References of "Richir, Jonathan"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailStructural Changes of Seagrass Seascapes Driven by Natural and Anthropogenic Factors: A Multidisciplinary Approach
Abadie, Arnaud ULiege; Richir, Jonathan ULiege; Lejeune, Pierre et al

in Frontiers in Ecology and Evolution (2019), 7

Seascape ecology has been widely applied to marine habitats, including seagrass meadows, through various approaches all over the world for the past 30 years. However, these methods mainly study seagrass ... [more ▼]

Seascape ecology has been widely applied to marine habitats, including seagrass meadows, through various approaches all over the world for the past 30 years. However, these methods mainly study seagrass meadows on a single spatial scale and monitor a single driver of heterogeneity. Additionally, few assess the seascape’s structural evolution. This creates gaps between the scientific data provided and those required by environmental managers and stakeholders in charge of seagrass meadow conservation. To meet their expectations, in this paper we developed a new multidisciplinary approach based on the coupling of mapping techniques, particle flux, and biometric investigations in a Mediterranean Bay, the Calvi Bay (Corsica, France), to assess the structural changes of Posidonia oceanica (L.) Delile meadows subject to disturbances. We focused our investigations on the structural characteristics, the spatial dynamics, and the particle fluxes of natural sand areas generated by bottom currents and dead matte patches which ensued from anchoring damages at 10, 15, and 20m depth. Natural sand patches and anchoring patches differed in size, the first the largest. They also displayed different erosion-colonization dynamics. Natural sand patches were eroded at a mean speed of 12 cm.a−1 and colonized at a rate of 7 cm.a−1. Anchoring patches showed a mean erosion speed of 3.5 cm.a−1 and a colonization rate of 6.5 cm.a−1. Regarding particle fluxes, continuous meadow, and natural patch sedimentation and resuspension rates were 3.7 gDW.m−2.d−1 and 4.1 gDW.m−2.d−1 in average, respectively. In contrast, anchoring patches at 20m depth acted as sediment traps (112.60 gDW.m−2.d−1 in winter) and showed a higher particle resuspension rate. Our results highlighted the dichotomous dynamics of seagrass seascapes influenced by natural and anthropogenic factors. Thus, the smallest anchoring patch will take about 27 years to be recolonized while the biggest requires 60 years to be covered by the plant. With an upscaling approach, together with the newest mapping tools of marine habitats, we suggest a new method to study the evolution of seagrass meadows at a large spatial scale. [less ▲]

Detailed reference viewed: 13 (0 ULiège)
Full Text
Peer Reviewed
See detailBiomonitoring environmental status in semi-enclosed coastal ecosystems using Zostera noltei meadows
Boutahar, L.; Maanan, M.; Bououarour, O. et al

in Ecological Indicators (2019)

Semi enclosed waters, such as estuaries and lagoons, are vulnerable ecosystems that are experiencing persistent trace element (TE) contamination. Seagrasses have been reported worldwide as valuable ... [more ▼]

Semi enclosed waters, such as estuaries and lagoons, are vulnerable ecosystems that are experiencing persistent trace element (TE) contamination. Seagrasses have been reported worldwide as valuable bioindicator species for coastal contamination monitoring purpose. This is, to our knowledge, the first time the TE contamination of semi-enclosed ecosystems has been monitored along the full latitudinal gradient of the Moroccan Atlantic coast. In these ecosystems, the dominant seagrass species is Zostera noltei. 23 TEs (Fe, Al, Cr, Mn, Co, Ni, V, Cu, Zn, Sr, Li, As, Ag, Cd, Sn, Sb, Mo, Ba, Ti, Pb, U, Bi and Hg) and four major elements (Na, Mg, K, Ca) were measured in sediments and seagrass leaf samples were collected upstream and downstream of five semi-enclosed areas. They contrasted in both climatic conditions and levels of environmental contamination. The Trace Element Pollution Index (TEPI) and the Trace Element Spatial Variation Index (TESVI) were calculated from chemical element concentrations in the samples. Of the five semi-enclosed areas, Sidi Moussa lagoon's sediments were the most contaminated (TEPI = 1.18). The TESVI differed highly between chemical elements among the five water bodies for sediments and seagrass leaves, the highest spatial variability being for Ag (TESVI = 72.01 and 21.05 respectively). For Z. noltei leaves, a latitudinal gradient of TE accumulation was recorded. A high bioconcentration factor (BCF > 1) for Cd, Mo, Sb, Ag, Zn and U indicated that the sediments were efficiently uptaken by the seagrass. Significant correlations (p < 0.05) between levels of Cd, Ag, Fe, Al, Ba, Hg, Mn and Zn in sediments and in Z. noltei leaves indicated similar contamination occurrences in both environmental matrices and their bioavailability for seagrasses. Overall, leaf TE bioconcentration among and within the study sites resulted from differences in element bioavailability and environmental conditions (climatic context, hydrological conditions and human impact). Ultimately, Z. noltei is a useful bioindicator of Cd, Mo, Sb, Ag, Zn, U, Al, Fe, Mn, Ba and Hg contamination in sediments. © 2019 Elsevier Ltd [less ▲]

