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Genomic Analysis of Acropora cervicornis Mucus and Sediments in the Florida Keys Tavernier NurseryZimmerman, Rachel 13 August 2018 (has links)
White Band disease has devastated the staghorn coral Acropora cervicornis in recent decades, and it continues to impinge upon restoration efforts. The etiological agent(s) remain unknown as Koch’s postulates have yet to be satisfied, but disease may originate when opportunistic pathogens in the surface mucus layer exploit a stressed host. Using 16s rRNA sequencing, differences in the taxonomic diversity and relative abundances of bacteria within the mucus of A. cervicornis were documented between colonies of the same genotype, genotypes (n=8) categorized as having either high or low WBD susceptibility, and during a transplantation event. A. cervicornis colonies suspended from midwater PVC trees via monofilament were sampled for mucus, after which half of the sampled colonies were relocated to the unconsolidated sediments below. Temporal changes in the microbiome of the pelagic and benthic corals were then monitored by sampling the same apical tip over time. Incidentally, all benthic colonies for this experiment became afflicted with WBD; thereby differences in healthy vs. diseased colonies and the effects of disease progression on the microbiome were documented. Water was sampled concurrently with all mucus experiments to resolve the degree of commonality in bacterial species between the two environments, and sediments were sampled in the transplant experiment to determine if sediments may act as a pathogen reservoir. In addition, sediment samples were collected to assess site and temporal differences in the benthic microbiome along a nearshore to offshore transect off Key Largo, Florida. Irrespective of the inclusion of water operational taxonomic units (OTUs), no differences between colonies of the same genotype were observed with regards to the bacterial communities sampled from mucus in either alpha diversity metrics [species richness, Shannon, Inverse Simpson] or phylogenetic relatedness as determined by weighted unique fraction (UniFrac) were detected between colonies. However, differences were observed in the Bray-Curtis dissimiliarity matrices based on relative abundance and presence/absence of either [with and without water OTU] scenarios. Bacterial communities associated with different coral genotypes differed in species richness and Inverse Simpson in both water scenarios, as did weighted UniFrac and Bray-Curtis relative abundance and presence/absence transformed dissimilarity matrices. Alpha diversity of mucus bacteria was similar between corals of different disease-susceptibilities when water OTUs were either included or excluded, except for the Inverse Simpson index upon removal of water OTUs. Removal of aqueous bacteria also revealed significant differences between disease-susceptibility groups in Bray-Curtis relative abundance and presence/absence dissimiliarity values that was not detected with the incorporation of water OTUs. Regardless of the presence of water OTUs, weighted UniFrac was similar between corals of different disease susceptibilities. Most notably, dispersion increased in the microbiome of coral genotypes with high disease susceptibility in all cases except for the relative abundance transformed Bray-Curtis dissimilarity matrix when water OTUs were incorporated. This finding is in accordance with the Anna Karenina Principle, which states that loss of microbial regulation leads to an unpredictable microbiome in diseased individuals. In the sediment experiment, location was the only factor influencing microbiome composition. These findings may be due to the short duration of the experiment and differences between the carbonate content of the sediments and hydrological regimes between sites.
