Univ., Diss--Hamburg, 2006. / Literaturverz. S. [125] - 133.

Throughout the Pacific, many species of echinoderms and molluscs have cultural value and are harvested extensively in subsistence fisheries. Many of these species are sedentary and often associated with distinct reef-top habitats. Despite the significance of reef habitats and their fauna for fisheries and biodiversity etc, little information has been available on the distribution of habitats and their influence on the reef-top fauna in the Cook Islands. This thesis developed a novel approach to assess the status of the shallow-water reef-tops of Rarotonga, Cook Islands, to provide critical information to fisheries and conservation managers. The approach used remote sensing (aerial photography with ground truthing) to map the spatial arrangement and extent of the entire reef-top habitats accurately, and historical wind data and coastline shape to determine the windward and leeward sides of the island. The benthic habitat maps and degree of wind exposure were used to design and undertake a stratified sampling programme to assess the distribution and abundance of the epibenthic macroinvertebrate fauna of the reef-top. I quantified the distribution and abundance of the epibenthic macroinvertebrates and how they varied with habitat, assessed the effectiveness of a traditional ra�ui (marine protected area) for conserving stocks of Trochus niloticus and other invertebrates, and investigated the reproductive biology and impacts of traditional gonad harvesting on Holothuria leucospilota. There were four major habitat types (rubble/rock, sand/coral matrix, algal rim and sand) identified, the most extensive being rubble/rock (45%) and sand/coral matrix (35%). The degree of exposure to winds was found to correlate with the reef development and habitat distribution. The assemblage composition of each major habitat type differed significantly from every other habitat. The rubble/rock habitat had the greatest substratum heterogeneity and structural complexity, and the highest number of species and individuals. The overall abundance of the fauna was dominated by holothurians (68%) and echinoids (30%), while Trochus niloticus and Tridacna maxima accounted for the remaining 2% of the total invertebrate assemblage. Clear habitat partitioning was also found for adult and juvenile Trochus niloticus and Tridacna maxima. In the traditional fishery for Holothuria leucospilota, the mature gonads of males are harvested by making an incision in the body-wall of the animal, removing the gonads and then returning the animal to the reef to allow regeneration. Monthly collections of H. leucospilota were used to describe the reproductive biology of this species. Gametogenesis and spawning were synchronous between the sexes and spawning occurred annually during summer, when water temperature and photoperiod were at their highest. Although the incision in the body-wall and gonad removal had no impact on the survival of H.leucospilota in experimental cages, their body weight, and general sheltering and feeding behaviors were affected. Gonads took at least 41 days to start regenerating, suggesting a considerable delay in the spawning of fished individuals. In 1998, five Rarotongan communities re-introduced the traditional ra�ui system of resource management, prohibiting all fishing and gathering from their reefs. The performance of the Nikao ra�ui, which had been put in place to allow trochus stocks to increase, was investigated. Comparisons of macroinvertebrate assemblage composition and species density were made between three fishing treatments, i.e. fished areas adjacent to the ra�ui, within the ra�ui after two years of protection, and in the ra�ui after it had been lifted for three weeks to allow a commercial trochus harvest. Analysis of variance on the count data for the twelve most abundant species, and non-metric multi-dimensional scaling indicated that there were no differences in the microhabitat or the invertebrate assemblage composition between the three fishing treatments. However, there were significant differences between the rubble/rock and sand/coral matrix habitat types. The results on the effectiveness of the Nikao ra�ui are equivocal, due to the small sample size, and the variability between samples which was highlighted by the wide confidence intervals. This study highlights the importance of habitat to the macroinvertebrate fauna of the reef-top and the need for accurate habitat maps to increase the cost-effectiveness of future resource surveys, to provide information to management, and for the design of Marine Protected Areas. The mapping and survey methods must be reliable and repeatable in terms of the limitations of time, and the availability of expertise, funding and resources. The results provide important information for fisheries and conservation managers of Rarotonga and other Pacific Islands to better design rigorous sampling programmes for monitoring the status of reef-top resources, and for evaluating and planning Marine Protected Areas.

Thesis (Ph.D.)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: p. 377-421.

Thesis (Ph.D.)--University of Wollongong, 2008. / Typescript. CD-ROM contains full thesis, appendix II database and abstract. Includes bibliographical references: p. 169-198.

