factors influencing algal blooms on tropical reefs with an emphasis on herbivory, nutrients and invas

425 Pages·2006·15.51 MB·English

UNIVERSITY OF HAWAII LJB~~
FACTORS INFLUENCING ALGAL BLOOMS ONTROPICALREEFS WITH AN
EMPHASIS ONHERBIVORY, NUTRIENTS AND INVASIVE SPECIES
A DISSERTATIONSUBMITTED TO THE GRADUATE DIVISION OF THE
UNIVERSITY OF HAWAI'IINPARTIALFULFILLMENT OF THE
REQUIREMENTS FORTHE DEGREE OF
DOCTOR OF PHILOSOPHY
IN
BOTANY (ECOLOGY, EVOLUTION AND CONSERVATION BIOLOGY)
DECEMBER 2003
By
JenniferE. Smith
Dissertation Committee:
CeliaSmith, Chairperson
CynthiaHunter
Lawrence Basch
Lucius Eldredge
Michael Hamnett
ABSTRACT
Algal blooms ontropical reefs havebecome increasinglycommon overthe last
several decades. Reduced herbivorepressure, eutrophication andthe introductionof
exotic species have all beenposited as factors that maydrive these transitions in
organism dominance. Several different types ofalgal blooms havebeenidentifiedon
reefs inthe HawaiianIslands includingmultispecies algal assemblages, monospecific
algal blooms and seasonal or ephemeralblooms. This studysoughtto determine the
causes ofthesedifferent types ofalgal bloomsbyconductingboth field and laboratory
experiments and quantitative field assessments.
In a factorial nutrient enrichment and herbivore exclusion experimentconducted
for 6 months onthe island ofHawai'i significantchanges in algal biomass, community
structure, sediment accumulation andmobile microinvertebrate abundancewere found.
Results ofthis studyshow thatbenthic reefcommunities canchangerapidlyin response
to changes inbothtop down and bottomup factors.
From field assessments across the mainHawaiianIslands atotal offive
(Acanthophora spicifera, Hypnea musciformis, Graci/aria salicornia, Kappaphycus spp.
andAvranvilleaamadelpha) species ofnonindigenous algae cannowbe considered
highlysuccessful. Detailed studies onthe ecologyofselectnonindigenous marine algae
(NIMA) have identifiedparticularconcerns andhighlighted the need for management
action. In summarymanagement ofthese invasive species will be challenging as aresult
ofunique ecological andphysiological strategiesthat eachNIMApossesses.
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The ephemeralbloom forming native alga Cladophora sericea was studiedduring
abloom cycleduring 2001 onthe island ofMaui. Results ofambient and sedimentpore
watersampling and algal physiologicalparameters suggest that ground waterintrusionis
occurring at this site and the algaappears to be utilizing this terrestrial basednutrient
source.
Upwelling and internaltides cannaturallydelivernutrient rich waterinto coral
reefecosystems. Inan areawhere internal tidal upwelling occurs inthe FloridaKeys, one
ofthe most commonbenthicreefalgaeHalimeda tuna reflectedpatterns associated with
natural nutrientenrichment. This studyprovides evidencethat rich and highlyproductive
benthic algae maythriveindeep watercoralreefenvironments inresponse to naturally
elevatednutrient conditions.
iv
TABLE OF CONTENTS
ABSTRACT .iii
LIST OF TABLES xi
LIST OFFIGURES xviii
CHAPTER 1. LITERATUREREVIEW AND DISSERTATIONPROPOSAL 1
INTRODUCTION....................................•..............................." 2
NUTRIENTDYNAMICSONTROPICALREEFS .4
NUTRIENTGRADIENTSONTROPICALREEFS " •.•....•.5
EFFECTSOFNUTRIENTENRICHMENTONBENTHICCOMMUNITIES 7
EFFECTSOFNUTRIENTENRICHMENTONALGALSPECIES 9
NATURALLYELEVATEDNUTRIENTSONTROPICALREEFS 14
SUMMARy 16
INTERACTIVEEFFECTSOFNUTRIENTSANDHERBIVORES " 17
TOP-DoWNANDBOTTOM-UPFACTORSINFLUENCINGALGAL
COMMUNITIES 17
SUMMARy 23
INTRODUCTIONOFNONINDIGENOUSSPECIESONTROPICALREEFS 23
IMPACTSOFSPECIESINTRODUCTIONS 23
ACCIDENTALINTRODUCTIONOFSEAWEEDS 24
SARGASSUMMUT/CUM...............................................•.....24
CAULERPA TAX/FOL/A 26
UNDARIA P/NNAT/F/DA 28
v