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Identifying Disease-Resistant and Thermal-Tolerant Genotypes in the Threatened Staghorn Coral, Acropora cervicornisHightshoe, Morgan V 27 April 2018 (has links)
Since the 1970s, loss of herbivores, coral bleaching, pollution, and disease epidemics have reshaped the ecological framework of coral reefs. Staghorn coral, Acropora cervicornis, was a major reef-building scleractinian coral found throughout Florida and the Caribbean that experienced unprecedented population declines primarily due to disease and coral bleaching. These two stressors are coupled; the highest coral disease prevalence occurs after periods of thermal stress caused by increased sea surface temperature. Previous research documented three disease-resistant A. cervicornis genotypes in Panama, but it is unknown if disease-resistant genotypes exist in the Florida Keys. Thermal tolerance has been found to be variable among different species of corals and is relatively unknown in A. cervicornis. To investigate disease resistance and thermal tolerance in corals collected from the Florida Keys, pathogen transmission, thermal tolerance experiments, and coral outplanting studies were conducted, along with histological work to assess the condition of coral tissues. Corals were challenged in situ with exposure to rapid tissue loss (RTL) and bleaching resistance was evaluated ex situ in temperature-controlled seawater tanks, using 39 A. cervicornis genotypes. Disease and bleaching were further characterized in the wild using outplanted colonies. In a pathogen transmission pilot study, 7 out of 39 genotypes developed signs of rapid tissue loss transmission. An expanded transmission experiment that used 12 potentially disease resistant genotypes (based on anecdotal information and results from the pilot study), all genotypes developed signs of RTL transmission. However, susceptibility was variable but not statistically different among genotypes (p>0.05), ranging from 40-100% transmission. Histological analyses revealed significant (p0.05) related to photosynthetic efficiency and tissue condition metrics. No significant differences in mortality, disease, or predation were found between disease resistant and disease susceptible genotypes in outplanting experiments (p>0.05). This study reports the first evidence that disease resistance is present in Florida A. cervicornis genotypes. The variability of disease resistance found within genotypes suggests that genotype is not the only factor influencing disease transmission. Short-term exposure to thermal stress revealed heat tolerant A. cervicornis genotypes, which corroborates with recent published studies. Taken together, these results provide insights into how Caribbean Acropora and other scleractinian species persist through multiple disease and coral bleaching events.
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Potential Habitat of Acropora spp. on Florida ReefsWirt, Katherine 01 January 2011 (has links)
Elkhorn and Staghorn corals (Acropora palmata, A. cervicornis) were listed as threatened species under the Endangered Species Act (ESA) in 2005. The threatened status of these species is unprecedented given the vital role they historically played as major constructors of western Atlantic and Caribbean coral reefs. The goal of my study was to evaluate the current extent of habitat of the two species using a database of reported in situ observations. From these observations, potential habitat maps were produced based on benthic substrata and depth parameters throughout the Florida reef tract using GIS software. Locations of 99% of A. palmata observations and 84% of A. cervicornis observations coincided with previously mapped reef or hardbottom habitat. These results indicate that potential habitat for A. palmata is currently well defined and that potential habitat for A. cervicornis is more variable than that for A. palmata.
This study provides a starting point in the creation of a revised critical habitat delineation for Acropora spp. in Florida. Using the mapped reef and hardbottom classifications throughout the Florida reef tract, probable habitat maps were generated using buffers that incorporated 95% and 99% of reported observations of colonies of Acropora spp. One of the most important differences between the previously generated critical habitat map and the new probable habitat map is observed in the southeast Florida region, where probable habitat extends further north than critical habitat and, thus, encompasses additional habitat for A. cervicornis and potentially A. palmata.
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Coral recruitment on a high-latitude reef at Sodwana Bay, South Africa : research methods and dynamics.Hart, Justin R. January 2011 (has links)
Coral recruitment is a key process that contributes to the community structure and resilience of coral
reefs. As such, quantification of this process is important to assist with the management of these
threatened ecosystems. While coral recruitment has been the focus of numerous studies over the past
30 years, an understanding of this process on the high-latitude reefs of South Africa is limited. In
addition, variations in methods used in recruitment studies make the results difficult to compare. A
rapid in-situ method for universal application in the detection of early post-settled recruits would
thus be useful.
In this study, scleractinian coral recruitment was investigated at three study sites on Two-mile Reef,
over two six-month sampling periods, covering summer and winter. Two components were
investigated by attaching settlement tiles consisting of ceramic and marble tiles, and ceramic tiles
conditioned with crustose coralline algae (CCA) onto the reef in a spatially structured experimental
design. Firstly, coral recruitment was compared on the three different tile surfaces and fluorescence
photography was investigated as a rapid in situ technique to detect early post-settled recruits.
