Contrasting styles of the Holocene highstand sedimentation and sediment dispersal systems in the northern shelf of the Gulf of Cadiz

Lobo, F. J.; Sánchez, Ricardo; González, Ramón; Dias, João Alveirinho; Hernández-Molina, F. Javier; Fernández-Salas, L.M.; Río, Víctor Díaz del; Mendes, Isabel

doi:10.1016/j.csr.2003.12.003

Cited by 62 publications

(27 citation statements)

References 41 publications

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“…Suspended materials released from them are presumably rapidly transported to the southeast, the main prevailing ocean circulation in this region García-Lafuente et al, 2006). Hence, this study supports the previous suggestions that the Guadalquivir is the main source of Holocene sediments (Lobo et al, 2004) and probably, dissolved organic material and nutrients (Ribas-Ribas et al, 2011) to the E. Gulf of Cadiz.…”

Section: Spatio-temporal Variability and Driving Mechanismssupporting

confidence: 80%

The influence of the Guadalquivir river on spatio-temporal variability in the pelagic ecosystem of the eastern Gulf of Cádiz

Caballero

Morris²,

Pietro³

et al. 2014

Medit. Mar. Sci.

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This study examines the spatio-temporal variability of the turbidity plume and phytoplankton biomass (in terms of chlorophyll) in the marine region influenced by the Guadalquivir estuary using ocean colour images over a period of 11 years (2003-2013). The area of the turbidity plume was calculated using water-leaving radiance at 555 nm (nLw555). Climatologic and monthly averages showed recurrent high nLw555 levels in winter and high chlorophyll in spring. Similar variability was confirmed by Empirical Orthogonal Function (EOF) analysis of 8-day composite images, illustrating the existence of different regions with similar behavior. The first EOF mode explained 60.7% and 31% of the variability in nLw555 and chlorophyll, respectively, and was associated with enhanced Total Suspended Solids (TSS) in autumn-winter and phytoplankton blooms in winter-spring periods. The results confirmed that the development of the turbidity plume and subsequent phytoplankton blooms were strongly regulated by river discharges and precipitation. Indeed, interannual variation in nLw555 was consistent with changes in the large-scale climate index, the North Atlantic Oscillation, a proxy for regional rainfall patterns. In the case of phytoplankton biomass, the second EOF mode revealed differentiation between offshore and nearshore areas, the latter characterized by delayed development of phytoplankton bloom due to light limitation by high TSS. This suggests that the stability of the water column, via its influence on phytoplankton light-limitation, influenced also the timing and magnitude of phytoplankton bloom events. The dynamic of the Guadalquivir estuary turbidity plume is a crucial factor for the pelagic ecosystem of the Eastern Gulf of Cadiz, governing phytoplankton productivity.

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Section: Spatio-temporal Variability and Driving Mechanismssupporting

confidence: 80%

The influence of the Guadalquivir river on spatio-temporal variability in the pelagic ecosystem of the eastern Gulf of Cádiz

Caballero

Morris²,

Pietro³

et al. 2014

Medit. Mar. Sci.

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“…1). In particular, the northeastern shelf of the gulf receives freshwater inputs from several rivers (such as Guadiana, Guadalquivir, Tinto, and Odiel), and its circulation is mainly controlled by the North Atlantic Surface Water (NASW), which flows towards the east and southeast to the Strait of Gibraltar, as well as by an intermittent counter current system that seems to be closely linked to the wind regime (Lobo et al 2004). Phytoplankton distribution is tightly coupled to meteorological and hydrodynamic conditions in this sector of the gulf, which presents the highest primary production within the basin .…”

Section: Methodsmentioning

confidence: 99%

Benthic nutrient recycling on the northeastern shelf of the Gulf of Cádiz (SW Iberian Peninsula)

Ferrón

Alonso-Pérez²,

Anfuso³

et al. 2009

Mar. Ecol. Prog. Ser.

