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See detailInterspecific variation of warning calls in piranhas: a comparative analysis
Melotte, Geoffrey ULg; Vigouroux, Régis; Michel, Christian ULg et al

Conference (2016, December 17)

Fish sounds are known to be species-specific, possessing unique temporal and spectral features. We have recorded and compared sounds in eight piranha species to evaluate the potential role of acoustic ... [more ▼]

Fish sounds are known to be species-specific, possessing unique temporal and spectral features. We have recorded and compared sounds in eight piranha species to evaluate the potential role of acoustic communication as a driving force in clade diversification. All piranha species showed the same kind of sound-producing mechanism: sonic muscles originate on vertebrae and attach to a tendon surrounding the bladder ventrally. Contractions of the sound-producing muscles force swimbladder vibration and dictate the fundamental frequency. It results the calling features of the eight piranha species logically share many common characteristics. In all the species, the calls are harmonic sounds composed of multiple continuous cycles. However, the sounds of Serrasalmus elongatus (higher number of cycles and high fundamental frequency) and S. manueli (long cycle periods and low fundamental frequency) are clearly distinguishable from the other species. The sonic mechanism being largely conserved throughout piranha evolution, acoustic communication can hardly be considered as the main driving force in the diversification process. However, sounds of some species are clearly distinguishable despite the short space for variations supporting the need for specific communication. Behavioural studies are needed to clearly understand the eventual role of the calls during spawning events. [less ▲]

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See detailManufacture and use of points at Maisières-Canal
Touzé, Olivier ULg; Coppe, Justin ULg; Taipale, Noora ULg et al

Conference (2016, December 17)

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See detailPrésentation du projet Economie et pratiques des sociétés gravettiennes dans le Nord-Ouest de l’Europe (ECOPRAT)
Touzé, Olivier ULg; Salomon, Hélène ULg; Goutas, Nejma et al

Poster (2016, December 17)

Nous présentons dans cette contribution un projet collectif porté par le Service de Préhistoire de l’Université de Liège et l’équipe Ethnologie préhistorique de l'unité mixte de recherche du CNRS ... [more ▼]

Nous présentons dans cette contribution un projet collectif porté par le Service de Préhistoire de l’Université de Liège et l’équipe Ethnologie préhistorique de l'unité mixte de recherche du CNRS Archéologie et Sciences de l'Antiquité. Le projet « ECOPRAT » entend contribuer au renouvellement des connaissances relatives aux sociétés gravettiennes du Nord-Ouest européen, et prolonger ainsi la dynamique de recherche actuelle touchant ces sociétés (Bodu et al., 2013). Il s’inscrit dans une perspective pluridisciplinaire envisagée grâce à l’association d’études technologiques, tracéologiques et archéozoologiques. Quatre sites majeurs du Nord-Ouest européen ont été retenus : les gisements de plein air de Maisières-Canal (Prov. Hainaut, Belgique) et d’Ormesson – Les Bossats (Seine-et-Marne, France), et les grottes de Goyet (Prov. Namur, Belgique) et du massif d’Arcy-sur-Cure (Yonne, France). Les sites sélectionnés possédant des historiques de recherche spécifiques, la stratégie d’analyse adoptée pour chacun d’eux est développée en adéquation avec l’état des connaissances actuelles. Les recherches sont ainsi guidées par l’obtention de données inédites qui doivent permettre, à terme : 1) une lecture renouvelée et croisée des industries lithiques et osseuses, ainsi que des ensembles fauniques et des matières colorantes découverts dans ces gisements, 2) un rééquilibrage quantitatif et qualitatif de l’intégration des différentes sources documentaires disponibles, la recherche s’étant davantage concentrée depuis plus d’un siècle sur les données de l’industrie lithique. Les deux gisements de plein air réunissent les conditions indispensables au développement d’une approche interdisciplinaire permettant de croiser objets et méthodes d’étude, afin de proposer une lecture fine des comportements techniques et économiques des sociétés gravettiennes. A cet égard, cette contribution est l’occasion de présenter les premiers résultats obtenus sur le site de Maisières-Canal. Les recherches réalisées jusqu’à présent permettent de réévaluer l’importance de l’industrie sur matières dures d’origine animale, au sein de laquelle le travail de l’ivoire de mammouth se révèle particulièrement significatif. En outre, le corpus faunique traduit une exploitation récurrente du lièvre, ce type de comportement s’avérant singulier au regard de ce qui est habituellement documenté chez les sociétés du Gravettien. Parmi les différentes activités susceptibles de laisser une trace archéologique, l’usage de matières colorantes apparaît particulièrement discret dans le cadre spatio-temporel considéré. Cet usage est cependant avéré dans les grottes d’Arcy-sur-Cure (grottes du Renne et du Trilobite), lesquelles permettront ainsi d’entreprendre une étude ciblée de ce phénomène. Enfin, les grottes de Goyet offrent la possibilité de contribuer à la connaissance de la séquence gravettienne du Nord-Ouest européen. Si le long historique des fouilles menées dans ces grottes, ainsi que les mélanges manifestes affectant les collections, ne permettent pas d’envisager une étude approfondie des comportements gravettiens, des observations préliminaires permettent en revanche de s’interroger sur le potentiel de ces sites pour la reconstitution de cette séquence. A l’instar de ce qu’ont montré les travaux récemment conduits sur le Gravettien de Spy (Pesesse & Flas, 2013), il est en effet vraisemblable que les grottes de Goyet aient été occupées à plusieurs moments de la période gravettienne. BODU P., CHEHMANA L., KLARIC L., MEVEL L., SORIANO S., TEYSSANDIER N. (dir.), 2013. Le Paléolithique supérieur ancien de l’Europe du Nord-Ouest : réflexions et synthèses à partir d’un projet collectif de recherche sur le centre et le sud du Bassin parisien, Actes du colloque de Sens, 15-18 avril 2009. Paris : Société préhistorique française (Mémoires de la Société préhistorique française, 56), 516 p. PESESSE D., FLAS D., 2013. Which Gravettians at Spy? In : ROUGIER H., SEMAL P. (eds), Spy Cave. 125 years of multidisciplinary research at the Betche-aux-Roches (Jemeppe-sur-Sambre, Province of Namur, Belgium). Volume I. Bruxelles : Institut royal des Sciences naturelles de Belgique, Société royale belge d'Anthropologie et de Préhistoire, NESPOS Society (Anthropologica et Praehistorica, 123), pp. 257-268. [less ▲]