Fluorescence photography was then used to compare recruitment on tiles with the surrounding
natural substrata. Secondly, the spatial and temporal variation in the abundance, composition and
size of recruits was investigated. Additionally, the percentage cover of biota surrounding each recruit
within three millimeters of its corallum was visually estimated to quantify the microhabitat
surroundings of coral recruits.
Overall recruitment on the three tile types differed, yet spatial variation in coral recruitment,
regardless of tile surface, accounted for most of the variance in recruitment. While the highest
recruitment occurred on CCA tiles, this was not significantly greater than ceramic tiles, indicating
that the conditioning of ceramic tiles with Mesophyllum funafutiense CCA did not enhance coral
settlement in this study. Although many recruits were not detected with fluorescent photography
(73%), it proved useful to reveal recruits as small as 0.75 mm in corallum diameter, and indicated
that recruitment on the tiles and natural substratum differ significantly. Spatially, the abundance and
composition of coral recruits differed between study sites, within sites, and predominantly occurred
on tile edges. Coral recruitment was lowest at shallower sites, and was dominated by pocilloporids
regardless of study site. Additionally, the abundance and composition of recruits differed between
the two sampling periods, with a 6.6-fold decrease in the mean abundance of recruits from summer
to winter, with only pocilloporid settlement occurring in the latter season. The majority of recruits
were <3 mm, and their microhabitat was dominated by bare substrata and crustose coralline algae.
The results suggest that, while the choice of artificial settlement surface used in such studies can
have a profound influence on the results, spatial variation in recruitment can be greater. The recovery
of scleractinian coral taxa on Two-mile Reef in the event of a severe disturbance is expected to
differ, with greatest recovery in areas of high levels of recruitment. The microhabitat surrounding
recruits is described here for the first time, suggesting that further research into coral-crustose
coralline algae interactions is warranted. Finally, while fluorescence photography has its limitations,
it shows promise as a useful tool for rapid qualitative, but not quantitative, assessment of
recruitment. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.
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Accretion versus bioerosion on the Maputaland reefs in South Africa - The major processes.Grimmer, Ashley. January 2011 (has links)
The development of coral reefs is largely restricted to areas within the tropics where favourable
conditions for both coral and reef growth prevail. There is, however, a continuum from these typical,
accretive reefs in the tropics to marginal, non-accretive, coral-dominated reef communities which
occur at higher latitudes. High-latitude reefs function similarly in many regards to their tropical
counterparts and are regulated by similar processes to a varying degree. In this study, the major
biological and physico-chemical processes were assessed which directly or indirectly prevent the
continued persistence of reefal frameworks and thus hinder reef accretion on high-latitude reefs in
the iSimangaliso Wetland Park. These reefs have a high diversity of hard and soft corals with
significant reef coverage, yet little evidence of any biogenic accretion has been observed. The
scleractinian coral, Acropora austera, is one of the few corals which may be responsible for reef
framework production. It exhibits a gregarious growth pattern, forming large, monospecific stands
with an interlocking framework characteristic of the early stages of reef accretion. The framebuilding
potential of A. austera and the continued persistence of such frameworks were thus determined by
in situ monitoring of coral growth, mortality, bioerosion and several physico-chemical parameters.
Growth rate and mortality of A. austera branches were measured at three sites of differing stand
size and apparent age. This was achieved by repeated image analysis and by staining branches with
the vital stain, Alizarin Red S. Both measures of growth yielded a similar linear extension rate of 24.5
mm/yr (n = 467), comparable to related species at similar latitudes. Mean branch mortality was as
high as 50%, with clear differences manifested between each A. austera stand. Branch extension
rates and branch mortality were inversely related between sites. Small, young stands exhibited
significantly faster coral growth rates, lower mortality and a net increase in overall branch length
over the study period, whilst the opposite was true of larger, more developed stands. In addition,
bioerosion was determined at each site to assess its potential for carbonate removal and its
destabilizing effect on reef frameworks. Bioerosion intensity was recorded as “percentage area
damage” within cross-sections and “frequency of occurrence” of bioeroding organisms in coral
rubble fragments (n = 120). The level of bioerosion was found to be substantial (up to 11.5% loss in
weight of coral fragments over the 12-month study period) and was found to decrease significantly
with a reduction in size of each A. austera stand.
