Valorisation des sous-produits agro-industriels dans l'alimentation du poisson-chat africain, Clarias gariepinus (Burchell 1822), au Rwanda

L’objectif de cette étude était de déterminer dans quelle mesure les farines de poissons pouvaient être remplacées par des sous-produits agro-industriels dans la formulation d’aliments destinés aux juvéniles de Clarias gariepinus (Burchell 1822) élevés au Rwanda. Trois sous-produits végétaux, les tourteaux d’arachide (TA) et de tournesol (TT), et la farine de haricot (FH), ont été inclus dans 6 régimes expérimentaux isoprotéiques et isoénergétiques (38 % de protéines brutes et 19-21 kJ d’énergie brute par kg d’aliment) de manière à remplacer partiellement, voire totalement, la farine de poissons. Le tourteau de tournesol (TT) fut également trempé (TTT) ou décortiqué (TTD) afin d’étudier les effets de ces deux prétraitements sur leur utilisation biologique. Les résultats des analyses zootechniques et biochimiques (taux de croissance spécifique, SGR, efficacité de conversion alimentaire, ECA, coefficient d’efficacité protéique, PER et rétention énergétique apparente, REA) furent analysés et comparés : les meilleurs résultats ont été obtenus avec le régime expérimental R3 contenant 25 % de farine de poissons, 25 % de TT et 20 % de FH, et les résultats les plus médiocres ont été obtenus avec le régime expérimental R5, dépourvu de farine de poissons, et contenant 22 % de TTT, 40 % de TA et 10 % de FH. Les SGR calculés pour les régimes R3 et R5 étaient de 3,17 et de 2,04 %.j-1, les ECA de 1,16 et de 0,74, les PER de 3,23 et de 2,21 et les REA de 33,7 et de 23,1 %, respectivement. Des résultats intéressants furent également obtenus avec le régime R6 dans lequel la farine de poissons était totalement remplacée par du TTD (30 %), du TA (32 %) et de la FH (10 %). Nous avons également analysé les teneurs en tannins, en acides phytiques et en facteurs antitrypsiques des différents ingrédients. Nous n’observons pas de différence significative entre les ingrédients, contrairement aux aliments pour lesquels les teneurs en facteurs antinutritionnels augmentent significativement lorsque le pourcentage en farine de poissons diminue. La farine de poissons peut donc être partiellement, voire totalement, remplacée par des sous-produits végétaux sans effets significatifs sur la croissance et l’efficacité alimentaire. Les graines de tournesol devraient préférentiellement être décortiquées, bien que les teneurs en facteurs antinutritionnels des aliments ne semblent pas influencer significativement les résultats obtenus.Valorisation de sous-produits agro-industriels dans l'élevage du poisson-chat africain Clarias gariepinus au Rwanda: influence sur les performances de croissance et de reproductio

Three decades of trace element sediment contamination: the mining of governmental databases and the need to address hidden sources for clean and healthy seas

peer reviewedTrace elements (TEs) frequently contaminate coastal marine sediments with many included in priority chemical lists or control legislation. These, improved waste treatment and increased recycling have fostered the belief that TE pollution is declining. Nevertheless, there is a paucity of long-term robust datasets to support this confidence. By mining UK datasets (100s of sites, 31 years), we assess sediment concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) and use indices (PI [Pollution], TEPI [Trace Element Pollution] and Igeo [Geoaccumulation]) to assess TE pollution evolution. PI and TEPI show reductions of overall TE pollution in the 1980s then incremental improvements followed by a distinct increase (2010–13). Zn, As and Pb Igeo scores show low pollution, whilst Cd and Hg are moderate, but with all remaining temporally stable. Igeo scores are low for Ni, Fe and Cr, but increasing for Ni and Fe. A moderate pollution Igeo score for Cu has also steadily increased since the mid-1990s. Increasing site trends are not universal and, conversely, minimal temporal change masks some site-specific increases and decreases. To capture this variability we strongly advocate embedding sufficient sentinel sites within observation networks. Decreasing sediment pollution levels (e.g. Pb and Hg) have been achieved, but stabilizing Igeo and recently increasing TEPI and PI scores require continued global vigilance. Increasing Ni and Fe Igeo scores necessitate source identification, but this is a priority for Cu. Local, regional and world analyses indicate substantial ‘hidden’ inputs from anti-fouling paints (Cu, Zn), ship scrubbers (Cu, Zn, Ni) and sacrificial anodes (Zn) that are also predicted to increase markedly. Accurate TE input assessments and targeted legislation are, therefore, urgently required, especially in the context of rapid blue economic growth (e.g. shipping).Channel Catchments Cluster (3C) programm

Trace Elements in Marine Environments : Occurrence, Threats and Monitoring with Special Focus on the Costal Mediterranean

peer reviewedTrace elements, as building blocks of matter, are naturally present in the environment. However, their extraction, production, use and release by men can lead to the increase of their environmental levels to concentrations that may be toxic for both men and the biota. The overall aim of this review is therefore to recall that trace elements remain contaminants of concern that still require scientific attention. Because marine coastal systems (and transitional environments in general) are particularly vulnerable to contamination processes, they deserve to be accurately monitored with quality indicator species. As an example, the 2 most widely quality indicator species used to assess the health status of the coastal Mediterranean are the seagrass Posidonia oceanica and the mussel Mytilus galloprovincialis. In this review, after a short introduction on human pressures on the World Ocean and the coastal Mediterranean in particular (1), we will redefine the term trace element from an environmental perspective and discuss their accumulation and toxicity for men and the biota (2). We will consider the benefits of using biological indicators instead of water and sediment measurements to assess the health status of the marine environment (3), and more particularly as regards the accurate and complementary indicators that are seagrasses (4) and mussels (5)