Detailed reference viewed: 11 (0 ULiège)
Full Text
See detailPAM fluorometry research in Posidonia oceanica
Richir, Jonathan ULiege; Abadie, Arnaud ULiege; Borges, Alberto ULiege et al

Scientific conference (2018, April 26)

Detailed reference viewed: 46 (17 ULiège)
Full Text
See detailEvolution et variations à long terme du mésozooplancton de la Baie de Calvi
Fullgrabe, Lovina; Grosjean, Philippe; Richir, Jonathan ULiege

Conference (2018, April 11)

Une série temporelle de 13 ans (2004-2016) du mésozooplancton de la baie de Calvi a été générée en adoptant une approche d’apprentissage supervisée (machine learning). A partir de méthodes d’analyse ... [more ▼]

Une série temporelle de 13 ans (2004-2016) du mésozooplancton de la baie de Calvi a été générée en adoptant une approche d’apprentissage supervisée (machine learning). A partir de méthodes d’analyse d’image et de classification (semi-) automatique, l’abondance mais également le spectre de taille de 14 groupes taxonomiques différents ont pu être déterminés avec un taux de réussite de classification de plus de 90%. L’abondance respective de chacun des groupes est caractérisée par une variation annuelle et/ou interannuelle et différentes corrélations avec des paramètres environnementaux sont soulignées. La caractérisation d’une variation annuelle moyenne par la succession d’ensemble de groupes a permis de décrire une variation interannuelle à l’échelle de communautés. Concernant la variation interannuelle des blooms printaniers, il est mis en évidence que bien que l’intensité du bloom soit corrélée à la température de l’eau, son présence/absence dépend de la concentration en nitrate. Aussi, les périodes et laps de temps caractérisant ces corrélations entre paramètres environnementaux et bloom ont été déterminés. De manière générale, le potentiel contenu dans ces données abondance mais aussi spectre de taille et la biomasse est suggéré. [less ▲]

Detailed reference viewed: 30 (1 ULiège)
Full Text
See detailContamination par les éléments traces en Méditerranée occidentale, focus sur la baie de Calvi et la Corse. Bilan et perspectives.
Gobert, Sylvie ULiege; Durieux, Eric; El Idrissi, Ouafa et al

Conference (2018, April 10)

Detailed reference viewed: 60 (4 ULiège)
Full Text
See detailEtude de la photosynthèse de Posidonia oceanica par fluorimétrie modulée
Richir, Jonathan ULiege; Abadie, Arnaud; Borges, Alberto ULiege et al

Conference (2018, April 10)

Numerous methods for measuring seagrass productivity and growth exist: evolution of O2 or CO2 (incubation chambers, optodes), biomass, shoot leaf elongation, determination of elementary contents … Another ... [more ▼]

Numerous methods for measuring seagrass productivity and growth exist: evolution of O2 or CO2 (incubation chambers, optodes), biomass, shoot leaf elongation, determination of elementary contents … Another possible method relies on pulse amplitude modulation fluorometry (PAM). This technique allows the determination of the photosynthetic quantum yield (Yield) from fluorescence re-emitted by chlorophyll a before and after the application of a saturating light pulse. The Yield determined along a gradient of irradiance draws a light curve (RLC, Rapid Light Curve) similar to photosynthesis-irradiance curves. Since spring 2015 several measurements of Posidonia oceanica photosynthetic activity have been performed at STARESO using diving-PAM fluorometers, for multiple related purposes. The results of these works show that: (i) the absorbance of light by P. oceanica leaves is lower than the average value of terrestrial plants, (ii) the Yield remains constant, being influenced neither by season nor by depth and only the strong light intensities at shallow depths cause its decrease (photoinhibition), (iii) RLCs highlight the high photochemical plasticity of the plant to environmental conditions, (iv) the maximum electron transfer rate modelled from RLCs seems to be a good indicator of the average elongation of shoot leaves and hence of shoot growth and (v) photosynthesis as a biomarker responds to short-term Cu exposures at environmentally relevant levels. Posidonia oceanica photosynthetic activity, which will further be monitored during an in situ shading experiment, is studied in parallel with the development of a new generic biomarker of stress, the ratio of concentrations of organosulfured coumpounds in the plant (dimethylsulfonioproprionate, DMSP and dimethylsulfoxide, DMSO). In conclusion, whether the scientific issue is ecophysiological, environmental, ecotoxicological, PAM fluorometry is a technical approach to consider. [less ▲]

