References of "Borges, Alberto"
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See detailA revised carbon budget for the North Sea
Paetsch, J.; Kuehn, W.; Borges, Alberto ULg et al

Conference (2009)

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See detailBiogeochemical Investigations of Coccolithophore Blooms along the Continental Margin of the Northern Bay of Biscay: Highlights of the PEACE Project
Chou, Lei; Harlay, Jérôme ULg; De Bodt, Caroline et al

Poster (2008, October 06)

Recent studies have demonstrated that changing ocean chemistry due to ocean acidification poses a growing threat for marine organisms such as corals, coccolithophores and many others that form calcareous ... [more ▼]

Recent studies have demonstrated that changing ocean chemistry due to ocean acidification poses a growing threat for marine organisms such as corals, coccolithophores and many others that form calcareous skeletons. Its biogeochemical feedbacks and impact on the oceanic carbon cycle are yet to be quantified. Coccolithophores are the major calcifying phytoplankton in the sub-polar and temperate regions of the world’s ocean. They produce furthermore transparent exopolymer particles (TEP), which are known to promote aggregate formation. Combined with the CaCO3 ballast effect, large-scale coccolithophore blooms could thus contribute to the export of organic carbon to deep waters on relatively short time scales. During the Belgian PEACE project, we have conducted yearly interdisciplinary biogeochemical surveys, assisted by remote sensing, along the continental margin of the northern Bay of Biscay where coccolithophore blooms dominated by Emiliania huxleyi are frequently and recurrently observed (Figure 1). Rates of various processes governing the coccolithophore ecosystem dynamics have been determined and associated biogeochemical parameters analysed. The overall objective is to evaluate the role in climate regulation of calcification, primary production and export processes during coccolithophore blooms. Here we report the principal results obtained during the 2006 campaign. [less ▲]

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See detailNet ecosystem production and carbon dioxide fluxes in the Scheldt estuarine plume
Borges, Alberto ULg; Ruddick, Kevin; Schiettecatte, Laure-Sophie et al

in BMC Ecology (2008), 8(15),

Background A time series of 4 consecutive years of measurements of the partial pressure of CO2 (pCO2) in the Scheldt estuarine plume is used here to estimate net ecosystem production (NEP). Results NEP in ... [more ▼]

Background A time series of 4 consecutive years of measurements of the partial pressure of CO2 (pCO2) in the Scheldt estuarine plume is used here to estimate net ecosystem production (NEP). Results NEP in the Scheldt estuarine plume is estimated from the temporal changes of dissolved inorganic carbon (DIC). The strong seasonal variations of NEP are consistent with previous reports on organic carbon dynamics in the area. These variations are related to successive phytoplankton blooms that partly feed seasonally variable heterotrophy the rest of the year. On an annual time scale the Scheldt estuarine plume behaves as a net heterotrophic system sustained with organic carbon input from the Scheldt inner estuary and the Belgian coast. During one of the years of the time-series the estuarine plume behaved annually as a net autotrophic system. This anomalous ecosystem metabolic behaviour seemed to result from a combination of bottom-up factors affecting the spring phytoplankton bloom (increased nutrient delivery and more favourable incoming light conditions). This net autotrophy seemed to lead to a transient aa accumulation of organic carbon, most probably in the sediments, that fed a stronger heterotrophy the following year. Conclusion The present work highlights the potential of using pCO2 data to derive detailed seasonal estimates of NEP in highly dynamic coastal environments. These can be used to determine potential inter-annual variability of NEP due to natural climatic oscillations or due to changes in anthropogenic impacts. [less ▲]

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See detailCoccolithophore bloom dynamics shape bacterioplankton communities in the northern Bay of Biscay
Van Oostende, Nicolas; Vyverman, Wim; Harlay, Jérôme ULg et al

Poster (2008, August 17)

Coccolithophores (Prymnesiophyceae) such as Emiliania huxleyi belong to the most productive calcifying organisms in the oceans. During two consecutive years we assessed bacterial diversity and dynamics ... [more ▼]

Coccolithophores (Prymnesiophyceae) such as Emiliania huxleyi belong to the most productive calcifying organisms in the oceans. During two consecutive years we assessed bacterial diversity and dynamics during the course of spring phytoplankton blooms dominated by coccolithophores in the northern part of the Bay of Biscay. Bacterioplankton community composition was assessed by means of denaturing gradient gel electrophoresis (DGGE) in combination with 16S rRNA gene clone libraries. We used ordination analysis to relate bacterioplankton community dynamics to phytoplankton pigment data and environmental parameters (nutrient concentrations, total alkalinity, concentration of transparent exopolymeric particles (TEP), pCO2). We found a clear difference in composition between the free-living and the particle-associated bacterial assemblage, with the identified Flavobacteria and Sphingobacteria phylotypes being characteristic for the particle-associated bacterial assemblage and Alfaproteobacteria and members of the SAR86 cluster dominating the free-living bacterial assemblage. Stations along the continental margin, at different stages in the coccolithophore bloom, were characterized by distinct bacterial assemblages which correlated well with changes in phytoplankton community composition and TEP abundance. We hypothesize that coccolithophore bloom dynamics shape both the free-living and the particle associated bacterial assemblages through phytoplankton group-specific associations and TEP production [less ▲]