In South Africa, the indigenous mussel Perna perna is threatened by both an invasive species and excessive human exploitation. The Mediterranean mussel Mytilus galloprovincialis is an invasive species that has been introduced to many parts of the world. In South Africa, this species arrived in the 1970s and spread rapidly along the west coast where today it is the dominant mussel species. Along the west coast, M. galloprovincialis is competitively superior in all aspects to the indigenous mussel species, and, as a result, has displaced some of them. On the south coast, M. galloprovincialis found more oligotrophic waters, higher species richness, and a stronger competitor in the indigenous mussel P. perna. The rate of spread of M. galloprovincialis along the south coast has decreased over the last 10 years and the present eastern limit of its distribution in South African is East London. On the south coast, M. galloprovincialis has not yet completely replaced P. perna; instead, the two exhibit spatial segregation, with P. perna dominating the low shore, M. galloprovincialis the high shore and an overlap zone between the two. An experiment on competition was carried out at one site on the south coast. The results showed that, on the low shore, P. perna is a more dominant competitor for space than M. galloprovincialis. Also byssus attachment of the two species differs, P. perna being much stronger than M. galloprovincialis, which suffers high mortality due to wave action on the low shore, especially in monospecific beds. As a result, mortality of M. galloprovincialis through wave action is reduced by the presence of P. perna, which seems to confer protection against dislodgement. However, in the absence of strong wave action, P. perna competitively excludes M. galloprovincialis. Human exploitation along 160 km of coast was examined by sampling mussel populations and using aerial surveys to determine where harvesters were distributed. Collectors did not seem to discriminate between species. The study has shown that higher abundances of mussels were found in protected or inaccessible sites, while in unprotected sites mussels were scarce. Coastal nature reserves are being proven to be effective in protecting mussel populations.

Overfishing in the Benguela Current Large Marine Ecosystem (BCLME) resulted in degradation of the ecosystem. This study used the Driver-Pressure-State-Impact-Response (DPSIR) indicator framework to determine whether the ecosystem is now recovering. Indicator trends were analysed using various data sources that included government institutions and intergovernmental institutions. The results showed that the overall effect of Driver indicators was negative. This was mainly because of socio-economic pressure such as the need to create more jobs in light of rising national unemployment and the declining contribution of the fisheries sector to Gross Domestic Product (GDP). In addition to scientific advice, socio-economic factors also influenced the determination of Total Allowable Catches (TACs). The overall trend of Pressure indicators was positively influenced by the effect of TACs. The TACs reduced the quotas allocated for commercial fishing. Environmental factors did not seem to play a significant role in this study. State indicators had mixed results with the indicators assessed almost split in the middle between those showing a positive trend and those showing a negative trend. On the other hand, Impact and Response indicators showed overall positive results. Therefore, the conclusion of the study was that the degradation of the BCLME has slowed down and there are some signs of recovery. / Environmental Sciences / M.Sc. (Environmental Science)

Overfishing in the Benguela Current Large Marine Ecosystem (BCLME) resulted in degradation of the ecosystem. This study used the Driver-Pressure-State-Impact-Response (DPSIR) indicator framework to determine whether the ecosystem is now recovering. Indicator trends were analysed using various data sources that included government institutions and intergovernmental institutions. The results showed that the overall effect of Driver indicators was negative. This was mainly because of socio-economic pressure such as the need to create more jobs in light of rising national unemployment and the declining contribution of the fisheries sector to Gross Domestic Product (GDP). In addition to scientific advice, socio-economic factors also influenced the determination of Total Allowable Catches (TACs). The overall trend of Pressure indicators was positively influenced by the effect of TACs. The TACs reduced the quotas allocated for commercial fishing. Environmental factors did not seem to play a significant role in this study. State indicators had mixed results with the indicators assessed almost split in the middle between those showing a positive trend and those showing a negative trend. On the other hand, Impact and Response indicators showed overall positive results. Therefore, the conclusion of the study was that the degradation of the BCLME has slowed down and there are some signs of recovery. / Environmental Sciences / M.Sc. (Environmental Science)