Aragonite saturation state is considered a major factor that limits the geographical range of coral
reefs globally. Although previously thought to be limiting in Maputaland, mean ΩArag values of
4.40±0.29 were measured on the reefs in summer and 4.33±0.21 in winter and thus would not have
limited reef development. Past studies have noted the turbulence on South African east coast reefs
and its adverse effect on reef development. This was corroborated in this study with the
measurement of considerable sediment re-suspension (0.17 g cm⁻² day⁻¹) and regular damage to both
living coral and the reef framework caused by large swells.
These results lead to the theory that Acropora austera stands senesce with increasing size and age.
Although large coral frameworks are found on the Maputaland reefs, they do not persist in the long
term. High rates of sediment re-suspension prevent infilling of the interstitial spaces and eventual
cementation, while high levels of bioerosion lead to framework instability over time. Rough seas
further hamper accretion by physical removal of both living coral and the coral-derived framework,
thus removing recent growth. This process is suspected to cause an imbalance in the carbonate
budget of these marginal reefs, ultimately favoring carbonate removal over carbonate deposition. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.
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Assessment of Nursery-Raised Acropora cervicornis Transplants in the Upper Florida KeysWare, Matthew 01 July 2015 (has links)
Over the last 40 years, the Caribbean has lost half of its live coral cover, mostly in the form of Acropora cervicornis and A. palmata, due to disease, bleaching from rising water temperatures, and other stressors. To help restore these corals to reefs in Florida, the Coral Restoration Foundation (CRF) created nearshore nurseries and transplanted over 30,000 acroporid colonies across the Florida Keys. The objective of this thesis was to evaluate the growth, survivorship, and condition of nursery-raised A. cervicornis colonies that were part of two transplant projects: 1) photographic analyses of 17 past CRF transplant projects over the last seven years; and 2) a transplant experiment at Little Conch Reef to additionally assess the effects of depth, colony density, and the genetic composition of transplants. The photographic analyses included 2,428 individual colonies, 38 genotypes, and six reefs from 2007 to 2013. Results from the photographs were combined with one in situ monitoring effort that used SCUBA in 2014. In the Little Conch Reef experiment, 1,288 colonies from 14 genotypes were transplanted in October and November, 2013 at two depths (5m and 12m) in either cluster or thicket configurations. At each depth, clusters comprised 14 colonies, each placed within in 1m diameter radius, with ten monogenetic and six multigenetic structures. Thickets were 3.5m by 1.5m in size, with 10 colonies from each genotype forming its own subunit within the larger configuration. In June 2014, 963 additional colonies were added to the shallow site by stacking them on top of six existing clusters and one thicket to evaluate whether larger three-dimensional structures affected growth or survival. The Little Conch Reef experiment was monitored through January 2015. Results from the photographic analyses were: 1) maximum size of A. cervicornis transplants was approximately 40cm in diameter; 2) mortality increased after approximately two years; 3) despite high mortality, some colonies survived the duration of each project; and 4) frequent and long-term monitoring is required to assess factors that affect survival and condition. Results from the Little Conch Reef experiment suggest: 1) maximum skeletal diameter was unaffected by any of the treatments; 2) percent survival and percent live tissue were higher at the shallow site compared to the deep site, and similarly, the clusters outperformed the thickets, and multigenetic clusters outperformed their monogenetic counterparts; 3) location within the shallow site had an impact on survival and condition, with clusters doing better on the south side than on the north; and 4) stacking did not positively impact growth, survival, or condition. In general, the sizes and condition of natural populations of A. cervicornis throughout the Florida Keys are similar to results from both experiments and with other transplant projects conducted in the Caribbean. Remarkably, despite high mortality in nearly all of the projects, small numbers of colonies transplanted for most projects, a few colonies survived to 2014/2015. These colonies have the potential to act as a “seed population” that might produce sexually dispersed larvae better adapted at surviving mortality events and asexual fragments that may be better acclimated to the stressors related to their location. Evidence of persistence in this species and expansion northward in Florida suggest that it is too early to consider coral reefs a lost cause, and that coral restoration holds promise for enhancing recovery of A. cervicornis.