Detailed reference viewed: 79 (5 ULiège)
Full Text
See detailEtude des séries temporelles : exemple de la température de l’eau
Richir, Jonathan ULiege; Borges, Alberto ULiege; Champenois, Willy ULiege et al

Conference (2018, April 10)

De nombreux paramètres biologiques, environnementaux, climatologiques sont mesurés à et par STARESO depuis des décennies. Les données récoltées sont accessibles via la base de données partagée RACE de ... [more ▼]

De nombreux paramètres biologiques, environnementaux, climatologiques sont mesurés à et par STARESO depuis des décennies. Les données récoltées sont accessibles via la base de données partagée RACE de l’Université de Liège. Dans le cas de séries temporelles, les paramètres suivis sont mesurés de manière séquentielle au cours du temps. La plus représentative est sans aucun doute la série des données de température de l’eau acquise depuis près de 40 ans. La température est un paramètre important qui permet de mettre en évidence sur le long-terme des changements notamment liés au réchauffement climatique, changements qui affectent le fonctionnement des océans tant dans la physique que dans la biologie. L’analyse des séries temporelles de données nécessitent souvent un important travail préparatoire de standardisation (intervalles de mesure irréguliers, trous dans la série, évolution des méthodes d’acquisition des données …). Une fois standardisées, les séries de données peuvent être analysées avec les outils et approches statistiques propres aux séries temporelles : décomposition de la série pour en extraire la tendance générale, statistiques glissantes, calcul des anomalies, analyse des quantiles, mise en évidence d’évènements extrêmes tels les vagues de chaleurs … Tout ce travail, conséquent, doit pouvoir être partagé, vérifié, validé et permettre la mise à jour ultérieure de l’analyse. C’est le concept même de science reproductible. Cette reproductibilité est rendue notamment possible par l’utilisation du langage de programmation R. Cette communication illustre, à travers l’exemple clef de l’évolution de la température de l’eau, l’analyse des séries temporelles de données dans le cadre de STARECAPMED. [less ▲]

Detailed reference viewed: 81 (4 ULiège)
Full Text
Peer Reviewed
See detailSuivi de la bioaccumulation de métaux traces dans la moule Mytilus galloprovincialis dans la région ouest algérienne
Rouabhi, Yamina Leila; Grosjean, Philippe; Rouane Hassene, Omar et al

Conference (2018, March 21)

L’Algérie est un pays côtier qui n’échappe pas aux pressions anthropiques multiples dont la pollution environnementale liée au développement démesuré de son littoral. Les contaminants notamment issus des ... [more ▼]

L’Algérie est un pays côtier qui n’échappe pas aux pressions anthropiques multiples dont la pollution environnementale liée au développement démesuré de son littoral. Les contaminants notamment issus des rejets urbains, agricoles et industriels impactent de manière croissante les écosystèmes aquatiques algériens. Ainsi, au niveau de la baie d’Oran, près de 80% des eaux usées sont rejetés en mer ou dans les oueds sans traitement préalable. A travers cette étude, nous avons évalué le degré de contamination du littoral algérien par les métaux traces : Zn, Cu, Pb, Fe et Ni. Nous avons réalisé un suivi saisonnier en 2010 de leurs bioaccumulation dans la moule Mytilus galloprovincialis prélevées en deux sites contrastés : le port d’Oran (site contaminé) et Ain Defla (Kristel) (site de référence). Les concentrations en métaux traces ont été mesurées par spectrophotométrie d’absorption atomique dans les branchies et les gonades de moules de 3 à 6 cm et dans des individus entiers (n = 30). Les résultats obtenus montrent que le port d’Oran est un site très contaminé, spécialement pour le Fe, le Zn et le Ni avec des concentrations de l’ordre de 66.57 ± 0.18, 31.31 ± 0.37 et 13.68 ± 0.07 ppm, respectivement dans les deux organes confondus. Les concentrations mesurées à Ain Defla pour ces mêmes métaux sont de 54.48 ± 0.15, 29.52 ± 0.63 et 2.92 ± 0.03 ppm, respectivement. Des différences du même ordre entre les deux sites ont été mesurées également dans les organismes entiers. Seul le Pb présente des concentrations plus élevées dans les branchies des moules prélevées à Ain Defla, soit 3.91 ± 0.29 ppm. Il existe une différence significative (p < 0.05) entre la bioaccumulation des métaux dans les deux organes du site de référence. Ainsi, à Ain Defla, le Fe, le Zn et le Cu sont plus concentrés dans les branchies (46.91 ± 1.60, 25.6 ± 1.07 et 2.68 ± 0.50 ppm, respectivement) que dans les gonades (29.06 ± 1.07, 21.76 ± 1.46 et 1.44 ± 0.20 ppm, respectivement). Dans le site contaminé du port d’Oran, seul le Zn présente des concentrations significativement différentes (p < 0.05) entre les deux tissus, avec des niveaux plus élevés dans les gonades. Chaque métal présente un cycle saisonnier de variation, avec des niveaux élevés durant les saisons hivernales et printanières dans les branchies et la moule entière et durant la saison printanière dans les gonades. La cinétique de bioaccumulation dans les branchies est par ailleurs similaire à celle de l’organisme entier (concentrations plus élevée en hiver) . La forte contamination du port d’Oran par les métaux traces révèle la nécessité d’un suivi écotoxicologique à plus grande échelle du littoral algérien. Or, un tel suivi y est actuellement quasi inexistant. Les branchies jouent un rôle dans la respiration, la filtration et l’excrétion. En tant qu’organe le plus exposé aux contaminants. On lui attribue donc souvent le rôle de tissu le plus approprié pour la biosurveillance. Dans des conditions de fortes contaminations telles que mesurées dans le port d’Oran, les différences tissulaires s’estompent néanmoins. Par ailleurs, M. galloprovincialis étant consommée par les populations locales, le suivi des teneurs en contaminants dans l’organisme entier est une problématique phytosanitaire à considérer. Quant à l’augmentation saisonnière des teneurs en éléments métalliques, elle peut s’expliquer à la fois par des changements de leur biodisponibilité dans le milieu et par le cycle éco physiologique de la moule. Notre étude démontre que M. galloprovincialis se révèle un bioindicateur approprié pour le monitoring de la contamination métallique des côtes algériennes, en prenant soin de normaliser son utilisation (taille, tissu, saison). [less ▲]

