Continental inputs of C, N, P and Si species to the Ría de Vigo (NW Spain)

Gago, Jesús; Álvarez‐Salgado, Xosé Antón; Nieto‐Cid, Mar; Brea, S.; Piedracoba, Sílvia

doi:10.1016/j.ecss.2005.05.008

Cited by 43 publications

(46 citation statements)

References 29 publications

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“…Extrapolation of nutrient measurements in partially mixed, estuarine waters of these rías to zero salinity (as a proxy for nutrient load in river waters) led to the conclusion of an increase in excess N from Ortigueira to Viveiro in a previous study (Xunta de Galicia 2009). The excess nutrients were attributed to increasing agricultural and urbanization pressures, but actual concentration values were typical of uncontaminated rivers in this region (Prego & Vergara 1998, Gago et al 2005). In the present study, ammonium and nitrite concentrations in rivers were quite low (0.2 µM nitrite and up to 4 µM ammonium) compared to values measured in rivers and estuaries with strong anthropogenic pressure (Paerl et al 2006, Castro et al 2007.…”

Section: Sources At Short Time Scalesmentioning

confidence: 97%

Continental and marine sources of organic matter and nitrogen for rías of northern Galicia (Spain)

Bode¹,

Varela²,

Prego³

2011

Mar. Ecol. Prog. Ser.

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Sources of organic matter and nitrogen to the rías of Ortigueira, O Barqueiro and Viveiro (Galicia, N Spain) were traced using stable carbon and nitrogen isotopes. Samples of water, seston, benthic organisms and sediments were collected in summer 2007 and 2008. Instantaneous sources were inferred from the concentrations and isotopic composition of seston, while averaged sources over longer time scales (months) were inferred from stable isotopes in macrophytes (Ascophyllum nodosum and Fucus vesiculosus) and mussels (Mytilus galloprovincialis). Dissolved nitrate, nitrite and ammonium concentrations in surface water were low in the estuarine zone and generally increased towards the river and the open sea in all rías. Nitrite and ammonium values were generally low, suggesting low importance of in situ nitrification and denitrification processes. The concentrations of ammonium, chlorophyll, and heavy nitrogen isotopes in seston were higher only in the main river of Viveiro, suggesting local pollution. Isotopic signatures and high nitrogen concentrations in seston discharged from the wastewater treatment plants indicated incomplete removal of nitrogen. However, taking into account water discharge fluxes and the isotopic composition of all compartments analysed, all rías shared similar biogeochemical and trophic diversity and showed a low impact of anthropogenic sources at both short and long time scales. Dominance of marine waters, low river flow, and small urban population sizes in the watershed all contribute to the maintenance of the relatively pristine status of northern Galician rías.

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Section: Sources At Short Time Scalesmentioning

confidence: 97%

Continental and marine sources of organic matter and nitrogen for rías of northern Galicia (Spain)

Bode¹,

Varela²,

Prego³

2011

Mar. Ecol. Prog. Ser.

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“…Input of continental runoff of particulate organic carbon (4.1 g C m -2 yr -1 ) represented only about 1.3 % of the NEM, of which 2.8 g C m -2 yr -1 derived from sewage treatment plants (Evans et al, 2011). If dissolved organic carbon (DOC) is also considered from the fluvial discharges, the input of continental runoff will reach 2.3% (Gago et al, 2005). Carbon extracted from mussel harvest (8.9 g C m -2 yr -1 ) represented 89 % of the total annual harvest in the Ría de Vigo, followed by wild catch of fishes (0.8 g C m -2 yr -1 ) and shellfishing (0.4 g C m -2 yr -1 ).…”

Section: Nem: Importance Of Benthic Fluxes Mussel Culture and Fisheriesmentioning

confidence: 99%

Benthic fluxes, net ecosystem metabolism and seafood harvest: Completing the organic carbon balance in the Ría de Vigo (NW Spain)