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Extraction and Analysis of Coral Reef Core Samples from Broward County, Florida.Stathakopoulos, Anastasios 01 December 2009 (has links)
The reefs off Broward County exist as three shore-parallel, sequentially deeper terraces named the "inner", "middle", and "outer" reefs and also a shallower, nearshore ridge complex. These structures span the continental coast of southeast Florida from Palm Beach County to southern Miami-Dade County and were characterized as relict, early Holocene shelf-edge and mid-shelf reefs along with limestone ridges. Presently, the reefs are colonized by a fauna characteristic of West Atlantic/Caribbean reef systems. Scleractinian coral cover is low except for a few dense patches of Acropora cervicornis, while Acropora palmata is absent except for a few individual living colonies.
Coral reef core-drilling is a useful analytical tool to extract observable and datable geological samples from within reefs. This technique was employed to retrieve 4 cores from the inner reef off Broward County to better understand its age, composition, and Holocene growth history. Sub-samples from corals in cores provided 7 new radiocarbon ages ranging from 7,860-5,560 cal BP, and reef accumulation rates of l.7-2.45 m/1,000 yrs were calculated from these ages. In addition, coral species composition and taphonomic characteristics were analyzed to identify former reef environments/reef zonation, and signals for inner reef termination. Reef zonation was detectable but no clear taphonomic signal for inner reef termination was evident.
Current data and radiocarbon ages from all three Broward County reefs suggest that the outer reef accumulated from ~10.6-8 ka cal BP, the middle reef from at least ~5.8-3.7 ka cal BP, and the inner reef from ~7.8-5.5 ka cal BP. A lack of significant age overlaps between the three reefs has led to the assertion that they represent backstepping reefs in response to Holocene sea-level rise. This study has provided the oldest and youngest ages from the inner reef thus far, and confirms that reef backstepping from the outer reef to the inner reef occurred within just a few hundred years after the termination of the outer reef. The middle reef remains poorly understood and thus a definitive Holocene growth history and ultimately an understanding of their formation are still largely unknown.
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Estimating the heritability of thermal tolerance in Acropora cervicornis and the physiological basis of adaptation that correlates to survival at elevated temperaturesYetsko, Kelsey L 01 January 2018 (has links)
Human activities have substantially increased the atmospheric concentrations of greenhouse gases, resulting in warmer ocean temperatures that are having a negative impact on reef corals, which are highly susceptible to changes in temperature. Understanding the degree to which species vary in their tolerance to elevated temperatures and whether this variation is heritable is important in determining their ability to adapt to climate change. In order to address this, Acropora cervicornis fragments from 20 genetically distinct colonies were kept at either ambient or elevated temperatures, and mortality was monitored for 26 days. Heritability of thermal tolerance was estimated using a clonal method comparing the difference in lifespan within and among clones in a one-way ANOVA, as well as a marker based method using the program MARK (Ritland 1996) to estimate relatedness between colonies. To understand the physiological basis of thermal tolerance, tissue samples from both treatments were taken after 12 hours to investigate gene expression associated with sub-lethal temperature stress at both the mRNA and the protein level. The results revealed that this population of A. cervicornis has a relatively high amount of total genetic variation in thermal tolerance (H2 = 0.528), but low additive genetic variation for this trait (h2 = 0.032). In addition, both gene expression and protein expression among colonies were highly variable and did not show consistent patterns related to differences in thermal tolerance among colonies. These results reveal that this population of A. cervicornis may have a limited capacity to respond to projected increases in ocean temperatures. In addition, the results suggest that the molecular basis of thermal tolerance in this species is complex and that there are potentially many genotypic combinations that can result in a heat-tolerant phenotype.
