COMPETITION BETWEEN ALGAL TURFS AND PORITES LOBATA A THESIS

105 Pages·2010·6.75 MB·English

U[\III/FRSITY OF HAWAI'I LIBRARY
CONFLICT AT THE BORDER:
COMPETITION BETWEEN ALGAL TURFS AND PORITES LOBATA
A THESIS SUBMInED TO THE GRADUATE DIVISION OF THE
UNIVERSITY OF HAWA I'I IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
IN
BOTANY
AUGUST 2007
By
Linda B. Preskitt
Thesis Committee:
Celia M. Smith, Chairperson
Charles Birkeland
Cynthia Hunter
Karla J. McDermid
We certify that we have read this thesis and that, in our opinion, it is satisfactory in
scope and quality as a thesis for the degree of Master of Science in Botany.
THESIS COMMlTIEE
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TABLE OF CONTENTS
TABLE OF CONTENTS ..•.....................................................•.....•.....•.................•............ iii
LIST OF TABLES ...•.............................•.....................•.......•...........•.................................. v
LIST OF FIGURES ............••........................•...•.•....................................................•......... vi
CHAPTER 1. EPILITHIC ALGAL COMMUNITIES ..................................................... 1
Introduction ...•........................................•.............................•.............................................. 1
The Turf Community ..............••......................•.....•.................•.....••..........•...........•..........•.. 2
Turf Ecology ....................................•..................•...........•..........•......•....•.........•.............••... 5
Turf Productivity ...•..........................................•.............................................•.....•.. 6
Boundary Layers and Flow Speed ........................................................................ 11
Effects of Sediments on Algal Turfs ..............................•...................................... 12
Seasonality in Algal Turf Communities ............................................................... 15
The Effects of Topographical Complexity ........................................................... 17
The Effects of Herbivory on Turf Community Structure ..................................... 18
Eutrophication and Algal Turf Communities ...................................•..•................ 22
Algal-CoraI Interactions .........•.................•........................•......................•........................ 26
Conclusion ......................................•..................•............................•................................. 31
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CHAPTER 2: A MANIPULATIVE STUDY ON THE INTERACTION OF SUBTIDAL
TURF COMMUNITIES AND PORITES LOBATA AT PUAKO, HAWA l'I ................. 33
Introduction .......................................................•................•.....................•........................ 33
Materials and Methods .........................................••...............•.................•......................... 36
Study Site .............................................................................................................. 36
Experimental Design. .•..................................•.................•.......................•............. 38
Materials ... .••.. ..... .........•... .•••. ...•.... ..••. ...... ..•... ...... ...... ..••.......... ......... ..•... ...... ........ 38
Methods. .........•....•............•...•.•...........•......•................••.....................•...........•....••. 39
Results ....................................................................•........................................................•. 45
Algal-Coral Border ........................•.............•...........................................•............ 45
Algal Community ....................................•........................................••................... 47
Coral Histology •.....•...........•..................•.................•......................•.................••... 49
Discussion .................................................................•......•..........•.............................•....... 50
Appendix A: Tables ................•...........•......•............................•..........•......•...................... 56
Appendix B: Figures ..........................................................................•................•............. 58
References .............................................•.........................................................................•. 89
iv
LIST OF TABLES
Table
1. Algal species found on caged algal plugs ............................................................. 56
v
LIST OF FIGURES
Figures
1. Map ofPuak'o, Hawaifi. Site of study on the west side of the
Island ofHawai'i. .............•......................••......•..........•..•.•...•........•....•...................... 62
2. Picture of experimental study site. Arrays in place ...........••................••••...•............ 63
3. Muiti-dimensional scaling plot (MDS) substrate analysis with all benthic
factors: coral, turf algae, crustose corallines, macroaIgae, sessile invertebrates
and sand. (stress=.14) •.•.....................••.......................................•.....••................•....• 64
4. Muiti-dimensional scaling plot (MDS) substrate analysis with coral species
representing 3% or greater of coral cover: Porites lobata, P. compressa,
P. evermanni, Pocillopora meandrina, and Montipora patula. Average coral
cover by site: 94.5%. (stress=.15) .....•....•.................•...........•................•..•...•........... 65
5. Picture of array showing coral and algal plug installation ....................................... 66
6. Picture of caged array in location in the field. .......................................................... 67
7. Picture of grid assembly used to quantitatively sample algal plugs ......................... 68
8. Change in coral area by age and treatment. Graph showing change in
coral area with age and caging treatment. Data are number of samples. Results
with all factors not significant <i=11.790, P=O.067) ............................................... 69
9. Change in coral area by treatment. Graph showing change in coral area
by caging treatment only. Data are number of samples. Change was not
significant <i=2.702, P=O.259). .. ........................................................................... 70
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10. Change in coral area by age. Graph showing change in coral area with age only.