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See detailA mathematical modelling of bloom of the coccolithophore Emiliania huxleyi in a mesocosm experiment
Joassin, Pascal ULg; Delille, Bruno ULg; Soetaert, Karline et al

Poster (2008, July 23)

A dynamic model has been developed to represent biogeochemical variables and processes observed during a bloom of Emiliania huxleyi coccolithophore. This bloom was induced in a mesocosm experiment during ... [more ▼]

A dynamic model has been developed to represent biogeochemical variables and processes observed during a bloom of Emiliania huxleyi coccolithophore. This bloom was induced in a mesocosm experiment during which the ecosystem development was followed over a period of 23-days through changes in various biogeochemical parameters such as inorganic nutrients (nitrate, ammonium and phosphate), total alkalinity (TA), dissolved inorganic carbon (DIC), partial pressure of carbon dioxide (pCO2), dissolved oxygen (O2), photosynthetic pigments, particulate organic carbon (POC), dissolved organic carbon (DOC), Transparent Exopolymer Particles (TEP), primary production, and calcification. This dynamic model is based on unbalanced algal growth and balanced bacterial growth. In order to adequately reproduce the observations, the model includes an explicit description of phosphorus cycling, calcification, TEP production and an enhanced mortality due to viral lysis. The model represented carbon, nitrogen and phosphorus fluxes observed in the mesocosms. Modelled profiles of algal biomass and final concentrations of DIC and nutrients are in agreement with the experimental observations. [less ▲]

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See detailCarbon dioxide dynamics in lake Kivu during the dry and wet seasons
Borges, Alberto ULg; Delille, Bruno ULg; Descy, J.-P. et al

Poster (2008, April)

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See detailSea ice pCO2 dynamics and related air-ice CO2 fluxes during a flood-freeze cycle (Bellingshausen Sea, Antarctica)
Geilfus, Nicolas-Xavier ULg; Tison, Jean Louis; Carnat, Gauthier et al

Poster (2008, April)

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See detailA mathematical modelling of bloom of the coccolithophore Emiliania huxleyi in a mesocosm experiment
Joassin, Pascal ULg; Delille, Bruno ULg; Soetaert, K. et al

in Biogeosciences Discussions (2008), 5

A dynamic model has been developed to represent biogeochemical variables and processes observed during a bloom of Emiliania huxleyi coccolithophore. This bloom was induced in a mesocosm experiment during ... [more ▼]

A dynamic model has been developed to represent biogeochemical variables and processes observed during a bloom of Emiliania huxleyi coccolithophore. This bloom was induced in a mesocosm experiment during which the ecosystem development was followed over a period of 23-days through changes in various biogeochemical parameters such as inorganic nutrients (nitrate, ammonium and phosphate), total alkalinity (TA), dissolved inorganic carbon (DIC), partial pressure of CO[SUB]2[/SUB] (pCO[SUB]2[/SUB]), dissolved oxygen (O[SUB]2[/SUB]), photosynthetic pigments, particulate organic carbon (POC), dissolved organic carbon (DOC), Transparent Exopolymer Particles (TEP), primary production, and calcification. This dynamic model is based on unbalanced algal growth and balanced bacterial growth. In order to adequately reproduce the observations, the model includes an explicit description of phosphorus cycling, calcification, TEP production and an enhanced mortality due to viral lysis. The model represented carbon, nitrogen and phosphorus fluxes observed in the mesocosms. Modelled profiles of algal biomass and final concentrations of DIC and nutrients are in agreement with the experimental observations. [less ▲]

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See detailUnderstanding the Black Sea ecosystem functioning during the eutrophication phase using mathematical modelling
Grégoire, Marilaure ULg; Capet, Arthur ULg; Barth, Alexander ULg et al

in Moncheva, Snejana (Ed.) Climate change in the Black Sea, hypthesis, observations, trends scenarios and mitigation strategy for the ecosystem (2008)

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See detailThe impact of lateral carbon fluxes on the European carbon balance
Ciais, P.; Borges, Alberto ULg; Abril, Gwenaël et al

in Biogeosciences (2008), 5

To date, little is known about the impact of processes which cause lateral carbon fluxes over continents, and from continents to oceans on the CO2 – and carbon budgets at local, regional and continental ... [more ▼]

