PARAZITI, BOLESTI I DEFORMACIJSKE PROMJENE KOD VRSTE COBIA

Cobia, Rachycentron canadum, is the only member of the family Rachycentridae (Order Perciformes) and as a warm–water fish is to be found in tropical and subtropical waters. The species has been reported in eastern Mediterranean waters and it is likely that in this particular case, cobia are lessespian. Cobia has been farmed in Taiwan since the early 1990s and today nascent cobia aquaculture operations operate throughout South East and Eastern Asia, in Gulf of Mexico and Caribbean Sea as well as in the United States. Many other nations are presently considering adopting cobia as a new species for aquaculture. Production by aquaculture experienced a 7000–fold increase from 1995 to 2005. The increased interest in the species has evolved due in large part to its many excellent characteristics which include good growth, with production of 6 kg live weight fish being possible over a year–long production cycle. Cobia are accepting of pond, net pens and recirculation–based culture; their fillet quality is high and meat delectable; They readily take formulated feeds and respond well to alternate proteins in their diets. Like other species new to aquaculture however, enlarged farming activities have been accompanied by increased incidence of commonly–encountered and emerging diseases. As an aid to current and potential producers as well as researchers, the following provides an overview of the published literature on cobia diseases, parasites and physical deformities.Cobia, Rachycentron canadum, jedna je od predstavnica porodice Rachycentridae (Red Perciformes) i kao toplovodna riba nađena je u tropskim i suptropskim vodama. Ova je vrsta ustanovljena u istočnim vodama Sredozemlja. Cobia se na Tajvanu uzgaja od ranih 1990–ih, a danas se njezin uzgoj proširio na jugoistočnu i istočnu Aziju, Meksički zaljev i Karibe, kao i SAD. Mnogi narodi rade na prilagodbi kobije kao nove vrste za uzgoj, jer je vrlo zanimljiva zbog svojih odličnih karakteristika kao što su dobar rast s produkcijom od 6 kg žive težine tijekom uzgojnog perioda od godine dana. To je vrsta koja je pogodna za uzgoj na razne načine kao što su kavezi i recirkulirajući sustavi. Meso joj je visoke kakvoće, a rado uzima peletiranu hranu. No, kao i kod svih intenzivnih uzgoja najveći su problem bolesti. Mnogi potencijalni proizvođači i istraživači rade na rješavanju toga problema pa postoji niz publikacija koje obrađuju tu temu. Tako i ovaj rad daje literaturni pregled o bolestima, nametnicima i fizikalnim deformacijama kod kobije

Egg quality determinants in cod (Gadus morhua L.): egg performance and lipids in eggs from farmed and wild broodstock

Lipids and essential fatty acids, particularly the highly unsaturated fatty acids, 20:5n-3 (eicosapentaenoic acid; EPA), 22:6n-3 (docosahexaenoic acid; DHA) and 20:4n-6 (arachidonic acid, AA) have been shown to be crucial determinants of marine fish reproduction directly affecting fecundity, egg quality, hatching success, larval malformation and pigmentation. In Atlantic cod (Gadus morhua L.) culture, eggs from farmed broodstock can have much lower fertilisation and hatching rates than eggs from wild broodstock. The present study aimed to test the hypothesis that potential quality and performance differences between eggs from different cod broodstock would be reflected in differences in lipid and fatty acid composition. Thus eggs were obtained from three broodstock, farmed, wild/fed and wild/unfed, and lipid content, lipid class composition, fatty acid composition and pigment content were determined and related to performance parameters including fertilisation rate, symmetry of cell division and survival to hatching. Eggs from farmed broodstock showed significantly lower fertilisation rates, cell symmetry and survival to hatching rates than eggs from wild broodstock. There were no differences in total lipid content or the proportions of the major lipid classes between eggs from the different broodstock. However, eggs from farmed broodstock were characterised by having significantly lower levels of some quantitatively minor phospholipid classes, particularly phosphatidylinositol. There were no differences between eggs from farmed and wild broodstock in the proportions of saturated, monounsaturated and total polyunsaturated fatty acids. The DHA content was also similar. However, eggs from farmed broodstock had significantly lower levels of AA, and consequently significantly higher EPA/AA ratios than eggs from wild broodstock. Total pigment and astaxanthin levels were significantly higher in eggs from wild broodstock. Therefore, the levels of AA and phosphatidylinositol, the predominant AA-containing lipid class, and egg pigment content were positively related to egg quality or performance parameters such as fertilisation and hatching success rates, and cell symmetry