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Field Ecology Patterns of High Latitude Coral CommunitiesFoster, Kristi A. 01 November 2011 (has links)
Some climate models predict that, within the next 30-50 years, sea surface temperatures (SSTs) will frequently exceed the current thermal tolerance of corals (Fitt et al. 2001; Hughes et al. 2003; Hoegh-Guldberg et al. 2007). A potential consequence is that mass coral bleaching may take place (i) during warm El Niño-Southern Oscillation (ENSO) events which are predicted to occur in some regions more frequently than the current 3-7 year periodicity (Hoegh-Guldberg 1999; Sheppard 2003) or (ii) perhaps as often as annually or biannually if corals and their symbionts are unable to acclimate to the higher SSTs (Donner et al. 2005, 2007). Global data also indicate an upward trend toward increasing frequencies, intensities, and durations of tropical hurricanes and cyclones (Emanual 2005; Webster et al. 2005). As coral communities have been shown to require at least 10-30 years to recover after a major disturbance (e.g. Connell 1997; Ninio et al. 2000; Bruno & Selig 2007; Burt et al. 2008), it is possible that future coral communities may be in a constant state of recovery, with regeneration times exceeding the periods between disturbances. Life history traits (e.g. reproduction, recruitment, growth and mortality) vary among species of hard corals; thus, gradients in community structures may have a strong influence on susceptibilities to disturbance and rates of recovery (Connell 1997; Ninio & Meekan 2002). Taxa which are more susceptible to bleaching and mechanical disturbance (e.g. tabular and branching acroporids and pocilloporids) may experience continual changes in population structure due to persistent cycles of regeneration or local extirpation, while the more resistant taxa (e.g. massive poritids and faviids) may display relatively stable population structures (Woodley et al. 1981; Hughes & Connell 1999; Baird & Hughes 2000; Marshall & Baird 2000; Loya et al. 2001; McClanahan & Maina 2003). Determining whether resistant coral taxa have predictable responses to disturbances, with consistent patterns over wide spatial scales, may improve predictions for the future affects of climate change and the composition of reefs (Done 1999; Hoegh-Guldberg 1999; McClanahan et al. 2004).
The work presented in this dissertation describes the spatial and temporal patterns in community structures for high latitude coral assemblages that have experienced the types of natural disturbances which are predicted to occur in tropical reef systems with increasing frequency as a result of climate change. The primary area of focus is the southeastern Arabian Gulf, where the coral communities are exposed to natural conditions that exceed threshold limits of corals elsewhere in the world, with annual temperature ranges between 14-36°C (Kinzie 1973; Shinn 1976) and salinities above 40 ppt. Two additional regions are included in this study for comparisons of high latitude coral community structures. The northwestern Gulf of Oman is adjacent to the southeastern Arabian Gulf (i.e. the two bodies of water are connected by the Strait of Hormuz); however, the environmental conditions are milder in the Gulf of Oman such that the number of coral taxa therein is threefold that found in the southeastern Arabian Gulf (i.e. 107 coral species in the Gulf of Oman compared to 34 species in this region of the Arabian Gulf (Riegl 1999; Coles 2003; Rezai et al. 2004)). Broward County, Florida is geographically remote from the Gulfs and, therefore, serves as a benchmark for testing whether consistent patterns in community structures exist despite different climatic and anthropogenic influences.
The coral communities within the southeastern Arabian Gulf, the northwestern Gulf of Oman, and Broward County, Florida have been exposed to recurrent elevated sea surface temperature (SST) anomalies, sequential cyclone and red tide disturbances, and frequent hurricanes and tropical storms, respectively. These disturbances and other impacts (e.g. bleaching episodes, disease outbreaks, anthropogenic stresses) have affected the more susceptible acroporids and pocilloporids, resulting in significant losses of coral cover by these families and shifts towards massive corals as the dominant taxa. During the post-disturbance scarcity or absence of branching and tabular corals, the resistant massive taxa have become the crux of the essential hard coral habitat for fish, invertebrates and other marine organisms.