Alonso-Pérez

Zúñiga

Arbones

et al. 2015

Estuarine, Coastal and Shelf Science

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Simultaneous direct measurements of primary production, pelagic and benthic respiration and vertical fluxes allowed, for the first time, the evaluation of the carbon metabolism in the Ría de Vigo (NW Spain) on seasonal and annual scales. With this aim, a total of 16 oceanographic cruises covering the main oceanographic conditions were carried out between April 2004 and January 2005. In addition, a 2D carbon budget, including extraction from mussel culture and fisheries activities, is proposed.The pelagic system was net autotrophic during the spring and summer periods and autotrophic or almost in balance during autumn and winter. Vertical fluxes of organic carbon were higher than net community production (NCP) during autumn and winter periods, probably due to resuspension processes and inputs of organic matter from continental runoff. Benthic mineralization is an important process in the Ría de Vigo, which gains significance during autumn and winter when benthic respiration accounts for 40% and 45% of the total respiration, respectively. The Ría de Vigo is net autotrophic on annual basis (317 ± 113 g C m -2 yr -1 ) even though the benthic metabolism reduces the NCP by 23%. Total annual carbon seafood harvest amounted 3% of the net ecosystem metabolism and it is dominated by mussel culture (89%).However, based on mean energy transfer efficiency between trophic levels of 10%, it is estimated that mussel culture and reported fish catches require up to 38% of the NCP.The organic carbon produced in situ at the Ría de Vigo and available for export to the adjacent shelf or to be buried in the sediment represents ¼ of the gross primary production and it is favoured during summer upwelling.3 HighlightsAn annual carbon budget including benthic fluxes and seafood harvest is proposed.The Ría de Vigo is net autotrophic on annual basis (317 ± 113 g C m -2 yr -1 ).Benthic remineralization reduces the autotrophy of the system by 23 %.Mussel culture and fisheries require 38 % of the net community production.Shelf carbon export and sediment burial account for ¼ of the gross primary production.

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“…Once S Q , B Q , Z Q and M have been calculated for boxes A, B and C, the average net ecosystem production rates (NEP) of dissolved oxygen and nutrient salts between two consecutive surveys, X NEP (in mmol s -1 ), can be calculated from the corresponding mass balance equations: (Pérez et al, 1992;Prego et al, 1999;Gago et al, 2005). Averages values of R X for dissolved oxygen were calculated assuming saturation at the average river temperature in July and October 07.…”

Section: The 2-d Box Model: Estimation Of Net Ecosystem Production Ratesmentioning

confidence: 99%

“…a prevalence of nutrient mineralization over uptake, develop in the Rías Baixas in response to downwelling episodes (Moncoiffe et al, 2000;Pérez et al 2000;Gilcoto et al, 2001). The organic matter imported from the adjacent shelf by the reversed circulation supports the transient heterotrophy because the organic load of Galician rivers are very low, <1.5 mg C L -1 (Gago et al, 2005). On the contrary, the Ría de Ares-Betanzos remains autotrophic under these conditions.…”

Section: Nutrient Fertilization and Net Utilization Patternsmentioning

confidence: 99%

“…In the case of the Rías Baixas, continental runoff represents <4% of the inorganic nitrogen and <10% of the silicon during the upwelling season . On the contrary, Galician rivers are minor sources of organic nutrients to the rías (Gago et al, 2005). Apart from the reduced Qr/V ratio of the Rías Baixas (see previous section), it should also be considered that the average depth of the Rías Baixas (20 m) is almost twice than in the Ria de Ares-Betanzos (11 m), which results in a more extensive mineralization in the vertical and a concomitant reduction of the relative contribution of the rivers as nutrient sources.…”

Section: Nutrient Fertilization and Net Utilization Patternsmentioning

confidence: 99%

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Net ecosystem metabolism of a coastal embayment fertilised by upwelling and continental runoff

Villegas‐Ríos

Álvarez‐Salgado

Piedracoba

et al. 2011

Continental Shelf Research

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O 2 , N, P and Si net ecosystem metabolism of the Ría de Ares-Betanzos (NW Iberian upwelling system) was estimated during two 3-wk periods of contrasting summer downwelling and autumn upwelling conditions by means of a transient 2-D kinematic box model. The subtidal circulation was positive in both situations, although it was depressed during downwelling and enhanced during upwelling. Concurrently, the ría was fertilised mainly by shelf bottom waters, which introduced from 69% (under downwelling) to almost 100% (under upwelling) of the limiting N nutrients. The ría was an efficient nutrient trap: about 70% of the N nutrients that entered the embayment were retained under downwelling conditions (average flushing time, 9 days) and about 50% under upwelling conditions (average flushing time 3 days). Although the trapping efficiency was lower, the net ecosystem production (NEP) was much higher under upwelling (from 1.0 ± 0.3 to 1.5 ± 0.4 g C m -2 d -1 ), than under downwelling favourable winds (from 0.2 ± 0.1 to 0.3 ± 0.1 g C m -2 ). The stoichiometry of NEP suggests that P and N compounds recycled faster than C compounds, specially in the inner segment of the ría. The net degree of silification was twice in the inner than in the outer segment of the ría.

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Continental inputs of C, N, P and Si species to the Ría de Vigo (NW Spain)

Cited by 43 publications

References 29 publications

Continental and marine sources of organic matter and nitrogen for rías of northern Galicia (Spain)

Continental and marine sources of organic matter and nitrogen for rías of northern Galicia (Spain)

Benthic fluxes, net ecosystem metabolism and seafood harvest: Completing the organic carbon balance in the Ría de Vigo (NW Spain)

Net ecosystem metabolism of a coastal embayment fertilised by upwelling and continental runoff

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