Assessment of aquatic food web alterations in the presence of the exotic clam, Corbicula fluminea and the cichlid, Oreochromis aureus

236 Pages·2000·4.3 MB·English

by  Brock, Robert J.

ASSESSMENTOFAQUATIC FOODWEBALTERATIONS IN
THEPRESENCEOFTHEEXOTICCLAM, Corbicula
flumineaANDTHECICHLID, Oreochromisaureus
By
ROBERTJ. BROCK
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAIN PARTIAL FULFILLMENT
OFTHEREQUIREMENTS FORTHE DEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
2000
ACKNOWLEDGMENTS
This researchwas supportedandimprovedbyanumberof
peopleandtrulyrepresents acollaborativeeffort. First
andforemost, Iwouldliketothankmycommitteemembers,
Drs. NordlieandBitton, fortheirpatience, support, and
guidance. Iwasalso fortunatetoenoughenroll inaclass
taughtbyeachprofessorandfeeltheirteaching
significantlyaddedtomyknowledgeoftheirparticular
fields. AveryspecialthankyougoestoDr. Williamsand
Dr. BestoftheU.S. GeologicalSurvey'sBiological
ResourcesDivision. Drs. WilliamsandBesthavebeena
constant sourceofenthusiastic support andguidance, as
well as friendship, andhave goneoutoftheirwaytomake
themselves andtheUSGS research facilityinGainesville
availabletome. Saving thebest forlast, there isnoway
that I canadequatelythankmysupervisorychair, Dr.
Crisman, forall thathehasdoneforme. Dr. Crisman is
theprimarilyreason IcametoUFandhasbeenmymentor,
guru, employer, slavedriver, andbest friendsincethevery
firstdayI arrivedoncampus. Everythingthat Idofrom
nowonbothacademicallyandprofessionallywillbea
ii
reflectionofhisguidanceandsupport.
Anumberofinstitutionsandagencieshavegoneoutof
theirwaytoaccommodatemewith laboratoryspaceand
equipment. Partial support forthis researchwasprovided
byNASA's PlanetaryBiologyInternshipProgram. I havenot
forgottentheeffortsoftheU.S. ArmyCorpsofEngineers,
theNationalParkServiceandtheUniversityofFlorida. I
thankeachofthemforall oftheirhelp.
TABLEOFCONTENTS
Page
ACKNOWLEDGMENTS ii
LISTOFTABLES vi
LISTOFFIGURES vii
ABSTRACT xi
CHAPTERS
1 INTRODUCTION 1
2 LITERATUREREVIEWANDDEVELOPMENTOFHYPOTHESES 8
Introduction 8
TheImportanceofExoticFishonthePlanktonic
StructureoftheWaterColumn 9
The ImportanceofExoticBenthicFilter-Feederson
theStructureoftheOverlyingWaterColumn 11
TheInfluenceofExoticMollusksonNutrientLevels
andRegeneration 19
InterspecificCompetitionofCorbiculawithOther
Mollusks inLoticEnvironments 22
PredationofAquaticOrganismsonCorbicula 26
DevelopmentofHypotheses 28
3 ASSESSINGNUTRIENTANDPLANKTONICCHANGES INLABORATORY
MICROCOSMS INTHEPRESENCEOFCorbicula fluminea ... 30
Introduction 30
Methods 31
ResultsandDiscussion 35
Macronutrients 35
Turbidity 38
Bacterioplankton 40
Chlorophyll-a 44
Rotifers 47
Macrozooplankton 50
Conclusions 54
4 SURVIVALOFLARVALFISHINLABORATORYMICROCOSMS
INTHEPRESENCEOFCorbicula fluminea 59
Introduction 59
Methods 64
ResultsandDiscussion 67
SuspendedParticles 67
Larval Fish 71
Conclusions 78
5 AQUALITATIVEASSESSMENTOFTHEACTIVITYOFALGAL
CELLSENCASEDINPSEUDOFECES PRODUCEDBYCorbicula
fluminea 8
Introduction 80
Methods 82
ResultsandDiscussion 86
6 ASSESSINGTHEIMPACTOFCorbiculaflumineaAND
OreochromisaureusONWATERQUALITYANDPLANKTONIN
OUTDOORMESOCOSMS 92
Introduction 92
Methods 93
RationaleforStatisticalMethods 95
ResultsandDiscussion 96
WaterTemperature 96
DissolvedOxygen 101
Phytoplankton (asChlorophyll-a) 107
Zooplankton 119
Rotifers 122
CladoceransandCopepods 139
Summary 161
7 CONCLUSIONS 175
REFERENCES 183
BIOGRAPHICALSKETCH 218
LISTOFTABLES
Table Page
Chronologyoftheintroductionofexotic
mollusks intoSanFranciscoBay 14
Rotifer, Cladoceran, andCopepodtaxa from
mesocosmexperiments 120
vi
LISTOFFIGURES
Figure Page
1. Steadyrise inthenumberof introduced
