@inbook {9390, title = {CO2 and CH4 emissions from coastal wetland soils}, booktitle = {Carbon Mineralization in Coastal Wetlands}, year = {2022}, pages = {55{\textendash}91}, publisher = {Elsevier}, organization = {Elsevier}, isbn = {978-0-12-819220-7}, doi = {10.1016/B978-0-12-819220-7.00006-6}, url = {https://linkinghub.elsevier.com/retrieve/pii/B9780128192207000066}, author = {Marchand, Cyril and Frank David and Jacotot, Adrien and Leopold, Audrey and Ouyang, Xiaoguang} } @article {7778, title = {Prokaryotic abundance, cell size and extracellular enzymatic activity in a human impacted and mangrove dominated tropical estuary (Can Gio, vietnam)}, journal = {Estuarine, Coastal and Shelf Science}, year = {2021}, month = {Jan-02-2021}, pages = {107253}, abstract = {Extracellular enzymatic activities constitute the first and limiting step of the whole process of organic matter (OM) cycling in aquatic ecosystems. This study aims to identify the factors controlling prokaryotes ability to hydrolyse OM in an Indo-Pacific tropical mangrove ecosystem (Can Gio, Vietnam). Prokaryotic abundance and leucine-aminopeptidase exo-proteolytic activity (EPA) were measured at vertical (from the sea-surface microlayer to bottom waters), spatial (along a transect within the estuary) and seasonal (wet and dry season) scales. Prokaryotic abundance ranged from 1.2 to 5.7\ {\texttimes}\ 109\ cells L-1\ and EPA ranged from 24 to 505\ nmol\ L-1\ h-1\ that was relatively similar to other highly productive ecosystems. The estuary was poorly stratified, most probably because of high water turbulence. Yet, exo-proteolytic activity was significantly higher in bottom waters, where higher loads of suspended particulate matter were measured. Seasonal and spatial differences in EPA suggest that the nature of OM transported by the Can Gio mangrove estuary affect EPA. The latter seems to be increased by two {\textquotedblleft}uncommon{\textquotedblright} situations: the input of fresh and labile OM (e.g.\ shrimp farm effluents) or the lack of labile OM and the need to hydrolyse refractory compounds (e.g.\ during the dry season).}, issn = {02727714}, doi = {10.1016/j.ecss.2021.107253}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0272771421000895}, author = {Frank David and Tarik Meziane and Marchand, Cyril and Rolland, Guillaume and Pham, Aur{\'e}lie and Thanh-Nho, Nguyen and Lamy, Dominique} } @article {7323, title = {Fatty acid compositions of four benthic species along the salinity gradient of a human impacted and mangrove dominated tropical estuary (Can Gio, Vietnam)}, journal = {Journal of Sea Research}, year = {2020}, month = {Jan-09-2020}, pages = {101955}, abstract = {Tropical estuaries are characterised by high spatial and temporal variability in the conditions they provide for living organisms, which in turn may affect their biochemical composition. Anthropogenic contaminants such as nutrients, antibiotics, pesticides and trace metals may also affect the biochemical composition of these coastal organisms, notably with regard to fatty acids (FA), of which optimal species-specific polyunsaturated FA ratios are required to maintain living species in healthy conditions. The objective of this study was to evidence changes in the FA profile of four ubiquist benthic species in relation to the salinity gradient of a human impacted and mangrove dominated tropical estuary (Can Gio, Southern Vietnam). Among the four benthic species studied, two exhibited spatial and seasonal changes in their FA composition: the varunid crab\ Metaplax elegans\ and the predatory mangrove murex snail\ Chicoreus capucinus. Proportions of the FA 16:1ω7, proportions of highly unsaturated FA and ratios of eicosapentanoic acid/arachidonic acid in the tissues of both species seemed related to upstream inputs. Different relative abundances of benthic microalgae affected both claw muscle and hepatopancreas FA composition of\ M. elegans, while the FA composition of\ C. capucinus\ shows that the influence of prey{\textquoteright}s diet might be transferred within trophic chains. Finally, some species, such as\ Nerita balteata\ and\ Metapenaeus ensis\ might have more adaptive capacities, because of their mobility, or because of their specific metabolic pathways, minimizing the potential impact of spatial and/or temporal changes in food resources quality. A starvation experiment involving\ N. balteata\ actually revealed the metabolic synthesis of non-methylene interrupted FA that may confer cell membranes a higher resistance to external stressors than common polyunsaturated FA. Our study highlights the future possibility of using the FA composition of sentinel organisms (i.e. feeding on specific food resources and/or especially subject to environmental stresses) as a bioindicator tool to assess mangrove ecosystems health.