A benthic environments classification system is devised from digital interpretations of multi-spectral IKONOS satellite imagery for 1,360 km2 of the carbonate platform and presented in a comprehensive digitized map. The classification scheme is designed as a 7th order hierarchical structure that integrates 5 Physiographic Realms, 24 Morphodynamic Zones, 11 Geoforms, 39 Landforms, 6 dominant surface sediment types, 9 dominant biological covers and 3 densities of biological covers for the description of benthic environments. Digital analysis of the high-resolution (4 m) IKONOS imagery employed ESRI's ArcMap to manually digitize 412 mapping units at a scale of 1:6,000 differentiated by spectral reflectance, color tones, and textures of seafloor topologies. The context of each morphodynamic zone is characterized by the content and areal distribution (in km2) of geomorphic forms and biological covers. Over 58% of the mapping area is occupied by sediment flats, and seagrasses are colonized in almost 80% of the topologies. / by Jacob Thomas Steinle. / Thesis (M.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

Latitudinal patterns in reef fish assemblages reflect the influence of long-term environmental conditions, evolutionary processes and the recent, short-term influence of fishing. Long-term processes generate the typically common latitudinal patterns in reef fish assemblages, such as decreases in diversity and herbivory towards higher latitudes. These patterns reflect the global gradient in water temperature and the isolation of temperate regions from the tropics. Fishing also influences reef fish assemblages in that it decreases the abundance of large-bodied carnivore species on reefs, often leading to over-exploitation, depletion and in some cases the extirpation of populations. Indirectly, the removal of these large-bodied carnivores can influence the abundance of their prey, leading to an increase in non-target species. This study examines the latitudinal patterns in reef fish assemblages across a unique biogeographic region, the temperate Western Australian coast, and incorporates an investigation of the influence of fishing on the structure of these assemblages. Seven regions across seven degrees of latitude and seven degrees of longitude covering approximately 1500 km of coastline were sampled. Fish assemblages were characterised at each region using diver operated stereo-video transects. At each region, four locations, and within each location, four reefs were surveyed totalling 1344 transects. A significant gradient in water temperature exists with latitude and longitude. Along the Western Australian coast, and in contrast to other regions species diversity of reef fish increased towards higher latitudes and there was no evidence for a decrease in the biomass and abundance of herbivorous reef fish. The presence of the poleward flowing warm water Leeuwin current combined with the absence of major extinction events means the temperate Western Australian coast contrasts with global latitudinal trends in reef fish assemblage structure. The unique biogeographic history of temperate Western Australia has also generated a high degree of endemism among reef fish. Nearly 30 % of the species found along the west coast in this study are endemic to Western Australia, with the narrow range of these species playing an important role in the large scale patterns and spatial vi heterogeneity in reef fish assemblage structure. Furthermore, many of these endemic species are large-bodied carnivores and targeted by fishers. The impact of fishing on the abundance of large-bodied carnivores throughout the Western Australian temperate region is clear both spatially and temporally. The distribution of fishing effort is greatest along the west coast and decreases towards the south following the gradient in SST. Along the west coast, high levels of fishing effort have reduced the biomass and abundance of target carnivores to well below the standing biomass of the south coast where a low level of fishing effort occurs. This reduction in biomass is related to the historical declines in catch per unit effort (CPUE) of many key target species. These target species include endemic species such as Choerodon rubescens, Glaucosoma herbraicum, Epinephilides armatus Nemadactylus valenciennesi and Achoerodus gouldii.

The Oxford English Dictionary defines 'omnifarious' as 'comprising or relating to all sorts or varieties', which quite accurately captures the very nature of octocorals and this thesis. The research reported here, aims to describe undocumented communities of coral reef organisms - the octocorals - which are an emergent dominant component within their threatened ecosystem of the Caribbean. Within the last four decades, coral reefs worldwide have experienced a precipitous plunge in many ecosystem services they provide, and most notably in the Caribbean. The foundation to reef resilience is structured on the ecosystem's ability to repair and restructure itself in the face of environmental shifts. These intricately complex strategies of resilience depend on repair mechanisms provided by a source of biodiversity, much of which remains poorly understood. This work explores many facets of the functioning within this potential future coral reef ecosystem. These reports are one of the most significant contributions to documenting and describing octocoral biodiversity (e.g. species, genetic, and community diversity) of the wider ecoregion of the Mesoamerican Barrier Reef System within the last three decades.

No description available.

