and soil data to facilitate optimization of the East
CaloosahatcheeFAVTsysteminanenvironmentallysoundmannerandinaccordancewith
establishedprotocols.
WaterChemistryintheFAVTsystem
Thesystembecamefullyoperational inSeptember2014,receivingregionalsourcewater
anddischargingthroughtheoutflowculverts,beginning9/15/14.Subsequentmonitoring
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ofsysteminflowandoutflowwaterchemistrywasconductedonaweeklybasis.Resultsof
ongoingwaterqualitymonitoringarepresentedfortheperiod7/1/2015–6/30/2016.
Water samples collected during each event were analyzed for the parameters listed in
Table1,usingstandardmethodsofanalysis.DissolvedorganicP(DOP)andparticulateP
(PP)werecalculatedfromTP,SRPandTSP(DOP=TSP‐SRPandPP=TP‐TSP);totalN(TN)
was calculated as the sum of TKN and NOx‐N. pH was measured on site during each
samplingevent.
Additionalweeklymonitoring,forTPandpHonly,wasconductedattheoutflowsofCells1
and2(equivalenttotheinflowsofCells2and3,respectively),startinginNovember2014.
The objective of this supplemental monitoring is to evaluate water chemistry changes
withineachofthethreesystemcells.Forthispurpose,thesysteminflowandoutflowdata
representtheCell1inflowandCell3outflow,respectively.
Table1.AnalyticalmethodsusedforlaboratoryanalysisofsurfacewatersampledfortheCaloosahatcheeFAVTproject.Methoddetectionlimits(MDL)areshownforeachchemicalparameteranalyzed.
Parameter Method MDL
Total Phosphorus (TP) SM4500‐P F 3 µg/L
Soluble reactive P (SRP) SM4500‐P F/DBE SOP OPO4 2 µg/L
Total Soluble Phosphorus (TSP) SM4500‐P F 3 µg/L
Alkalinity EPA 310.1 3 mg CaCO3/L
Nitrate + nitrite (NOx‐N) EPA/353.2/SM4500 NO3‐F 0.016 mg/L
Total ammonia (NH3+NH4) EPA 350.11 0.020 mg/L
Total Kjeldahl Nitrogen (TKN) EPA 351.2 0.033 mg/L
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Figure2.WaterqualitysamplinglocationsintheFAVTfacilityforsamplingperformedJuly2015throughJune2016.
Characterizationofinflowandoutflowwaterchemistry
During the July 2015 – June 2016monitoring period, system outflow TP concentrations
were consistently lower than inflow TP concentrations (Figure 3). Inflow TP
concentrationsrangedfrom33µg/Lto147µg/L.OutflowTPconcentrationsrangedfrom
12to41µg/L,showingagenerallydecliningtrendoverthesamplingperiod.Overallmean
TP concentrations in the inflowandoutflowstreamswere73and23µg/L, respectively.
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TotalPinflowconcentrationsweregenerallyhigherforthissamplingperiod,comparedto
the2014‐2015period,eventhoughmeaninflowconcentrationswerenearlyidentical for
the two periods. Lower TP inflow concentrations duringmost of the 2014‐2015 period
were offset by several very high inflow values. Despite higher inflow TP concentration
during July 2015 – June 2016, outflow TP was on average 10 µg/L lower than the
September2014– June2015samplingperiod.Thismayreflectsystemmaturationanda
decliningreleaseoflegacysoilTPtothewatercolumn.
SolublereactivePconcentrationwasconsiderablyreducedintheoutflowstream,relative
to inflow concentration (Figure 4). Inflow SRP concentrations averaged 30 µg/L, but
rangedwidely, from6to85µg/L,duringthemonitoringperiod.Incontrast,outflowSRP
concentrationswere always below10 µg/L, ranging fromnon‐detectable (<2 µg/L) to 6
µg/L,andaveraging3µg/L.Onaverage,SRPaccountedfor41percentofTPintheinflow
stream,and11percentofTPintheoutflowstream.ThereductioninSRPconcentrationis
assumed to be due largely to plant uptake. As with TP, inflow SRP concentration was
consistently higher during the 2015 – 2016monitoring period, compared to the 2014 ‐
2015period.Thismayreflectrecentchanges in thewatershed,orperhapsdifferences in
seasonal factors between the periods. As with TP, despite higher average inflow SRP
concentrationinthecurrentperiod,outflowSRPwasmaintainedatlowlevels,oftenbelow
the limit of detection. Temporal changes in inflow SRP concentrationswere significantly
correlatedwithchangesininflowTP(r2=0.87).Thus,factorsinthewatershedthatgovern
bioavailablePareresponsibleforregulatingtheoverallsupplyofPtotheFAVT,andlikely
theCaloosahatcheeRiveraswell.