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See detailTrophic ecology of Southern Ocean sea stars inferred from stable isotopes ratios of C and N
Le Bourg, Baptiste ULg; Blanchard, Alice; Danis, Bruno et al

Conference (2016, December 17)

The Southern Ocean undergoes strong and contrasted impacts of climate change. Increasing seawater temperature and sea ice cover reduction in Western Antarctic Peninsula and associated regions will likely ... [more ▼]

The Southern Ocean undergoes strong and contrasted impacts of climate change. Increasing seawater temperature and sea ice cover reduction in Western Antarctic Peninsula and associated regions will likely impact food web structure and function. Sea stars (Echinoderms: Asteroidea) are an important group of the Southern Ocean benthos. They typically have highly variable feeding habits and are potentially more resistant than other organisms to temperature changes. Consequently, they will likely be impacted by modifications of the food web rather than by direct warming. Investigating their trophic ecology is therefore necessary to infer how climate change will impact them. In this context, the aim of this study was to use stable isotopes ratios of C, N and S to infer sea stars trophic ecology. During austral summers 2006 and 2009, sea stars were sampled in Subantarctic and Antarctic locations, with most of the samples coming from South Shetland Islands and South Georgia. The isotopic niche (proxy of the trophic niche) associated to each sea star population was explored through SIBER (Stable Isotope Bayesian Ellipses in R) metrics. Stable isotope ratios of sea stars were clearly different between South Shetland Islands and South Georgia. Sea stars of South Shetland Islands had smaller isotopic niches than sea stars of South Georgia. The overlap between the isotopic niches of sea star species was also important in South Shetland Islands, while isotopic niches of South Georgia were well separated. Difference of niche width and overlap between the two regions may be the result of different environmental conditions. In South Shetland Islands, sea star species may exploit a common benthic community relying on organic matter released during sea ice summer melting. In contrast, South Georgia is an oligotrophic environment with no sea ice. As resources are more limited, a higher trophic segregation between sea stars may appear to limit competition. Ultimately, this project highlighted the importance of sea ice in the trophic ecology of Antarctic sea stars. Our results suggest that future reduction of sea ice extent in Western Antarctica may have deleterious effect on sea star populations. [less ▲]

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See detailImportance de l'utilisation des Systèmes d'Information Géographique pour les vastes sites de plein air du Paléolithique Moyen en France septentrionale. L'exemple de Caours (Somme, France).
Moreau, Gwénaëlle ULg; Locht, Jean-Luc

Conference (2016, December 17)

During the middle Palaeolithic, the northern France was only occupied by Neanderthals groups. However, successions of glacial and interglacial cycles explain a complex and discontinuous settlement ... [more ▼]