mollusks intoSanFranciscoBay 14
2. DecreaseofthenativeEurytemoraaffinis .. 15
3. Increase inbiomassof Potamocorbula 17
4. Changesinmacronutrient concentrations .... 36
5. Changes inoverallturbidity (NTU's) 39
6. Changes inmicrocosmbacteriaabundance 42
7. Changes inchlorophyll-ainmicrocosms 45
8. Changes inrotiferbiomass inmicrocosms ... 48
9. Changes incladoceranbiomass inmicrocosms. 51
10. Changes incopepodbiomass inmicrocosms ... 51
11. Changes intotal zooplanktonbiomass 57
12. General sizeofpreyanimals throughthe
earlylifecycleoflarval fish 61
13. Changes inturbidityinmicrocosms over
504 hours 68
14. Changes inchlorophyll-a inmicrocosms
overa 504 hours 68
15. Changes inrotiferbiomass inmicrocosms
overa504hours 70
16. Fisheggstransformedto larvae 74
17. Numberofsurviving larvae (336hours) 76
vii
18. Numberofsurviving larvae (504 hours) 77
19. NoINTformazancrystalsareseen 87
20. INT-formazancrystalsareseen 88
21. Changes inmesocosmwatertemperatures (°C)
duringthewintersamplingperiod 97
22. Changes inmesocosmwatertemperature (°C)
duringthespringsamplingperiod 99
23. Changes inmesocosmwatertemperature (°C)
duringthesummersamplingperiod 100
24. Changes inmesocosmdissolvedoxygenduring
thewintersamplingperiod 102
25. Changes inmesocosmdissolvedoxygenduring
thespring samplingperiod 104
26. Changes inmesocosmdissolvedoxygenduring
thesummersamplingperiod 105
27. Changes inmesocosmchlorophyll-aduring
thewintersamplingperiod 108
28a. Relationshipbetweenwatertemperatureand
chlorophyll-aduringwinter 110
28b. Relationshipbetweenwatertemperatureand
chlorophyll-aduringwinter Ill
29. Changes inmesocosmchlorophyll-aduring
spring 114
30. Changes inmesocosmchlorophyll-aduring
summer 116
31. Changes inmesocosmrotiferbiomassduring
winter 124
32a. Relationshipbetweenrotifersand
phytoplanktonduringwinter 126
32b. Relationshipbetween rotifersand
phytoplanktonduringwinter 127
viii
33. Changes inmesocosmrotiferbiomassduring
spring 129
34a. Relationshipbetweenrotifersand
phytoplanktonduringspring 131
34b. Relationshipbetweenrotifersand
phytoplanktonduring spring 133
35. Changes inmesocosmrotiferbiomassduring
summer 134
36a. Relationshipbetweenrotifersand
phytoplanktonduringsummer 136
36b. Relationshipbetweenrotifersand
phytoplanktonduringsummer 137
37. Changes inmesocosmmacrozooplankton
biomassduringwinter 142
38a. Relationshipbetweencladoceransandcopepods
andphytoplanktonduringwinter 145
38b. Relationshipbetweencladoceransandcopepods
andphytoplanktonduringwinter 146
39. Changes inmesocosmmacrozooplanktonbiomass
duringspring 148
40a. Relationshipbetweencladoceransandcopepods
andphytoplanktonduringthe spring 150
40b. Relationshipbetweencladoceransandcopepods
andphytoplanktonduringspring 151
41. Changes inmesocosmmacrozooplanktonbiomass
duringsummer 154
42a. Relationshipbetweencladoceransandcopepods
andphytoplanktonduringsummer 156
42b. Relationshipbetweencladoceransandcopepods
andphytoplanktonduringsummer 157
43a. Change inphytoplankton, rotifer, cladoceran/
copepodbiomassduringwinter 163
43b. Changeinphytoplankton, rotifer, cladoceran/
copepodbiomassduringwinter 164
44a. Change inphytoplankton, rotifer, cladoceran/
copepodbiomassduringspring 165
44b. Changeinphytoplankton, rotifer, cladoceran/
copepodbiomassduring 166
45a. Change inphytoplankton, rotifer, cladoceran/
copepodbiomassduringsummer 167
45b. Changeinphytoplankton, rotifer, cladoceran/
copepodbiomassduringsummer 168
46. Averagenumberofcladoceransandcopepodsat
startandendofeachsamplingperiod 170
47. Averagenumberofrotifers at thestart
andendofeachsamplingperiod 172
48. Comparisonofpooleddatainallmesocosms
afteroneyearofsampling 178