}, issn = {13851101}, doi = {10.1016/j.seares.2020.101955}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1385110120301556}, author = {Frank David and Marchand, Cyril and Van, Vinh Truong and Taillardat, Pierre and Thanh-Nho, Nguyen and Tarik Meziane} } @article {7545, title = {Public Perceptions of Mangrove Forests Matter for Their Conservation}, journal = {Frontiers in Marine Science}, volume = {7}, year = {2020}, month = {Jul-11-2021}, abstract = {Iconic species and landscapes attract public attention to help reverse the degradation of ecosystems and their biodiversity (Thompson and Rog, 2019); sharing their images on social media can act as a powerful way to influence perceptions and drive positive actions by the public (Wu et al., 2018). Social media platforms such as Twitter, Facebook and Instagram have been used to great effect to communicate the urgency required to halt and reverse tropical forest loss (Lamb et al., 2005) and the plight of coral reefs (Curnock et al., 2019). Ecosystems such as seagrass meadows, mudflats, and mangrove forests receive substantially less media exposure (Duarte et al., 2008). Yet these under-recognized ecosystems are hugely important for local and global societies, providing benefits such as shoreline protection (Barbier, 2016), fisheries (Carrasquilla-Henao and Juanes, 2017), carbon capture and storage (Duarte et al., 2013), alongside supporting rich marine and terrestrial biodiversity (Sievers et al., 2019;\ Thompson and Rog, 2019) (Figure 1). Apart from these important ecosystem functions, goods and services, mangrove forests are home to a huge diversity of organisms with ecologically and evolutionarily unique adaptations to life in the intertidal zone, including vivipary and salt tolerance in trees, air-breathing in crabs and amphibious behavior in fish (mudskippers); this makes mangrove forests a dynamic and fascinating evolutionary laboratory.}, doi = {10.3389/fmars.2020.60365110.3389/fmars.2020.603651.s001}, url = {https://www.frontiersin.org/articles/10.3389/fmars.2020.603651/full}, author = {Dahdouh-Guebas, Farid and Ajonina, Gordon N. and Amir, A. Aldrie and Andradi-Brown, Dominic A. and Aziz, Irfan and Balke, Thorsten and Barbier, Edward B. and Cannicci, Stefano and Cragg, Simon M. and Cunha-Lignon, Mar{\'\i}lia and Curnick, David J. and Duarte, Carlos M. and Duke, Norman C. and Endsor, Charlie and Fratini, Sara and Feller, Ilka C. and Fromard, Fran{\c c}ois and Hug{\'e}, Jean and Huxham, Mark and Kairo, James G. and Kajita, Tadashi and Kathiresan, Kandasamy and Koedam, Nico and Lee, Shing Yip and Lin, Hsing-Juh and Mackenzie, Jock R. and Mangora, Mwita M. and Marchand, Cyril and Tarik Meziane and Minchinton, Todd E. and Pettorelli, Nathalie and Polan{\'\i}a, Jaime and Polgar, Gianluca and Poti, Meenakshi and Primavera, Jurgenne and Quarto, Alfredo and Rog, Stefanie M. and Satyanarayana, Behara and Schaeffer-Novelli, Yara and Spalding, Mark and Van der Stocken, Tom and Wodehouse, Dominic and Yong, Jean W. H. and Zimmer, Martin and Friess, Daniel A.