SPECIESINTRODUCEDFORCULTUREINTHETROPICS .30
/(APPAPHYCUSANDEUCHEUMA .30
EFFECTSOFSEAWEEDINTRODUCTIONS .33
A CASESTUDY: KANE'OHEBAY 35
TYPESOFALGALBLOOMS 38
RESEARCHPROPOSALANDOUTLINE .40
TABLES 42
FIGURES 59
LITERATURECITED 60
CHAPTER2. AN EXPERIMENTALANALYSIS OF THE EFFECTS OF
HERBIVORY AND NUTRIENT ENRICHMENT ONBENTHIC COMMUNITY
SUCCESSION ONA HAWAIIANREEF 83
ABSTRACT 84
INTRODUCTION 85
METHODSANDMATERIALS " 90
RESULTS 98
DISCUSSION 105
CONCLUSIONS 110
ACKNOWLEDGEMENTS 111
TABLES 112
VI
FIGURES 129
LITERATURECITED .143
CHAPTER 3. DISTRIBUTIONAND REPRODUCTIVE CHARACTERISTICS OF
NONINDIGENOUS AND INVASIVEMARINE ALGAE INTHE HAWAIIAN
ISLANDS 151
ABSTRACT 152
INTRODUCTION 153
METHODSANDMATERIALS 156
RESULTS 159
DISCUSSION 163
CONCLUSIONS 170
ACKNOWLEDGEMENTS 172
TABLES 173
FIGURES 179
LITERATURECITED 183
CHAPTER4. THE ECOLOGY OF THE INVASIVERED ALGA GRACILARIA
SALICORNIA (C. AGARDH) E.Y. DAWSON ON O'AHU, HAWAI'I.. 188
ABSTRACT '" 189
INTRODUCTION 191
vii
METHODSANDMATERIALS 195
RESULTS 203
DISCUSSION 208
CONCLUSIONS 214
ACKNOWLEDGEMENTS 215
TABLES 216
FIGURES 217
LITERATURECITED 225
CHAPTER 5. ABUNDANCE AND SPREAD OF THE INVASIVE RED ALGA,
KAPPAPHYCUSSPP., INKANE'OHE BAY, HAWAI'IAND AN EXPERIMENTAL
ASSESSMENT OF MANAGEMENT OPTiONS 231
ABSTRACT 232
INTRODUCTION 233
METHODSANDMATERIALS 236
RESULTS 241
DISCUSSION 245
CONCLUSIONS 250
ACKNOWLEDGEMENTS 251
TABLES 252
FIGURES 254
LITERATURECITED 263
V111
CHAPTER6. INVASNE SPECIES ON CORALREEFS: ANEW THREAT TO
DNERSITYAND CORALHEALTH? 268
ABSTRACT 269
INTRODUCTION 270
METHODSANDMATERIALS 272
RESULTS 274
DISCUSSION " "..277
CONCLUSIONS 280
ACKNOWLEDGEMENTS 282
TABLES 283
FIGURES 290
LITERATURECITED 296
CHAPTER 7. FIELD AND NUTRIENT CHARACTERISTICS OF THE EPHEMERAL
BLOOM-FORMINGGREEN ALGA CLADOPHORA SERICEA G. HUDSON ON
THE REEFS OF WESTMAUl, HAWAI'I. 301
ABSTRACT 302
INTRODUCTION " '" 303
METHODSANDMATERIALS 307
RESULTS 313
DISCUSSION 316
CONCLUSIONS 320
ACKNOWLEDGEMENTS 322
ix
TABLES 323
FIGURES 330
LITERATURECITED 340
CHAPTER8. NUTRIENTAND GROWTH DYNAMICS OFHALIMEDA TUNA
(ELLIS ET SOLANDER) LAMOUROUX ALONGA DEPTH GRADIENT INTHE
FLORIDAKEYS: POSSIDLE INFLUENCE OF INTERNAL TIDES ONNUTRIENT
STATUS AND PHySIOLOGy? .346
ABSTRACT 347
INTRODUCTION " 348
METHODSANDMATERIALS .353
RESULTS 358
DISCUSSION................................................................•.......'" 363
CONCLUSIONS '" 372
ACKNOWLEDGEMENTS 374
TABLES 375
FIGURES 382
LITERATURECITED 391
CHAPTER9. SYNTHESIS 401
x
LIST OFTABLES
TABLE PAGE
1.1 Phase shiftsthat have occurredorare occurring ontropical reefs around the
world 66
1.2 Experimental designs andresults for field studies examining factorial nutrient
enhancement andherbivore exclusion 70
1.3 Introductionofalgal species inthe tropics for thepurposes ofaquaculture......73
1.4 Summaryofdifferent types ofalgal blooms ontropical reefs and theirsingle
factor causes 80
2.1 Dissolvedorganicnitrogenandphosphorus concentrations (J.lM) inthe area
adjacent to nutrient enrichmentpots 112
2.2 Results offour-way factorial analyses ofvariance for log transformed algal dry
weights 113
2.3 Meanofalgal functional group biomass 114
2.4 Results offour-way factorial analysis ofvariance for sedimentweight and
numberofmobile invertebrates 115
2.5 Listofal algal species identified on experimental surfaces andpresenceineach
time andtreatmentcategory 116
2.6 Results ofANOSIM test for species communitydata from factorial
experiment. 121
2.7 Results ofNPMANOVA test for species communitydatafrom factorial
experiment. 122
2.8 Pairwise comparisons forthe significant interactionterm from the
NPMANOVAoncommunitydata 123
2.9 DISTLM analysis ofvariance for species communitydata 124
2.10 Results ofNPMANOVA for species composition datagroupedinto functional
group categories 125
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