Oceanography of the Cape Verde Basin and Mauritanian Slope Waters

Pelegrí, Josep Lluís; Peña-Izquierdo, Jesús; Machín, Francisco; Meiners, César; Presas-Navarro, C.

doi:10.1007/978-94-024-1023-5_3

Cited by 20 publications

(23 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…South of Cap Timiris (ca. 19 • 30 N), the PUC intensifies during summer/fall and remains at the subsurface during winter/spring (Pelegrí et al, 2017). The encountering of the northward-flowing MC-PUC system with the southward flowing currents in the Canary Basin leads to flow confluence at the CVFZ (Zenk et al, 1991) and the offshore water export visible as the giant Mauritanian chlorophyll filament (Gabric, 1993;Pelegrí et al, 2006Pelegrí et al, , 2017.…”

Section: Oceanographic Setting Of the Study Areamentioning

confidence: 99%

See 1 more Smart Citation

Flux variability of phyto- and zooplankton communities in the Mauritanian coastal upwelling between 2003 and 2008

et al. 2020

View full text Add to dashboard Cite

Abstract. Continuous multiyear records of sediment-trap-gained microorganism fluxes are scarce. Such studies are important to identify and to understand the main forcings behind seasonal and multiannual evolution of microorganism flux dynamics. Here, we assess the long-term flux variations and population dynamics of diatoms, coccolithophores, calcareous and organic dinoflagellate cysts, foraminifera and pteropods in the eastern boundary upwelling ecosystem of the Canary Current. A multiannual, continuous sediment trap experiment was conducted at the mooring site CBeu (Cap Blanc eutrophic; ∼20∘ N, 18∘ W; trap depth is ca. 1300 m) off Mauritania (northwest Africa), between June 2003 and March 2008. Throughout the study, the reasonably consistent good match of fluxes of microorganisms and bulk mass reflects the seasonal occurrence of the main upwelling season and relaxation and the contribution of microorganisms to mass flux off Mauritania. A clear successional pattern of microorganisms, i.e., primary producers followed by secondary producers, is not observed. High fluxes of diatoms, coccolithophores, organic dinoflagellate cysts, and planktonic foraminifera occur simultaneously. Peaks of calcareous dinoflagellate cysts and pteropods mostly occurred during intervals of upwelling relaxation. A striking feature of the temporal variability of population occurrences is the persistent pattern of seasonal groups contributions. Species of planktonic foraminifera, diatoms, and organic dinoflagellate cysts typical of coastal upwelling, as well as cooler-water planktonic foraminifera and the coccolithophore Gephyrocapsa oceanica, are abundant at times of intense upwelling (late winter through early summer). Planktonic foraminifera and calcareous dinoflagellate cysts are dominant in warm pelagic surface waters, and all pteropod taxa are more abundant in fall and winter when the water column stratifies. Similarly, coccolithophores of the upper and lower photic zones, together with Emiliania huxleyi, and organic dinoflagellate cysts dominate the assemblage during phases of upwelling relaxation and deeper layer mixing. A significant shift in the “regular” seasonal pattern of taxa relative contribution is observed between 2004 and 2006. Benthic diatoms strongly increased after fall 2005 and dominated the diatom assemblage during the main upwelling season. Additional evidence for a change in population dynamics is the short dominance of the coccolithophore Umbilicosphaera annulus, the occurrence of the pteropod Limacina bulimoides and the strong increase in the flux of calcareous dinoflagellate cysts, abundant in warm tropical oligotrophic waters south of the study area after fall 2005. Altogether, this suggests that pulses of southern waters were transported to the sampling site via the northward Mauritania Current. Our multiannual trap experiment provides a unique opportunity to characterize temporal patterns of variability that can be extrapolated to other eastern boundary upwelling ecosystems (EBUEs), which are experiencing or might experience similar future changes in their plankton community.

show abstract

Section: Oceanographic Setting Of the Study Areamentioning

confidence: 99%

“…A coastal countercurrent, the Poleward Undercurrent (PUC; Fig. 1), occurs mainly due to wind-driven offshore divergence (Pelegrí et al, 2017). North of Cap Blanc (ca.…”

Section: Oceanographic Setting Of the Study Areamentioning

confidence: 99%

Flux variability of phyto- and zooplankton communities in the Mauritanian coastal upwelling between 2003 and 2008

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Here we report on the long-term variability of the particle fluxes and composition at the coastal eutrophic CBeu site (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016) and the offshore mesotrophic CBmeso site (1988-2016; Figure 1), both located within the CC-EBUEs. We will focus on the record from the coastal upwelling at CBeu which is located close to the CVFS (Pelegrí et al, 2017;Zenk et al, 1991) and is influenced by the warm northward Mauritanian Current as well. CBeu is located in a highly dynamic coastal upwelling zone where carbon sinking in the water column and deposition to the seafloor is maximal, that is, at the slope depocenter.…”