} } @article {9389, title = {Respective contribution of urban wastewater and mangroves on nutrient dynamics in a tropical estuary during the monsoon season}, journal = {Marine Pollution Bulletin}, volume = {160}, year = {2020}, pages = {111652}, abstract = {Estuaries of Southeast Asia are increasingly impacted by land-cover changes and pollution. Here, our research objectives were to (1) determine the origins of nutrient loads along the Can Gio estuary (Vietnam) and (2) identify the processes that affect the nutrient pools during the monsoon. We constructed four 24-h time-series along the salinity gradient measuring nutrient concentrations and stable isotopes values. In the upper estuary, urban effluents from Ho Chi Minh City were the main input of nutrients, leading to dissolved oxygen satura- tion \< 20\%. In the lower estuary, ammonium and nitrite concentration peaks were explained by mangrove export. No contribution from aquaculture was detected, as it represents \< 0.01\% of the total river discharge. Along the salinity gradient, nutrient inputs were rapidly consumed, potentially by phytoplankton while nitrate dual-stable isotopes indicated that nitrification occurred. Thus, even in a large and productive estuary, urban wastewater can affect nutrient dynamics with potentially important ecological risks.}, issn = {0025326X}, doi = {10.1016/j.marpolbul.2020.111652}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0025326X20307700}, author = {Taillardat, Pierre and Marchand, Cyril and Friess, Daniel A. and Widory, David and Frank David and Ohte, Nobuhito and Nakamura, Takashi and Van Vinh, Truong and Thanh-Nho, Nguyen and Ziegler, Alan D.} } @article {9384, title = {Assessing nutrient dynamics in mangrove porewater and adjacent tidal creek using nitrate dual-stable isotopes: A new approach to challenge the Outwelling Hypothesis?}, journal = {Marine Chemistry}, volume = {214}, year = {2019}, pages = {103662}, abstract = {The importance of mangrove-derived material in sustaining coastal food webs (i.e. the Outwelling Hypothesis) is often invoked in support of mangroves conservation. Biogeochemical cycling, particularly nitrogen (N) and phosphorus (P) in mangrove ecosystems, however, is poorly understood because of high spatial heterogeneity and temporal variability of sources, sinks, and transformation pathways. Here we show that the distribution of N and P are intimately related to vegetation distribution, tidal cycles, and seasonality. We examined the dynamics of N and P in sediments and in a tidal creek of the Can Gio Mangrove Forest, Vietnam. Our objectives were to (1) determine the spatial distribution of dissolved inorganic nitrogen and phosphorus in the mangrove forest along a Rhizophora-Avicennia-mudflat transect; and (2) identify the respective inputs and transformation pathways of N and P in the water column via 24-h time series measurements in a tidal creek. Sediment porewater had N-NH4+ and N-NO3- concentrations \< 11 μM, except in the mudflat where N-NH4+ was as high as 162 μM. This difference was likely due to N-NH4+ uptake by trees in the vegetated areas and suggests that mangrove sediments can be a zone of NH4+ production via ammonification of organic nitrogen. In all stands, P-PO43- concentrations were three-fold higher during the wet season, with a maximum of 34.4 μM. This can be explained by enhanced microbial activity during the rainy season. The phosphorus seasonal trend was also observed in the creek water but with a maximum P-PO43- value of 4.3 μM only. In the tidal creek, NNH4+ was highly variable (0 to 51 μM), with the higher values measured at low tide and related to porewater discharge from the mudflat. Our data suggest that mangroves act both as a sink of dissolved inorganic nutrients via vegetation uptake and a source of ammonium from unvegetated mudflat porewater towards the tidal creek. The dual stable isotopes approach (δ15NNO3 \& δ18ONO3) revealed that this ammonium was later nitrified within the water column. Moreover, the approach showed that some nitrate originated from the river-estuarine system during rising tides. The export of ammonium from mangrove porewater is presumably entirely consumed before exiting the tidal creek, thereby limiting the spatial extent of mangrove Outwelling. Nevertheless, our multi-isotope approach leads us to conclude that nutrients recycling via mangrove-derived organic matter mineralization may play a fundamental role in sustaining coastal food web.