Detailed reference viewed: 29 (1 ULiège)
Full Text
Peer Reviewed
See detailChronic exposure to copper and zinc induces DNA damage in the polychaete Alitta virens and the implications for future toxicity of coastal sites
Watson, G. J.; Pini, J. M.; Richir, Jonathan ULiege

in Environmental Pollution (2018)

Copper and zinc are metals that have been traditionally thought of as past contamination legacies. However, their industrial use is still extensive and current applications (e.g. nanoparticles and ... [more ▼]

Copper and zinc are metals that have been traditionally thought of as past contamination legacies. However, their industrial use is still extensive and current applications (e.g. nanoparticles and antifouling paints) have become additional marine environment delivery routes. Determining a pollutant's genotoxicity is an ecotoxicological priority, but in marine benthic systems putative substances responsible for sediment genotoxicity have rarely been identified. Studies that use sediment as the delivery matrix combined with exposures over life-history relevant timescales are also missing for metals. Here we assess copper and zinc's genotoxicity by exposing the ecologically important polychaete Alitta virens to sediment spiked with environmentally relevant concentrations for 9 months. Target bioavailable sediment and subsequent porewater concentrations reflect the global contamination range for coasts, whilst tissue concentrations, although elevated, were comparable with other polychaetes. Survival generally reduced as concentrations increased, but monthly analyses show that growth was not significantly different between treatments. The differential treatment mortality may have enabled the surviving worms in the high concentration treatments to capture more food thus removing any concentration treatment effects for biomass. Using the alkaline comet assay we confirm that both metals via the sediment are genotoxic at concentrations routinely found in coastal regions and this is supported by elevated DNA damage in worms from field sites. However, combined with the growth data it also highlights the tolerance of A. virens to DNA damage. Finally, using long term (decadal) monitoring data we show stable or increasing sediment concentrations of these metals for many areas. This will potentially mean coastal sediment is a significant mutagenic hazard to the benthic community for decades to come. An urgent reappraisal of the current input sources for these ‘old pollutants’ is, therefore, required. Chronic exposure of zinc and copper via sediment at environmentally relevant concentrations induces DNA damage in a marine polychaete. © 2018 Elsevier Ltd [less ▲]

Detailed reference viewed: 13 (0 ULiège)
Peer Reviewed
See detailMetal bioaccumulation and Oxydatif stress in A. noae.
Ghribi, Feriel; Aouini, Fatma; Bejaoudi, Safa et al

Conference (2017, December)

Detailed reference viewed: 11 (1 ULiège)
Full Text
See detailBioaccumulation des métaux traces dans les organes la moule Mytilus galloprovincialis de la région ouest algérienne
Rouabhi, Yamina Leila; Rouane-Hacene, Omar; Grosjean, Philippe et al

Scientific conference (2017, September 26)

Detailed reference viewed: 44 (2 ULiège)
Full Text
See detailDes indices pour la définition de l'état des masses d'eau en milieu marin, mises au point, applications et aide à la gestion
Gobert, Sylvie ULiege; Richir, Jonathan ULiege

Conference (2017, March 29)

Comme les écosystèmes dulçaquicoles, les écosystèmes marins sont soumis à une pression humaine croissante qui altère la qualité de l’eau et les communautés aquatiques. Près de 98 pourcents de l’eau de ... [more ▼]

