Browsing by Author "Karenyi, Natasha"

Now showing 1 - 8 of 8
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    Advancing Marine Ecosystem Based Management at the Science Policy Society Interface
    (2023) Sink, Kerry J; van der Bank, Megan G; Atkinson, Lara J; Karenyi, Natasha; Skein, Lisa; Adams, Luther; Subramoney, Avril-Castelle; McQuaid, Kirsty; Morgera, Elisa; Sloterdijk, Hans; Dunga, Loyiso; Shannon, Lynne; Rodrigues, João G; Sousa Pinto, Isabel
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    Defining seascapes for marine unconsolidated shelf sediments in an eastern boundary upwelling region: The southern Benguela as a case study
    (Estuarine, Coastal and Shelf Science, 2016) Karenyi, Natasha; Nel, Ronel
    Marine unconsolidated sediment habitats, the largest benthic ecosystem, are considered physically controlled ecosystems driven by a number of local physical processes. Depth and sediment type are recognised key drivers of these ecosystems. Seascape (i.e., marine landscape) habitat classifications are based solely on consistent geophysical features and provide an opportunity to define unconsolidated sediment habitats based on processes which may vary in distribution through space and time. This paper aimed to classify unconsolidated sediment seascapes and explore their diversity in an eastern boundary upwelling region at the macro-scale, using the South African west coast as a case study. Physical variables such as sediment grain size, depth and upwelling-related variables (i.e., maximum chlorophyll concentration, austral summer bottom oxygen concentration and sediment organic carbon content) were included in the analyses. These variables were directly measured through sampling, or collated from existing databases and the literature. These data were analysed using multivariate Cluster, Principal Components Ordination and SIMPER analyses (in PRIMER 6 + with PERMANOVA add-in package). There were four main findings; (i) eight seascapes were identified for the South African west coast based on depth, slope, sediment grain size and upwelling-related variables, (ii) three depth zones were distinguished (inner, middle and outer shelf), (iii) seascape diversity in the inner and middle shelves was greater than the outer shelf, and (iv) upwelling-related variables were responsible for the habitat diversity in both inner and middle shelves. This research demonstrates that the inclusion of productivity and its related variables, such as hypoxia and sedimentary organic carbon, in seascape classifications will enhance the ability to distinguish seascapes on continental shelves, where productivity is most variable.
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    Imperfect detection distorts depth-related trends in marine macrofaunal species richness
    (2018-10-01) Karenyi, Natasha; Nel, Ronel; Clark, Alan; Altwegg, Res
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    Iterative mapping of marine ecosystems for spatial status assessment, prioritization, and decision support
    (2023-03-31) Harris, Linda R.; Karenyi, Natasha; Porter, Sean; Kirkman, Stephen; Pfaff, Maya; van Niekerk, Lara; Atkinson, Lara J.; Bernard, Anthony; Cawthra, Hayley; de Wet, Willem; Filander, Zoleka; Green, Andrew; Herbert, David; Holness, Stephen; Lamberth, Stephen; Livingstone, Tamsyn; Lück-Vogel, Melanie; Mackay, Fiona; Makwela, Mapula; Palmer, Ryan; van Zyl, Wilhem
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    Progress in marine ecosystem classification, mapping and targets: Testing the boundaries
    (SANBI, 2015-06-25) Livingstone, Tamsyn
    This presentation summarises the approach taken in the mapping and classification of marine ecosystems in South Africa and the first work in setting quantitative biodiversity targets for unconsolidated marine ecosystem types. The inaccessible, three dimensional, dynamic ocean environment poses many challenges which have been addressed through a range of approaches including biophysical seascape and biotope classifications, research to understand marine biodiversity surrogates, citizen science to map reefs and the use of species area curves to develop the first local biodiversity targets. The data-informed, expert-derived classification and map used in 2011 was reasonably well supported since fish, macrofauna and eipfauna data showed support for the divisions 29 involved and yielded better results than a purely physical data based approach. Progress since 2012 is reviewed and proposed methods, data sources and research opportunities to advance this work are identified. These include new approaches in habitat mapping, testing surrogacy through collaborative research cruises, co-operative work with offshore industries, and inclusion of data from the fisheries and petroleum government agencies. Priority habitat types for further work are discussed.
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    South African National Biodiversity Assessment 2018 Technical Report Volume 4: Marine Realm. South African National Biodiversity Institute
    (SANBI, 2019-09-29) Harris, Linda; Atkinson, Lara; Kirkman, Stephen; Karenyi, Natasha