}, issn = {03044203}, doi = {10.1016/j.marchem.2019.103662}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0304420319300489}, author = {Taillardat, Pierre and Ziegler, Alan D. and Friess, Daniel A. and Widory, David and Frank David and Ohte, Nobuhito and Nakamura, Takashi and Evaristo, Jaivime and Thanh-Nho, Nguyen and Van Vinh, Truong and Marchand, Cyril} } @article {6869, title = {Fatty acids, C and N dynamics and stable isotope ratios during experimental degradation of shrimp pond effluents in mangrove water}, journal = {Marine Environmental Research}, volume = {150}, year = {2019}, month = {Jan-09-2019}, pages = {104751}, issn = {01411136}, doi = {10.1016/j.marenvres.2019.104751}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0141113619301953}, author = {Vivier, Baptiste and Frank David and Cyril Marchand and Thanh-Nho, Nguyen and Tarik Meziane} } @article {5984, title = {Short-term changes in the quality of suspended particulate matter in a human impacted and mangrove dominated tropical estuary (Can Gio, Vietnam)}, journal = {Continental Shelf Research }, volume = {178}, year = {2019}, month = {01/05/2019}, pages = {59-67}, abstract = {

Suspended particulate matter (SPM) is a key component of coastal food webs and a key variable of nutrient budgets. Understanding its variability across short time scales in estuaries may help ecologists understand seasonal and diurnal migration of estuarine organisms, and answer how their nutritional requirements are fulfilled. It may also inform biogeochemists regarding the factors that influence import and export of nutrients between terrestrial and coastal ecosystems. This study aimed to link the dynamics of fatty acids, stable isotopes (δ13C and δ15N) and C/N ratios of SPM, revealing organic matter quality, to rapidly varying factors (SPM concentration, salinity and presence of daylight) and comparing this variability to the seasonal variation induced by the alternation of dry and wet seasons in the studied region. Our results revealed that these rapidly varying factors had a strong influence on the bacterial and the phytoplanktonic compartments of SPM. They suggest that tidally resuspended particles are the site of intense heterotrophic activity and that estuarine phytoplankton store lipids during the daytime up to substantially modifying SPM quality. Our study also shows higher freshness of SPM during the wet season. We expect this study to raise the interest of both biologists and biogeochemists to introduce daily variability of SPM in food webs and nutrient budgets modelling.

}, doi = {10.1016/j.csr.2019.03.011}, author = {Frank David and Cyril Marchand and Najet Thiney and Tran-thi, N and Tarik Meziane} } @article {5769, title = {Trophic relationships and basal resource utilisation in the Can Gio Mangrove Biosphere Reserve (Southern Vietnam)}, journal = {Journal of Sea Research}, year = {2019}, abstract = {

Abstract Fatty acid biomarkers and dual stable isotopes (δ13C and δ15N) were used to identify the preferred food sources of consumers in a mangrove tidal creek and nearby unforested (mud bank) and forested areas located in the Can Gio Mangrove Biosphere Reserve (Southern Vietnam). We analysed 15 macro-invertebrates and 1 fish species representing primary consumers and their immediate predators in this area. Specific groups of fatty acids were used to trace the fate of various food sources (i.e., suspended particulate organic matter, mangrove litter and sedimentary organic matter). The δ13C and δ15N of consumers ranged from -26.9 to -18.8{\textperthousand} and from 1.1 to 9.9{\textperthousand}, respectively. The trophic pathway based on mangrove litter, characteristic of mangrove ecosystems, is nutritionally sustaining various crab and snail species. In contrast, it appears that the most mobile species (fish and shrimps), living in the water column and possibly migrating with tides, are mostly feeding on suspended particulate organic matter, suggesting that this trophic pathway is of great importance for connectivity among tropical coastal ecosystems. Our study suggests that snails and crabs mainly act as mineralisers, processing high quantities of detrital material to meet their nutritional needs and thus releasing nutrients through the production of faeces, that are further mineralised by microorganisms, while locally grown phytoplankton reintegrates these compounds into its biomass and feeds migrating species. We highlight here a possible link between mangrove litter and coastal food webs.