PARASITES, DISEASES AND DEFORMITIES OF COBIA

Cobia, Rachycentron canadum, is the only member of the family Rachycentridae (Order Perciformes) and as a warm–water fish is to be found in tropical and subtropical waters. The species has been reported in eastern Mediterranean waters and it is likely that in this particular case, cobia are lessespian. Cobia has been farmed in Taiwan since the early 1990s and today nascent cobia aquaculture operations operate throughout South East and Eastern Asia, in Gulf of Mexico and Caribbean Sea as well as in the United States. Many other nations are presently considering adopting cobia as a new species for aquaculture. Production by aquaculture experienced a 7000–fold increase from 1995 to 2005. The increased interest in the species has evolved due in large part to its many excellent characteristics which include good growth, with production of 6 kg live weight fish being possible over a year–long production cycle. Cobia are accepting of pond, net pens and recirculation–based culture; their fillet quality is high and meat delectable; They readily take formulated feeds and respond well to alternate proteins in their diets. Like other species new to aquaculture however, enlarged farming activities have been accompanied by increased incidence of commonly–encountered and emerging diseases. As an aid to current and potential producers as well as researchers, the following provides an overview of the published literature on cobia diseases, parasites and physical deformities

Influence of spreading ridge's subduction on plate dynamics: insights fromlaboratory models

International audienc

Effets de la subduction d’une dorsale sur ladynamique d’une plaque continentale :apports de la modélisation analogique

National audienceUne série de modèles analogiques de subduction d’une plaqueocéanique sous une plaque continentale ont été reproduits àl’échelle du laboratoire, afin de mieux comprendre les relationsentre phénomènes profonds se produisant lors de la subductiond’une dorsale, et la réponse associée en surface. Ces modèles ontété réalisés au sein du laboratoire de modélisation analogique del’Univ. Rennes 1. Dans ces modèles, l’épaisseur de la plaqueocéanique augmente en direction de la fosse (plaque en forme debiseau), afin de simuler la variation d’épaisseur de la plaque depuisla dorsale jusqu’à la fosse où elle rentre en subduction. L’objectifde ces expériences est d’observer l’effet de la subduction d’uneplaque océanique de plus en plus jeune, et finalement de la subductiond’une dorsale, sur la géométrie de la subduction et la dynamiquedu système. Un exemple de subduction de dorsale peutêtre observé actuellement dans les Andes Australes, en Patagonie,où la dorsale du Chili plonge sous le continent sud-américainvers 47S. L’objectif de ce travail est de comprendre l’effet de lasubduction de cette dorsale sur la dynamique de la plaque continentale.Plusieurs paramètres (vitesse de convergence, largeur etforme de la plaque plongeante...) ont été testés afin de modéliserleur impact sur la subduction, sur l’évolution du pendage et surles déformations de la plaque continentale

Nutrient deposition partitioning and priorities between body compartments in two size classes of rainbow trout in response to feed restriction

International audienceAdaptations in growth dynamics in fish, i.e. how fish prioritise tissue accretion between organs, remains poorly understood. In the present study, we investigated the effects of graded feed restriction levels on nutrient deposition in 1·3 g fingerlings and 70 g juveniles. At the whole-body level, highly restricted juveniles strove to maintain body protein while mobilising lipid reserves and compensating for mass loss by increasing water content. In contrast, fingerlings maintained body water and energy contents. Additionally, we investigated deposition patterns in four body compartments (red and white axial muscles, viscera and rest of the carcass) in juveniles and changes in the cellularity of the white and red muscles in fingerlings. We provide evidence of priorities in growth and nutrient deposition in body compartments in response to low feeding levels. In juveniles, feed intake (FI) primarily affected the white muscle, while the red muscle and the viscera appeared to be preserved. Specific proteins (45 and 173 kDa) were preferentially deposited in the white muscle, while others (22 and 32 kDa) were preferentially mobilised. In fingerlings' muscle anterior to the anus, the cross-sectional surface areas increased with increasing FI in a logarithmic fashion in the white muscle, and in linear fashion in the red muscle. The maximum diameter of white fibres decreased linearly with fish length, while that of red fibres remained stable. This suggests an adaptation mechanism by decreasing white muscle hyperplasia in favour of hypertrophy when feed is restricted. Overall, these results indicate some mechanisms by which fish cope with low food availability. Our findings also suggest different adaptation strategies employed by fish of different body weight

Nutrient partitioning and feeding level : response of four body compartments in rainbow trout Oncorhynchus mykiss

Résumé communication oraleInternational audienc

Trench-parallel spreading ridge subduction and its consequences for the geological evolution of the overriding plate: Insights from analogue models and comparison with the Neogene subduction beneath Patagonia