Comme les écosystèmes dulçaquicoles, les écosystèmes marins sont soumis à une pression humaine croissante qui altère la qualité de l’eau et les communautés aquatiques. Près de 98 pourcents de l’eau de notre planète bleue est contenue dans les océans qui constituent le réceptacle final de tout ce que nous rejetons comme déchets (volontairement ou non). Moins accessible, les océans sont méconnus, souvent oubliés ou négligés et considérés comme une zone inépuisable et où tout se dilue ; actuellement encore 80% des eaux usées sont rejetées en mer sans traitement préalable, à peine 2 % des surfaces marines sont protégées. La Méditerranée est particulière à plus d’un égard, bassin de concentration, de faible surface (1% des océans) abritant pourtant plus de 10% de la biodiversité mondiale. Cette petite mer est un modèle pour les océanographes : en mesurant ce qui s’y passe, nous pouvons prédire ce que se déroulera à court ou moyen terme dans le reste des océans. Le laboratoire d’Océanologie est activement impliqué depuis une quinzaine d’années dans la mise au point d’indice de la qualité des masses d’eau côtières. Ces indices sont construits sur base des connaissances du milieu (variations naturelles), par la mesure des niveaux de contamination et des effets (observation et contamination en mésocosme) de cette pollution sur les communautés. Nous avons développé et validé des indices biologiques (PREI : Posidonia Rapid and Easy Index, ICAR Indice Caulerpa cylindracea ; espèce envahissante), de pollution (TEPI : Trace Element Pollution Index, TESVI : Trace Element Spatial Variation Index), de qualité paysagère (LIMA LIttoral MArin) … Ces indices sont utilisés actuellement dans le cadre de la DCE (Directive Cadre Eau), la DCSMM (Directive Cadre Stratégie pour le Milieu Marin) et dans des réseaux de surveillance en Méditerranée, ils sont un relais et un moyen de communication entre les scientifiques et les politiques, les gestionnaires. L’exportation et l’apprentissage de l’utilisation de ces indices sont un atout pour une gestion globale de l’eau à l’échelle de la Méditerranée. Leurs applications sur l’ensemble de la façade méditerranéenne ont, entre autre, mis en évidence l’impact positif de l’application de directives européennes en matière de gestion des eaux par rapport aux côtes de Nord de l’Afrique. [less ▲]

Detailed reference viewed: 203 (14 ULiège)
Full Text
See detailFrom seascape level to functional ecology: A case study over P. oceanica seagrass meadows in Calvi, Corsica
Lapeyra Martin, Jon ULiege; Abadie, Arnaud; Richir, Jonathan ULiege et al

in Cartographie des habitats marins benthiques : de l’acquisition à la restitution. (2017)

see long abstract

Detailed reference viewed: 111 (25 ULiège)
Full Text
See detailSTARECAPMED, des indices pour La Méditerranée
Leduc, Michèle; Abadie, Arnaud; Donnay, Annick et al

in Cartographie des habitats marins benthiques : de l’acquisition à la restitution (2017)

Le projet STARECAPMED (STAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystems Drifts) a pour objectif (i) d’améliorer la compréhension du ... [more ▼]

Le projet STARECAPMED (STAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystems Drifts) a pour objectif (i) d’améliorer la compréhension du fonctionnement des différents écosystèmes marins côtiers présents en Méditerranée et (ii) de décrire l’influence des activités humaines sur les processus qui gouvernent ce fonctionnement. La baie de Calvi, par sa situation exceptionnelle, est un site de référence de la Directive Européenne Cadre sur l’Eau (DCE), du monitoring de l’eutrophisation et de la contamination par les éléments traces. La Station de recherches océanographiques STARESO, implantée dans la baie depuis près de 50 ans, possède un accès unique à la mer et de nombreuses facilités logistiques. Elle a développé au fil du temps une expertise scientifique reposant notamment sur l’acquisition de longues séries temporelles de données environnementales. Ensemble, Baie et Station s’intègrent en un site atelier dédié à l’évaluation de l’état de santé des écosystèmes marins côtiers de Méditerranée Nord-Occidentale. En particulier, différents indices et indicateurs y sont développés en collaboration avec de nombreux laboratoires partenaires. Ainsi, nous avons développé, d’une part, une version non destructive de l’indice PREI (Posidonia Rapid Easy Index) d’évaluation de la qualité des eaux côtières reposant sur le suivi des herbiers à Posidonia oceanica, et d’autre part, deux indices d’évaluation de l’impact des ancrages, puis testé   l’indice EBQI (Ecosystem Based Quality Index), une approche sur la diversité écologique. Les indices TEPI (Trace Element Pollution Index) et TESVI (Trace Element Spatial Variation Index) permettent d’évaluer la contamination par les éléments traces. Le BeMSI (BEnthic Methodology Simplification) est un nouvel indicateur de la qualité du milieu défini à partir de la composition des peuplements macrobenthiques des substrats meubles et plus généralement, l’indice LIMA traduit l’attrait paysager et la richesse patrimoniale du benthos méditerranéen entre 0 et –40 m. Quant à l’indice ICAR (Indice paysager CAulerpa Racemosa), il permet d’évaluer les niveaux de colonisation par l’algue invasive Caulerpa cylindracea. Enfin, une approche innovante reposant sur l’enregistrement des sons permet d’évaluer la qualité du milieu à partir d’un paysage acoustique sous-marin. En conclusion, le développement et l’application combinée de ces différents indices et indicateurs développés dans le cadre du programme pluridisciplinaire STARECAPMED fournissent une estimation globale des états du milieu côtier méditerranéen à différents niveaux d’organisation, depuis l’espèce jusqu’à l’écosystème. De plus, leur mise en œuvre dans ce même site atelier privilégié permet de les confronter, de les ajuster et de les intercalibrer pour à terme les proposer aux gestionnaires du milieu côtier. [less ▲]

