Spelling suggestions: "subject:"coralreefs"" "subject:"forereefs""
91 |
Coral propagation for aquarium specimens.Jordan, Ingrid Elizabeth. January 2001 (has links)
Coral reefs are being destroyed and degraded by natural and anthropogenic
processes. Live corals are becoming increasingly popular as marine aquarium
specimens, in both the commercial and private sectors, leading to the degradation of
coral reefs. This often has serious economic implications for the fishing, aquarium and
tourist industries. It is clear that there is a need for the management and protection of
these fragile ecosystems. The artificial propagation of coral is desirable as it will
alleviate the demand for wild coral specimens, and will also provide a stock for the
rehabilitation of damaged reefs. Although corals are being propagated worldwide by
hobbyists, reports on their work are mainly anecdotal and there is little in the scientific
literature on the specific requirements for optimal growth rates and survival in suitable
coral species. This study thus focused on developing techniques to propagate a range
of appropriate coral species and to promote their optimal growth.
The results revealed that different morphological groups of scleractinian corals
require specialised techniques of fragmentation and attachment to ensure survival.
The corals were broken using a hammer and chisel. Attachment techniques varied
from the use of superglue (which is widely used in the United States), to thermoplastic
glue. The mean mortality using superglue was 73% (n=120, ±0.167), using epoxy,
62% (n=120, ±0.127) and with thermoplastic glue it was 11% (n=120, ±0.108)
Superglue was extremely difficult to work with and proved ineffective, especially when
attempting to glue uneven surfaces. Certain species did not survive using this
adhesive due to exposure of the coral to air. The most effective method of rapid
attachment was the use of thermoplastic glue that set rapidly underwater. The use of
electrolysis to promote the attachment of coral nubbins was tested as an alternative to
the various adhesives. This method increased the survival of the nubbins and
eliminated exposure to air. It has proven suitable for both coral propagation and in situ
reef rehabilitation.
Growth experiments revealed that the manipulation of current flow, light and
the addition of different feeds had different effects on the growth rates of selected
candidate species. A suite of optima was thus developed for each species. The
majority of species grew best in a bi-directional current flow, with yeast as feed, under
actinic blue light. An experiment that combined the optimal current flow, feed and light
conditions, revealed that the majority of species grew best under mixed light with
yeast as feed.
The trade in corals is sensitive in terms of their handling, transportation and
CITES (Convention on International Trade in Endangered Species) status. Having
established the viability of their propagation, consideration was given to appropriate
regulatory and marketing procedures to accommodate this sensitivity of the cultivated
material. / Thesis (M.Sc.)-University of Natal, Durban, 2001.
|
92 |
Macroalgae in tropical seascapes : regulating factors and functions in the coastal ecosystemLilliesköld Sjöö, Gustaf January 2010 (has links)
Although macroalgae usually are inconspicuous on pristine coral reefs, they often thrive on reefs that are subjected to various types of anthropogenic disturbance. This thesis consists of five papers and investigates how biomass and composition of macroalgal communities on coral reefs are affected by regulating factors, such as nutrient availability, herbivory, substrate availability and hydrodynamic forces. In addition, ecological functions and potential impacts of both wild and farmed macroalgal communities are evaluated. Paper I describes a method for using macroalgal tissue nutrient concentrations as bioindicator for nutrient availability, with the possibility to map nutrient loading from larger coastal cities. Papers II and III are manipulative studies comparing top-down and bottom-up regulation of macroalgal communities, where herbivore consumption seems to be the main regulator of biomass whereas nutrient availability mainly influences community composition. Exclosure of large-bodied herbivores had a positive influence on algal biomass in both studies, and during different climatic periods. Paper III also includes the influence of hydrodynamic forces on algal community biomass and structure by comparing a reef crest and a back reef-habitat. Alterations of top-down and bottom-up regulation generally had a stronger effect within the protected back reef-habitat, suggesting that such environments may be more sensitive to anthropogenic influence. Paper IV confirms the general conclusions from papers II and III by studying macroalgal biomass and composition on reef sites with different environmental prerequisites. This study also supports the notion that herbivorous fish can suppress accumulation of macroalgal biomass if substrate availability is low, but not where coral cover is reduced and plenty of substrate is open to macroalgal colonization. The study also found a large temporal variation of macroalgal standing stock and associated nutrients at sites with low top-down regulation. Paper V evaluates potential impacts of seaweed farming on coral reefs and nutrients in the seascape by experimentally studying growth, survival and nutrient binding capacity of Eucheuma denticulatum. This study showed that seaweed farms counteract eutrophication through nutrient extraction and that the risk of farmed algae colonizing local reefs seems to be small as they were rapidly consumed. In conclusion, the studies in this thesis contribute to the understanding of macroalgal regulation and function in tropical seascapes, thereby adding to the knowledge base for coastal management. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript. Paper 5: Manuscript.</p>
