Patrón reproductivo y fecundidad de la merluza (Merluccius merluccius (Linnaeus, 1758)) en el Mediterráneo occidental

12 pages, 12 figures[EN] The spawning cycle of the European hake (Merluccius merluccius, (Linnaeus, 1758)) was studied in two western Mediterranean areas, the Catalan Sea and the northern Tyrrhenian Sea, including observation of the monthly seasonal variation of the gonad maturity and the gonadosomatic index (GSI). The estimation of the maturity stages by GSI gave similar values in the two study areas: the spawning stage (IV) was easily distinguished from the other maturity stages and its range of variation showed a low overlap with stage III and no overlap with other stages. Although in both study areas active females were present during all the sampled months, the peak of reproductive activity was concentrated from February to May in the northern Tyrrhenian Sea but from August to December in the Catalan Sea, which was subjected to winter cascading events. Batch fecundity gave similar values in the Catalan and northern Tyrrhenian Seas: 204 and 202 eggs per gonad-free female gram, respectively. An asynchronous oocyte development is suggested for M. merluccius in the western Mediterranean[ES] Se ha estudiado el ciclo reproductivo de la merluza (Merluccius merluccius, (Linnaeus, 1758)) en dos áreas del Mediterráneo occidental, el Mar Catalán y el norte del Mar Tirreno, analizando la evolución mensual de la madurez en las gónadas y el índice gonadosomático (GSI). La estimación del estadio de madurez mediante el GSI dio resultados parecidos en ambas áreas de estudio: el estadio de puesta (IV) resultó fácil de distinguir de los otros estadios de madurez y su rango de variación mostró poca superposición con el estadio III y ninguna con los otros estadios. Aunque en ambas áreas de estudio se encontraron hembras activas durante todos los meses muestreados, el pico de actividad reproductiva se concentró entre febrero y mayo en el norte del Mar Tirreno, mientras que en el Mar Catalán es entre agosto y diciembre, esta última área sujeta en invierno a fenómenos de cascadas submarinas. La fecundidad relativa presentó valores similares en los mares Catalán y Tirreno norte: 204 huevos por gramo de hembras sin gónada y 202, respectivamente. Se sugiere un desarrollo ovocitario asíncrono para M. merluccius del Mediterráneo occidentalThis work was supported by the EU LLUCET Project (FAIR CT-97-3522)Peer reviewe

Which Class Design can Accommodate both Process and Independent Evaluation? : The Value and Significance of Evaluation for Learner and Teacher

The reproductive biology of the European hake (Merluccius merluccius, Linnaeus, 1758) was studied on the eastern central Atlantic Moroccan coast from November 2001 to December 2003. The sex ratio was close to 1:1 for the specimens with a total length of less than 45 cm. European hake spawned all year round, though two spawning peaks were recorded with a certain interannual variability: the first and main peak in winter and a secondary intermittent peak in summer. Length at first maturity was estimated as 28.6 cm and 33.8 cm total length for males and females, respectively. These values are closer to Mediterranean than Atlantic hake values. The mean batch fecundity was 299872 eggs ind–1. The relative batch fecundity was estimated as 228 eggs per gram of gutted weight. Batch fecundity increased proportionally with fish length and weight. The batch fecundity of European hake in the Moroccan Atlantic area is higher than that in northern Atlantic and northwestern Mediterranean areas

Approche spatio-temporelle des relations hydroclimat-dynamique des especes pelagiques en region d'upwelling : cas de la sardine du stock central marocain

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 78619 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Modelling, forecasting and scenarios in comparable upwelling ecosystems: Californie, Canary and Humboldt.