}, doi = {10.1016/j.seares.2018.12.006}, url = {https://www.sciencedirect.com/science/article/pii/S1385110118301679}, author = {Frank David and Cyril Marchand and Nguyen, Thanh-Nho and Pierre Taillardat and Tarik Meziane} } @article {5465, title = {Carbon biogeochemistry and CO2 emissions in a human impacted and mangrove dominated tropical estuary (Can Gio, Vietnam)}, journal = {Biogeochemistry}, year = {2018}, month = {27/04/2018}, pages = {1-15}, abstract = {

The quantitative contribution of tropical estuaries to the atmospheric CO2\ budget has large uncertainties, both spatially and seasonally. We investigated the seasonal and spatial variations of carbon biogeochemistry downstream of Ho Chi Minh City (Southern Vietnam). We sampled four sites distributed from downstream of a highly urbanised watershed through mangroves to the South China Sea coast during the dry and wet seasons. Measured partial pressure of CO2(pCO2) ranged from 660 to 3000\ μatm during the dry season, and from 740 to 5000\ μatm during the wet season. High organic load, dissolved oxygen saturation down to 17\%, and pCO2up to 5000\ μatm at the freshwater endmember of the estuary reflected the intense human pressure on this ecosystem. We show that releases from mangrove soils affect the water column pCO2\ in this large tropical estuary (~600\ m wide and 10{\textendash}20\ m deep). This study is among the few to report direct measurements of both water pCO2\ and CO2\ emissions in a Southeast Asian tropical estuary located in a highly urbanised watershed. It shows that the contribution of such estuaries may have been previously underestimated, with CO2\ emissions ranging from 74 to 876\ mmol\ m-2\ day-1\ at low current velocity (\<\ 0.2\ m\ s-1). Corresponding gas transfer velocities k600,\ ranging from 1.7 to 11.0\ m\ day-1,\ were about 2 to 4 times of k600\ estimated using published literature equations.

}, doi = {https://doi.org/10.1007/s10533-018-0444-z}, author = {Frank David and Tarik Meziane and Tran-thi, N and Truong Van, V and Th{\`a}nh-Nho, N and Pierre Taillardat and Cyril Marchand} } @article {9382, title = {Carbon dynamics and inconstant porewater input in a mangrove tidal creek over contrasting seasons and tidal amplitudes}, journal = {Geochimica et Cosmochimica Acta}, volume = {237}, year = {2018}, pages = {32{\textendash}48}, abstract = {Constraining the contribution of mangrove-derived carbon in tidal creeks is fundamental to understanding the fate of mangrove primary production and the role of mangroves as coastal carbon sinks. Porewater measurements and 24-h time series in a mangrove tidal creek were conducted during the dry and wet season, and over contrasting tidal ranges at the Can Gio Biosphere Reserve, Vietnam. Surface water carbon concentrations (dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), partial pressure of carbon dioxide (pCO2)) and their respective d13C values were correlated with radon, suggesting that porewater input drives mangrove-derived carbon in the tidal creek. Based on three complementary mixing models, porewater input contributed to about 30\% of the water volume and 46\% to 100\% of DOC and DIC pools in the tidal creek at low tide, with variabilities between seasons and tidal amplitudes. The creek carbon pool was 88\% DIC, 6\% DOC, and 6\% particulate organic carbon (POC). The pCO2 values during the wet season (2973{\textendash}16,495 latm) were on average 5-fold higher than during the dry season (584{\textendash}2946 latm). This was explained by a potential greater mineralization attributed to higher organic matter availability and residual humidity that stimulate bacterial activity, and by a potential tidal dilution changing the pCO2/DIC ratio as suggested by the Revelle factor. Consequently, average CO2 evasion from the creek was estimated at 327{\textendash}427 mmolC m{\`A}2 d{\`A}1 during the wet season and 92{\textendash}213 mmolC m{\`A}2 d{\`A}1 during the dry season, using two independent approaches. Tidal amplitude seemed to influence porewater input and its carbon loads, with a higher contribution during frequent and high tidal amplitudes (symmetric). However, the highest input occurred in a tidal cycle which was preceded by tidal cycle of low amplitude (asymmetric). We explain this ambiguity by the influence of both, rapid water turnover intensifying porewater exchange, and long water residence time enhancing carbon load in porewater.