To date, little is known about the impact of processes which cause lateral carbon fluxes over continents, and from continents to oceans on the CO2 – and carbon budgets at local, regional and continental scales. Lateral carbon fluxes contribute to regional carbon budgets as follows: Ecosystem CO2 sink=Ecosystem carbon accumulation+Lateral carbon fluxes. We estimated the contribution of wood and food product trade, of emission and oxidation of reduced carbon species, and of river erosion and transport as lateral carbon fluxes to the carbon balance of Europe (EU-25). The analysis is completed by new estimates of the carbon fluxes of coastal seas. We estimated that lateral transport (all processes combined) is a flux of 165 Tg C yr−1 at the scale of EU-25. The magnitude of lateral transport is thus comparable to current estimates of carbon accumulation in European forests. The main process contributing to the total lateral flux out of Europe is the flux of reduced carbon compounds, corresponding to the sum of non-CO2 gaseous species (CH4, CO, hydrocarbons, . . . ) emitted by ecosystems and exported out of the European boundary layer by the large scale atmospheric circulation. [less ▲]

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See detailCarbon dynamics in the highly eutrophicated Belgian Coastal Zone
Gypens, N.; Borges, Alberto ULg

in Current status of eutrophication in the Belgian coastal zone (2008)

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See detailCarbon biogeochemistry of the Betsiboka Estuary (north-western Madagascar)
Ralison, Olivier Harifidy; Borges, Alberto ULg; Dehairs, Frank et al

in Organic Geochemistry (2008), 39

Madagascar’s largest estuary (Betsiboka) was sampled along the salinity gradient during the dry season to document the distribution and sources of particulate and dissolved organic carbon (POC, DOC) as ... [more ▼]

Madagascar’s largest estuary (Betsiboka) was sampled along the salinity gradient during the dry season to document the distribution and sources of particulate and dissolved organic carbon (POC, DOC) as well as dissolved inorganic carbon (DIC). The Betsiboka was characterized by a relatively high suspended matter load, and in line with this, low DOC/POC ratios ( 0.4–2.5). The partial pressure of CO2 (pCO2) was generally above atmospheric equilibrium (270–1530 ppm), but relatively low in comparison to other tropical and subtropical estuaries, resulting in low average CO2 emission to the atmosphere (9.1 ± 14.2 mmol m 2 d 1). Despite the fact that C4 vegetation is reported to cover >80% of the catchment area, stable isotope data on DOC and POC suggest that C4 derived material comprises only 30% of both pools in the freshwater zone, increasing to 60–70% and 50–60%, respectively, in the oligohaline zone due to additional lateral inputs. Sediments from intertidal mangroves in the estuary showed low organic carbon concentrations (<1%) and d13C values (average 19.8‰) consistent with important inputs of riverine imported C4 material. This contribution was reflected in d13C signatures of bacterial phospholipid derived fatty acids (i + a15:0), suggesting the potential importance of terrestrial organic matter sources for mineralization and secondary production in coastal ecosystems. [less ▲]

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See detailEmission of CO2 and CH4 to the atmosphere by sediments and open waters in two Tanzanian mangrove forests
Kristensen, Erik; Flindt, Mogens R.; Ulomi, Shadrack et al

in Marine Ecology. Progress Series (2008)

Carbon gas balance was evaluated in an anthropogenically impacted (Mtoni) and a pristine (Ras Dege) mangrove forest in Tanzania. Exchange of carbon dioxide (CO2) was measured for inundated and air-exposed ... [more ▼]

Carbon gas balance was evaluated in an anthropogenically impacted (Mtoni) and a pristine (Ras Dege) mangrove forest in Tanzania. Exchange of carbon dioxide (CO2) was measured for inundated and air-exposed sediments during day and night using in situ and laboratory incubations. In situ methane (CH4) emissions were measured in the dark during air exposure only. Emission of CO2 and CH4 from open waters (e.g. creeks) was estimated from diurnal measurements of CO2, partial pressure (pCO2) and CH4 concentrations. CO2 emission from darkened sediments devoid of biogenic structures was comparable during inundation and air exposure (28 to 115 mmol m–2 d–1) with no differences between mangrove forests. Benthic primary production was low with only occasional net uptake of CO2 by the sediments. Emissions of CH4 from air-exposed sediment were generally 3 orders of magnitude lower than for CO2. Presence of pneumatophores and crab burrows increased low tide emissions several fold. Emissions from open waters were dependent on tidal level and wind speed. Lowest emission occurred during high tide (1 to 6 mmol CO2 m–2 d–1; 10 to 80 μmol CH4 m–2 d–1) and highest during low tide (30 to 80 mmol CO2 m–2 d–1; 100 to 350 μmol CH4 m–2 d–1) when supersaturated runoff from the forest floor and porewater seepage reached the creek water. Based on global average primary production and measured gas emissions, the carbon gas balance of the 2 mangrove forests was estimated. The densely vegetated Ras Dege forest appears to be an efficient sink of greenhouse carbon gases, while extensive clear-cutting at the Mtoni forest apparently has reduced its capacity to absorb CO2, although it is seemingly still a net sink for atmospheric CO2. [less ▲]