International audienceThe three eastern boundary ecosystems comparable to the Benguela ecosystem (BCE) display differences and commonalities. The California (CalCE) and Humboldt Current (HCE) ecosystems are continuous topographically, whereas the Canary Current ecosystem (CanCE) is interrupted by the Gulf of Cadiz and the Canaries archipelago. All have similar regimes of equatorward flow over shelf and slope associated with upwelling and a subsurface poleward flow over the slope, though in the HCE multiple flows and counter-flows appear offshore. All systems exhibit year round upwelling in their centre and seasonal upwelling at their extremes as the trade wind systems that drive them migrate north and south, though the HCE is strongly skewed toward the equator. All systems vary on scales from the event or synoptic scale of a few days, through seasonal, to inter-decadal and long term. Productivity of each system follows the upwelling cycle, though intra-regional variations in nutrient content and forcing cause significant variability within regions. The CanCE is relatively unproductive compared to the CalCE and HCE as a result of differences in large scale circulation between the Pacific and Atlantic. The latter two systems are dominated by El Niño-Southern Oscillation (ENSO) variability on a scale of 4-7 years. Physical modeling with the Princeton Ocean Model and the Regional Oceanic Modeling System has advanced recently to the stage of reproducing realistic mesoscale features and energy levels with climatic wind forcing. Operational forecasting by these models with assimilation of sea surface temperature and other data is successfully implemented in CalCE. On longer time scales, the Lamont-Doherty Earth Observatory model is able to hindcast El Niño variability over the long term up to 2 years in advance. Empirical ecological models in all three systems have attempted prediction of permissible catch level (fractional Maximum Sustainable Yield), recruitment, catches or onset of migration with lack of continued success, partly because discontinuous or inadequate observations hamper model implementation and assessment. Moreover, empirical models tuned to particular environments fail when fundamental regime shifts occur. One of the most successful approaches is that of intensive monitoring of catch and environmental parameters linked to an informal Operational Management Procedure (OMP) to inform fisheries management off Peru. This OMP contributed to preservation of anchovy stock during the 1997-8 El Niño but remains to be formalized or tested under varying conditions. Prediction on time scales of global warming are uncertain because physical climate models still disagree on whether upwelling will intensify or weaken. Possible scenarios on decadal scale based on warming or cooling of waters in the Eastern Boundary Current systems can be proffered, albeit with little confidence at present. Future approaches for all systems, including the BCE, will in the long run likely combine coupled atmospheric/ocean models with biological process models. Judicious application of purely statistical modeling based on inherent time series properties will assist, though such techniques are unable to cope with regime shifts

Preoxidation and Activation of the Lignin Char: Carbonization and Oxidation Procedures

A comprehensive process of pretreatment and oxidation of lignin char was developed to optimize the production of activated carbon. The lignin char was obtained by carbonization of lignin under nitrogen at 600°C for 2 hours. The optimum time and temperature used to oxidize the char without destruction were, respectively, 6 hours and 245°C. The oxygen improves the reactivity of the sample in CO2 and evolved the sample of a thermoplastic behaviour to a thermosetting behaviour. The oxygenation in air of the lignin char does not change the mode of deformation acquired by the material during the carbonization. The preoxidized coal reacts more than the nonoxidized coal during the CO2 activation, whereas the reduction in volume in the first case is smaller than in the second. The preoxidized and then activated carbon shows the formation and the development of microporosity at the expense of macroporosity. This microstructure is one of the main characteristics of activated carbon, which can be used as adsorbent for different pollutants

How does fishing alter marine populations and ecosystems sensitivity to climate?

Evidence has accumulated that climate variability influences the state and functioning of marine ecosystems. At the same time increasing pressure from exploitation and other human activities has been shown to impact exploited and non-exploited species and potentially modify ecosystem structure. There has been a tendency among marine scientists to pose the question as a dichotomy, i.e., whether (1) "natural" climate variability or (2) fishery exploitation bears the primary responsibility for population declines in fish populations and the associated ecosystem changes. However, effects of both climate and exploitation are probably substantially involved in most cases. More importantly, climate and exploitation interact in their effects, such that climate may cause failure in a fishery management scheme but that fishery exploitation may also disrupt the ability of a resource population to withstand, or adjust to, climate changes. Here, we review how exploitation, by altering the structure of populations and ecosystems, can modify their ability to respond to climate. The demographic effects of fishing (removal of large-old individuals) can have substantial consequences on the capacity of populations to buffer climate variability through various pathways (direct demographic effects, effects on migration, parental effects). In a similar way, selection of population sub-units within meta-populations may also lead to a reduction in the capacity of populations to withstand climate variability and change. At the ecosystem level, reduced complexity by elimination of species, such as might occur by fishing, may be destabilizing and could lead to reduced resilience to perturbations. Differential exploitation of marine resources could also promote increased turnover rates in marine ecosystems, which would exacerbate the effects of environmental changes. Overall (and despite the specificities of local situations) reduction in marine diversity at the individual, population and ecosystem levels will likely lead to a reduction in the resilience and an increase in the response of populations and ecosystems to future climate variability and change. Future management schemes will have to consider the structure and functioning of populations and ecosystems in a wider sense in order to maximise the ability of marine fauna to adapt to future climates