|
93 |
Macroalgal community dynamics on coral reefs : Implications for managementMörk, Erik January 2011 (has links)
Although rather inconspicuous on healthy coral reefs, macroalgae form the basis of coral food webs. Today, macroalgae are generally increasing and many reefs undergo transitions from coral to macroalgal dominance resulting from e.g. enhanced nutrient loading or increased fishing. This thesis aims to investigate the relative importance of top-down and bottom-up regulation, and different herbivore types, on macroalgal distribution, fecundity and community composition on coral reefs. Papers I and II indicate that macroalgal abundance in a coral reef system is largely governed by top-down regulation through grazing by herbivores, while bottom-up regulation through enhanced nutrient availability rather influence algal species composition. Paper II also shows that these regulating effects are not as evident in an area with relatively strong water motion, suggesting that impacts of anthropogenic disturbance may be site-specific. Paper III shows that herbivory is an important factor influencing macroalgal growth and subsequent reproduction. Furthermore, Paper IV and V conclude that efficiency in removing macroalgal biomass is dependent on the type of dominant herbivore, where sea urchins seem to be more effective than fish. Paper IV indicates a seasonal variation in macroalgal biomass and distribution in a small geographic scale but with relatively high temporal resolution. Paper V on the other hand shows these same effects, but with a focus on geographic variation, including a large part of the East African region, as well as between year temporal variations in Kenya. Together, results from the two latter studies indicate that herbivory by fish may not be able to prevent a macroalgal bloom in a degraded system where substrate availability for algal colonization is high, but that it may still facilitate coral recovery over time. Thus, a large algal biomass may not necessarily indicate a reef beyond the possibility of recovery. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Accepted. Paper 4: Manuscript. Paper 5: Manuscript.</p>
|
94 |
Hard Habits to Break: Investigating Coastal Resource Utilisations and Management Systems in Sulawesi, Indonesia.Idrus, Rijal January 2009 (has links)
This research investigates the paradox that many coastal communities in developing countries are resource rich but income poor. Another aspect of this paradox is the belief that local communities possess traditional knowledge that respects nature. This belief contrasts the fact that major tropical coastal ecosystems, namely coral reefs and mangroves, are being destroyed at rapid and increasing rates, in many cases by the people whose livelihoods depend on them.
These paradoxical circumstances lead to a central question: if the sustainability of coastal resources is vital for the livelihood of local communities, why are these resources being degraded, often to the point of complete destruction? This study explores the motives and consequences of destructive methods of coastal resource utilisation and examines the potential for sustainable livelihoods based on coastal resources currently under threat from destructive use patterns. The analysis is based on a field study conducted in 2006 and 2008 in eleven sites around the island of Sulawesi, Indonesia. This area is characterised by great biodiversity, including one of the highest marine biodiversities in the Asia-Pacific region.
Coral and mangrove ecosystem resource use was found to be driven by different processes and activities; hence the destructive practices impacting both ecosystems were also different. Blast and poison fishing were the most widespread destructive resource use methods found for coral reefs whereas large-scale habitat conversion was responsible for mangrove ecosystem reduction. In the field both resources were found to be under enormous anthropogenic pressures, with published data suggesting that only 5.8% of Indonesian coral reefs are currently in excellent condition and only 38% of mangrove cover remaining in Sulawesi relative to that of 25 years ago. The dynamics of these coastal resources, and of their destruction, are classic examples of the ’tragedy of the commons’.
Research findings further indicate that formal institutions tasked with managing these resources have not been able to promote their effective conservation. An array of competing demands and conflicting interests, coupled with inefficient institutional arrangements and under-investment, have rendered inadequate many resource management efforts, including the externally-imposed concepts, allowing destructive patterns of resource utilization to persist. Local communities are disempowered when confronted with (1) the intricate network of destructive-fishing actors targeting coral reefs, or (2) large company-government bureaucracy collusions allowing mangrove conversion. The existence of this collusive network must be considered in any effort to address problems of effective management.
Empirical insights suggest that conservation at local level has to face the challenges of market-driven resource extraction at a global scale. Only when a coastal community manages to overcome the dilemma in managing common-pool resource, conservation measures can be implemented and a degree of sustainability attained. Findings from this research have important implications for the discourses on coastal resource policy and research. This research advances the discussions to the area where the core of conflict of interests among stakeholders took place, and yet has rarely been addressed previously. The synthesis from this study provides a strong basis to understand the nature of asymmetric relations amongst the resource stakeholders, and therefore will help in generating effective policies for a fairer coastal resource management regime.