International audienceA series of 3-D asthenospheric-scale analogue models have been conducted in the laboratory in order to simulate the arrival of a spreading ridge at the trench and understand its effect on plate kinematics, slab geometry, and on the deformation of the overriding plate. These models are made of a two-layered linearly viscous system simulating the lithosphere and asthenosphere. We reproduce the progressive decrease in thickness of the oceanic lithosphere at the trench. We measure plate kinematics, slab geometry and upper plate deformation. Our experiments reveal that the subduction of a thinning plate beneath a freely moving overriding continent favors a decrease of the subduction velocity and an increase of the oceanic slab dip. When the upper plate motion is imposed by lateral boundary conditions, the evolution of the subducting plate geometry largely differs depending on the velocity of the overriding plate: the larger its trenchward velocity, the smaller the superficial dip of the oceanic slab. A slab flattening episode may occur resulting from the combined effect of the subduction of an increasingly thinner plate and the trenchward motion of a fast overriding plate. Slab flattening would be marked by an increase of the distance between the trench and the volcanic arc in nature. This phenomenon may explain the reported Neogene eastward motion of the volcanic arc in the Southern Patagonian that occurred prior to the subduction of the Chile Ridge

Spreading ridge subduction and geological evolution of the Southern Patagonia: insights from analogue modelling

International audienceThe Chile spreading ridge is subducting beneath Southern Patagonia since 18 Ma. Increasingly younger and thinner Nazca oceanicplate subducted beneath that part of the Andes during the lower Miocene before ridge subduction, and an asthenospheric windowopened there following the ridge subduction. These modifications in the process of subduction may explain several of the geologicalevents that occurred in Southern Patagonia during the Neogene. We present 3D mantle-scale analogue models simulating thearrival at trench of a spreading ridge to understand its possible effects on plate kinematics, slab geometry, and on the deformationof the overriding plate. Oceanic and continental lithospheres are modeled using Newtonian viscous plates made of silicones withdifferent densities. They initially float above glucose syrup modeling the upper mantle. We reproduce the progressive thicknessdecreaseof the oceanic lithosphere arriving at the trench. Experiments reveal that the subduction of a thinning plate beneath afreely moving overriding continent favors a decrease of the subduction velocity and an increase of the oceanic slab dip. Whenthe upper plate motion is imposed by lateral boundary conditions, the evolution of the subducting plate’s geometry largely differsdepending on the velocity of the overriding plate: the larger its trenchward velocity, the smaller the superficial dip of the oceanicslab. A slab flattening episode may occur resulting from the combined effects of the subduction of an increasingly thinner plateand a fast overriding plate trenchward motion. Slab flattening would be marked by an increase of the distance between the trenchand the volcanic arc in Nature. This phenomenon may explain the reported Neogene eastward motion of the volcanic arc in theSouthern Patagonia that occurred prior to the subduction of the Chile Ridge. Moreover, models also confirm that the early Mioceneepisode of shortening observed in the Southern Patagonian Andes may partly result from the ridge approaching the trench, andthat the end of shortening in the Southern Patagonia coincides with ridge subduction

Mining impacts assessment using the LCA methodology: case study of Afema gold mine in Ivory Coast

International audienceEnvironmental impact assessment studies are mandatory for major industrial or infrastructure projects in most countries. These studies are usually limited to on‐site impacts during exploitation but do not consider indirect impacts generated off‐site or those concerning other steps of the project, including dismantling. National regulations in various countries have recently begun to include these neglected impacts to obtain a better appreciation of project trade‐offs. Several scientists have highlighted the substantial potential of using the life cycle assessment methodology to increase the level of detail and completeness of EIA studies.Even if mining activities are known to produce significant local impacts, their consequences outside an extraction site have not yet been well documented. The implementation of the LCA methodology in the EIA procedure has been carried out in a gold mining project by separating on‐site and off‐site impacts during the entire life cycle of the mine from prospection to site restoration following the end of exploitation.Mining projects occur over large time periods and require diverse materials and processes. The main difficulty of such analysis is the data collection that needs to be extrapolated for some of the activities. Even with these limitations, the Afema case study highlighted the significant share of off‐site impacts (from a spatial perspective) and the major contribution of the exploitation phase of the mine (from a temporal perspective). Operating activities, especially excavation, ore and waste rock transportation, blasting, ore processing and tailing treatments, are the main impacts produced during the exploitation phase and are involved in climate change, particulate matter formation, and land destruction.Therefore, this standardized LCA method should be recommended by the regulatory authorities for use in EIA procedures