Concentration of DOP, which is not readily available for plant uptake, was consistently
lowerintheoutflowstreamthanintheinflowstreamduringthemonitoringperiod(Figure
5). The overallmean inflowDOP concentrationwas 17µg/L, comparedwith an outflow
mean concentration of 7 µg/L. Inflow DOP concentrations were considerably more
variable,rangingfrom5to38µg/L,relativetooutflowDOPconcentrations,whichranged
from 2 to 18 µg/L. On average, the proportion of DOP as a fraction of total P increased
slightlybetweenthesysteminflowandoutflow,from24to31percentofTP,reflectingthe
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lower bioavailability of DOP versus SRP. Unlike TP and SRP, inflow DOP declined on
averagefortheJuly2015–June2016period,comparedtothepreviousyear.Also,removal
ofDOPwassubstantiallybetteracross theFAVTcells,withapproximately50%of inflow
DOPremoved.
RemovalofPPwasconsistentlymoreeffectiveduringthismonitoringperiod,comparedto
2014–2015.(Figure6),with inflowandoutflowPPconcentrationsaveraging26and13
µg/L, respectively. InflowPPconcentrations ranged from6 to55µg/L,whileoutflowPP
concentrationsrangedfrom5to29µg/L.Thoughoverallmeaninflowconcentrationsfor
thetwosamplingyearswerethesame(26µg/L),inflowPPfortheJuly2015–June2016
periodwasconsistentlygreaterthanthepreviousyear.Thesamemeanconcentrationfor
bothperiodsreflects theeffectofseveralveryhighPPvalues forSeptember2014– June
2015 sampling period on the overall mean. There appears to be a seasonal effect on
outflow PP, with higher values associated with the wetter months (August – October)
compared with dry season concentrations. The stability in outflow PP concentration
relativeto inflowPPis indicativeofeffectivesettlingofparticulatesoverawiderangeof
inflowPconcentrations.
Aswasthecasefortheprevious(September2014throughJune2015)monitoringperiod,
TN concentrations in the inflow and outflow streamswere similar (Figure 7), reflecting
littleornonetremovalofNduringthisperiod.InflowTNconcentrationsrangedfrom1.03
to2.33mg/L,whileoutflowTNconcentrationsweremorevariable,ranging from0.98to
1.92mg/L.TheoverallmeanTNconcentration in theoutflowstreamwasslightlyhigher
thanthemeaninflowTNconcentration(1.50vs.1.42mg/L,respectively).Boththeaverage
concentrations and the seasonal pattern inTNwere strikingly similar for both sampling
years. Higher concentrations in TNwere observed in warmer summer and fall months,
withanetdecreasefromDecemberthroughMay.OnlyasmallfractionoftheTNloadtothe
system was in inorganic form, either as NOx‐N or ammonia‐N (Figure 8 and Figure 9).
Inflowandoutflowammonia‐Naveraged0.073mg/Land0.047mg/L,respectively.Inflow
andoutflowNOx‐Naveraged0.047mg/Land0.017mg/L,respectively,possiblyreflecting
someplantuptakeforbothformsof inorganicN. InorganicN(NHx+NOx‐N)represented
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8%ofTNattheinflowand5%ofTNattheoutflow.ThelargefractionoforganicNinthe
systeminflowrepresentsasubstantialpoolofNthatisnotreadilybioavailable.Althoughit
ispossiblethatreleaseoflegacysoilorganicNcontributesthelackofnetTNremoval,itis
likelythatthesimilaritybetweeninflowandoutflowTNconcentrationsaftermorethana
yearofoperationsimplyreflectsahighlevelofresistancetodegradation(recalcitrance)of
organicN in the inflow stream.Within themuch smaller inorganicNpool in the system
inflow, there is evidence of depletion of NOx‐N either through plant uptake or
denitrification,andammonia‐Nviaplantuptakeornitrification.