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Orientador: Otto Bismarck Fazzano Gadig / Abstract: The establishment of no-take marine reserves (NTRs), i.e. areas with total fishing restrictions, has been an alternative worldwide aiming to preserve both biodiversity and ecosystem functions. Brazil has important NTRs with few studies describing their relevance and efficiency for marine life. With this, the central objective of this thesis was to evaluate the effects of NTRs on fish assemblage, testing the hypothesis that the differences in richness, abundance, biomass and fish body size is more explained by protection status than environmental characteristics. Thus, innovative techniques in Brazil, Baited Remote Underwater stereo-Videos (stereo-BRUVs) and Diver Operated stereo-Videos (stereo-DOVs) were tested in the Southwestern Atlantic, comparing with traditional visual census (stationary point count and belt transects), and used to analyze the effects of the Tupinambás Ecological Station and Abrolhos Marine National Park on fish assemblages. For this, fish assemblage characteristics, such as richness, abundance, biomass and body size, were compared to areas where fishing is allowed, and the habitat complexity was estimated through the footages. Concerning methods comparison, stereo-DOV showed to be more effective, sampling more richness and abundance within less effort, and Stereo-BRUVs showed to sample a very specific assemblage, comprised mostly by mobile and large bodied fish species, usually targeted by fisheries. Within both NTRs evaluated, target species characteri... (Complete abstract click electronic access below) / Resumo: O estabelecimento de reservas marinhas de restrição total (No-take reserves - NTRs), ou seja, áreas com proibição total de pesca, tem sido uma alternativa mundial para preservar a biodiversidade e as funções dos ecossistemas. O Brasil tem importantes NTRs com poucos estudos descrevendo sua relevância e eficiência para a vida marinha. Com isso, o objetivo central desta tese foi avaliar os efeitos de NTRs em assembleias de peixes, testando a hipótese de que as diferenças em riqueza, abundância, biomassa e tamanho corporal dos peixes são mais explicadas pelo status de proteção do que por características ambientais. Para tanto, técnicas inovadoras no Brasil, estéreo-vídeos subaquáticos com isca (Baited Remote Underwater stereo-Videos - stereo-BRUVs) e estéreo-vídeos operados por mergulhador (Diver Operated stereo-Videos - stereo-DOVs) foram testados no Atlântico Sudoeste, comparando com os censos visuais tradicionalmente aplicados (estacionário e transecto), e utilizados para analisar os efeitos da Estação Ecológica Tupinambás e do Parque Nacional Marinho dos Abrolhos nas assembleias de peixes. Para isso, as características das assembleias de peixes em termos de riqueza, biomassa, abundância e tamanho corpóreo, foram comparadas com as áreas onde a pesca é permitida, e a complexidade do habitat foi estimada através das imagens. Em relação à comparação dos métodos, o estéreo-DOV apresentou maior eficiência, amostrando mais riqueza e abundância com menor esforço, e o estéreo-BRUV am... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

[Truncated abstract] The ecological effects of marine protected areas (MPAs) in temperate ecosystems are poorly understood relative to their tropical counterparts. The limited number of rigorous empirical studies supporting existing theoretical models, increasing public awareness of the importance of marine conservation strategies and legislative requirements to review management effectiveness provide further impetus to study temperate MPAs. Investigations should consider confounding effects of natural variability if MPA effects are to be clearly demonstrated. This research helps to address these needs by investigating the short term effects of sanctuary zones (no-take MPAs where fishing is prohibited) and wave exposure at Marmion Marine Park, Western Australia. The three sanctuary zones at Marmion Marine Park are extremely small (0.061 0.279 km2) compared to most reported in the literature. The sanctuary zones are nested within a larger, fished zone (94.95 km2). The sanctuary zones have been protected from fishing since the year 2000. A post-hoc, asymmetrical sampling design was used in this study and involved surveys of fishes, mobile invertebrates and macroalgae at one sanctuary zone and two fished sites (controls) at each of three successive, subtidal reef lines. The three reef lines are exposed to a gradient in wave energy. The size structure and abundance of the heavily exploited Panulirus cygnus (Western Rock Lobster) were positively affected by protection from fishing in sanctuary zones, despite the highly mobile nature of this migratory species. The mean abundance of legal size lobsters was higher in sanctuary zones compared to fished sites during an interannual study (2003, 2005 and 2006). The total abundance of lobsters and the mean abundance of legal size lobsters were higher at inshore and offshore sanctuary zones compared to fished control sites during a 2005/2006 fishing season study. These zoning effects did not vary with the time of survey. ... Furthermore, the abundance of large lobsters in sanctuary zones decreased with the duration of the 2005/2006 fishing season. Similarly, it is likely that sanctuary zones are too small relative to the movement of fishes to adequately protect stocks of some targeted species. The small sanctuary zones at Marmion are unlikely to offer protection to highly mobile species over the long term. And finally, ecological assemblages within each level of wave exposure are distinct. Consequently for each assemblage type, the current reserve design does not include replication of sanctuary zones and does not offer any 'insurance' in the event of isolated impacts affecting a particular zone. This study has identified the benefits and deficiencies of the design and function of small no-take temperate MPAs in Western Australia. An increase in the size and number of sanctuary zones within each wave exposure level will help to address the v shortfalls of the zoning scheme and enhance the conservation benefits of management at Marmion Marine Park. More generally, this study demonstrates that the mobility of the species to be protected from fishing should be considered when designing MPAs. Lessons learned from this work will be beneficial for the future management and conservation of resources in the region and elsewhere.