Mariana Ribas-Ribas | Carl von Ossietzky University of Oldenburg (original) (raw)

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Papers by Mariana Ribas-Ribas

Deep Sea Research Part II: Topical Studies in Oceanography, 2016

Biogeosciences Discussions, 2014

ABSTRACT We present here a high resolution surface water pH dataset obtained in the Northwest Eur... more ABSTRACT We present here a high resolution surface water pH dataset obtained in the Northwest European shelf seas in summer 2011. This is the first time that pH has been measured at such a high spatial resolution (10 measurements h-1) in this region. The aim of our paper is to investigate the carbonate chemistry dynamics of the surface water using pH and ancillary data. The main processes controlling the pH distribution along the ship's transect, and their relative importance, were determined using a statistical approach. The study highlights the impact of biological activity, temperature and riverine inputs on the carbonate chemistry dynamics of the shelf seas surface water. For this summer cruise, the biological activity formed the main control of the pH distribution along the cruise transect. Variations in chlorophyll and nutrients explained 29% of the pH variance along the full transect and as much as 68% in the northern part of the transect. In contrast, the temperature distribution explained ca. 50% of the pH variation in the Skagerrak region. Riverine inputs were evidenced by high dissolved organic carbon (DOC) levels in the Strait of Moyle (northern Irish Sea) and the southern North Sea with consequent remineralisation processes and a reduction in pH. The DOC distribution described 15% of the pH variance along the full transect. This study highlights the high spatial variability of the surface water pH in shelf seawaters where a range of processes simultaneously impacts the carbonate chemistry.

Scientia Marina

Four surveys (Jun'06 and Nov'06; Feb'07 and May'07) were carried out on the north... more Four surveys (Jun'06 and Nov'06; Feb'07 and May'07) were carried out on the northeastern shelf of the Gulf of Cadiz (southwest Iberian Peninsula) to relate the spatio-temporal distribution of the carbon cycle parameters (dissolved inorganic carbon and dissolved organic carbon) to picophytoplankton biomass and community composition. In addition, the net ecosystem production and the picophytoplankton contribution to the air-sea CO2 exchange process were investigated. The results showed that chlorophyll-a, carbon cycle parameters and picophytoplankton composition showed large seasonality, and the Guadalquivir Estuary plays an important role in the contribution of nutrient and suspended particular material over the year. Regarding picophytoplankton composition, the flow cytometry analysis demonstrated that Prochlorococcus and Synechococcus were the main populations in the studied area and their temporal and spatial distributions were complementary: the Prochlorococcus po...

Four carbonate system variables were measured in surface waters during a cruise aimed at investig... more Four carbonate system variables were measured in surface waters during a cruise aimed at investigating ocean acidification impacts traversing northwestern European shelf seas in the summer of 2011. High-resolution surface water data were collected for partial pressure of carbon dioxide (pCO 2 ; using two independent instruments) and pH using the total pH scale (pH T ), in addition to discrete measurements of total alkalinity and dissolved inorganic carbon. We thus overdetermined the carbonate system (four measured variables, two degrees of freedom), which allowed us to evaluate the level of agreement between the variables on a cruise whose main aim was not intercomparison, and thus where conditions were more representative of normal working conditions. Calculations of carbonate system variables from other measurements generally compared well with direct observations of the same variables (Pearson's correlation coefficient always greater than or equal to 0.94; mean residuals were similar to the respective accuracies of the measurements). We therefore conclude that four of the independent data sets of carbonate chemistry variables were of high quality. A diurnal cycle with a maximum amplitude of 41 µatm was observed in the difference between the pCO 2 values obtained by the two independent analytical pCO 2 systems, and this was partly attributed to irregular seawater flows to the equilibrator and partly to biological activity inside the seawater supply and one of the equilibrators. We discuss how these issues can be addressed to improve carbonate chemistry data quality on future research cruises.

Scientia Marina, 2013

were carried out on the northeastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to ... more were carried out on the northeastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to relate the spatio-temporal distribution of the carbon cycle parameters (dissolved inorganic carbon and dissolved organic carbon) to picophytoplankton biomass and community composition. In addition, the net ecosystem production and the picophytoplankton contribution to the air-sea CO 2 exchange process were investigated. The results showed that chlorophyll-a, carbon cycle parameters and picophytoplankton composition showed large seasonality, and the Guadalquivir Estuary plays an important role in the contribution of nutrient and suspended particular material over the year. Regarding picophytoplankton composition, the flow cytometry analysis demonstrated that Prochlorococcus and Synechococcus were the main populations in the studied area and their temporal and spatial distributions were complementary: the Prochlorococcus population showed its maximum concentration in May'07 and Jun'06 and in the surface oceanic water, whereas the Synechococcus population was at its maximum during Feb'07 and Nov'06, and off the Guadalquivir Estuary and Bay of Cádiz. In addition, a relationship between the studied parameters and the fugacity of CO 2 was also observed, suggesting that primary production is an important factor in the regulation of this parameter in the studied area. The calculated carbon budget showed that the area acts as a carbon sink on an annual basis.