Alkalinitylevelsintheinflowwateraveraged150mg(asCaCO3)/Landrangedfrom92to
214 mg/L, which is essentially the same as the previous year (Figure 10). Unlike the
September2014– June2015period, therewasadifference inalkalinitybetween inflow
andoutflow.Outflowalkalinitywaslower,averaging118mg/Landrangingfrom86to148
mg/L.Thisprobablyreflects theestablishmentofarobustsubmergedaquaticvegetation
(SAV) community inCell 3 andphotosynthetic removalofHCO3‐ from thewater column.
OutflowpHwas consistentlyhigher than inflowpH (Figure11), likelydue inpart to the
consumptionofdissolvedCO2bySAVinCell3ofthetreatmentsystem.Forthemonitoring
period,inflowpHrangedfrom6.7to7.7,averaging7.3.OutflowpHrangedfrom7.0to8.1
andaveraged7.6.
13
Figure3.TPconcentrationsintheCaloosahatcheeFAVTsysteminflowandoutflowstreams.MonitoringwasconductedonaweeklybasisfromJuly2015throughJune2016.
Figure 4. SRP concentrations in the Caloosahatchee FAVT system inflow and outflowstreams.MonitoringwasconductedonaweeklybasisfromJuly2015throughJune2016.
14
Figure 5. DOP concentrations in the Caloosahatchee FAVT system inflow and outflowstreams.MonitoringwasconductedonaweeklybasisfromJuly2015throughJune2016.
Figure6.PPconcentrationsintheCaloosahatcheeFAVTsysteminflowandoutflowstreams.MonitoringwasconductedonaweeklybasisfromJuly2015throughJune2016.
15
Figure7.TNconcentrationsintheCaloosahatcheeFAVTsysteminflowandoutflowstreams.MonitoringwasconductedonaweeklybasisfromJuly2015throughJune2016.
Figure 8.Nitrate+nitrite (NOx) concentrations in the Caloosahatchee FAVT system inflowandoutflowstreams.Monitoringwasconductedonaweeklybasisfrom July2015throughJune2016.
16
Figure9.Ammonia‐NconcentrationsintheCaloosahatcheeFAVTsysteminflowandoutflowstreams.MonitoringwasconductedonaweeklybasisfromJuly2015throughJune2016.
Figure 10. Alkalinity in the Caloosahatchee FAVT system inflow and outflow streams.MonitoringwasconductedonaweeklybasisfromJuly2015throughJune2016.
17
Figure11.pH in theCaloosahatcheeFAVTsystem inflowandoutflowstreams.MonitoringwasconductedonaweeklybasisfromJuly2015throughJune2016.
TPandpHmonitoringatcellinflowsandoutflows
With the exception of one sample, all Cell 1 outflow samples were lower in TP
concentration thanCell 1 inflows (Figure12). This is in sharp contrast to theNovember
2014–June2015samplingperiod,whereonlyinthelaterportionoftheperiodwasthere
acleardifferenceininflowandoutflowTPforCell1. AverageTPconcentrationdeclined
acrossCell1, from73µg/Lto28µg/L,ora62%reduction. Cell1outflowconcentration
wasrelativelystableovertheperiod,withthemajorityofvaluesfallingbetween20and40
µg/L.
TotalPremovalwasnotasdramaticinthetwodownstreamcells,althoughitislikelythat
theoverall recalcitranceof P increaseddownstream fromCell 1. Total Pdeclined across
Cell2,fromaninflowmeanconcentrationof28µg/L,to18µg/Lattheoutflow(Figure13).
Since May 2015, Cell 2 outflow TP concentration has been relatively stable, with most
valuesfallingbetween10‐20µg/L.
As observed during the latter part of theNovember 2014 – June 2015 sampling period,
averageTPconcentrationincreasedslightlyacrossCell3,from18µg/Lattheinflowto23
µg/Lat theoutflow(systemoutflow)(Figure14).HigheraverageoutflowTPwasmostly
18
duetohigheroutflowvaluesovertheperiodJuly2015throughDecember2015,whereTP
averaged28µg/L.For the remainderof thesamplingperiod,Cell3outflowaveraged18
µg/L versus 17 µg/L for Cell 3 inflow. As pointed out in the previous report, a lack of
reductioninTPacrossCell3couldbeduetoanumberoffactors,includingslowreleaseof
phosphorusthathasaccumulatedduringpreviousfarmmanagementpractices.Inaddition,
itislikelythatmuchoftheremainingTPinthewatercolumnconsistsofrefractoryforms
ofPthatarenotreadilyavailabletotheplantcommunityandthisfractionsimply“passes
through” the FAVT system. It is clear from Figure 5 and Figure 6 that, even though
substantialDOPisremovedbytheFAVTsystem,apersistent5–10µg/LDOPremainsat
thesystemoutflow,asdoesapproximately10µg/LPP.Thesetwofractions,inadditionto
any soil P release, could account for the approximately 20 µg/L TP that remains at the
systemoutflow.