During the middle Palaeolithic, the northern France was only occupied by Neanderthals groups. However, successions of glacial and interglacial cycles explain a complex and discontinuous settlement, raising complication in the study of its dynamics at a regional scale. Therefore, some aspects of Neanderthals behaviour are still mischaracterize: in most cases, the function of the site and its territorial management over the northern France have to be specified. The spatial analysis of open air sites from northern France will help us to answer those questions. However, for Middle Palaeolithic sites, we can’t see systematically on the field the spatial organisation directly, we sometimes need modelization. Therefore, we started to build a spatial analysis protocol adapted to this site and applied to such sites. The sites of Caours (Somme, France) and Beauvais (Oise, France) are two open air sites that are exceptionally well preserved and displaying a large amount of faunal and lithic rests. Both are perfect candidate to apply and test the new protocol. First results proved that for each site the existence of a spatial organisation as remains concentration zones. Then, we characterize this areas – number, distribution. Finally, we were able to associate them to human activity areas like hearths, butchery or knapping areas. [less ▲]

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See detailMulti-GNSS relative positioning with Galileo, BeiDou and GPS
Deprez, Cécile ULg; Warnant, René ULg

Conference (2016, December 16)

For several years, the number of Global Navigation Satellite Systems (GNSS) has been increasing, opening new perspectives in the field of precise positioning. Particularly, the European system, Galileo ... [more ▼]

For several years, the number of Global Navigation Satellite Systems (GNSS) has been increasing, opening new perspectives in the field of precise positioning. Particularly, the European system, Galileo, is experiencing a prompt expansion with the launch, in 2015 and 2016, of 8 satellites belonging to the new Full Operational Capability (FOC) generation. Broadcasting new signals, with new modulations, the first studies addressing this system reveal promising level of precisions on both code and carrier phase observables. Yet, Galileo is far from being the only GNSS undergoing a noteworthy revolution. Alternatively, the Chinese program BeiDou, still in a developing phase, as well as the American GPS, currently undergoing a modernization of its signals, also knew major progress these last two years. Indeed, 7 new satellites have reached the initial BeiDou constellation, bringing to 20 the number of active satellites. Among them, 5 spacecraft inaugurated the Phase III generation, broadcasting the new B1, B2 and B3 signals. Regarding GPS, the block IIF, made of L5 signal broadcasting satellites, kept expanding but at a less steep rate than BeiDou or Galileo. In this study, we first estimated the individual precisions of each signals broadcast by the aforementioned GNSS. For this purpose, we created two short baselines of approximatively 5 meters between similar type receivers. We combined their measurements to form double differences, leaving in the position equations only multipath and receiver noise. The great expectations regarding Galileo’s quality turned into affirmations as long as we studied this system. As a matter of a fact, the code pseudoranges values of the 4 signals of Galileo we have considered (E1, E5a, E5b, E5a+b) presented outstanding precisions (from 5 to 17 centimetres on code pseudoranges with an elevation mask of 10 degrees) when compared to GPS (from 12 to 20 centimetres on codes pseudoranges) and BeiDou (from 26 to 40 centimetres for codes and for phases) in identical conditions. Even though the precision of Galileo observables is noticeable, the influence of the poor geometry of the satellite constellation degrades in a significant way the resulting precision of the position estimated, no matter the recent increase in the number of satellites. Indeed, in this incomplete constellation, the addition of new satellites results in longer visibility period but not in larger number of satellites observed at a single epoch. Combining Galileo with GPS or BeiDou is a way to solve this issue, as the three systems have been designed to be compatible. Therefore, multi-GNSS relative positioning based on overlapping frequencies should entail better accuracy and reliability in position estimations. However, the differences between satellite systems induce inter-system biases (ISBs) inside the multi-GNSS equations of observation. The overlapping frequencies of these GNSS are the L1 and L5 frequencies of GPS with the E1 and E5a signals of Galileo, respectively. As far as BeiDou is concerned, the B2 signal of emitted by the Phase II BeiDou satellites corresponds to the E5b frequency of Galileo. Regarding the new Phase III satellites, the B2 frequencies will correspond to the Galileo E5a+b signal and B1 of BeiDou will be compatible with E1 of Galileo and GPS. The combined use of these overlapping frequencies in zero baseline double differences (ZB DD) based on a unique pivot satellite is employed to resolve ISBs. This model removes all the satellite- and receiver-dependent error sources by differentiating and the zero baseline configuration allows atmospheric and multipath effects elimination. We conducted this study on the L1/E1, L5/E5a, B1(phase II)/E5b overlapping frequencies. Our receivers were not able to receive the phase III signals of BeiDou satellites. An analysis of the long-term stability of ISBs (GPS- Galileo and Galileo - BeiDou) was conducted on various pairs of receivers over large time spans. The possible influence of temperature variations inside the receivers over ISB values was also investigated. Our study is based on the 6 multi-GNSS receivers (2 Septentrio PolaRx4, 1 Septentrio PolaRxS, 1 Septentrio PolaRx5 and 2 Trimble NetR9) installed on the roof of our building in Liege. The estimated ISBs are then used as corrections in the multi- GNSS observation model and the resulting accuracy of multi-GNSS positioning is compared to GPS, Galileo and BeiDou standalone solutions. [less ▲]