Marine Chemistry, 2011

were carried out in the north eastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to... more were carried out in the north eastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to investigate the dynamics of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in a coastal area affected mainly by river input, but also by primary production/respiration, resuspension from the sediments, and mixing. In the period of the present study, DOC values ranged from 42 to 198 μM, while DON ranged from 0 to 20 μM. The seasonal variations showed high mean surface concentrations of DOC (106.2 ± 25.6 μM-C) and DON (8.6 ± 3.1 μM-N) in May, shifting to low DOC (89.1 ± 26.4 μM-C) and DON (4.2 ± 2.8 μM-N) in February. In spring, DOC and DON released by phytoplankton are likely to be the most significant source of organic matter. Low DOC and DON concentrations during winter are probably due to the uptake of DOC and DON by bacteria and to the strong mixing of the water column. The spatial variations showed the highest mean concentrations of dissolved organic matter (DOM) in the lower part of the Guadalquivir Estuary and the lowest mean concentrations of DOM in the bottom water of the oceanic zone. The very high mean DOC and DON concentrations measured off the Guadalquivir Estuary may be due to river input and/or re-suspension of the organic matter from the bottom sediments. The very low mean DOC and DON concentrations measured in the bottom water of the continental shelf may be due to mineralization and a surplus of more refractory organic carbon.

Estuarine, Coastal and Shelf Science, 2011

The role of coastal lagoons and estuaries as sources or sinks of inorganic carbon in upwelling ar... more The role of coastal lagoons and estuaries as sources or sinks of inorganic carbon in upwelling areas has not been fully understood. During the months of MayeJuly, 2005, we studied the dissolved inorganic carbon system in a coastal lagoon of northwestern Mexico during the strongest period of upwelling events. Along the bay, different scenarios were observed for the distributions of pH, dissolved inorganic carbon (DIC) and apparent oxygen utilization (AOU) as a result of different combinations of upwelling intensity and tidal amplitude. DIC concentrations in the outer part of the bay were controlled by mixing processes. At the inner part of the bay DIC was as low as 1800 mmol kg À1 , most likely due to high water residence times and seagrass CO 2 uptake. It is estimated that 85% of San Quintín Bay, at the oceanic end, acted as a source of CO 2 to the atmosphere due to the inflow of CO 2 -rich upwelled waters from the neighboring ocean with high positive fluxes higher than 30 mmol C m À2 d À1 . In contrast, there was a net uptake of CO 2 and HCO 3 À by the seagrass bed Zostera marina in the inner part of the bay, so the pCO 2 in this zone was below the equilibrium value and slightly negative CO 2 fluxes of À6 mmol C m À2 d À1 . Our positive NEP and DDIC values indicate that Bahía San Quintín was a net autotrophic system during the upwelling season during 2005.

Continental Shelf Research, 2011

There is scatter information of the inorganic carbon system in the coastal zones and it is import... more There is scatter information of the inorganic carbon system in the coastal zones and it is important to increment our knowledge and understand the global carbon cycle. We investigated the distribution of inorganic carbon system parameters and its controls in the coastal waters of the north eastern shelf of the Gulf of Cá diz (GoC) during four cruises that took place . The objectives of this study are: (1) to describe the spatio-temporal distribution of inorganic carbon system parameters in waters of the north eastern shelf of the GoC using four cruises, each undertaken in one of the four seasons, (2) to calculate net ecosystem production (NEP) and to examine factors controlling these distributions. The distribution of inorganic carbon system parameters in the north eastern shelf of the Gulf of Cá diz showed temporal and spatial variability. River input, mixing, primary production, respiration, CO 2 air-sea exchange, and remineralization were factors that controlled such distributions. The coastal zone of the GoC is autotrophic on an annual scale at a rate of 1.0 mmol m À 2 d À 1 . Further measurements are needed it to improve the NEP calculation and to evaluated to intra-annual variability.