Detailed reference viewed: 83 (11 ULiège)
Full Text
Peer Reviewed
See detailSeasonal characterization of the nutrients state in Oualidia Lagoon (Moroccan Atlantic coast)
Damsiri, Zainab; Natij, L.; Khalil, Karima et al

in Journal of Materials and Environmental Science (2017), 8(1), 67-77

The nutrient cycle in Oualidia lagoon, on the Atlantic Moroccan coast, was studied at both spatial and temporal scales, covering spring and summer conditions. Water samples were collected bimonthly at ... [more ▼]

The nutrient cycle in Oualidia lagoon, on the Atlantic Moroccan coast, was studied at both spatial and temporal scales, covering spring and summer conditions. Water samples were collected bimonthly at high tide from March to August during years 2011 and 2012 at six stations distributed throughout the lagoon. The physico- chemistry (temperature, salinity, dissolved O2) and nutrient enrichment of the lagoon surface water were monitored. The average nutrient concentration of surface water were 14.4 μmol.l-1 and 28.1 μmol.l-1 for NH4+, 20.4 μmol.l-1 and 19.9 μmol.l-1 for PO43- and 3.7 μmol.l-1 and 7.6 μmol.l-1 for NO2- in 2011 and 2012, respectively. Strong seasonal differences of nutrient distribution at the different stations were noticed. Temperature, salinity and dissolved O2 were correlated with nutrient concentrations, all parameters showing low spatial (inter-station) variability. Hydrological conditions exert a major control on the nutrient cycling in the lagoon. Results of this study are important to increase the richness on the scientific knowledge of nutrient dynamics along the Moroccan Atlantic coast, particularly in the semi-enclosed lagoons that are important transitional systems. [less ▲]

Detailed reference viewed: 45 (12 ULiège)
Full Text
Peer Reviewed
See detailCopper toxicity on coral holobiont photosynthetic processes
Georges, Nadège; Richir, Jonathan ULiege; Batigny, Antoine et al

Poster (2016, December 16)

Copper (Cu), an essential micronutrient to organisms, may become toxic when present at too high environmental concentrations. This metal remains an aquatic contaminant of concern, notably because of its ... [more ▼]

Copper (Cu), an essential micronutrient to organisms, may become toxic when present at too high environmental concentrations. This metal remains an aquatic contaminant of concern, notably because of its recent re-use as biocide in metal-based antifouling paints. The aim of this study was to monitor the physiological alterations in a zooxanthellate coral species and its endosymbionts (i.e. the coral holobiont) exposed to increasing Cu concentrations. Nubbins of Seriatopora hystrix were exposed for 8 days in 1 L intermittent respirometers to 5 nominal Cu concentrations: 0-2-5-15-50 ppb. Respirometers were maintained at 25.0±0.2°C with successive open/close cycles of 30 min. A 12/12 hours day-night light regime was applied with constant daylight intensity of 200 μmol photons m-2 s-1. Water renewal rate during the 30 min open cycles was 15 mL.min-1. The photosynthetic performances of coral endosymbionts were assessed daily with a fluorescence imaging system (imaging-PAM). At the end of the 8-days experiment, the maximal photochemical quantum yield (FV/FM) of coral nubbins had decreased by 12% and 38%, respectively, in the 15 ppb and 50 ppb treatments. This decrease was even greater for the effective photochemical quantum yield (ɸPSII) with values dropping by 41% and 54%, respectively. Cu exposure also affected the symbiosis between the coral host and its endosymbionts. Nubbins of the 15 ppb treatment slightly lightened from day 6, whilst nubbins exposed to the 50 ppb treatment lightened from day 3, and started to bleach from day 6. The analysis of nubbins’ primary productivity did not coincide with the above observations, the oxygen production within each respirometer remaining relatively constant during the overall experiment for all treatments. This unexpected observation may be the sign of a compensation mechanism. In conclusion, Cu affected the photosynthetic processes of S. histrix within 8 days from relevant environmental concentrations of 15 ppb. The exposure of corals to toxic chemicals thus has to be considered as an additional stressor to, e.g., ocean acidification or elevated temperature, which may disturb their ecophysiology and lead to bleaching. [less ▲]