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See detailInsects complex associated with the tropical basil, Ocimum gratissimum L. (Lamiaceae) in southern Benin.
Yarou, Boni Barthélémy ULg; Bokonon-Ganta, H. Aimé; Assogba Komlan, Françoise et al

Poster (2016, December 16)

Tropical basil is an aromatic leafy vegetable used for its medicinal and therapeutic properties in numerous countries in West Africa (Benin, Nigeria, Togo, etc.). In Benin, it is produced on almost all ... [more ▼]

Tropical basil is an aromatic leafy vegetable used for its medicinal and therapeutic properties in numerous countries in West Africa (Benin, Nigeria, Togo, etc.). In Benin, it is produced on almost all urban and periurban garden throughout the year for fresh market. Until now there are few or nearly no publications about the arthropod community of this specie, even less in the context of Benin. Thus, to assess this community, basil plots were mowed using a sweep net in three localities (Ouidah, Togba and Sèmè) of southern Benin. Preliminary results focus on the different insect families that colonized tropical basil in southern Benin environmental conditions. These include: Aphididae (Homoptera), Cercopidae (Homoptera), Chrysomelidae (Coleoptera), Coccinelledidea (Coleoptera), Meloidae (Coleoptera), Braconidae (Hymenoptera), Ichneumonidae (Hymenoptera), Formicidae (Hymenoptera), Vespidae (Hymenoptera), Apoidae (Hymenoptera), Reduviidae (Heteroptera), Pentatomidae (Heteroptera), Pyrgomorphidae (Orthoptera), Acrididae (Orthoptera), Syrphidae (Diptera), Diopsidae (Diptera). Among these families, there are pests: Aphis gossypii G. (Homoptera: Aphididae), Zonocerus variegatus L. (Orthoptera: Pyrgomorphidae), etc.; predators: Ischiodon aegyptius W. (Diptera: Syrphidae), Cheilomenes spp. (Coleoptera: Coccinelledidea), Rhynocoris spp. (Heteroptera: Reduviidae), etc.; parasitoids and pollinators. From this study, it appeared that there is a large diversity of families and functional groups (pests, predators, parasitoids and pollinators) associated with tropical basil . Moreover, the presence of natural enemies could be an advantage for farmers in intercropping systems. This would help reduce the use of synthetic insecticides. This result, which is a first knowledge of the insect fauna associated with tropical basil under the environmental conditions of Southern Benin, will be supplemented by a spatio temporal study to assess the variability and the dynamics of this insect fauna. [less ▲]

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See detailTuta absoluta (Lepidoptera: Gelechiidae) ability to develop on potato tubers
Bawin, Thomas ULg; De Backer, Lara ULg; Yarou, Boni Barthélémy ULg et al

Poster (2016, December 16)

Tuta absoluta (Lepidoptera: Gelechiidae) is a widespread pest that threatens commercial production of solanaceous crops. Larvae feed on the mesophyll of all aerial parts of the plants resulting in ... [more ▼]

Tuta absoluta (Lepidoptera: Gelechiidae) is a widespread pest that threatens commercial production of solanaceous crops. Larvae feed on the mesophyll of all aerial parts of the plants resulting in significant yield losses and cosmetic damages.It is classically assumed that underground plant parts are not affected but larval development on potato tubers has recently been suspected. However, this assumption is poorly supported in the literature. Potato tubers might represent an unsuspected mean of persistence and dispersal in agricultural environments.Oviposition tests were here conducted using dormant and active (sprouts less than 5 cm) potato tubers in net cages. Oviposition only occurred on the sprouts of active tubers, supporting larval growth until adult emergency. Tuber dissection revealed burrows starting from sprouts inside the flesh. Additional fitness assays were conducted on non-sprouted tubers and revealed that first instar larvae were able to enter the skin and create burrows, living inside and feeding on potato flesh, although none of them survived. [less ▲]

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See detailEnergy Dissipation in Saturn’s Magnetotail: A Comparative Magnetotail Approach
Yao, Zhonghua ULg; Coates, Andrew; Ray, Licia et al

Poster (2016, December 16)

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See detailDetermining the Substorm Onset Instability Using Ground and Space-Based Measurements
Rae, Jonathan; Watt, Clare; Murphy, Kyle et al

Poster (2016, December 16)

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See detailChapter VIII "Equations and languages" in J.-É. Pin, Mathematical Foundations of Automata Theory
Stipulanti, Manon ULg

Conference (2016, December 16)

We present the chapter VIII titled "Equations and Langages" in Jean-Éric Pin, Mathematical Foundations of Automata Theory.