Data are number of samples. Change was significant C:i=7.807. P=O.020) ........... 71
11. Photograph of array at retrieval. Note the caged tiles (right) versus
the uncaged tiles (left) .........•..............................•................•......•......................•...... 72
12. Photographs showing the effect of grazing on an algal plug. Note the
difference in size of the same algal plug upon instaI1ation (A) and upon
retrieval (B) three months later. ................................................................................ 73
13. Photographs showing the difference between the algal growth on the caged tiles.
Some were heavily overgrown by Tolypiocladia glomerulata and Dictyota
ceylanica (A). whiles others had little algae growing on the algal plug or on the
tile around the plug (B). Occasionally, smaIl urchins and crabs were found in
the cages. Possibly grazed by smaIl herbivores .............•.............................•........... 74
14. Photographs ofuncaged algal plug showing grazing marks (A) and lack
of any algal growth other than endolithic (B) .....•............................•.....•.................. 75
15. Multi-dimensional scaling plot (MDS) of square-root transformed species
data for caged (gray) and uncaged sample (black) with data for one representative
uncaged sample (stress=.21) (A). and multi-dimensional scaling plot (MDS) of
square-root transformed species data for caged (gray) and all uncaged
samples (black) (stress=.01)(B) ......•............•............................................................ 76
16. Photographs of algal mats overgrowing coral. Jania pumila (A) and
green unicellar mat (B). ........•.......................•.................•......................................... 77
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17. Photograph of Lobophora variegata overgrowing coral (A) and the tissue
beneath when it was removed (B). ........................................................................... 78
18. Algal filaments in lower gastrovascular canals in tissues under
Lobophora variegata. ...............•......•...•.........................•...•...........•..•..........•......•..... 79
19. Gregarine-like protozoans in the calicodermis accompanied by a
concentration of fine granular cells ..••...............•••...•.......................•....••....•............. 80
20. Photography of area underneath after removing a mixed turf mat with
predominately Junia pumila and Tolypiocladio glomerulata ................................... 81
21. Histological slides of tissues under mixed turfmat from Figure 13. Algal
filaments invading gastrovascular cana1s (A) and distortion of the calicoblast
epithelium (B). •..........•..................•........................•....•.......................•..................... 82
22. Algal filaments surrounded and encased by coral tissue .......................................... 83
23. Layer of mucus and detritus overlay the epithelium of a coral sample (A).
Mucus mat and algae extending down into gastrovascular canals (B)• .................... 84
24. Tissue necrosis as a result of smothering by algal mats• .••.••.••••••••••••••••••••••••••••••••••. 85
25. Fungal filaments in gastrovascular cana1 ••................•..••.•.•.•••.•.................•...•....•.....• 86
26. Presumptive bacteria\ aggregate in necrotic gastrodermis tissue (A). Presumptive
bacterial aggregates in the gastrovascular cana1 (B): (1) and presumptive
bacterial aggregates in tissue (2). Unidentified algal mass (3) ................................ 87
27. Presumptive bacterial aggregates in tentacles (A). Unusual aggregate in
epidermis (note zooxanthellae). possible bacterial (B) ............................................ 88
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28. Bacterial aggregates with algal filaments in gastrovascu1ar canals ..••••.•••••....•....•.... 89
29. (A): (1) Bacterial aggregate in the mucus layer over the epithelium: Unidentified
algal filaments (2). Gregarine in the gastrovascular canal accompanied by a
concentration of fine granules (3). (B) Photomicroscopy of an actual algal mat with
bacterial aggregates •• •••••• •••••••••.•• •••• ••• ••• ••• ••••••••• ••• •••. ••••.••• ••••••••••• •••• •••••• •••••.••••..•• •••••• 90
30. Gregarine sporocysts in the gastrovascu1ar canals accompanied by a concentration
of fine granules (organic matrix proteins) in the nearby calicodermis .........•....•...... 91
31. Degraded gregarine sporocysts in degrading tissue .....•.....•...................................... 92
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CHAPTER 1. EPILITHIC ALGAL COMMUNITIES
Introduction
Coral reef ecosystems are highly diverse, productive communities adapted to
thrive in tropic and subtropic oligotrophic coasts. Reefs teem with animal life in the form
of corals, fish, and invertebrates, yet, in terms of living biomass, the plant world
dominates. Research on marine flora in the first half of the nineteenth century is mainly
concerned with the taxonomy and distributions of marine algae throughout the world
oceans. With atomic bomb testing in the 1940's on atolls in the south Pacific and the
burgeoning science of marine ecology in the 1950's, ecological interactions of organisms
on coral reefs became one of the focal points in marine research. A great deal of
attention was paid to coral biology, and the algae of most interest were the symbiotic
zooxanthe11a.e that are so important to coral survival in oligotrophic waters. However.
zooxanthellae are only a small fraction of the total plant biomass on a coral reef.
On healthy reefs, turf and calcified algae are nugor contributors to reef primary
production and make important contributions to calcification and reef building, often
occupying large proportions of space (Adey 1998). Turfs may cover up to 80% of the
substrate on coral reefs, are principal foods for herbivorous reef fish and are the
fouodation of the coral reef trophic structure (Odum and Odum 1955). Over the years,
research has treated the important turf community primarily as a functional form in the
reef ecosystem, focusing primarily on algal turfs' important role as the source of most of
the reefs primary productivity and the herbivory interactions that influence that
production.
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