}, issn = {00167037}, doi = {10.1016/j.gca.2018.06.012}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0016703718303272}, author = {Taillardat, Pierre and Ziegler, Alan D. and Friess, Daniel A. and Widory, David and Truong Van, Vinh and Frank David and Thanh-Nho, Nguyen and Marchand, Cyril} } @article {5310, title = {Nutritional composition of suspended particulate matter in a tropical mangrove creek during a tidal cycle (Can Gio, Vietnam)}, journal = {Estuarine, Coastal and Shelf Science}, volume = {200}, year = {2018}, pages = {126-130}, doi = {10.1016/j.ecss.2017.10.017}, url = {https://doi.org/10.1016/j.ecss.2017.10.017}, author = {Frank David and Cyril Marchand and Pierre Taillardat and Th{\`a}nh-Nho, N and Tarik Meziane} } @article {9383, title = {Trace metals partitioning between particulate and dissolved phases along a tropical mangrove estuary (Can Gio, Vietnam)}, journal = {Chemosphere}, volume = {196}, year = {2018}, pages = {311{\textendash}322}, abstract = {Mangroves can be considered as biogeochemical reactors along (sub)tropical coastlines, acting both as sinks or sources for trace metals depending on environmental factors. In this study, we characterized the role of a mangrove estuary, developing downstream a densely populated megacity (Ho Chi Minh City, Vietnam), on the fate and partitioning of trace metals. Surface water and suspended particulate matter were collected at four sites along the estuarine salinity gradient during 24 h cycling in dry and rainy seasons. Salinity, pH, DO, TSS, POC, DOC, dissolved and particulate Fe, Mn, Cr, As, Cu, Ni, Co and Pb were measured. TSS was the main trace metals carrier during their transit in the estuary. However, TSS variations did not explain the whole variability of metals distribution. Mn, Cr and As were highly reactive metals while the other metals (Fe, Ni, Cu, Co and Pb) presented stable log KD values along the estuary. Organic matter dynamic appeared to play a key role in metals fractioning. Its decomposition during water transit in the estuary induced metal desorption, especially for Cr and As. Conversely, dissolved Mn concentrations decreased along the estuary, which was suggested to result from Mn oxidative precipitation onto solid phase due to oxidation and pH changes. Extra sources as pore-water release, runoff from adjacent soils, or aquaculture effluents were suggested to be involved in trace metal dynamic in this estuary. In addition, the monsoon increased metal loads, notably dissolved and particulate Fe, Cr, Ni and Pb.}, issn = {00456535}, doi = {10.1016/j.chemosphere.2017.12.189}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0045653517321677}, author = {Thanh-Nho, Nguyen and Strady, Emilie and Nhu-Trang, Tran{\textendash}Thi and Frank David and Marchand, Cyril} } @article {4396, title = {Meiofauna distribution in a mangrove forest exposed to shrimp farm effluents (New Caledonia)}, journal = {Marine Environmental Research}, volume = {119}, year = {2016}, pages = {100 - 113}, abstract = {

Abstract Meiofauna abundance, biomass and individual size were studied in mangrove sediments subjected to shrimp farm effluents in New Caledonia. Two strategies were developed: i) meiofauna examination during the active (AP) and the non-active (NAP) periods of the farm in five mangrove stands characteristics of the mangrove zonation along this coastline, ii) meiofauna examination every two months during one year in the stand the closest to the pond (i.e. Avicennia marina). Thirteen taxonomic groups of meiofauna were identified, with nematodes and copepods being the most abundant ones. Meiofauna abundance and biomass increased from the land side to the sea side of the mangrove probably as a result of the increased length of tidal immersion. Abundance of total meiofauna was not significantly different before and after the rearing period. However, the effluent-receiving mangrove presented twice the meiofauna abundance and biomass than the control one. Among rare taxa, mites appeared extremely sensitive to this perturbation.