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Peer Reviewed
See detailThe role of AIP mutations in pituitary adenomas: 10 years on
Daly, Adrian ULg; BECKERS, Albert ULg

in Endocrine (2016)

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See detailDe niet-toepassing van de mainplévie in Maastricht
Lagasse, Benoît ULg

Conference (2016, December 16)

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See detailRelationship between jaw morphology, bite performance and diet in Serrasalmidae (Characiformes, Teleostei)
Huby, Alessia ULg; Lowie, Aurélien; Herrel, Anthony et al

Conference (2016, December 16)

Serrasalmidae are mainly known for “piranhas” and their negative reputation of ferocious predatory fishes. A recent study demonstrated that the piranha $Serrasalmus rhombeus£ had an extreme bite force ... [more ▼]

Serrasalmidae are mainly known for “piranhas” and their negative reputation of ferocious predatory fishes. A recent study demonstrated that the piranha $Serrasalmus rhombeus£ had an extreme bite force that is even proportionally greater than that of the white shark. However, these sharp teeth fishes represent only a minority of Serrasalmidae. Other serrasalmid species (pacus and myleus) feed on plants, fruits or seeds and their bite force and feeding capacities are still uninvestigated. In the present research, in vivo bite forces were measured and compared according to jaw morphology in ten species of Serrasalmidae including six herbivorous and four carnivorous species. The Bite Force Quotient (BFQ) was calculated for each individual to compare the jaw strength across species. The results of the analysis showed that species feeding on fins and fish flesh have a significant greater bite force than species feeding on plants, fruits or seeds. This difference can be explained by the larger adductor mandibulae muscle in carnivorous species which have comparatively longer and higher skull than herbivorous species. In addition, there is a significant difference in the lower jaw morphology between piranhas and pacus and relatives. The piranha species have longer lower jaws than pacus and myleus species which have shorter and higher lower jaws. This study shows that the Serrasalmidae family regroups remarkable biters whose bite performance is mostly related to diet. [less ▲]

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See detailExploring a Mediterranean mesozooplankton 13 year time-series.
Fullgrabe, Lovina; Richir, Jonathan ULg; 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 ▲]

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See detailStream-aquifer interactions: a combined field - methodological approach in fractured carbonate catchments
Brouyère, Serge ULg; Briers, Pierre ULg; Orban, Philippe ULg et al

Conference (2016, December 16)

Stream-aquifer studies remain a challenge due to numerous factors impacting these interactions. They play a fundamental role in terms of quantity and quality of water, in particular on the ecological ... [more ▼]

Stream-aquifer studies remain a challenge due to numerous factors impacting these interactions. They play a fundamental role in terms of quantity and quality of water, in particular on the ecological status of rivers. Field quantification of such interactions is a first step but it has to be in relation with the whole budgets of water and transported substances across the catchment in order to represent their importance on overall fluxes. Numerous complementary investigations have to be undertaken to achieve such understanding of catchment behavior, in particular to estimate specific indicators and to achieve representative data for modeling stream-aquifer interactions. From that situation, our study aims to characterize and quantify stream-aquifer interactions to assess reliability of diverse field experiments methodologies. A catchment has been studied for 3 years in quantitative and qualitative ways via a dense instrumentation and monitoring. Numerous complementary investigations (discharge measurements, hydrogeochemistry, distributed temperature sensing, base flow separation…) have been applied to reach the objectives. We achieved a large and diversified measurement dataset of groundwater-surface water interactions and whole water budget. This allowed reaching an improved understanding of the catchment behavior to quantify importance of the groundwater component on the dynamics and chemistry of the stream and on the consequences on river ecological status. The investigations on several subcatchments allows also to propose a general typology of stream catchment in terms of groundwater dependence based on the combination of various groundwater contexts and groundwater-stream interaction indicators. Methodologies applied in this study allow to emphasize strength and weakness of numerous investigations in a stream aquifer project and conclusions can be reproduced and generalized to other contexts. [less ▲]

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See detailCopper toxicity on coral holobiont photosynthetic processes
Georges, Nadège; Richir, Jonathan ULg; 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 ▲]

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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 ▲]

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