SysteminflowpHaveraged7.26units,withastandarddeviationof0.23(Figure12).Cell1
management activities for both sampling periods did appear to have resulted in a slight
decline (0.07 units for July 2015 – June 2016) in pH across the cell. Also, wet season
months(July–November)wereonaveragelowerinpHforbothinflowandoutflow.For
example, inflowpHaveraged7.18 for thewetseasonvs.7.30 for thedryseason.Aswas
true for the November 2014 – June 2015 period, pH increased across Cell 2, increasing
significantlyfromanaverageof7.19to7.52(Figure13).AfurtherslightincreaseinpHwas
observedbetweentheinflowandoutflowofSAV‐dominatedCell3,thoughthiseffectwas
not as consistentor aspronouncedasduring theNovember2014– June2015 sampling
period(Figure14).
Figure15summarizes theoveralldecreasingtrend inTPconcentrationalong thesystem
flow path during the July 2015 ‐ June 2016 period. The mean system inflow TP
concentrationof73µg/Lduringthatperioddecreasedtoameanvalueof28µg/Latthe
Cell 1 outflowand furtherdecreased to18µg/L at theCell 2 outflow.The simultaneous
decreaseovertimeinCell2outflowTPconcentrationandlackofchangeinCell3outflow
TP concentration (Figure 14) is reflected in Figure 15 as a slight increase in the overall
meanoutflowTPconcentration(23µg/L)ascomparedtomeanCell2outflowTP.Thisisa
19
verysimilarresulttothatobservedfortheNovember2014–June2015samplingperiod.
StandarddeviationsofmeanTPconcentrationsatthecellinflowandoutflowpointsreflect
asubstantialdecrease intemporalvariability inTPconcentrationsalongthesystemflow
path,andare indicativeofsubstantialattenuationwithin thesystemofhighly fluctuating
inflowTPconcentrationsobservedduringthemonitoringperiod.TheFAVTsystemisthus
quite effective in moderating abrupt changes in inflow parameters, particularly with
respecttoformsofphosphorus,NOx‐N,ammonia‐N,andalkalinity.
Changes in pH across sequential treatment cells are summarized in Figure 16.Mean pH
values for the July 2015 – June 2016period indicate the small decrease in pH observed
betweenthesysteminflowandCell1outflow,andsubsequentincreasesinpHacrossCells
2and3.ThemeanpHof7.34atthesysteminflowdecreasedslightlytoameanpHof7.19
attheCell1outflow,whilethemeanpHvaluesfortheCell2andCell3outflowswere7.52
and7.62,respectively.TheseresultsareverysimilartoresultsobservedfortheNovember
2014–June2015period.
20
Figure12.SurfacewaterTPconcentrationandpHattheinflowandoutflowofCell1oftheCaloosahatcheeFAVTsystem.Monitoringwasconductedonaweeklybasis from July2015throughJune2016.
21
Figure13.SurfacewaterTPconcentrationandpHattheinflowandoutflowofCell2oftheCaloosahatcheeFAVTsystem.Monitoringwasconductedonaweeklybasis from July2015throughJune2016.
22
Figure14.SurfacewaterTPconcentrationandpHattheinflowandoutflowofCell3oftheCaloosahatcheeFAVTsystem.Monitoringwasconductedonaweeklybasis from July2015throughJune2016.
23
Figure 15. Mean surface water TP concentration (±1 standard deviation) at the systeminflow (=Cell1 inflow),Cell1outflow (=Cell2 inflow),Cell2outflow (=Cell3 inflow),andsystemoutflow(=Cell3outflow)oftheCaloosahatcheeFAVTsystem.Valueswerecalculatedfromdatacollectedduring34weeklymonitoringeventsfromJuly2015throughJune2016.
