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Gohin F.,French Research Institute for Exploitation of the Sea | Bryere P.,ACRI HE | Griffiths J.W.,French Research Institute for Exploitation of the Sea | Griffiths J.W.,Bangor University
Journal of Marine Systems | Year: 2015

A succession of storms during the winter 2013-2014 enhanced the resuspension of sediments in the surface waters of the North-West European shelf seas. The effects of waves on satellite-derived non-algal SPM (Suspended Particulate Matters) are discussed for the January 2008-March 2014 period. A simple statistical model relating locally SPM to tidal intensity and waves helps us analyse the main characteristics of the winter 2013-2014. The exceptional run of storms observed in this stormy and rainy winter has resulted in the highest SPM concentration in the Celtic Sea and the Bay of Biscay ever observed by remote-sensing during the 1998-2014 period. Despite the lower clarity of the surface waters over a large part of the continental shelf during the first days of March 2014, blooms occurred early off the coast of Southern Brittany (Bay of Biscay) and later in April, as usual, in the Celtic Sea. Off the coast of southern Brittany, a region of freshwater influence, the lower clarity of the waters was counterbalanced by stronger haline stratification, due to high river discharges, enabling the initiation of blooms in late winter when the solar irradiance is sufficient; which was the case in March 2014 with 7 sunny days in a row just after the last storm. As a consequence, we can postulate that a possible increase in the intensity of waves occurring from December to early March, along with a possible scenario of global change, would not restrict the productive period in the Bay of Biscay. However an extension of the period of storms later in March would delay the timing of the blooms as observed in March 2008 in most of the investigated area. © 2015 Elsevier B.V. Source

Sicard P.,ACRI HE | Augustaitis A.,Lithuanian University of Agriculture | Belyazid S.,University of Stockholm | Calfapietra C.,CNR Institute of Agro-environmental and Forest Biology | And 9 more authors.
Environmental Pollution | Year: 2016

Research directions from the 27th conference for Specialists in Air Pollution and Climate Change Effects on Forest Ecosystems (2015) reflect knowledge advancements about (i) Mechanistic bases of tree responses to multiple climate and pollution stressors, in particular the interaction of ozone (O3) with nitrogen (N) deposition and drought; (ii) Linking genetic control with physiological whole-tree activity; (iii) Epigenetic responses to climate change and air pollution; (iv) Embedding individual tree performance into the multi-factorial stand-level interaction network; (v) Interactions of biogenic and anthropogenic volatile compounds (molecular, functional and ecological bases); (vi) Estimating the potential for carbon/pollution mitigation and cost effectiveness of urban and peri-urban forests; (vii) Selection of trees adapted to the urban environment; (viii) Trophic, competitive and host/parasite relationships under changing pollution and climate; (ix) Atmosphere-biosphere-pedosphere interactions as affected by anthropospheric changes; (x) Statistical analyses for epidemiological investigations; (xi) Use of monitoring for the validation of models; (xii) Holistic view for linking the climate, carbon, N and O3 modelling; (xiii) Inclusion of multiple environmental stresses (biotic and abiotic) in critical load determinations; (xiv) Ecological impacts of N deposition in the under-investigated areas; (xv) Empirical models for mechanistic effects at the local scale; (xvi) Broad-scale N and sulphur deposition input and their effects on forest ecosystem services; (xvii) Measurements of dry deposition of N; (xviii) Assessment of evapotranspiration; (xix) Remote sensing assessment of hydrological parameters; and (xx) Forest management for maximizing water provision and overall forest ecosystem services. Ground-level O3 is still the phytotoxic air pollutant of major concern to forest health. Specific issues about O3 are: (xxi) Developing dose-response relationships and stomatal O3 flux parameterizations for risk assessment, especially, in under-investigated regions; (xxii) Defining biologically based O3 standards for protection thresholds and critical levels; (xxiii) Use of free-air exposure facilities; (xxiv) Assessing O3 impacts on forest ecosystem services. © 2016 Elsevier Ltd. Source

Han B.,National Ocean Technology Center | Han B.,University of the Littoral Opal Coast | Han B.,Nanjing University of Information Science and Technology | Loisel H.,University of the Littoral Opal Coast | And 11 more authors.
Remote Sensing | Year: 2016

