Resolving relationships between deep-sea benthic diversity and multi-scale topographic heterogeneity

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dc.contributor.authorDu Preez, Cherisse
dc.contributor.supervisorTunnicliffe, Verena
dc.date.accessioned2015-01-02T19:46:23Z
dc.date.available2015-11-22T12:22:05Z
dc.date.copyright2014en_US
dc.date.issued2015-01-02
dc.degree.departmentDepartment of Biology
dc.degree.levelDoctor of Philosophy Ph.D.en_US
dc.description.abstractResolving diversity patterns and their underlying drivers has application for both ecological theory and ocean management. Because seafloor characteristics are often used to assess bottom habitat, I examined the relationship between deep-sea benthic (bottom-living) diversity and multi-scale topographic heterogeneity. Most work occurred on the Canadian Pacific continental shelf at Learmonth Bank with additional sites in Strait of Georgia (BC) and Gulf of Maine (Atlantic shelf). High-resolution species distribution and seafloor data were annotated from remotely operated vehicle benthic imagery surveys while large-scale seafloor data were derived from multibeam sonar. New method development to address problems of current methods and to facilitate comparison among ecosystems is a major outcome. My new MiLS method (microtopographic laser scanning) can profile the deep seafloor at a resolution of ~1-2 cm with high accuracy and precision. I also developed a new ACR (arc-chord ratio) rugosity index as a measure of 3-D topographic heterogeneity that is simple, accurate and highly versatile. Model systems and scales vary among my studies but results consistently yield a positive relationship between diversity and topographic heterogeneity and identify bottom hydrodynamics as an important underlying driver. Rockfish Sebastes spp. associate with higher seafloor rugosity non-randomly and select for deep-sea corals and sponges over inert substrata alone. Data indicate that degradation of biogenic structures is a long-term detriment to rockfish species. Gorgonian coral- and sponge-dominant biotopes strongly associate with a single substratum type. These relationships were used to map coral and sponge distributions. This work, which collectively adds new information on the ecological relevance and distribution of corals and sponges, is pertinent to the conservation and management of fish stocks and vulnerable marine ecosystems. Epibenthic community variables abundance, richness, and Shannon diversity positively correlated with both the local microtopographic heterogeneity on a scale of 10 m2 and with the surrounding regional large-scale topographic heterogeneity on scales of 25 to 250,000 m2. Relationships were strongest between epibenthic community variables and the largest scale rugosity and were used to generate and test predictive diversity models. Where management strategies rely on surrogate measures in data-poor areas, mapping benthic diversity using ACR rugosity will provide good indicators. Although bottom hydrodynamics is consistently identified as an underlying driver of epibenthic patterns related to topographic heterogeneity, data suggest the nature of the relationship varies across spatial scales. At small scales, high topographic heterogeneity likely increases diversity by increasing the number of available niches (including hydrodynamic gradients; e.g., the abrupt vertical rugosity created by tall corals and sponges provides rockfish refuge from currents) while at large scales, high topographic heterogeneity increases local diversity less directly through distant hydraulic events that alter bottom flow hydrodynamics.en_US
dc.description.proquestcode0329en_US
dc.description.proquestcode0416en_US
dc.description.proquestcode0799en_US
dc.description.proquestemailcdupreez@uvic.caen_US
dc.description.scholarlevelGraduateen_US
dc.identifier.bibliographicCitationDu Preez, C. 2014. A new arc-chord ratio (ACR) rugosity index for quantifying three-dimensional landscape structural complexity. Landscape Ecology. doi: 10.1007/s10980-014-0118-8.en_US
dc.identifier.bibliographicCitationDu Preez, C. & V. Tunnicliffe. 2011. Shortspine thornyhead & rockfish (Scorpaenidae) distribution in response to substratum, biological structures, & trawling. Marine Ecology Progress Series 425:217-231.en_US
dc.identifier.bibliographicCitationDu Preez, C. & V. Tunnicliffe. 2012. A new video survey method of microtopographic laser scanning (MiLS) to measure small-scale seafloor bottom roughness. Limnology and Oceanography: Methods 10: 899-909.en_US
dc.identifier.bibliographicCitationDu Preez, C., J.W.F. Chu, & J. Rose. (In review) A scientist's guide to remotely operated vehicles (ROVs) for benthic imagery surveys. In Recent research studies on seabed structure & benthic biodiversity relationships in Canadian Marine habitats. Edited by P. Lawton and E. Edinger. Canadian Technical Report of Fisheries and Aquatic Sciences, XXXX.en_US
dc.identifier.bibliographicCitationDu Preez, C., J. Curtis, S.C. Davies, E. Clarke, & E.L. Fruh (In review) Cobb Seamount species inventory. Canadian Technical Report of Fisheries and Aquatic Sciences, XXXX.en_US
dc.identifier.bibliographicCitationEdinger, E., C. Du Preez, S. Leys, J.W.F. Chu, & M. Lacharitè (In review) Cold-water corals & sponges & their habitats in Canadian waters. In Recent research studies on seabed structure & benthic biodiversity relationships in Canadian Marine habitats. Edited by P. Lawton and E. Edinger. Canadian Technical Report of Fisheries and Aquatic Sciences, XXXX.en_US
dc.identifier.bibliographicCitationNeves, B., C. Du Preez, & E. Edinger. 2014. Mapping coral & sponge habitats on a shelf-depth environment using multibeam sonar & ROV video observations: Learmonth Bank, Northern British Columbia, Canada. Deep Sea Research II 99:169-183.en_US
dc.identifier.bibliographicCitationTunnicliffe, V. & C. Du Preez (In review) Notable offshore environments: hydrothermal vents & seamounts. In Recent research studies on seabed structure & benthic biodiversity relationships in Canadian Marine habitats. Edited by P. Lawton and E. Edinger. Canadian Technical Report of Fisheries and Aquatic Sciences, XXXX.en_US
dc.identifier.urihttp://hdl.handle.net/1828/5828
dc.languageEnglisheng
dc.language.isoenen_US
dc.rights.tempAvailable to the World Wide Weben_US
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/2.5/ca/*
dc.subjectDiversityen_US
dc.subjectBenthicen_US
dc.subjectHeterogeneityen_US
dc.subjectRugosityen_US
dc.subjectLandscape ecologyen_US
dc.subjectRoughnessen_US
dc.subjectRockfishen_US
dc.subjectCoralen_US
dc.subjectSpongeen_US
dc.subjectDeep-seaen_US
dc.subjectRemotely operated vehicleen_US
dc.subjectMultibeam bathymetryen_US
dc.subjectLearmonth Banken_US
dc.titleResolving relationships between deep-sea benthic diversity and multi-scale topographic heterogeneityen_US
dc.typeThesisen_US

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