Figure 16.Mean surfacewater pH (±1 standard deviation) at the system inflow (=Cell 1inflow),Cell1outflow (=Cell2 inflow),Cell2outflow(=Cell3 inflow),andsystemoutflow(=Cell 3 outflow) of the Caloosahatchee FAVT system. Valueswere calculated from datacollectedduring34weeklymonitoringeventsfromJuly2015throughJune2016.
24
FloatingandSubmergedAquaticVegetationSurveys
Visualassessmentofspeciationandarealcoverage(i.e.,relativeabundance)ofFAV(Cells1
and 2) and SAV (Cell 3)was performed on a routine basis at stations located on a pre‐
determinedgridpattern acrossCells 1 (21 stations), 2 (33 stations) and3 (53 stations).
Thesesurveyswereconductedmonthly fromJuly2015 through June2016.Surveydates
were7/30/2015,8/25/15,9/23/2015,10/20/2015,11/5/2015,11/24/2015,12/15/15,
1/12/16,2/16/2016,3/15/2016,4/12/2016,5/11/2016,and6/14/2016.
DuringturbidwaterconditionsorwhenSAVwasnotvisibleinthewatercolumn,theSAV
assessment in Cell 3 was performed using a systematic collection method, whereby a
garden rake was dragged three times along the bottom (~1 m distance) to collect the
vegetation. Note that this rake method was not used if dense SAV was present. The
coverageofeachspecieswasscoredbasedonthefive‐pointscalebelow.ForSAV,eachof
thesecoveragecategoriesincludedvegetationobservedwithinthewatercolumnaswellas
anyvegetationcollectedwiththerake.
Vegetationcoverage(relativeabundance)categorieswerereportedasfollows:
None Sparse:0–10percent ModeratelyDense:10–40percent Dense:10–80percent Verydense:>80percent
Results of the FAV surveys reflect a further increase inmoderately‐dense to very‐dense
(hereafterreferredtoas“dense”)coverageofwaterhyacinth(Figure17)inCell1between
September 2015 and July 2016 (Figure 18). Dense coverage increased from 86% of the
samplingstationsto100%byApril2016andremainedatthatdensityfortheremainderof
the sampling period. Unlike the same period in 2014, the extent of “dense” hyacinth
coverage inCell2steadilydeclinedfrom67percent to33percent.Withtheexceptionof
the July andAugust2015periods,waterhyacinth coveragewas always greater inCell 1
compared to Cell 2, presumably due to the higher concentrations of plant‐available
nutrients inCell1.Unlike the2014–2015vegetationsurvey,hyacinthwasnot foundat
everystationinCell1,althoughitwasalwayspresentat>90%ofstations(Figure19).For
25
Cell2,hyacinthwasfoundatapproximately80%ofstations.Itspresencedeclinedoverthe
intervalJuly2015–June2016,topresenceatonly70%ofstationsbytheendoftheperiod.
Thisisincontrasttothe2014–2015samplingperiod,wherehyacinthwasfoundatnearly
100% of sampling stations in Cell 2. Thus, both density, and presence of hyacinth has
declined inCell 2 compared to thepreviousperiod.Asmentioned in theprevious year’s
annualreport,totalPattheinflowtoCell2declinedsteadilyovertheNovember2014to
June2015period.ThisdeclinemayhaveimpactedproductivityofhyacinthinCell2.
Coverage of Pistia stratiotes (water lettuce; Figure 20) was consistently lower than
hyacinthcoverage,inbothcells1and2.InCell1,“dense”coverageofPistiawasfoundat
less than20percentofstationsduring thismonitoringperiod(Figure18).Theredidnot
appeartobeaseasonaleffectonPistiadensity.PistiadensityinCell1declinedcompared
totheSeptember2014–June2015period,with6ofthe13samplingeventsreportingless
thanevenmoderatelydensecoverage.PistiadensityinCell2wasgenerallyslightlygreater
thanCell 1, ranging from3 to 15percent of stationswith at leastmoderate coverage of
Pistia.PresenceofPistiainCell1,atalldensities,hasundergoneasteadydeclineoverthe
entireperiodofrecord,from81percentofstationsreportingPistiainOctober2014,to24
percentofstationsreportingPistiainJune2016(Figure19).
Insummary,hyacinthismuchmoreprevalentandalsodenserthanPistiainCell’s1and2.
