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Article

A Major Ecosystem Shift in Coastal East African Waters During the 1997/98 Super El Niño as Detected Using Remote Sensing Data

1
National Oceanography Centre, Southampton SO14 3ZH, UK
2
Department of Biology, National and Kapodistrian University of Athens, 15764 Athens, Greece
3
Plymouth Marine Laboratory, Plymouth PL1 3DH, UK
4
Coastal Oceans Research and Development–Indian Ocean (CORDIO East Africa), 9 Kibaki Flats, Mombasa P.O. Box 10135-80101, Kenya
5
Department of Environment and Geography, University of York, Heslington, York YO10 5NG, UK
6
Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown 6140, South Africa
7
Nelson Mandela University, Ocean Science and Marine Food Security, Port Elizabeth 6001, South Africa
8
South African Environmental Observation Network, Egagasini Node, Cape Town 8012, South Africa
9
Institute of Marine Sciences, Zanzibar P.O Box 668, Tanzania
*
Author to whom correspondence should be addressed.
Authors contributed equally to this review.
Remote Sens. 2020, 12(19), 3127; https://doi.org/10.3390/rs12193127
Received: 14 August 2020 / Revised: 18 September 2020 / Accepted: 22 September 2020 / Published: 23 September 2020
(This article belongs to the Special Issue Remote Sensing for Fisheries and Aquaculture)
Under the impact of natural and anthropogenic climate variability, upwelling systems are known to change their properties leading to associated regime shifts in marine ecosystems. These often impact commercial fisheries and societies dependent on them. In a region where in situ hydrographic and biological marine data are scarce, this study uses a combination of remote sensing and ocean modelling to show how a stable seasonal upwelling off the Kenyan coast shifted into the territorial waters of neighboring Tanzania under the influence of the unique 1997/98 El Niño and positive Indian Ocean Dipole event. The formation of an anticyclonic gyre adjacent to the Kenyan/Tanzanian coast led to a reorganization of the surface currents and caused the southward migration of the Somali–Zanzibar confluence zone and is attributed to anomalous wind stress curl over the central Indian Ocean. This caused the lowest observed chlorophyll-a over the North Kenya banks (Kenya), while it reached its historical maximum off Dar Es Salaam (Tanzanian waters). We demonstrate that this situation is specific to the 1997/98 El Niño when compared with other the super El-Niño events of 1972,73, 1982–83 and 2015–16. Despite the lack of available fishery data in the region, the local ecosystem changes that the shift of this upwelling may have caused are discussed based on the literature. The likely negative impacts on local fish stocks in Kenya, affecting fishers’ livelihoods and food security, and the temporary increase in pelagic fishery species’ productivity in Tanzania are highlighted. Finally, we discuss how satellite observations may assist fisheries management bodies to anticipate low productivity periods, and mitigate their potentially negative economic impacts. View Full-Text
Keywords: upwelling; super El-Niño; ecosystem changes; remote sensing; modelling; western Indian Ocean; ocean currents upwelling; super El-Niño; ecosystem changes; remote sensing; modelling; western Indian Ocean; ocean currents
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MDPI and ACS Style

Jacobs, Z.L.; Jebri, F.; Srokosz, M.; Raitsos, D.E.; Painter, S.C.; Nencioli, F.; Osuka, K.; Samoilys, M.; Sauer, W.; Roberts, M.; Taylor, S.F.W.; Scott, L.; Kizenga, H.; Popova, E. A Major Ecosystem Shift in Coastal East African Waters During the 1997/98 Super El Niño as Detected Using Remote Sensing Data. Remote Sens. 2020, 12, 3127. https://doi.org/10.3390/rs12193127

AMA Style

Jacobs ZL, Jebri F, Srokosz M, Raitsos DE, Painter SC, Nencioli F, Osuka K, Samoilys M, Sauer W, Roberts M, Taylor SFW, Scott L, Kizenga H, Popova E. A Major Ecosystem Shift in Coastal East African Waters During the 1997/98 Super El Niño as Detected Using Remote Sensing Data. Remote Sensing. 2020; 12(19):3127. https://doi.org/10.3390/rs12193127

Chicago/Turabian Style

Jacobs, Zoe L., Fatma Jebri, Meric Srokosz, Dionysios E. Raitsos, Stuart C. Painter, Francesco Nencioli, Kennedy Osuka, Melita Samoilys, Warwick Sauer, Michael Roberts, Sarah F.W. Taylor, Lucy Scott, Hellen Kizenga, and Ekaterina Popova. 2020. "A Major Ecosystem Shift in Coastal East African Waters During the 1997/98 Super El Niño as Detected Using Remote Sensing Data" Remote Sensing 12, no. 19: 3127. https://doi.org/10.3390/rs12193127

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