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| Sabarros, Philippe S.; Gremillet, David; Demarcq, Herve; Moseley, Christina; Pichegru, Lorien; Mullers, Ralf H. E.; Stenseth, Nils C.; Machu, Eric. |
| Oceanic structures such as mesoscale fronts may become hotspots of biological activity through concentration and enrichment processes. These fronts generally attract fish and may therefore be targeted by marine top-predators. In the southern Benguela upwelling system, such fronts might be used as environmental cues by foraging seabirds. In this study we analyzed high-frequency foraging tracks (GPS, 1 s sampling) of Cape gannets Morus capensis from two colonies located on the west and east coast of South Africa in relation to mesoscale fronts detected on daily high-resolution chlorophyll-a maps (MODIS, 1 km). We tested the association of (i) searching behavior and (ii) diving activity of foraging birds with mesoscale fronts. We found that Cape gannets shift... |
| Tipo: Text |
Palavras-chave: Seabird; Environmental cue; Behavioral shift; Area-restricted search; Feeding activity; Fractal landscape; Oceanographic fronts; Morus capensis; Southern Benguela; South Africa. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00236/34756/34575.pdf |
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| Jarre, Astrid; Marine Research Institute, University of Cape Town, South Africa; ajarre@gmail.com; Ragaller, Sven M.; Marine Research Institute, University of Cape Town, South Africa; sven.ragaller@gmail.com; Hutchings, Laurence; Marine Research Institute, University of Cape Town, South Africa; larry.hutchings@gmail.com. |
| South Africa's small pelagics fishery is currently the largest in volume and second largest in value in the southern Benguela. It exploits short-lived, small pelagic fishes such as anchovy (for reduction into fish meal and oil) and sardine (for reduction as well as human consumption through canned products), and to a lesser extent redeye round herring and mesopelagics, largely for reduction. We explore the recent history (1940s to present) of the social-ecological system around this fishery. The natural subsystem, at the scales of the ocean environment and the ecosystem, is characterized by high interannual and documented decadal-scale variability. We characterize the human social subsystem at the scales of the fishing industry, legislation, and west... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Anchovy; Coastal communities; Inshore fishery; Marine social-ecological systems; Purse seining; Rock lobster; Small pelagic fishery; South Africa; Southern Benguela; Sardine. |
| Ano: 2013 |
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| Veitch, Jennifer; Hermes, Juliet; Lamont, Tarron; Penven, Pierrick; Dufois, Francois. |
| The dynamics and seasonal variability of jet currents on the southern Benguela shelf-edge are investigated using a climatologically forced ROMS model. The jet is primarily forced by the intense horizontal gradients that exist across the southern Benguela shelf. These gradients are set up by nearshore cooling via the strongly seasonal upwelling regime and variable offshore warming by the advection of Agulhas waters. While the nearshore cooling is prevalent only during the spring and summer upwelling season, the offshore warming exists throughout the year. As a result intensified geostrophically adjusted currents exist throughout the year, particularly off the Cape Peninsula and Cape Columbine. However, the distinct shelf-edge jet features are most intense... |
| Tipo: Text |
Palavras-chave: Southern Benguela; Shelf-edge jet; Numerical model. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00403/51401/51976.pdf |
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