}, keywords = {New Caledonia}, issn = {0141-1136}, doi = {http://dx.doi.org/10.1016/j.marenvres.2016.05.028}, url = {http://www.sciencedirect.com/science/article/pii/S0141113616300976}, author = {L. Della Patrona and Cyril Marchand and C{\'e}dric Hubas and Nathalie Molnar and J. Deborde and Tarik Meziane} } @article {3559, title = {Concentrations and Fractionation of Carbon, Iron, Sulfur, Nitrogen and Phosphorus in Mangrove Sediments Along an Intertidal Gradient (Semi-Arid Climate, New Caledonia)}, journal = {J. Mar. Sci. Eng.}, year = {2015}, month = {02/2015}, pages = {52-57}, type = {OPEN ACCESS}, abstract = {

In mangrove ecosystems, strong reciprocal interactions exist between plant and substrate. Under semi-arid climate, Rhizophora spp. are usually predominant, colonizing the seashore, and Avicennia marina develops at the edge of salt-flats, which is the highest zone in the intertidal range. Along this zonation, distribution and speciation of C, Fe, S, N, and P in sediments and pore-waters were investigated. From the land-side to the sea-side of the mangrove, sediments were characterized by I/ increase in: (i) water content; (ii) TOC; (iii) mangrove-derived OM; II/ and decrease in: (i) salinity; (ii) redox; (iii) pH; (iv) solid Fe and solid P. Beneath Avicennia and Rhizophora, TS accumulated at depth, probably as a result of reduction of iron oxides and sulfate. The loss of total Fe observed towards the sea-side may be related to sulfur oxidation and to more intense tidal flushing of dissolved components. Except the organic forms, dissolved N and P concentrations were very low beneath Avicennia and Rhizophora stands, probably as a result of their uptake by the root systems. However, in the unvegetated salt-flat, NH4+ can accumulate in organic rich and anoxic layers. This study shows: (i) the evolution of mangrove sediment biogeochemistry along the intertidal zone as a result of the different duration of tidal inundation and organic enrichment; and (ii) the strong links between the distribution and speciation of the different elements.

}, keywords = {biogeochemistry, Mangrove, New Caledonia, zonation}, issn = {2077-1312}, author = {Jonhatan Deborde and Cyril Marchand and Nathalie Molnar and Luc Della-Patrona and Tarik Meziane} } @article {3663, title = {Foraminiferal assemblages as bioindicators to assess potential pollution in mangroves used as a natural biofilter for shrimp farm effluents (New Caledonia)}, journal = {Marine Pollution Bulletin}, volume = {93}, year = {2015}, month = {15 April 2015}, pages = {103-120}, type = {Research}, abstract = {

In New Caledonia, semi-intensive shrimp farms release untreated effluents into the mangrove. Foraminiferal assemblages were analyzed for assessing the impact of effluent release on the benthic compartment. Comparison was made between samples collected (1) in an effluent receiving mangrove before and after the rearing cycle, and (2) for one-year monitoring an effluent receiving and a control mangrove. The distribution of foraminiferal assemblages was primarily driven by the gradient between\ Rhizophora\ stands and salt-flats, related to salinity and tidal elevation, and by seasonal cycles. The potential impact of effluent release was due to the combined effects of normal-saline effluents on surface salinity, and of nutrient input and microbial stimulation on food availability. Foraminiferal assemblages did not indicate a substantial impact of farm effluents and suggest that semi-intensive shrimp farming using mangrove for effluent discharge may appear as a sustainable solution in New Caledonia, when considering only the impact on the mangrove itself.