Section: Biological Oceanographymentioning

confidence: 99%

“…Description of the study area. (a) Major currents systems in the Cape Verde Basin and the Cape Blanc filament area (Pelegrí et al, ) and the CBmeso and CBeu study sites. High dust supply is indicated by orange arrows.…”

Section: Introductionmentioning

confidence: 99%

“…Upwelling of cold and nutrient‐rich subsurface waters causes high biological productivity in the CC‐EBUEs although nutrient levels are rather low compared to the Peruvian upwelling (Summerhayes et al, ). The Cape Blanc area is situated north of the Cape Verde Frontal System (CVFS; Pelegrí et al, ; Zenk et al, ), which is a major open‐ocean boundary, separating tropical from subtropical water masses (Figure ). However, at the continental slope, a meridional exchange between both regions occurs with opposing along‐slope flows of the Mauritania Current (MC) and the poleward undercurrent (PUC; Figure ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Changes in the Dust‐Influenced Biological Carbon Pump in the Canary Current System: Implications From a Coastal and an Offshore Sediment Trap Record Off Cape Blanc, Mauritania

Fischer

Romero

Toby

et al. 2019

Global Biogeochemical Cycles

View full text Add to dashboard Cite

Long‐term data characterizing the oceans' biological carbon pump are essential for understanding impacts of climate variability on marine ecosystems. The “Bakun upwelling intensification hypothesis” suggests intensified coastal upwelling due to a greater land‐sea temperature gradient influenced by global warming. We present long time series of bathypelagic (approximately 1,200–3,600 m) particle fluxes from a coastal (CBeu: 2003–2016) and an offshore (CBmeso: 1988–2016) sediment trap setting located in the Canary Current upwelling. Organic carbon (Corg) and biogenic opal (BSi, diatoms) fluxes were twofold to threefold higher at the coastal upwelling site compared to the offshore site, respectively, and showed higher seasonality with flux maxima in spring. A relationship between winter and spring BSi fluxes to the North Atlantic Oscillation index was best expressed at the offshore site CBmeso. Lithogenic (dust) fluxes regularly peaked in winter when frequent low‐altitude dust storms and deposition occurred, decreasing offshore by about threefold. We obtained a high temporal match of short‐term peaks of BSi and dust fluxes in winter to spring at the inner site CBeu. We found synchronous flux variations at both sites and an anomalous year 2005, characterized by high BSi and Corg fluxes under a low North Atlantic Oscillation. Corg and BSi fluxes revealed a decreasing trend from 2006 to 2016 at the coastal site CBeu, pointing to coastal upwelling relaxation during the last two decades. The permanent offshore upwelling zone of the deflected Canary Current represented by the flux record of CBmeso showed no signs of increasing upwelling as well which contradicts the Bakun hypothesis.

show abstract

Changes to upper‐ocean ecosystems may directly impact abyssal scavenger communities

de Jonge,

Smith,

Sweetman

2024

Limnology & Oceanography

View full text Add to dashboard Cite

Human pressures are changing ocean environments, such as a shift from fish‐ to squid‐dominated ecosystems in overfished, poorly oxygenated environments. After death, carcasses of upper ocean fauna sink to the seafloor where they provide food for demersal scavengers. It is unclear how shifts in carcass type impact abyssal scavengers. We performed baited benthic camera lander deployments in the Cabo Verde Abyssal Basin to test how a shift from fish‐ to squid‐dominated carrion could modify abyssal scavenger ecology. At the fish bait, peak scavenger abundance was greater and occurred later for the majority of observed fauna. However, removal rates of squid bait were up to 10‐fold greater, and a significantly different community composition developed, favoring faster organisms with lower chemosensory thresholds. At the fish bait, slower organisms were less disadvantaged as the bait persisted for longer periods allowing the development of a more complex community and dense amphipod aggregations. The rapid squid consumption indicates that the accumulation of this type of food fall at the seafloor may not occur, preventing scientific observations necessary to estimate the importance of squid carrion to the biological C pump and deep‐sea food webs. As such, the flux of squid carrion to the seafloor is likely greater than currently recognized in this part of the Atlantic. The differences observed between bait types indicate how future changes in upper ocean ecosystems may impact abyssal scavengers and their ecosystem functions, including controlling seafloor biomass, regulating the behavior of benthic fauna, and contributing to nutrient cycling and energy transfer.

show abstract

Oceanography of the Cape Verde Basin and Mauritanian Slope Waters

Cited by 20 publications

References 31 publications

Flux variability of phyto- and zooplankton communities in the Mauritanian coastal upwelling between 2003 and 2008

Flux variability of phyto- and zooplankton communities in the Mauritanian coastal upwelling between 2003 and 2008

Changes in the Dust‐Influenced Biological Carbon Pump in the Canary Current System: Implications From a Coastal and an Offshore Sediment Trap Record Off Cape Blanc, Mauritania

Changes to upper‐ocean ecosystems may directly impact abyssal scavenger communities

Contact Info

Product

Resources

About