Deep Sea Research Part II: Topical Studies in Oceanography, 2016

Deep Sea Research Part II: Topical Studies in Oceanography, 2016

Biogeosciences Discussions, 2014

ABSTRACT We present here a high resolution surface water pH dataset obtained in the Northwest Eur... more ABSTRACT We present here a high resolution surface water pH dataset obtained in the Northwest European shelf seas in summer 2011. This is the first time that pH has been measured at such a high spatial resolution (10 measurements h-1) in this region. The aim of our paper is to investigate the carbonate chemistry dynamics of the surface water using pH and ancillary data. The main processes controlling the pH distribution along the ship's transect, and their relative importance, were determined using a statistical approach. The study highlights the impact of biological activity, temperature and riverine inputs on the carbonate chemistry dynamics of the shelf seas surface water. For this summer cruise, the biological activity formed the main control of the pH distribution along the cruise transect. Variations in chlorophyll and nutrients explained 29% of the pH variance along the full transect and as much as 68% in the northern part of the transect. In contrast, the temperature distribution explained ca. 50% of the pH variation in the Skagerrak region. Riverine inputs were evidenced by high dissolved organic carbon (DOC) levels in the Strait of Moyle (northern Irish Sea) and the southern North Sea with consequent remineralisation processes and a reduction in pH. The DOC distribution described 15% of the pH variance along the full transect. This study highlights the high spatial variability of the surface water pH in shelf seawaters where a range of processes simultaneously impacts the carbonate chemistry.

Scientia Marina

Four surveys (Jun'06 and Nov'06; Feb'07 and May'07) were carried out on the north... more Four surveys (Jun'06 and Nov'06; Feb'07 and May'07) were carried out on the northeastern shelf of the Gulf of Cadiz (southwest Iberian Peninsula) to relate the spatio-temporal distribution of the carbon cycle parameters (dissolved inorganic carbon and dissolved organic carbon) to picophytoplankton biomass and community composition. In addition, the net ecosystem production and the picophytoplankton contribution to the air-sea CO2 exchange process were investigated. The results showed that chlorophyll-a, carbon cycle parameters and picophytoplankton composition showed large seasonality, and the Guadalquivir Estuary plays an important role in the contribution of nutrient and suspended particular material over the year. Regarding picophytoplankton composition, the flow cytometry analysis demonstrated that Prochlorococcus and Synechococcus were the main populations in the studied area and their temporal and spatial distributions were complementary: the Prochlorococcus po...

Four carbonate system variables were measured in surface waters during a cruise aimed at investig... more Four carbonate system variables were measured in surface waters during a cruise aimed at investigating ocean acidification impacts traversing northwestern European shelf seas in the summer of 2011. High-resolution surface water data were collected for partial pressure of carbon dioxide (pCO 2 ; using two independent instruments) and pH using the total pH scale (pH T ), in addition to discrete measurements of total alkalinity and dissolved inorganic carbon. We thus overdetermined the carbonate system (four measured variables, two degrees of freedom), which allowed us to evaluate the level of agreement between the variables on a cruise whose main aim was not intercomparison, and thus where conditions were more representative of normal working conditions. Calculations of carbonate system variables from other measurements generally compared well with direct observations of the same variables (Pearson's correlation coefficient always greater than or equal to 0.94; mean residuals were similar to the respective accuracies of the measurements). We therefore conclude that four of the independent data sets of carbonate chemistry variables were of high quality. A diurnal cycle with a maximum amplitude of 41 µatm was observed in the difference between the pCO 2 values obtained by the two independent analytical pCO 2 systems, and this was partly attributed to irregular seawater flows to the equilibrator and partly to biological activity inside the seawater supply and one of the equilibrators. We discuss how these issues can be addressed to improve carbonate chemistry data quality on future research cruises.

Scientia Marina, 2013

were carried out on the northeastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to ... more were carried out on the northeastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to relate the spatio-temporal distribution of the carbon cycle parameters (dissolved inorganic carbon and dissolved organic carbon) to picophytoplankton biomass and community composition. In addition, the net ecosystem production and the picophytoplankton contribution to the air-sea CO 2 exchange process were investigated. The results showed that chlorophyll-a, carbon cycle parameters and picophytoplankton composition showed large seasonality, and the Guadalquivir Estuary plays an important role in the contribution of nutrient and suspended particular material over the year. Regarding picophytoplankton composition, the flow cytometry analysis demonstrated that Prochlorococcus and Synechococcus were the main populations in the studied area and their temporal and spatial distributions were complementary: the Prochlorococcus population showed its maximum concentration in May'07 and Jun'06 and in the surface oceanic water, whereas the Synechococcus population was at its maximum during Feb'07 and Nov'06, and off the Guadalquivir Estuary and Bay of Cádiz. In addition, a relationship between the studied parameters and the fugacity of CO 2 was also observed, suggesting that primary production is an important factor in the regulation of this parameter in the studied area. The calculated carbon budget showed that the area acts as a carbon sink on an annual basis.