Detailed reference viewed: 81 (6 ULiège)
Full Text
Peer Reviewed
See detailBioaccumulation of trace metals in Mytilus galloprovincialis from the Algerian west coast
Rouabhi, Leila; Rouanne, Hassen Omar; Benkrama, Hadjer et al

Poster (2016, December 16)

Algeria has a 1622 km long coastal strip where a large proportion of the population and the main economic and industrial activities of the country are concentrated. Its coastal fringe therefore suffers ... [more ▼]

Algeria has a 1622 km long coastal strip where a large proportion of the population and the main economic and industrial activities of the country are concentrated. Its coastal fringe therefore suffers from various degradations. In particular, the Bay of Oran is housing industrial, commercial, fishing and recreational activities, where 80 % of domestic and industrial wastewaters are not purified before being discharged into the sea. Thus, the aim of the present work was to evaluate the degree of metallic contamination of coastal waters of western Algeria. Trace metals (Zn, Cu, Ni, Fe and Pb) were measured by atomic absorption spectroscopy in the dry soft tissues (gills and gonads) of the mussel Mytilus galloprovincialis Lamarck, 1819 collected during the four seasons of year 2010 in 2 sites: the highly polluted Oran harbor (S1) and Ain Defla (S2), a site distant enough from Oran and presumed little contaminated. Oran harbor was globally more contaminated than Ain Defla, especially for Fe, Zn and Ni. However, Pb levels were higher at Ain Defla with concentrations up to 3.35 ± 0.25 ppm in the gills. Metal concentrations differed between organs. Fe, Zn and Cu were more accumulated in gills (46.91 ± 1.60 ppm, 25.6 ± 1.07 ppm, 2.68 ± 0.50 ppm, respectively) compared to gonads (29.06 ± 1.07 ppm, 21.76 ± 1.46 ppm ppm, 1.44 ± 0.20 ppm, respectively). Each metal followed a seasonal trend, showing concentration peaks during winter and spring for gills and autumn for gonads. This study demonstrated the need to biomonitor the metallic contamination of Algerian coasts. But such monitoring surveys, relying on organisms, will require consensual sampling and analytical protocols to avoid hazardous conclusions due to tissue speciation and accumulation seasonality. [less ▲]

Detailed reference viewed: 58 (5 ULiège)
Full Text
Peer Reviewed
See detailExploring a Mediterranean mesozooplankton 13 year time-series.
Fullgrabe, Lovina; Richir, Jonathan ULiege; Batigny, Antoine et al

Poster (2016, December 16)

Zooplankton plays diverse crucial roles within the marine ecosystem and can also be used as bio- indicator of climate changes since it is very sensitive to environmental changes. Therefore it is essential ... [more ▼]

Zooplankton plays diverse crucial roles within the marine ecosystem and can also be used as bio- indicator of climate changes since it is very sensitive to environmental changes. Therefore it is essential to consider long-term plankton series. Given the analysis of plankton samples is time- consuming, it requires an effective and rapid analytical method. We have used in this work a supervised learning approach adapted for the semi-automatic classification of digital images of the mesozooplankton of the Bay of Calvi (Corsica, France) by using the Zoo/PhytoImage software. Together with a 11-years long zooplankton time-series, a set of nine environmental variables were monitored in order to identify controlling factors and determine whether the communities were sensitive to global environmental changes. The main components of the mesozooplankton community were characterized by both seasonal and inter-annual variability. Additionally, variation of holoplankton and meroplankton differentiated one from each other. The holoplanktonic community could be split into two subgroups according to its variation in function of the environment: cladocerans and appendicularians, and to a lesser extent, copepods on one hand, and cnidarians, chaetognathes and thaliaceans, on the other hand. Regarding inter-annual variation, one year (2007) showed particularly low production of total zooplankton which was also the case for all the different holoplanktonic taxa. Accounting for that phenomenon were identified some potentially underlying environmental factors. Finally, although water temperature increased significantly over the last years along with the frequency of marine heat wave events, no evident change in the global zooplankton composition was observed yet. [less ▲]

Detailed reference viewed: 74 (11 ULiège)
Full Text
See detailAssessing edge-effects in Posidonia oceanica seagrass meadows: A multidisciplinary approach
Lapeyra, Jon; Abadie, Arnaud; Lejeune, Pierre et al

Conference (2016, December)

Structural boundaries in ecosystems play an important role both in the context of seascape architecture, ecological processes and biodiversity. The Mediterranean Seagrass Posidonia oceanica (L.) Delile is ... [more ▼]