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Benthic fluxes of nutrients and dissolved nitrous oxide (N 2 O) were determined by benthic chamber incubations in 2 regions on the northeastern near-shore continental shelf of the Gulf of Cádiz (depth range: 8 to 34 m), one off the Guadalquivir River mouth and the other in the Bay of Cádiz and its neighboring shelf. In total, 25 in situ benthic chamber incubations were performed dur- , accounted on average for <1% of total inorganic nitrogen fluxes. The regeneration of NH 4 + and Si(OH) 4 was mainly influenced by organic carbon oxidation rates and bulk organic carbon in surface sediments, whereas HPO 4 2 -regeneration was mostly influenced by bottom water oxygen concentration and water depth. Denitrification was estimated to account for between 9 and 13% of organic matter remineralization and for a loss of between 57 and 67% of potentially recyclable nitrogen. Overall, benthic remineralization was estimated to degrade about 47% of overlying primary production, supplying about 15 and 12% of the phytoplankton N and P requirements, respectively. This highlights the importance of benthic organic matter remineralization on the biogeochemistry of the northeastern continental shelf of the Gulf of Cádiz.

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“…Three transgressive parasequences exposed across the inner to middle shelf were identified in high-resolution seismic profiles (Lobo et al, 2001). Highstand deposits occur on the inner shelf as a prodeltaic wedge and on the middle shelf as an extensive muddy belt Lobo et al, 2004;Nelson et al, 1999). Recent studies have characterized the geochemical, micropaleontological, and sedimentological properties of those highstand deposits (e.g.…”

Section: Study Areamentioning

confidence: 99%

Natural and human-induced Holocene paleoenvironmental changes on the Guadiana shelf (northern Gulf of Cadiz)

et al. 2012

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Three contrasting sedimentary environments on the continental shelf off the Guadiana River (northern Gulf of Cadiz) were integrated in a chronological framework and analysed in terms of sedimentology and benthic foraminiferal assemblages to understand the Holocene paleoenvironmental evolution. The analysed environments differ in terms of their depositional regimes and benthic foraminiferal assemblages. However, a dominant fluvial origin of the sand fraction was observed in all three environments. Holocene sedimentary processes were mainly controlled by natural (sea level changes and climate variations) and human-induced processes (e.g. deforestation, agriculture) along four evolutionary stages. The three older stages were mainly influenced by natural processes, such as sea level variations and fluvial inputs, whereas the most recent stage reflects a combination of climatic-and human-induced processes. A deepening of sedimentary environments related to a period of rapid sea level rise, strongly influenced by river discharges occurred from c. 11,500 to c. 10,000 cal. yr BP. A reduction in sediment export to the shelf, as a result of the continuous and rapid sea level rise and enhanced estuary infilling reflects the second stage, from c. 10,000 to c. 5000 cal. yr BP. The beginning of the third stage, from c. 5000 to c. 1500-1000 cal. yr BP, is marked by a sea-level slowdown and the relatively stable climate and environmental conditions. The fourth stage, from c. 1500-1000 cal. yr BP to Recent times, reflects the intensification of human-induced processes and climatic variability in the Guadiana River basin. This stage also reflects modern depositional conditions, with the formation of a proximal prodeltaic wedge and a distal muddy body.

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Contrasting styles of the Holocene highstand sedimentation and sediment dispersal systems in the northern shelf of the Gulf of Cadiz

Cited by 62 publications

References 41 publications

The influence of the Guadalquivir river on spatio-temporal variability in the pelagic ecosystem of the eastern Gulf of Cádiz

The influence of the Guadalquivir river on spatio-temporal variability in the pelagic ecosystem of the eastern Gulf of Cádiz

Benthic nutrient recycling on the northeastern shelf of the Gulf of Cádiz (SW Iberian Peninsula)

Natural and human-induced Holocene paleoenvironmental changes on the Guadiana shelf (northern Gulf of Cadiz)

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