Marine Chemistry, 2011

were carried out in the north eastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to... more were carried out in the north eastern shelf of the Gulf of Cádiz (southwest Iberian Peninsula) to investigate the dynamics of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in a coastal area affected mainly by river input, but also by primary production/respiration, resuspension from the sediments, and mixing. In the period of the present study, DOC values ranged from 42 to 198 μM, while DON ranged from 0 to 20 μM. The seasonal variations showed high mean surface concentrations of DOC (106.2 ± 25.6 μM-C) and DON (8.6 ± 3.1 μM-N) in May, shifting to low DOC (89.1 ± 26.4 μM-C) and DON (4.2 ± 2.8 μM-N) in February. In spring, DOC and DON released by phytoplankton are likely to be the most significant source of organic matter. Low DOC and DON concentrations during winter are probably due to the uptake of DOC and DON by bacteria and to the strong mixing of the water column. The spatial variations showed the highest mean concentrations of dissolved organic matter (DOM) in the lower part of the Guadalquivir Estuary and the lowest mean concentrations of DOM in the bottom water of the oceanic zone. The very high mean DOC and DON concentrations measured off the Guadalquivir Estuary may be due to river input and/or re-suspension of the organic matter from the bottom sediments. The very low mean DOC and DON concentrations measured in the bottom water of the continental shelf may be due to mineralization and a surplus of more refractory organic carbon.

Estuarine, Coastal and Shelf Science, 2011

The role of coastal lagoons and estuaries as sources or sinks of inorganic carbon in upwelling ar... more The role of coastal lagoons and estuaries as sources or sinks of inorganic carbon in upwelling areas has not been fully understood. During the months of MayeJuly, 2005, we studied the dissolved inorganic carbon system in a coastal lagoon of northwestern Mexico during the strongest period of upwelling events. Along the bay, different scenarios were observed for the distributions of pH, dissolved inorganic carbon (DIC) and apparent oxygen utilization (AOU) as a result of different combinations of upwelling intensity and tidal amplitude. DIC concentrations in the outer part of the bay were controlled by mixing processes. At the inner part of the bay DIC was as low as 1800 mmol kg À1 , most likely due to high water residence times and seagrass CO 2 uptake. It is estimated that 85% of San Quintín Bay, at the oceanic end, acted as a source of CO 2 to the atmosphere due to the inflow of CO 2 -rich upwelled waters from the neighboring ocean with high positive fluxes higher than 30 mmol C m À2 d À1 . In contrast, there was a net uptake of CO 2 and HCO 3 À by the seagrass bed Zostera marina in the inner part of the bay, so the pCO 2 in this zone was below the equilibrium value and slightly negative CO 2 fluxes of À6 mmol C m À2 d À1 . Our positive NEP and DDIC values indicate that Bahía San Quintín was a net autotrophic system during the upwelling season during 2005.

Continental Shelf Research, 2011

There is scatter information of the inorganic carbon system in the coastal zones and it is import... more There is scatter information of the inorganic carbon system in the coastal zones and it is important to increment our knowledge and understand the global carbon cycle. We investigated the distribution of inorganic carbon system parameters and its controls in the coastal waters of the north eastern shelf of the Gulf of Cá diz (GoC) during four cruises that took place . The objectives of this study are: (1) to describe the spatio-temporal distribution of inorganic carbon system parameters in waters of the north eastern shelf of the GoC using four cruises, each undertaken in one of the four seasons, (2) to calculate net ecosystem production (NEP) and to examine factors controlling these distributions. The distribution of inorganic carbon system parameters in the north eastern shelf of the Gulf of Cá diz showed temporal and spatial variability. River input, mixing, primary production, respiration, CO 2 air-sea exchange, and remineralization were factors that controlled such distributions. The coastal zone of the GoC is autotrophic on an annual scale at a rate of 1.0 mmol m À 2 d À 1 . Further measurements are needed it to improve the NEP calculation and to evaluated to intra-annual variability.

Deep Sea Research Part II: Topical Studies in Oceanography, 2016