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Reef coral populations: spatial and temporal differences observed on six reefs off West MauiBrown, Eric January 2004 (has links)
Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 259-277). / Electronic reproduction. / Also available by subscription via World Wide Web / xvi, 277 leaves, bound ill. 29 cm
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Radiometric ages of selected Hawaiian coralsHammond, Dale Alden January 1971 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii, 1971. / Bibliography: leaves 159-166. / xi, 166 l illus., tables
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Distribution, Recruitment and Development of the Borer Community in Dead Coral on Shallow Hawaiian ReefsWhite, Janet K. F. 12 1900 (has links)
Twenty-seven species of known or suspected coral skeletal
borers were identified from shallow Hawaiian reefs. In
comnarison to inventories of the borer communities collected
from other tropical areas Hawaiian corals had an abundance
of polychaetous annelids, fewer species of sipunculans,and
acrothoracican barnacles, and far fewer boring sponges.
Polychaetes were responsible for the majority of the
bioerosion of dead coral in Kaneohe Bay, Oahu.
Comparisons of living and dead sections of coral colonies
indicated that the borer community was more diverse and
abundant in areas of the skeletons lacking living tissue.
Skeletal densities of three common coral species with branching
growth form were found to influence the abundance of coral
borers. The least dense skeletons had greater population
densities of borers. It is suggested that these three species
of corals can coexist in close proximity due, in part, to the
development of varying abilities to withstand invasion by
skeletal borers.
In order to determine rates, si te preference and seasona.li.ty
of settlement a series of settlement plates were cut from coral
and placed in the field at ten sites in Kaneohe Bay, Oahu.
Extrapolating from the surface area of the settlement plates,
mean recruitment rates of coral borers were found to be
10,000 - 50,000 individuals m-2 month-1. The recruitment
rates and species composition of epibiotic and borer faunas
settling; on the dead coral plates differed dramatically between
areas in Kaneohe Bay due to the effects of differences in
physical and biological factors caused by sewage and slltation.
The larvae of coral borers generally lacked clear
seasonal settlement periods, suggesting that one or more
mechanisms (e.g. continuous reproduction, long pelagic phase,
etc.) functioned to assure the presence of larvae throughout
the year. The ultimate cause for the development of such a
strategy may be that the time and location of the production of
suitable settlement sites on the reef surface is. unpredictable.
Some of the larvae of both epibiotic and borer species exhibited
settlement selectivity with respect to the position of the
settlement surface. This finding indicates that the distribution
of borers in coral skeletons might be due, in part, to active
selection by the laryae for particular conditions.
Development of the epibiotic and borer communities of dead
coral was monitored using sequentially collected blocks cut
from the coral Porites lobata. The abundance and species
composition of these communities were found to differ between
sites in Kaneohe Bay because of several biological and physical
factors. In the south bay increased food supplies (in the
form of plankton and plankton-derived detrital material).
due to sewage enrichment, support extensive populations of
filter and deposit-feeding invertebrates including coral
borers. Sewage diversion did not appear to have had any
dramatic effect on these communities by the end of the study
period. In the north bay, where food availability is lower,
fewer borers and epibiotic organisms were collected.
The effects of fish grazing are considered to be another
important factor determining the species composition and
abundance of the coral borer community. Grazing fish were
rare in south Kaneohe Bay during the study period, which may
help to explain the abundance of sessile epifaunal species.
In the north bay fish grazing is extensive and contributes
to the growth of encrusting coralline algae on the test blocks
and the benthos.
Based on the results of the long term block study it was
found that in Hawaii sessile filter-feeding invertebrates do
not exclude coral borers from the substratum or inhibit their
growth. In south Kaneohe Bay, where conditions caused
increased abundances and growth rates of filter and depositfeeding
invertebrates, bioerosion rates were accelerated.
Encrusting coralline algae, which flourish on reefs exposed to
fish grazing (eg. north Kaneohe Bay), inhibit settlement of
borers and grow over burrow apertures, thus reducing the
population of borers within the dead coral. Bioerosion rates
of exposed, coralline algal covered, dead coral substrata
are very low on pristine shallow Hawaiian reefs. / Bibliography: leaves 181-192.
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Zonation of Reef Corals off the Kona Coast of HawaiiDollar, Stephen J. 05 1900 (has links)
Analysis of the pattern of zonation of reef corals off
the Kona coast of Hawaii revealed the existence of four
clearly defined zones. This pattern was confirmed at three
sites where corals were counted using a series of 45 meter
long transects running parallel to shore from depths of 3 to
40 meters. Clustering analysis dendrographs, spatial changes
in illumination and rates of water movement, as well as
growth and survival of coral transplants also confirmed the
zonation pattern.
Each of the four zones is characterized by a dominant
coral species, substratum type, depth, and range of physical
conditions. Each zone also appears to be in a different stage
of community succession due to the frequency of large scale
environmental disturbances from winter storm waves.
The shallowest zone begins at the base of the shoreline
cliff, ranges in depth from 2.5 to 8 meters, and has a bottom
cover consisting mainly of irregularly shaped basaltic boulders;
Pocillopora meandrina dominates coral cover in this zone.
This species appears to be the first to colonize new substrata
and persists in large numbers only in the near-shore boulder
zone where mechanical stress from wave action is great enough
to restrict the growth forms of more competitive species.
Due to this high wave stress, the P. meandrina bolder zone
appears to be in an early successional stage with low coral
cover and dominance and relatively hiqh species diversity.
Moving into deeper water the Porites lobata reef
building zone ranges in depth from 6 to 14 meters and is
characterized by a gently sloping solid basalt and limestone
bottom. Porites lobata dominates coral cover by growing in
massive lobed and encrusting colonies. While succession
seems to be in an advanced stage, monopolization of available
space does not appear to be complete enough to exclude a
variety of less competitive species, resulting in relatively
high species diversities.
The third zone occurs on the reef slope and ranges in
depth from 14 to 30 meters. Solid substrata is scarce and
succession may be a late stage due to domination of bottom
cover by thickets of Porites compressa. Most of the other
species that persist in this zone avoid competitive interactions
by growing above the level of P. compressa. Storm
wave stress is most devastating to corals in this zone, and
breakage of living colonies seems to increase diversity by
reducing P. compressa dominance. Transport of living coral
fragments appears to extend zonal boundaries and create new
colonies. Extensive "rubble channels" occur in this zone,
and these channels may get progressively larger due to
churning of rubble fragments with each successive storm.
The Porites lobata rubble zone occurs below the deep border of the
P. compressa thickets and extends to approximately
50 meters, the depth at which coraIs cease to appear.
Substrata consists mostly of fine sand and a variety of small
encrusting corals are found growing on scattered rubble
fragments. Specialized species with narrow physiological
tolerances limited to this zone also increase species diversity.
While maximum size of corals may be reduced in this
zone due to low light intensity, lack of solid substrata
probably determines the lower depth limit of coral occurance.
Sand and rubble that is carried downslope during storms
cause this zone to be physically unstable and succession
appears to be constantly interrupted at early stages. This
is in contrast to other deep reef areas, such as off Maui
and the Red Sea, where substrata is solid to the depth limit
of coral growth. These communities appear to be highly
stable and diverse, and in late or climax stages.
The depauperate nature of Hawaiian coral fauna is
probably due to fairly rigorous environmental conditions in
combination with difficulties in larval transport from coral
evolutionary centers in the western Pacific. However, reef
areas off Kona are relatively rich for Hawaii due to complete
protection from tradewind generated seas, partial protection
from long period north swells, and the steep nearshore slopes
that extend below wavebase. / Typescript. Bibliography: leaves 173-181.
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