}, keywords = {Effluents, fatty acids, Foraminifera, Mangrove, Shrimp farming, SW Pacific}, doi = {10.1016/j.marpolbul.2015.02.009}, author = {Debenay, J-P and Cyril Marchand and Nathalie Molnar and Ad{\'e}laide Aschenbroich and Tarik Meziane} } @article {3522, title = {Spatio-temporal variations in the composition of organic matter in surface sediments of a mangrove receiving shrimp farm effluents (New Caledonia)}, journal = {Science of The Total Environment}, volume = {512{\textendash}513}, year = {2015}, pages = {296 - 307}, abstract = {

In order to investigate spatio-temporal variations in the composition and origin of the benthic organic matter (OM) at the sediment surface in mangrove receiving shrimp farm effluents, fatty acid (FA) biomarkers, natural stable isotopes (δ13C and δ15N), C:N ratios and chlorophyll-a (chl-a) concentrations were determined during the active and the non-active period of the farm. Fatty acid compositions in surface sediments within the mangrove forest indicated that organic matter inputs varied along the year as a result of farm activity. Effluents were the source of fresh particulate organic matter for the mangrove, as evidenced by the unsaturated fatty acid (UFA) distribution. The anthropogenic \{MUFA\} 18:1ω9 was not only accumulated at the sediment surface in some parts of the mangrove, but was also exported to the seafront. Direct release of bacteria and enhanced in situ production of fungi, as revealed by specific FAs, stimulated mangrove litter decomposition under effluent runoff condition. Also, microalgae released from ponds contributed to maintain high benthic chl-a concentrations in mangrove sediments in winter and to a shift in microphytobenthic community assemblage. Primary production was high whether the farm released effluent or not which questioned the temporary effect of shrimp farm effluent on benthic microalgae dynamic. This study outlined that mangrove benthic organic matter was qualitatively and quantitatively affected by shrimp farm effluent release and that responses to environmental condition changes likely depended on mangrove stand characteristics.

}, keywords = {Chlorophyll-a, fatty acids, Mangrove, Organic matter, Shrimp farming, Stable isotopes}, issn = {0048-9697}, doi = {http://dx.doi.org/10.1016/j.scitotenv.2014.12.082}, url = {http://www.sciencedirect.com/science/article/pii/S0048969714017938}, author = {Ad{\'e}laide Aschenbroich and Cyril Marchand and Nathalie Molnar and Jonhatan Deborde and C{\'e}dric Hubas and Herv{\'e} Rybarczyk and Tarik Meziane} } @article {3994, title = {Seasonal Pattern of the Biogeochemical Properties of Mangrove Sediments Receiving Shrimp Farm Effluents (New Caledonia)}, journal = {Journal of acquaculture research \& development}, volume = {05}, year = {2014}, issn = { 2155-9546}, author = {Cyril Marchand and Molnar, N and Deborde, J and Patrona, LC and Tarik Meziane} } @article {7333, title = {Impacts of shrimp farm effluent on water quality, benthic metabolism and~N-dynamics in a mangrove forest (New Caledonia)}, journal = {Estuarine, Coastal and Shelf Science}, volume = {117}, year = {2013}, month = {Jan-01-2013}, pages = {12 - 21}, issn = {02727714}, doi = {10.1016/j.ecss.2012.07.012}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0272771412002739}, author = {Molnar, Nathalie and Welsh, David T. and Marchand, Cyril and Deborde, Jonathan and Tarik Meziane} }