|
95 |
Planning an underwater parkSmith-Coffin, Margaret A. January 1987 (has links)
This creative project concerned the planning of an underwater park off the western coast of Negril, Jamaica. Negril is the westernmost point in Jamaica. Negril was traditionally a small fishing village before the development of tourism in the late 1960's. The rapid growth of tourism and haphazard development that followed has had detrimental effects on the marine environment and local community. Much of the local economy still depends on fishing for its subsistence. The underwater park is an attempt to preserve and protect the reefs and linked habitats in Negril.Protecting the reef will ultimately benefit the local fishing economy. The reef, with its warm, shallow waters is a breeding ground for fish. The fish rely on natural protection in the reef until they are large enough to move out into open waters. The park will prohibit collecting of any fish or plant species within the park area or any other activity with negative impacts to the reef ecology.The intent of the study was to locate and identify the underwater interpretive resources (coral communities), closely linked marine habitats and to recommend park boundaries and designate levels of use and protection. Further intent was to identify current and potential impacts, determine the proper status for the park, outline management objectives, regulations, and specify management plans for the park.The Negril Underwater Park will exist for the purpose of encouraging maximum compatible development of the coral reef system, as a visitor attraction and recreation area, while preserving the resources from degradation through a program of controlled use. The park is also intended to protect habitats linked to the coral reef especially the Great Negril Morass, Sea-grass, beach, and Mangrove areas. / Department of Landscape Architecture
|
96 |
Human disturbance alters Pacific coral reef fish beta-diversity at three spatial scalesWiwchar, Logan Douglas 07 March 2014 (has links)
Coral reefs are the most diverse marine ecosystem, but are increasingly threatened by local and global anthropogenic changes. In this thesis, I examine the impact of local stressors on the spatial variability of coral reef fish community composition by modeling the !-diversity of 35 islands across the Pacific Ocean that are characterized by either low or high human disturbance. By examining !-diversity across three spatial scales (within island, within island group, and across island group), and using null models to control for differences in alpha-diversity or abundance, I reveal previously undocumented effects of human disturbance on coral reef fish assemblages. At all scales, human disturbances alter !-diversity. At the largest-scale, islands with high human disturbance have lower incidence- and abundance-based !-diversity, consistent with biotic homogenization. This pattern was driven by both species with high and low abundances that differed across islands. At the smaller two scales (within islands or island groups), the presence of low abundance species is more variable on islands with high human disturbance (manifest in greater incidence-based !-diversity), but these islands have lower abundance-based !- diversity driven by moderately abundant and widespread species. Multivariate techniques show that islands with high human disturbance have a weaker species-environment relationship, and as such, I suggest that homogenization of coral reef fish assemblages by human disturbances is resulting in greater stochasticity of species composition. / Graduate / 0329 / wiwchar@uvic.ca
|
97 |
Hard Habits to Break: Investigating Coastal Resource Utilisations and Management Systems in Sulawesi, Indonesia.Idrus, Rijal January 2009 (has links)
This research investigates the paradox that many coastal communities in developing countries are resource rich but income poor. Another aspect of this paradox is the belief that local communities possess traditional knowledge that respects nature. This belief contrasts the fact that major tropical coastal ecosystems, namely coral reefs and mangroves, are being destroyed at rapid and increasing rates, in many cases by the people whose livelihoods depend on them. These paradoxical circumstances lead to a central question: if the sustainability of coastal resources is vital for the livelihood of local communities, why are these resources being degraded, often to the point of complete destruction? This study explores the motives and consequences of destructive methods of coastal resource utilisation and examines the potential for sustainable livelihoods based on coastal resources currently under threat from destructive use patterns. The analysis is based on a field study conducted in 2006 and 2008 in eleven sites around the island of Sulawesi, Indonesia. This area is characterised by great biodiversity, including one of the highest marine biodiversities in the Asia-Pacific region. Coral and mangrove ecosystem resource use was found to be driven by different processes and activities; hence the destructive practices impacting both ecosystems were also different. Blast and poison fishing were the most widespread destructive resource use methods found for coral reefs whereas large-scale habitat conversion was responsible for mangrove ecosystem reduction. In the field both resources were found to be under enormous anthropogenic pressures, with published data suggesting that only 5.8% of Indonesian coral reefs are currently in excellent condition and only 38% of mangrove cover remaining in Sulawesi relative to that of 25 years ago. The dynamics of these coastal resources, and of their destruction, are classic examples of the ’tragedy of the commons’. Research findings further indicate that formal institutions tasked with managing these resources have not been able to promote their effective conservation. An array of competing demands and conflicting interests, coupled with inefficient institutional arrangements and under-investment, have rendered inadequate many resource management efforts, including the externally-imposed concepts, allowing destructive patterns of resource utilization to persist. Local communities are disempowered when confronted with (1) the intricate network of destructive-fishing actors targeting coral reefs, or (2) large company-government bureaucracy collusions allowing mangrove conversion. The existence of this collusive network must be considered in any effort to address problems of effective management. Empirical insights suggest that conservation at local level has to face the challenges of market-driven resource extraction at a global scale. Only when a coastal community manages to overcome the dilemma in managing common-pool resource, conservation measures can be implemented and a degree of sustainability attained. Findings from this research have important implications for the discourses on coastal resource policy and research. This research advances the discussions to the area where the core of conflict of interests among stakeholders took place, and yet has rarely been addressed previously. The synthesis from this study provides a strong basis to understand the nature of asymmetric relations amongst the resource stakeholders, and therefore will help in generating effective policies for a fairer coastal resource management regime.