Because recovery to pre-disturbance community structures may take decades or may not occur at all, it is vital that scientists and resource managers have a better understanding of the spatial and temporal ecology patterns of the corals that survive and fill in the functional gaps that are created by such disturbances. To aid in this understanding, this dissertation presents spatial and temporal patterns for the coral assemblages which have developed after the respective disturbances. Spatial ecology patterns are analyzed using graphical descriptions (e.g. taxa inventories, area cover, densities, size frequency distributions), univariate techniques (e.g. diversity indices), distributional techniques (e.g. k-dominance curves) and multivariate techniques (e.g. hierarchical clustering, multidimensional scaling). Temporal comparisons at monitoring sites within the southeastern Arabian Gulf and northwestern Gulf of Oman describe the coral population dynamics and are used to create size class transition models that project future population structures of massive corals in the recovering habitats.
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Land-Based Coral Nurseries: A Valuable Tool for Production and Transplantation of Acropora cervicornisO'Neil, Keri L. 01 April 2015 (has links)
Coral nurseries have become a popular and successful method to produce coral fragments for reef-restocking and restoration projects worldwide. Numerous in-situ coral nurseries have been established and many studies have focused on the most effective way to produce coral fragments in offshore nurseries. In contrast, production of coral fragments in land-based nurseries is rarely studied despite a growing knowledge of coral husbandry and coral aquaculture. Little data exist on the success of tank-raised corals when transplanted back into reef environments. This thesis presents the results of a study designed to assess the use of land-based coral nurseries in production of fragments of the Atlantic staghorn coral Acropora cervicornis for the purposes of reef re-stocking and restoration.
The first objective of the study was to assess if A. cervicornis fragments can be produced in aquarium conditions at comparable rates to offshore nurseries. Fragments from the same wild donor colonies were placed in an offshore nursery and a land-based nursery and monitored for survival, growth, branch production, and branch thickness for 16 months. Survival was lower in the land-based nursery, largely due to a mechanical failure. Linear extension was lower in the land-based nursery until nursery conditions were evaluated and optimized. The optimization process included changes to water quality, temperature control, and lighting. Post-optimization, linear extension in the land-based nursery exceeded the offshore nursery, with a maximum monthly growth rate of 16.0 ± 5.3 mm month-1. The maximum monthly rate in the offshore nursery was 10.6 ± 4.1 mm month-1. Branch number and thickness were also lower initially in the land-based nursery, however both metrics increased rapidly after optimization. This experiment shows that A. cervicornis can be successfully grown in a land-based nursery, and that linear extension and fragment production can be higher than in offshore nurseries if environmental conditions are maintained within optimum ranges. This experiment highlights some of the conditions that promoted high linear extension rates in this species.
The second objective of this study was to examine the success of corals outplanted from land-based nurseries and to determine whether corals reared in a land-based nursery would show the same growth and survival after transplantation as those reared in a traditional offshore nursery. This was examined in two experiments. In the first experiment, small fragments were outplanted from colonies reared offshore and from colonies reared in a land-based system. In the second experiment, larger colonies reared in the two separate land-based systems were outplanted to the same location. All transplanted corals were monitored for survival, growth, branch number, and incidence of predation, breakage, and disease over one year. Two major storm events occurred during this portion of the study, so the potential for differences in breakage or storm damage were also assessed.
There were no significant differences in survival or growth of fragments outplanted from a land-based nursery and an offshore nursery. Colony outplants from one land-based location had better survival and growth than colonies from a second land-based location. Tropical storm activity greatly increased the occurrence of breakage and tissue loss in all groups, resulting in decreases in colony volume and additional mortality. Survival ranged from 85% to 100% after six months, and survival ranged from 70% to 89% after one year and the passing of two tropical storms. Small (5 cm) transplants did not have significantly lower survivorship than large transplants. Overall, the transplant of fragments and colonies raised in land-based nurseries was successful, as measured by growth and survival rates that were comparable to or exceeded those observed for corals raised in offshore nurseries. Large colony transplants exhibited the best survivorship and extension rates, but were also highly prone to breakage.
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