Does upwelling intensity determine larval fish habitats in upwelling ecosystems? The case of Senegal and Mauritania

Abstract

European sardine (Sardina pilchardus) and round sardinella (Sardinella aurita) comprise two‐thirds of total landings of small pelagic fishes in the Canary Current Eastern Boundary Ecosystem (CCEBE). Their spawning habitat is the continental shelf where upwelling is responsible for high productivity. While upwelling intensity is predicted to change through ocean warming, the effects of upwelling intensity on larval fish habitat expansion is not well understood. Larval habitat characteristics of both species were investigated during different upwelling intensity regimes. Three surveys were carried out to sample fish larvae during cold (permanent upwelling) and warm (low upwelling) seasons along the southern coastal upwelling area of the CCEBE (13°–22.5°N). Sardina pilchardus larvae were observed in areas of strong upwelling during both seasons. Larval habitat expansion was restricted from 22.5°N to 17.5°N during cold seasons and to 22.5°N during the warm season. Sardinella aurita larvae were observed from 13°N to 15°N during cold seasons and 16–21°N in the warm season under low upwelling conditions. Generalized additive models predicted upwelling intensity driven larval fish abundance patterns. Observations and modeling revealed species‐specific spawning times and locations, that resulted in a niche partitioning allowing species' co‐existence. Alterations in upwelling intensity may have drastic effects on the spawning behavior, larval survival, and probably recruitment success of a species. The results enable insights into the spawning behavior of major small pelagic fish species in the CCEBE. Understanding biological responses to physical variability are essential in managing marine resources under changing climate conditions.

Mesopredatory fishes from the subtropical upwelling region off NW-Africa characterised by their parasite fauna

“…Species richness in EBUEs is considered to be low in comparison to other tropical marine ecosystems ( Angel, 1993 ; Sakko, 1998 ). Strong seasonal upwelling activities and circulation of cold, nutrient rich water do not only require adaption of the host organisms (e.g., fish spawning and recruitment), but also the parasite fauna ( Carvalho & Luque, 2011 ; Cropper, Hanna & Bigg, 2014 ; Sambe et al, 2016 ; Tiedemann & Brehmer, 2017 ; Tiedemann et al., 2017 ). As a consequence, the parasite diversity found in EBUEs should be lower than in other coastal ecosystems.…”

Implikasi Upwelling terhadap Produktivitas Perikanan Laut di Indonesia dan Upaya Konservasinya

“…Hal yang mengkhawatirkan ialah apabila upwelling terjadi dalam kondisi yang tidak ideal, yaitu dengan intensitas terlalu lemah atau terlalu kuat. Akibatnya, proses rekrutmen sumber daya ikan juga agak terganggu (Tiedemann et al, 2017). Hal ini dapat terjadi sebagai dampak dari adanya pemanasan global dan perubahan iklim.…”

Spatial shift of small pelagic fish in North-West Africa related to long-term intense warming and local decrease in marine productivity

“…This challenge is particularly pronounced in developing countries, where the association of limited data availability and uncertainties regarding future climate change scenarios and their impacts adds complexity. This uncertainty is especially acute in marine ecosystems and sheries, including the highly productive Eastern Boundary Upwelling Systems (Auger et al, 2016;Tiedemann et al, 2017;Sumaila et al, 2011). Small pelagic sh resources are typically distributed among several countries.…”