Hyacinth growth in Cell 1 has been vigorous,with only48%of stations reportingdense
hyacinthinOctober2014,increasingto100%ofstationsreportingdensecoveragebyApril
2016.Pistiacoverageinbothcellshasbeenconsiderablylowerindensityandoccurrence
across thesamplinggrid.ForCell2,densityand frequencyofoccurrenceofhyacinthhas
declined over the period July 2015 – June 2016. Frequency of occurrence of Pistia was
overall slightly greater for Cell 2 than Cell 1, and it was present at less than 40% of
samplingstationsforbothcells.
ThespatialdistributionsofhyacinthandPistiaareshownformonthlyintervals,fromJuly
2015throughJune2016,inFigure21throughFigure33.Cell1maintainedadensetovery
dense coverage of hyacinth throughout the sampling period. Lower densities were
associatedwithinflowandoutflowregions.Therewereonlyoccasionalisolatedpocketsof
26
openwater.Densityofhyacinthdeclined January throughMarch,but recoveredbyApril
andbyJunewereasrobustasthebeginningoftheperiod,withapproximately90%ofthe
areaof the cell having verydensehyacinth coverage. Cell 2 showed constantdeclines in
hyacinthcoveragethroughtheperiod.Persistentregionsofopenwaterappearedalongthe
western and southern regions of the cell, and in the outflow region. Greater hyacinth
densitieswithin Cell 2 seemed to be associatedwith cypress domes, perhaps due to the
effectof thecypressdomesonwindmovementofplants.By June2016, therewere large
areasofopenwateronthewesternandsouthernregionofCell2,andmostofthecellwas
characterizedashavingasparse(orless)coverageofhyacinth.Pistiawasgenerallyabsent
atmost stations inbothCell 1 andCell 2.When it occurred inCell 1, itwas foundmost
frequentlyinthesouthernendofthecell,andwasusuallyfoundatasparseorlessdensity.
The April 2016 sampling found a complete lack ofPistia for Cell 1. Cell 2 usually had a
greater coverage area and a greater density of Pistia. Pistia seemed to favor the region
between the two cypress domes in Cell 2, perhaps also due to the effect of the cypress
domes onwind distribution of the plants. Unlike hyacinth in Cell 2,Pistia coverage and
density in Cell 2 did not seem to show a temporal trend. In fact, there seemed to be a
greater density and distribution of Pistia during the final June 2016 sampling than the
initialJuly2015sampling.ThismightbeduetoPistiacolonizingregionsofCell2thathad
seendeclinesinhyacinthcoverage.
27
Figure17.VerydensematofEichhorniacrassipes(waterhyacinth)andPistiastratiotes(waterlettuce)inCell1
28
Cell 1:
Cell 2:
Figure18.Time‐seriesforFAVspecieswithinCells1and2depictingthepercentofstationsthatwasmoderatelydenseorgreaterforeachspecies.
29
Cell 1:
Cell 2:
Figure19.Time‐seriesforFAVspecieswithinCells1and2depictingthepercentofstationsthateachspeciespresent.
30
Figure20.MixedspeciesmatwithEichhorniacrassipes(waterhyacinth)andPistiastratiotes(waterlettuce)inCell1.
31
Figure21.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringJuly2015.
Figure22.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringAugust2015.
32
Figure23.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringSeptember2015.
Figure24.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringOctober2015.
33
Figure25.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringearlyNovember2015.
Figure26.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringlateNovember2015.
34
Figure27.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringDecember2015.
Figure28.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringJanuary2016.
35
Figure29.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringFebruary2016.
Figure30.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringMarch2016.
36
Figure31.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringApril2016.
Figure32.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringMay2016.
37
Figure33.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringJune2016.
