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Title: Benthic habitats of the extended Faial Island shelf and their relationship to geologic, oceanographic and infralittoral biologic features
Author: Tempera, Fernando
ISNI:       0000 0004 2717 705X
Awarding Body: University of St Andrews
Current Institution: University of St Andrews
Date of Award: 2009
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This thesis presents a new template for multidisciplinary habitat mapping that combines the analyses of seafloor geomorphology, oceanographic proxies and modelling of associated biologic features. High resolution swath bathymetry of the Faial and western Pico shelves is used to present the first state-of-the-art geomorphologic assessment of submerged island shelves in the Azores. Solid seafloor structures are described in previously unreported detail together with associated volcanic, tectonic and erosion processes. The large sedimentary expanses identified in the area are also investigated and the large bedforms identified are discussed in view of new data on the local hydrodynamic conditions. Coarse-sediment zones of types hitherto unreported for volcanic island shelves are described using swath data and in situ imagery together with sub-bottom profiles and grainsize information. The hydrodynamic and geological processes producing these features are discussed. New oceanographic information extracted from satellite imagery is presented including yearly and seasonal sea surface temperature and chlorophyll-a concentration fields. These are used as proxies to understand the spatio-temporal variability of water temperature and primary productivity in the immediate island vicinity. The patterns observed are discussed, including onshore-offshore gradients and the prevalence of colder/more productive waters in the Faial-Pico passage and shelf areas in general. Furthermore, oceanographic proxies for swell exposure and tidal currents are derived from GIS analyses and shallow-water hydrographic modelling. Finally, environmental variables that potentially regulate the distribution of benthic organisms (seafloor nature, depth, slope, sea surface temperature, chlorophyll-a concentration, swell exposure and maximum tidal currents) are brought together and used to develop innovative statistical models of the distribution of six macroalgae taxa dominant in the infralittoral (articulated Corallinaceae, Codium elisabethae, Dictyota spp., Halopteris filicina, Padina pavonica and Zonaria tournefortii). Predictive distributions of these macroalgae are spatialized around Faial island using ordered logistic regression equations and raster fields of the explanatory variables found to be statistically significant. This new approach represents a potentially highly significant step forward in modelling benthic communities not only in the Azores but also in other oceanic island shelves where the management of benthic species and biotopes is critical to preserve ecosystem health.
Supervisor: Bates, Richard Sponsor: Fundação para a Ciência e Tecnologia ; Programa Operacional Ciência e Inovação 2010 ; Structural Funds of the European Union ; Governo da República Portuguesa ; Departamento de Oceanografia e Pescas da Universidade dos Açores
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Faial and Pico islands ; Azores ; Volcanic island shelves ; Multibeam ; Geomorphology ; Tectonic faults ; Lava flows ; Boulder fields basin ; Submerged volcanic cones ; Cliff palaeo-shorelines ; Large bedforms ; Impinging currents ; Rippled scour depressions ; Sorted bedforms ; Sea surface temperature ; Chlorophyll-a ; Spatio-temporal variability ; Infralittoral dominant macroalgae ; Abundance ; Statistical models ; Predictive distribution maps ; GC87.2A86T4 ; Ocean bottom--North Atlantic Ocean ; Benthos--North Atlantic Ocean ; Submarine geology--Azores