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See detailMangrove production and carbon sinks: a revision of global budget estimates
Bouillon, Steven; Borges, Alberto ULg; Castañeda-Moya, Edward et al

in Global Biogeochemical Cycles (2008), 22(GB2013),

Mangrove forests are highly productive but globally threatened coastal ecosystems, whose role in the carbon budget of the coastal zone has long been debated. Here we provide a comprehensive synthesis of ... [more ▼]

Mangrove forests are highly productive but globally threatened coastal ecosystems, whose role in the carbon budget of the coastal zone has long been debated. Here we provide a comprehensive synthesis of the available data on carbon fluxes in mangrove ecosystems. A reassessment of global mangrove primary production from the literature results in a conservative estimate of 218 ± 72 Tg C a 1. When using the best available estimates of various carbon sinks (organic carbon export, sediment burial, and mineralization), it appears that >50% of the carbon fixed by mangrove vegetation is unaccounted for. This unaccounted carbon sink is conservatively estimated at 112 ± 85 Tg C a 1, equivalent in magnitude to 30–40% of the global riverine organic carbon input to the coastal zone. Our analysis suggests that mineralization is severely underestimated, and that the majority of carbon export from mangroves to adjacent waters occurs as dissolved inorganic carbon (DIC). CO2 efflux from sediments and creek waters and tidal export of DIC appear to be the major sinks. These processes are quantitatively comparable in magnitude to the unaccounted carbon sink in current budgets, but are not yet adequately constrained with the limited published data available so far. [less ▲]

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See detailDissolved inorganic carbon dynamics in the waters surrounding forested mangroves of the Ca Mau Province (Vietnam)
Koné, J. M.; Borges, Alberto ULg

in Estuarine Coastal & Shelf Science (2008), 7(3), 409-421

Dissolved inorganic carbon (DIC) and ancillary data were obtained during the dry and rainy seasons in the waters surrounding two 10-yearold forested mangrove sites (Tam Giang and Kieˆn Va`ng) located in ... [more ▼]

Dissolved inorganic carbon (DIC) and ancillary data were obtained during the dry and rainy seasons in the waters surrounding two 10-yearold forested mangrove sites (Tam Giang and Kieˆn Va`ng) located in the Ca Mau Province (South-West Vietnam). During both seasons, the spatial variations of partial pressure of CO2 (pCO2) were marked, with values ranging from 704 ppm to 11481 ppm during the dry season, and from 1209 ppm to 8136 ppm during the rainy season. During both seasons, DIC, pCO2, total alkalinity (TAlk) and oxygen saturation levels (%O2) were correlated with salinity in the mangrove creeks suggesting that a combination of lower water volume and longer residence time (leading to an increase in salinity due to evaporation) enhanced the enrichment in DIC, pCO2 and TAlk, and an impoverishment in O2. The low O2 and high DIC and pCO2 values suggest that heterotrophic processes in the water column and sediments controlled these variables. The latter processes were meaningful since the high DIC and TAlk values in the creek waters were related to some extent to the influx of pore waters, consistent with previous observations. This was confirmed by the stochiometric relationship between TAlk and DIC that shows that anaerobic processes control these variables, although this approach did not allow identifying unambiguously the dominant diagenetic carbon degradation pathway. During the rainy season, dilution led to significant decreases of salinity, TAlk and DIC in both mangrove creeks and adjacent main channels. In the Kieˆn Va`ng mangrove creeks a distinct increase of pCO2 and decrease of %O2 were observed. The increase of TSM suggested enhanced inputs of organic matter probably from land surrounding the mangrove creeks, that could have led to higher benthic and water column heterotrophy. However, the flushing of water enriched in dissolved CO2 originating from soil respiration and impoverished in O2 could also have explained to some extent the patterns observed during the rainy season. Seasonal variations of pCO2 were more pronounced in the Kieˆn Va`ng mangrove creeks than in the Tam Giang mangrove creeks. The airewater CO2 fluxes were 5 times higher during the rainy season than during the dry season in the Kieˆn Va`ng mangrove creeks. In the Tam Giang mangrove creeks, the airewater CO2 fluxes were similar during both seasons. The airewater CO2 fluxes ranged from 27.1 mmol C m 2 d 1 to 141.5 mmol C m 2 d 1 during the dry season, and from 81.3 mmol m 2 d 1 to 154.7 mmol m 2 d 1 during the rainy season. These values are within the range of values previously reported in other mangrove creeks and confirm that the emission of CO2 from waters surrounding mangrove forests are meaningful for the carbon budgets of mangrove forests. [less ▲]

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