38
Themoststriking findingof thesubmergedaquaticvegetation(SAV)surveys for the July
2015–June2016periodistheincreasingextentanddensityofHydrilla(Figure34).During
February of 2015 (previous reporting period), Hydrilla was found at only 5% of the
monitoringstations,andatnostationwasitfoundtobeevenmoderatelydense.ByJuneof
2016,Hydrillawasfoundtobeatleastmoderatelydenseat50%ofthestations(Figure35)
andwaspresentat80%of thestations(Figure36).Thishasbeenaccompaniedby large
declines in Utricularia (Figure 37). During the September 2014 – June 2015 period,
Utricularia density was relatively stable, with 40‐70% of stations having densities of
moderatelydenseorgreater.ByNovember2015,thishaddeclinedto2%ofstationswith
moderatelydenseorgreaterUtricularia(Figure35).Throughoutthe2014–2015period,
Utricularia was found at approximately 80% of sampling stations. By June of 2016, that
declined to only 30% of stationswithUtricularia present. Thus,Hydrilla seems to have
mostly replaced Utricularia in Cell 3.Najas (Figure 38) greatly increased in both areal
extentanddensityinthepreviousSeptember2014–June2015monitoringperiodandwas
found at 83% of stations, and 70% of stations had moderately dense or greater plant
density. This extent and density has remained constant for the July 2015 – June 2016
period(Figure35andFigure36).
TheothersurveyedSAVspeciesCeratophyllum,Ludwigiarepens,Potamogeton,Charaand
BacopatendedtobeaminorcomponentoftheCell3SAVcommunity.Thosespecieswere
typicallypresentat<20%ofmonitoringstationsandwith<10%ofstationsreportingat
leastmoderatedensities.Overall,SAVcoveragerangedfrom83to100%oftheareaofCell
3(Figure36)).
The spatial extent of the most prevalent SAV species, Najas, Utricularia and Hydrilla,
exhibiteduniquespatialpatternsduring themonitoringperiod(Figure39).Forexample,
(as was found in the previous report)Najas tended to colonize the inflow and outflow
regionsofCell3overtime,whileHydrillaproliferatedprimarilyinthemid‐regionofCell3.
The final June 2016 survey suggests thatHydrilla is displacingNajas in the inflow and
outflow regions as well. The sparse and irregular distribution of Bacopa had mostly
disappeared from Cell 3 by March 2016. The decline in Utricularia began in the Cell 3
39
inflow region and progressed southward. ByMarch 2016,Utricularia was limited to the
westernsideofCell3,withsomeregionsoftrace‐moderatelydenseUtriculariasurvivingin
thesouthernoutflowregionofthecell.Changesindensityandspeciescompositionduring
theearlystagesofsystemoperationwilllikelycontinueduringtheshorttermaswaterand
soil chemistry across the system stabilize. In addition, inter‐specific competition as has
beenobservedbetweenHydrilla,Utricularia,andNajaswillplayalargeroleintheeventual
distributionofSAVspeciesinCell3.
Continued monitoring of both SAV and FAV will be performed in FY 2017, in order to
enhancesystemoperationsandmanagementpractices,andtofacilitateourunderstanding
ofspatialandtemporalpatternsinTPremovalperformance.
Figure34.Hydrillaverticillata,aninvasiveSAVspecies,attheCell2culvert.
40
Figure35.Time‐seriesforSAVspecieswithinCell3depictingthepercentofstationsthatstationsthatwasmoderatelydenseorgreaterforeachspecies.
41
Figure36.Time‐seriesforSAVspecieswithinCell3depictingthepercentofstationsthateachspeciesispresent.
42
Figure37.MixedSAVassemblagecontainingUtriculariasp.(bladderwort)andotherspeciesinCell3.Figure38.Najasguadalupensis(southernnaiad)growingneartheoutflowofCell3.
43
Figure39.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheJuly2015vegetationsurvey.
44
Figure40.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheAugust2015vegetationsurvey.
45
Figure41.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheSeptember2015vegetationsurvey.
46
Figure42.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheOctober2015vegetationsurvey.
47
Figure43.RelativecoverofSAVspecies inCell3of theCaloosahatcheewetlandduring theearlyNovember2015vegetationsurvey.
48
Figure44.Relative coverof SAV species inCell3of theCaloosahatcheewetlandduring the lateNovember2015 vegetationsurvey.
49
Figure45.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheDecember2015vegetationsurvey.
50
Figure46.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheJanuary2016vegetationsurvey.
51
Figure47.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheFebruary2016vegetationsurvey.
52
Figure48.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheMarch2016vegetationsurvey.
53
Figure49.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheApril2016vegetationsurvey.
54
Figure50.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheMay2016vegetationsurvey.
55
Figure51.RelativecoverofSAVspeciesinCell3oftheCaloosahatcheewetlandduringtheJune2016vegetationsurvey.
