Modeling approach to regime shifts of primary production in shallow coastal ecosystems

Pristine coastal shallow systems are usually dominated by extensive meadows of seagrass species, which are assumed to take advantage of nutrient supply from sediment. An increasing nutrient input is thought to favour phytoplankton, epiphytic microalgae, as well as opportunistic ephemeral macroalgae that coexist with seagrasses. The primary cause of shifts and succession in the macrophyte community is the increase of nutrient load to water; however temperature plays also an important role. A competition model between rooted seagrass (Zostera marina), macroalgae (Ulva sp), and phytoplankton has been developed to analyse the succession of primary producer communities in these systems. Successions of dominance states, with different resilience characteristics, are found when modifying the input of nutrients and the seasonal temperature and light intensity forcing.Comment: 33 pages, including 10 figures. To appear in Ecological Complexit

Joint effects of nutrients and contaminants on the dynamics of a food chain in marine ecosystems

We analyze the joint effect of contaminants and nutrient loading on population dynamics of marine food chains by means of bifurcation analysis. Contaminant toxicity is assumed to alter mortality of some species with a sigmoidal dose-response relationship. A generic effect of pollutants is to delay transitions to complex dynamical states towards higher nutrient load values, but more counterintuitive consequences arising from indirect effects are described. In particular, the top predator seems to be the species more affected by pollutants, even when contaminant is toxic only to lower trophic levels

Predictive habitat suitability models to aid conservation of elasmobranch diversity in the central Mediterranean Sea

Commercial fisheries have dramatically impacted elasmobranch populations worldwide. With high capture and bycatch rates, the abundance of many species is rapidly declining and around a quarter of the world’s sharks and rays are threatened with extinction. At a regional scale this negative trend has also been evidenced in the central Mediterranean Sea, where bottom-trawl fisheries have affected the biomass of certain rays (e.g. Raja clavata) and sharks (e.g. Mustelus spp.). Detailed knowledge of elasmobranch habitat requirements is essential for biodiversity conservation and fisheries management, but this is often hampered by a poor understanding of their spatial ecology. Habitat suitability models were used to investigate the habitat preference of nine elasmobranch species and their overall diversity (number of species) in relation to five environmental predictors (i.e. depth, sea surface temperature, surface salinity, slope and rugosity) in the central Mediterranean Sea. Results showed that depth, seafloor morphology and sea surface temperature were the main drivers for elasmobranch habitat suitability. Predictive distribution maps revealed different species-specific patterns of suitable habitat while high assemblage diversity was predicted in deeper offshore waters (400–800 m depth). This study helps to identify priority conservation areas and diversity hot-spots for rare and endangered elasmobranchs in the Mediterranean Sea

A high-yielding traits experiment for modeling potential production of wheat: field experiments and AgMIP-Wheat multi-model simulations

Grain production must increase by 60% in the next four decades to keep up with the expected population growth and food demand. A significant part of this increase must come from the improvement of staple crop grain yield potential. Crop growth simulation models combined with field experiments and crop physiology are powerful tools to quantify the impact of traits and trait combinations on grain yield potential which helps to guide breeding towards the most effective traits and trait combinations for future wheat crosses. The dataset reported here was created to analyze the value of physiological traits identified by the International Wheat Yield Partnership (IWYP) to improve wheat potential in high-yielding environments. This dataset consists of 11 growing seasons at three high-yielding locations in Buenos Aires (Argentina), Ciudad Obregon (Mexico), and Valdivia (Chile) with the spring wheat cultivar Bacanora and a high-yielding genotype selected from a doubled haploid (DH) population developed from the cross between the Bacanora and Weebil cultivars from the International Maize and Wheat Improvement Center (CIMMYT). This dataset was used in the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Phase 4 to evaluate crop model performance when simulating high-yielding physiological traits and to determine the potential production of wheat using an ensemble of 29 wheat crop models. The field trials were managed for non-stress conditions with full irrigation, fertilizer application, and without biotic stress. Data include local daily weather, soil characteristics and initial soil conditions, cultivar information, and crop measurements (anthesis and maturity dates, total above-ground biomass, final grain yield, yield components, and photosynthetically active radiation interception). Simulations include both daily in-season and end-of-season results for 25 crop variables simulated by 29 wheat crop models