Aquatische Gemeinschaften sind stark körpergrößenstrukturiert mit einer exponentiellen Abnahme der Häufigkeit der Individuen mit zunehmender Körpergröße, die als Größenspektrum (SS) bezeichnet wird. Körpergrößenbasierte Ansätze bieten eine einfache und kostengünstige Methode zur Beantwortung komplexer ökologischer Fragestellungen in aquatischer Forschung. Widersprüchliche Ergebnisse zu den wichtigsten Faktoren, die Größenspektren beeinflussen unterstreichen jedoch die Notwendigkeit weiterer Studien. Um einige dieser widersprüchlichen Schlussfolgerungen anzugehen, habe ich eine Reihe von Fragen in den Bereichen Limnologie und Korallenriffökologie untersucht. In dieser Dissertation wurden größenbasierte Ansätze wie SS verwendet, um zu untersuchen, (i) was die Größenverteilung von Zooplankton beeinflusst und ob Zooplankton-fressende Fische (topdown) oder Ressourcenverfügbarkeit und Umweltbedingungen (bottom-up) die SS der Zooplanktongemeinschaft bestimmen, (ii) ob traditionelle Schleppnetze oder moderne hydroakustische Methoden Fisch-SS zuverlässiger darstellen, und (iii) ob SS von Korallenriff- Fischgemeinschaften und die strukturelle Komplexität der Korallen bzw. deren Beziehung zueinander sich unter verschiedenen anthropogenen Stressoren verändert. Zuallererst konnte ich zeigen, dass weder Top-down- noch Bottom-up-Kräfte stark die Größenverteilung der Zooplanktongemeinschaft beeinflussten. Zooplankton SS scheinen robust gegenüber Prädationseffekten zu sein, aber ein empfindlicher Indikator für die Energieverfügbarkeit und Transfereffizienz im Nahrungsnetz des untersuchten Sees. Des Weiteren konnten meine Studien bestätigen, dass hydroakustische Methoden die SS von pelagischen Fischgemeinschaften zuverlässig darstellen, was sie zu einer kostengünstigen und minimalinvasiven Alternative zu traditionellen Fischentnahmemethoden macht. Ich konnte jedoch kein allgemeingültiges Muster hinsichtlich der Größenverteilung von Korallenrifffischen und der strukturellen Komplexität der Korallen in Beziehung zu unterschiedlichen anthropogenen Stressoren finden. Insgesamt zeigt die Dissertation das weite Anwendungsspektrum von SS, um Strukturen und Prozesse in aquatischen Gemeinschaften und Fischfangmethoden zu untersuchen. Die hohe Variabilität von Größenspektren und der Einfluss von Umweltbedingungen unterstreicht weiter die Wichtigkeit, Daten über einen langen Zeitraum einzubeziehen. Darüber hinaus unterstreichen die Ergebnisse dieser Arbeit auch die Grenzen der Anwendung von SS, da für die Beantwortung mancher ökologischer Fragestellungen artenspezifische Informationen, wie Lebensraum- und Nahrungspräferenzen benötigt werden. / Aquatic communities are highly body-size structured with an exponential decline of abundance with increasing body size, which is referred to as the size spectrum (SS). The importance of body size as a principal and simplifying framework within aquatic communities, has led to a high number of theoretical and empirical studies on energy fluxes in food webs and predatorprey interactions using Size Spectra. These size-based approaches offer a rather simple and inexpensive method to answer complex ecological questions. However, conflicting findings on the key drivers of SS highlight the need for further studies. To address some of these conflicting conclusions, I investigated a range of questions within the fields of limnology and coral reef ecology. In this thesis size-based approaches such as SS were employed to explore (i) what drives zooplankton size distribution and whether zooplanktivorous fish (top-down) or resource availability and environmental condition (bottom-up) determine zooplankton community SS, (ii) whether traditional midwater trawling or modern hydroacoustic methods more reliably represent fish SS, and (iii) coral reef fish community SS and habitat structural complexity and their relationship across site-specific anthropogenic stressors. By analysing long term data, I first found that neither top-down or bottom-up forces drove the zooplankton community size distribution. Zooplankton SS seem robust against predation effects but a sensitive indicator for lake-wide energy availability and transfer efficiency in the food web. Then I found that hydroacoustic methods reliably represent pelagic fish community SS, making it a great alternative to traditional and more invasive fish removal sampling methods. Finally, I discovered that coral reef fish SS slope and structural complexity of the reef exhibited a significant negative relationship on two of the examined reef sites which are least exposed to anthropogenic disturbances. A consistent pattern of fish SS and reef complexity was missing, indicating that other environmental factors may also impact the assessed parameters. Overall, my studies show the range of applications of SS to effectively answer universal questions from trophic interactions and the importance of habitat characteristics in a community to a methodological comparison of fish sampling methods. The high variability of SS behaviour and the influence of environmental conditions further underlines the importance to include data on a large temporal scale. Community information, such as taxonomic identity and consideration of species-specific feeding and habitats preferences, for example, are still beneficial in some cases to answer ecologically questions extensively.

[Truncated abstract] Kelp beds of South-Western Australia have high alpha (within habitat) diversity, through high species turnover at small spatial scales. The E. radiata canopy has a strong negative influence on the diversity of the understorey through intense interspecific competition for light. Literature suggests that when the competitively dominant species such as E. radiata are physically removed, diversity will increase, as less competitive species become more abundant. Apart from disturbance, evidence suggests that reef topography at the 1-10 m vertical scale also has an influence on the structure of the kelp beds, particularly in reference to relative abundance of canopy algae and species richness of the assemblage. In this thesis, I explore the role of algal assemblage recovery from physical disturbance to maintain high diversity. I also investigate the influence of reef structure (in terms of topography at the 1-10 m vertical scale) on assemblage recovery. This thesis provides a valuable functional explanation for the high diversity observed in South-Western algal assemblages. In addition, it explores the influence of reef topography which has received little attention to date . . . Overall, this thesis argues that the high alpha diversity in algal assemblages of South-Western Australia is due to local scale processes including disturbance and assemblage recovery which generate diversity by the creation of species rich gap states and by phase-shifts during the recovery process, creating a mosaic of different patch types. Assemblage recovery is composed of several processes, including survival of juvenile kelp sporophytes and canopy shading, added to macroalgal diversity through spatial and temporal variation in their outcomes. Reef topography contributed to algal diversity by influencing the processes associated with assemblage recovery through alteration of key physical variables including light levels and water motion.