The Ecosystem Approach to Fisheries: Reconciling Conservation and Exploitation

International audienceMarine fisheries have a direct impact on the resources they exploit but also indirectly affect other species, habitats and the way ecosystems work. Ecosystem approach to fisheries (EAF) is a major aspect for the exploitation of marine resources and conservation of species. An ecosystem is set formed by a community of living beings and their biological, geological, edaphic, hydrological, climatic environment. Organisms are distributed as patches across a wide continuum of spatiotemporal scales. The marine strategy framework directive (MSFD) proposes an ecosystem approach for the assessment of the marine environment. Bottom-up control of predator fish through small pelagic fish has been noticed in the Benguela and Humboldt Current and in Guinea, since several predator fish suffer when their prey stock collapses. The scientific community needs to set up a long-term scientific strategy in order to enhance its ability to provide suitable competences for the ecosystem approach to marine resources

Sub-regional ecosystem variability in the Canary current upwelling

15 páginas, 2 tablas, 5 figurasThe Canary Current upwelling ecosystem (CanC) constitutes one of the four main eastern boundary upwelling ecosystems (EBUEs) of the world, thus hosting high productivity and fisheries. Recent observations indicate that the CanC region as a whole has been experiencing a progressive warming and a decrease in productivity over the last decades. This overall trend is however not directly reflected in the fisheries of the region. Here we update recent results and previous reviews on the CanC, covering aspects from the physical environment to fish populations and fisheries on a range of time scales. We approach these topics, when possible, through a comparative exploration of the biogeographical characteristics of different sub-regions comprising this ecosystem. This review shows that variability in coastline configuration, shelf width, coastal upwelling, nutrient fertilization, productivity, or retentive vs. dispersive physical mechanisms, among other factors, may help explain sub-regional differences in fish distributions and abundances in the CanC. Nevertheless, the lack of systematic information on the regional variability of physical and biological processes hampers an integrated understanding of the relative contribution of natural vs. human-induced variability in the populations of at least small-pelagic fishes and their associated fisheriesThis work was partly funded by the Spanish projects ZOTRACOS (REN2003- 06633-C03-02/MAR), RODA (CTM2004-06842-C03/MAR) and CAIBEX (CTM2007- 66408-C02/MAR), and the French IRD Program ECO-UP (UR097). EDB, XAA-S and FGF were partially supported by project CRIA (PDIGIT05RMA40201PR) from the Xunta de Galicia.Peer reviewe

Canary Current upwelling: does geographical diversity make the difference?

Eastern boundary upwelling ecosystems: integrative and comparative approaches, 2-6 June 2008, Las Palmas, Gran Canaria, SpainThe Large Marine Ecosystem of the Canary Current (CC) is one of the four major eastern boundary upwelling systems of the world ocean, and thus an area of intensive fisheries activity. The coastline is separated into two distinct areas -the Iberian coast and the NW African coast- at the Strait of Gibraltar, where the Mediterranean Sea and the Atlantic Ocean exchange water. The two areas share similarities in local oceanography, productivity and fisheries, but also exhibit their own particularities. In the northern most Iberian region, the Rías Baixas represent a unique ecosystem, strongly interacting with the coastal upwelling and amplifying its signal. Although seasonality in the Trade wind regime is more pronounced in the northern and southern extremes of the CC, the whole region exhibits high annual productivity and fish population yield. Nevertheless, a large fraction of the productivity is presumably lost to the open ocean. In particular, the NW African shelf between Cape Guir (32 N) and Cape Blanc (21 N) exhibits numerous upwelling filaments. These appear topographically generated in general and those arising south of 28 N result largely from the interplay of the coastal jet with eddies shed downstream the Canaries Archipelago. Filaments facilitate nearshore-offshore exchange of water parcels and properties and a net productivity loss. In recent years, considerable information has been gathered from these coastal ecosystems, and several review papers have been published on plankton biology, biogeochemistry or regional fisheries. Here, we present an updated global review of the CC, covering aspects ranging from hydrography, through biogeochemistry to trophic interactions and fisheries, all of which are affected by processes occurring on distances from mesoscale to large scale and over periods from days to decades. The synthesis will highlight recent major advances in experimental studies, both over the coastal shelf and in the open-ocean transition zone, as well as in modelling exercises. Ongoing numerical models range from large-scale and regional circulation off Iberia and NW Africa to coupled physical-biological models looking at plankton productivity or fish population dynamicsN