Shifts in N-Efficiency of Different Farm Types in Response to Climate Change

Climate change may affect European farms, but in contrast to individual crops - the sensitivity of whole farming systems has not been the subject of much research. At the farm level, where different farm units are linked through the availability and flow of nitrogen (N), effects on individual crops are interlinked, and through shifts in grasslands and related animal production with altered nutrient flows. Ideally, N flows into the system and N-export with products should be equal, and thus N-use-efficiency (NUE), expressed as the ratio of N export to N loss, would be maximal. The objective of this study was to test the effect of gradually changing temperature (T) and precipitation (P) on NUE of two farm types under Swiss conditions

An integrated approach for bioaccumulation assessment in mussels: Towards the development of Environmental Quality Standards for biota

International audienceThe possibleuseofchemicalconcentrationsmeasuredinmussels(Mytillus galloprovincialis) forcompliancecheckingagainstEnvironmentalQualityStandards(EQS)establishedforbiotaisanalyzedwith thehelpofanintegratedmodel.Themodelconsistsofa3Dplanktonicmodulethatprovidesbiomassesinthedifferentcompartments,i.e.,phytoplankton,zooplanktonandbacteria;a3Dfatemodulethat providestheconcentrationsofcontaminantsinthewatercolumnandinthesediments;anda3Dbioaccumulationmodulethatcalculatesinternalconcentrationsinrelevantbioticcompartments.Thesemodulesfeeda0Dgrowthandbioaccumulationmoduleformussels,basedontheDynamicEnergyBudget(DEB)approach.Theintegratedmodelhasbeenappliedtostudythebioaccumulationofpersistentorganicpollutants(POPs)intheThaulagoon(France).Themodelcorrectlypredictstheconcentrationsofpolychlorinatedbiphenyls(PCBs)andpolychlorinateddibenzodioxinsanddibenzofurans(PCDD/Fs)inmusselsasafunctionoftheconcentrationsinthewatercolumnandinphytoplankton.Italsoshedslighton theoriginofthecomplexityassociatedwiththeuseofEQSforbiotaandtheirconversiontowatercolumn concentrations.Theintegratedmodelispotentiallyusefulforregulatorypurposes,forexampleinthe contextoftheEuropeanWaterFramework(WFD)andMarineStrategyFrameworkDirectives(MSFD)

Polychlorinated Biphenyls (PCBs) Atmospheric Concentrations and Deposition in Sub-Alpine Northern Italy

Atmospheric transport and deposition are important processes determining the fate of many persistent organic pollutants (POPs) in the environment. Research has been carried out in the last decades on ambient concentrations and controls of numerous POPs families. Experimental measurements alone (active and passive sampling) or combined with model estimations have been used to study the POPs environmental processing, transport and behavior in specific regions. However, there are many areas for which little or no information on POPs ambient levels is available. Such is the case with Southern-Western Europe, that remains uncovered by the EMEP POPs monitoring network. Moreover, the scarcity of consistent experimental data sets on atmospheric concentrations poses a problem for proper validation of models. Our main objective was to initiate POPs atmospheric measurements (weekly resolution) in order to assess air concentrations and seasonal variations of selected POPs in a sub-alpine location where little information is available on POPs ambient levels. To achieve this goal, a monitoring and research station was set up at the Joint Research Centre EMEP site (Ispra, Italy). We present and discuss a one year data set (2005-2006) on PCB air concentrations (gas and particulate phases). ¿7PCBs monthly averaged concentration varied from 31-76 pg m-3. These values are within the range of those reported for rural, semi-rural or remote areas around the world. Advection of air masses and re-volatilization from local sources seem to play a dominant role as drivers of PCB atmospheric concentrations in the area. The importance of the wet deposition in this region (1 ug m-2 yr-1 ¿7PCBs yearly total wet deposition flux; 650-2400 pg L-1 rainwater concentrations) is emphasizedJRC.DDG.H.5-Rural, water and ecosystem resource