Structural boundaries in ecosystems play an important role both in the context of seascape architecture, ecological processes and biodiversity. The Mediterranean Seagrass Posidonia oceanica (L.) Delile is considered an ecosystem engineer species, forming habitats of great ecological value and providing many ecosystem services. This study aims to (1) determine whether there are differences between seagrass-sand corridors edges and the adjacent continuous meadow, and (2) investigate whether anthropogenic pressures can cause disturbances in the measured parameters along the edges and the meadow. We have developed a multidisciplinary approach combining plant physiology, faunal canopy community studies and seagrass structural parameters characterization. We performed in situ chlorophyll fluorescence measurements using a Pulse Amplitude Modulated (Diving-PAM) fluorometry in order to assess the photosynthetic rate of the shoots. Vagile macrofauna of the leaf stratum was sampled by a hand-towed net, and the major taxonomic groups were sorted, counted, and identified. Meadow’s biometric measurements and the epiphytic biomass were also determined. Regarding edge-meadow matrix, results have shown highest differences on matrix structural parameters such as shoot density and shoot type proportions. Shoot density was found to decrease in edges considerably. We found c.a to 60 % plagiotropic shoots on edges while in continuous meadow orthotropics were predominant (up to 90 %). Howerver vagile-fauna population densities and diversity did not differ significantly among stations studied, neither by sites. Photosynthetic rate and leaf surface values also did not show changes between edges and continuous meadow. However, results did show that plagiotropic shoots had higher photosynthetic rate than orthotropics, and also that epiphyte abundance sorted out to be much higher (up to 54 %) on edges. [less ▲]

Detailed reference viewed: 135 (30 ULiège)
Full Text
Peer Reviewed
See detailEcoNum, a research unit devoted to marine environment monitoring
Richir, Jonathan ULiege; Batigny, Antoine; Georges, Nadège et al

Conference (2016, October 27)

The monitoring of coastal environments remains a research domain of great interest and concern. Coastal ecosystems are threatened by natural and human-induced stressors and are, as transitional ... [more ▼]

The monitoring of coastal environments remains a research domain of great interest and concern. Coastal ecosystems are threatened by natural and human-induced stressors and are, as transitional environments, particularly sensitive to disturbances. EcoNum first research thematic revolves around hermatypic corals, calcifying organisms, and their adaptation potentials to environmental changes including by using original and patented chemostats. The studied organisms are grown and maintained in artificial mesocosms that simulate environmental conditions of a natural system. This infrastructure allows to perform long-term experiments, giving time to organisms to adapt to the tested conditions (e.g., increased temperature or lowered pH). Longer-term studies have demonstrated that many organisms are more resistant to environmental stressors than previously observed on the short-term. EcoNum also studies coastal plankton abundance and diversity. Plankton is particularly sensitive to physicochemical changes of water bodies. The classification and the enumeration of planktonic organisms require specialized tools in order to analyse time series of multiple samples. EcoNum has developed a software for the semi-automatic classification of planktonic organisms called Zoo/PhytoImage. This software has been used to study a 10-year time series of coastal Mediterranean zooplankton samples. The concomitant analysis of environmental parameters registered at high frequency with specific statistical tools such as the R package pastecs allows to understand the processes governing the changes observed in plankton assemblages. The use and the development of statistical tools in R (e.g., Zoo/Phytoimage, pastecs) is a priority of EcoNum to favour open access knowledge and reproductive sciences. EcoNum research topics also focus on coastal ecotoxicology. Chemicals, including trace elements, remain contaminants of concern, mainly in coastal environments that are the final sink of inland pollution sources. The chemical integrity of coastal ecosystems thus has to be accurately monitored. The partitioning of chemicals between their dissolved, particulate and sedimentary phases does not provide information on their bioavailability. EcoNum thus monitors coastal waters using bioindicator species such as seagrasses, mussels or sand worms. A global map of the contamination of the Mediterranean by trace elements has been drawn using seagrasses has bioindicator species. EcoNum also studies trace element ecology and toxicology. For instance, it has demonstrated the toxicity of copper on the coral Seriatopora hystrix and it's symbiont's photosynthetic processes, or its bioaccumulation and basipetal translocation towards rhizomes in the seagrass Posidonia oceanica as reserve nutrient for subsequent leaf growth. Finally, coastal vegetated systems are potential carbon thinks (or sources) in the global carbon cycle. Therefore, EcoNum studies the primary productivity of seagrass meadows, from the individual to the community, with measuring techniques as diverse as PAM-fluorometry or biomass production determination. To conclude, EcoNum is a research unit devoted to marine environment monitoring. It develops research thematics on major coastal communities such as coral reefs, seagrass beds or plankton assemblages and studies their natural dynamics and the effects of stressors on their global functioning. [less ▲]

Detailed reference viewed: 129 (8 ULiège)