Indices to determine the status of marine coastal water bodies: Development, applications and support to management

peer reviewedQuatre indices de qualité des masses d’eau marine ont été mis au point dans une baie-type de référence en Méditerranée: un indice de qualité biologique pour la Directive-Cadre sur l’Eau (PREI), un indice de colonisation par une espèce invasive (ICar), un indice de valeur patrimoniale du paysage (LIMA) et un indice de pollution (TEPI). Ces indices ont été validés scientifiquement. La qualité environnementale qu’ils expriment peut être facilement visualisée par des codes simples de couleurs ou de combinaisons lettres-chiffres positionnés sur une carte. Ils ont ensuite été appliqués à plus larges échelles spatiales et/ou temporelles ; leur principe de calcul peut être transposé vers d’autres régions et/ou écosystèmes moyennant la mise en place de bornes adaptées à l’écosystème, à la région investigués.Four marine water quality indices have been developed in a reference bay in the Mediterranean: a biological quality index for the European Water Directive (Posidonia Rapid and Easy Index, PREI), an invasive species colonization index (Indice Caulerpa cylindracea, ICar), a landscape heritage value index (indice Littoral Marin, LIMA) and a pollution index (Trace Element Pollution index, TEPI). These indices have been validated scientifically. The environmental quality they express can be easily visualized by simple codes of colors or combinations of figures-letters positioned on a map. These indices were then applied to larger spatial and/or temporal; their calculation principle can be transposed to other regions and/or ecosystems by setting up reference conditions for the ecosystem, the region investigated.STARECAPMEDFRFC 2.4.502.08; ARC RACE 05 / 10-33

Trace metals in soft tissue of marine bivalve Noah's ark (Arca noao) from Bizerte lagoon (Northern Tunisia)

peer reviewedThis study aimed to monitor the bioaccumulation of 5 trace elements (TEs: Zn, Fe, Cu, Cd, and Pb) in the soft tissue of the Ark shell (Arca noae), seasonally sampled in Bizerte lagoon, northern Tunisia, in order to assess the nutritional quality of this bivalve and to promote its consumption as marine resource in Tunisia. The levels of all trace metals analyzed in Arca noae are below maximum admissible level which makes this species a healthy and safe food for human consumption

Structural Changes of Seagrass Seascapes Driven by Natural and Anthropogenic Factors: A Multidisciplinary Approach

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 20 m 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 20 m 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

Seasonal characterization of the nutrients state in Oualidia Lagoon (Moroccan Atlantic coast)

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.Peer reviewe

Exploring a Mediterranean mesozooplankton 13 year time-series.

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.STARECAPME

Data on elemental concentrations in marine sediments from the South and South West of England

peer reviewedThe present Data In Brief methodological paper details the acquisition, mining and pre-processing of elemental concentration data in marine sediments (coastal and open sea) of Southern England, presented and discussed in the co-submitted Environment International paper entitled: “Three decades of trace element sediment contamination: the mining of governmental databases and the need to address hidden sources for clean and healthy seas” [1]. Elemental sediment concentration data were obtained from the two main UK environmental sources, i.e. the Environment Agency (EA) and the Marine Environment Monitoring and Assessment National database (MERMAN) managed by the British Oceanographic Data Centre (BODC). The merged database is the result of a rigorous data selection-validation process and provides spatially and temporally extensive records of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) concentrations for hundreds of sites over 31 years (1983-2013). More spatially and temporally limited records of manganese (Mn), aluminium (Al), lithium (Li), tin (Sn) [and tributyltin, TBT], barium (Ba), antimony (Sb), boron (B), calcium (Ca), molybdenum (Mo), cobalt (Co), selenium (Se), potassium (K), magnesium (Mg), beryllium (Be), vanadium (V), titanium (Ti), sodium (Na), silver (Ag), thallium (Tl) and strontium (Sr) are also included. The full secondary database is hosted in the Mendeley Data repository and the geo-spatial information to map sites is given in supplementary files to the paper. To provide end-users with the relevant context on spatial and temporal coverage, monitoring statistics are given for the nine trace elements (TEs). Site-specific statistics include: the first and last year of sediment monitoring, the number of years monitored, and minimum, maximum, mean and median numbers of years monitored. Also given are summary data on the number of sites monitored each year, from the first records from 1983 to 2013. For the nine TEs (total and strong acid digestion techniques are considered separately for Cr and Fe), monitoring statistics are presented separately for coastal and open sea sites. Data are relevant to diverse end-users to assess the local and regional contaminant loads and to contextualize anthropogenic threats to benthic systems in multiple locations from the, French/English Channel, southern North and Celtic Seas.Channel Catchments Cluster (3C) programm