Remote sensing of suspended particulate matter, SPM, from space has long been used to assess its spatio-temporal variability in various coastal areas. The associated algorithms were generally site specific or developed over a relatively narrow range of concentration, which make them inappropriate for global applications (or at least over broad SPM range). In the frame of the GlobCoast project, a large in situ data set of SPM and remote sensing reflectance, Rrs(λ), has been built gathering together measurements from various coastal areas around Europe, French Guiana, North Canada, Vietnam, and China. This data set covers various contrasting coastal environments diversely affected by different biogeochemical and physical processes such as sediment resuspension, phytoplankton bloom events, and rivers discharges (Amazon, Mekong, Yellow river, MacKenzie, etc.). The SPM concentration spans about four orders of magnitude, from 0.15 to 2626 g·m-3. Different empirical and semi-analytical approaches developed to assess SPM from Rrs(λ) were tested over this in situ data set. As none of them provides satisfactory results over the whole SPM range, a generic semi-analytical approach has been developed. This algorithm is based on two standard semi-analytical equations calibrated for low-to-medium and highly turbid waters, respectively. A mixing law has also been developed for intermediate environments. Sources of uncertainties in SPM retrieval such as the bio-optical variability, atmospheric correction errors, and spectral bandwidth have been evaluated. The coefficients involved in these different algorithms have been calculated for ocean color (SeaWiFS, MODIS-A/T, MERIS/OLCI, VIIRS) and high spatial resolution (LandSat8-OLI, and Sentinel2-MSI) sensors. The performance of the proposed algorithm varies only slightly from one sensor to another demonstrating the great potential applicability of the proposed approach over global and contrasting coastal waters. © 2016 by the authors. Source

Thomas Y.,CNRS Sea, Molecules and Health | Pouvreau S.,French Research Institute for Exploitation of the Sea | Alunno-Bruscia M.,French Research Institute for Exploitation of the Sea | Barille L.,CNRS Sea, Molecules and Health | And 3 more authors.
Journal of Biogeography | Year: 2016

Aim: The spread of non-indigenous species in marine ecosystems world-wide is one of today's most serious environmental concerns. Using mechanistic modelling, we investigated how global change relates to the invasion of European coasts by a non-native marine invertebrate, the Pacific oyster Crassostrea gigas. Location: Bourgneuf Bay on the French Atlantic coast was considered as the northern boundary of C. gigas expansion at the time of its introduction to Europe in the 1970s. From this latitudinal reference, variations in the spatial distribution of the C. gigas reproductive niche were analysed along the north-western European coast from Gibraltar to Norway. Methods: The effects of environmental variations on C. gigas physiology and phenology were studied using a bioenergetics model based on Dynamic Energy Budget theory. The model was forced with environmental time series including in situ phytoplankton data, and satellite data of sea surface temperature and suspended particulate matter concentration. Results: Simulation outputs were successfully validated against in situ oyster growth data. In Bourgneuf Bay, the rise in seawater temperature and phytoplankton concentration has increased C. gigas reproductive effort and led to precocious spawning periods since the 1960s. At the European scale, seawater temperature increase caused a drastic northward shift (1400 km within 30 years) in the C. gigas reproductive niche and optimal thermal conditions for early life stage development. Main conclusions: We demonstrated that the poleward expansion of the invasive species C. gigas is related to global warming and increase in phytoplankton abundance. The combination of mechanistic bioenergetics modelling with in situ and satellite environmental data is a valuable framework for ecosystem studies. It offers a generic approach to analyse historical geographical shifts and to predict the biogeographical changes expected to occur in a climate-changing world. © 2016 John Wiley & Sons Ltd. Source

Proietti C.,University of Rome La Sapienza | Anav A.,ENEA | Anav A.,University of Exeter | De Marco A.,ENEA | And 2 more authors.
Science of the Total Environment | Year: 2016

Ozone (O3) is both a greenhouse gas and a secondary air pollutant causing adverse impacts on forests ecosystems at different scales, from cellular to ecosystem level. Specifically, the phytotoxic nature of O3 can impair CO2 assimilation that, in turn affects forest productivity. This study aims to evaluate the effects of tropospheric O3 on Gross Primary Production (GPP) at 37 European forest sites during the time period 2000-2010. Due to the lack of carbon assimilation data at O3 monitoring stations (and vice-versa) this study makes a first attempt to combine high resolution MODIS Gross Primary Production (GPP) estimates and O3 measurement data. Partial Correlations, Anomalies Analysis and the Random Forests Analysis (RFA) were used to quantify the effects of tropospheric O3 concentration and its uptake on GPP and to evaluate the most important factors affecting inter-annual GPP changes. Our results showed, along a North-West/South-East European transect, a negative impact of O3 on GPP ranging from 0.4% to 30%, although a key role of meteorological parameters respect to pollutant variables in affecting GPP was found. In particular, meteorological parameters, namely air temperature (T), soil water content (SWC) and relative humidity (RH) are the most important predictors at 81% of test sites. Moreover, it is interesting to highlight a key role of SWC in the Mediterranean areas (Spanish, Italian and French test sites) confirming that, soil moisture and soil water availability affect vegetation growth and photosynthesis especially in arid or semi-arid ecosystems such as the Mediterranean climate regions.Considering the pivotal role of GPP in the global carbon balance and the O3 ability to reduce primary productivity of the forests, this study can help in assessing the O3 impacts on ecosystem services, including wood production and carbon sequestration. © 2016 Elsevier B.V. Source

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