|
98 |
Economic valuation of coral reefs : a case study of the costs and benefits of improved management of Dhigali Haa, a marine protected area in Baa Atoll, Maldives : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Environmental Science at the University of Canterbury /Mohamed, Mizna. January 1900 (has links)
Thesis (M. Sc.)--University of Canterbury, 2007. / Typescript (photocopy). "August 2007." Includes bibliographical references (p. 119-127). Also available via the World Wide Web.
|
99 |
Case studies in coral restoration: assessing life history and longterm survival patterns in restoration outplants of Acropora cervicornis (Staghorn Coral) and Acropora palmata (Elkhorn Coral) in the Florida Keys and BelizeGarfield, Eliza Newell 23 November 2016 (has links)
This thesis is composed of two articles. The first is an analysis of long-term survival among A. cervicornis outplants in the Florida Keys, from 2007 to the present. The second is a review of literature that informs coral restoration and guides both restoration practitioners and coral researchers towards greater effectiveness in outplant survival and understanding biological processes involved in restoration.
In the first article, despite promising initial evidence of outplant survival and health, the long-term results, using Weibull survival analysis, are discouraging with almost all out planted corals over an 8 year long study exhibiting steep declines in percent live tissue and survival between three and five years. Not only is this 3-5 year collapse apparent in all the outplanted cohorts, but the evidence is highly significant that the length of outplant survival is decreasing with each passing year (diminished resilience). These findings suggest that some shared, likely environmental factor, is increasingly impacting all outplants. Further, no cohorts appear to adapt to the environmental conditions in which these declines are occurring (diminished adaptive capacity), a trend that would be evident if their declines slowed or reversed and Weibull beta-parameterization would show.
The second article, reviews several areas of recent study which offer avenues for future research: these include, ecological history and biogeography, developmental pathways of colonial form and function, polarity and symmetry, genetics, wound healing, fecundity, reproduction, sexual maturity and community interactions. The thesis concludes with questions for further research and understanding in the field of coral restoration.
|
100 |
Effects of heat stress and local human disturbance on the structure of coral reef ecosystems at multiple scales of biological organizationMagel, Jennifer 04 January 2019 (has links)
The world’s coral reefs are being impacted by myriad disturbances, from localized overfishing and nutrient pollution to global climate change-induced temperature increases and ocean acidification. Conservation of coral reefs in the face of increasing variability and uncertainty requires an understanding of the interacting effects of multiple stressors on the diverse components of these vital ecosystems. In this thesis, I use data from reefs around Kiritimati atoll (Republic of Kiribati) in the central equatorial Pacific Ocean to examine the effects of a severe pulse heat stress event and local human disturbance on two important components of the coral reef ecosystem – three-dimensional (3D) structural complexity and reef fish assemblages. Using 3D reef models constructed through structure-from-motion photogrammetry, I examined changes in reef structural complexity in the year following the 2015-2016 El Niño and mass coral bleaching event. I found that exposure to prolonged thermal stress and subsequent coral mortality resulted in declines in reef structural complexity, particularly reef surface rugosity and terrain ruggedness. Baseline levels of structural complexity were also negatively influenced by local human disturbance, while complexity was positively related to the densities of branching and massive coral growth forms. These findings have important implications for the maintenance of healthy reef ecosystems, as high levels of structural complexity are important for supporting diverse reef-associated fish assemblages. Next, using underwater visual censuses of reef fish assemblages, I quantified fish abundance, biomass, species richness, and assemblage structure before, during, and after the 2015-2016 El Niño. Total reef fish abundance, biomass, and species richness declined during the El Niño, suggesting that pulse heat stress events may have short-term, negative consequences for reef fish. Although these metrics did not vary substantially across the local human disturbance gradient, recovery of assemblages following the heat stress event was impeded by higher levels of local human disturbance. Reef fish assemblage structure was influenced by a more diverse array of factors, showing significant shifts in response to heat stress, human disturbance, and net primary productivity. Given the many important roles that fish play on coral reefs, declines such as those observed here may impair the ecological functioning of these ecosystems. Together, my results highlight the negative impacts of heat stress and local human disturbance on coral reefs, demonstrating ways in which these stressors may interact to limit reef resilience in the face of increasing anthropogenic pressures. / Graduate / 2019-12-07
|
Page generated in 0.0318 seconds