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Inproceedings Reference Intra-annual variations of the diet of gentoo penguins (Pygoscelis papua) at South Georgia (Southern Ocean)
Located in Library / RBINS Staff Publications
Conference Reference Impact of projected wind and temperature changes on larval recruitment of sole in the North Sea.
The impact of climate change on larval dispersal remains poorly known. The case of sole (Solea solea) is of particular interest because it is one of the most valuable commercial species in the North Sea. It is important to understand how the retention/dispersal of larvae would be affected by climate change in order to propose appropriate measures for stock management. The transport of sole larvae from the spawning grounds to the nurseries is driven by hydrodynamic processes but the final dispersal pattern and larval abundance may be affected by behavioural and environmental factors. A temperature increase could affect for instance the spawning period, the duration of the pelagic stage, the mortality of eggs and larvae, and the match-mismatch with prey fields. Modifications in the magnitude and direction of the wind regime might affect egg and larval retention and dispersal through changes in the hydrodynamics. We compare scenarios of a particle-tracking transport model (IBM) coupled to a 3D hydrodynamic model (COHERENS) to investigate the impact of climate change through temperature increase and wind regime change. The model has been implemented in the area between 48.5°N-4°W and 57°N-10°E over the period 1995 to 2011. A larval mortality parameterization based on remote sensing algal bloom timing is tested. Sensitivity of larval recruitment to climate change is assessed by estimating the impact of a hypothetical (i) temperature increase and (ii) changes in wind magnitude/direction following IPCC scenarios. The results of projections will be discussed relatively to interannual variability.
Located in Library / RBINS Staff Publications
Conference Reference Integrating field data to parameterize a larval transport model of sole and improve knowledge on recruitment in the North Sea.
Inter-annual recruitment variability of sole (Solea solea) in the North Sea is high. Among many fish taxa, the early life stages are critical in determining recruitment. With a Lagrangian larval transport model, coupling a physical model with an Individual-Based Model (IBM), it has been shown that hydrodynamics explains part of this variability in sole (Lacroix et al. 2013). IBMs require a good knowledge of the biological processes governing larval dispersal. However, it is difficult to obtain observations of life history traits; their estimates may strongly influence larval connectivity / retention and successful migration as predicted by the model. Various assumptions about these traits can be tested by comparing simulation results with field data. Several datasets, from the literature and from a 2-year-long monthly sampling at 13 stations in the southern North Sea, will be used to identify the most plausible model parameterisation. It represents a first step towards the calibration and improvement of a larval dispersal model of sole in the North Sea and the development of a tool for fisheries management.
Located in Library / RBINS Staff Publications
Conference Reference A dual-nutrient-reduction strategy to control eutrophication in the southern North Sea continental waters.
For decades the marine ecological models have sustained progressive developments and been subjected to an increasing degree of complexity in their processes, forcings and parameterization. In parallel, the validation techniques have evolved from visual to statistical comparisons, allowing fair estimates of the bias and correlations between model results and reference data. Still, it is difficult to estimate in advance what will be the uncertainty attached to any model prediction because of the complexity of the ecological models and the non linearity of their response to a change. Also, it is not trivial to determine the uncertainty of the model response due to one specific forcing, especially when this forcing is variable in time and space. The uncertainty in an ecological model response is somewhat linked to the model sensitivity to a perturbation. Since the non-linear model response to a perturbation may vary in a wide range of possibilities, we chose to base our assessment on the probability theory by applying a “light” Monte-Carlo experiment. It consists in a reduced number of randomly-perturbed simulations where knowledge of the system allows narrowing the range of perturbations. We applied the light Monte-Carlo experiment on a biogeochemical model in the English Channel and the southern North Sea (3D-MIRO&CO). The uncertainty on modelled chlorophyll a prediction was studied as a response, first, to random wind perturbations and, second, to random phytoplankton autolysis values. Statistical and probabilistic quantification of the results is being presented for the Belgian coastal and offshore zones.
Located in Library / RBINS Staff Publications
Inproceedings Reference Retrieval of oceanic constituents from ocean color using simulated annealing
Located in Library / RBINS Staff Publications
Inproceedings Reference Optical remote sensing in support of eutrophication monitoring in Belgian waters
Located in Library / RBINS Staff Publications
Inproceedings Reference The COASTCOLOUR dataset
The objective of the ESA DUE CoastColour project is to fully exploit the potential of the MERIS instrument for remote sensing of the coastal zone. The product requirements have been derived from a user consultation process. Users have provided in-situ data from many locations, which were used for algorithm development and validation. The MERIS data archive from 2005 onwards has been processed with the finally selected algorithms for 27 globally distributed coastal sites. The CoastColour dataset comprises an improved Level 1b product (L1P), a product that contains directional and normalised water leaving reflectances (L2R) and a product for water properties (L2W). The total data volume is 100TB. All data are online and available from the CoastColour Website. A near real time service was operated from October 2011 until end of the ENVISAT mission. Plans exist to continue the service with Sentinel data.
Located in Library / RBINS Staff Publications
Inproceedings Reference Use of ocean color satellite data to study the dynamics of suspended particles in the Yangtze River plume (East China Sea)
A multi-sensor algorithm is applied to MODIS and MERIS satellite data in order to quantify suspended particulate matter (SPM) in the Yangtze River plume (East China Sea). Several atmospheric correction methods are tested; a simple but operational method is finally selected as appropriate for MODIS, MERIS and GOCI satellite data. As most of the methods for atmospheric corrections of satellite data fail over such highly turbid waters, an adaptation of the black pixel assumption is used to correct for the aerosol contribution. The retrieved seawater reflectance at red wavebands appears as the most sensitive to SPM concentrations but tends to saturate at concentrations beyond 100 mg.l(-1). By opposition the near-infrared seawater reflectance does not saturate even at extremely high concentrations of 1000 mg.l(-1). Overall, the most robust relationship between the SPM concentration and seawater reflectance is obtained considering a spectral ratio between the near-infrared (e. g., 850 nm) and visible (e. g. 550 nm). This relationship is applied to atmospherically corrected ocean color satellite data to retrieve SPM concentrations in the Yangtze River plume. Results show that ocean color satellite data can be used to study the seasonal dynamics of SPM and better understand the role played by the main physical processes involved (river discharge, tidal cycles, wind and regional circulation).
Located in Library / RBINS Staff Publications
Conference Reference Linking human activities to eutrophication in the Southern North Sea.
The Southern North Sea faces eutrophication problems. They result from growing anthropogenic pressure in the river watersheds, and subsequent increase in nutrients (nitrogen and phosphorus) loading to the sea. Establishing the link between human activities and eutrophication problems requires the identification of the major nutrient sources and the ecological response of the coastal ecosystem to these nutrient alterations. This information is crucial to mitigate eutrophication in coastal zones by applying appropriate dual-nutrient reduction strategies, therefore achieving the Good Environmental Status of EU marine waters by 2020. Very recently, MIRO&CO has been upgraded to MIRO&CO V2 and coupled to a generic watershed model based on Riverstrahler/Seneque (Billen et al. 1994). A nutrient tracking approach (Ménesguen et al. 2006) has been adapted and implemented in MIRO&CO V2. The transboundary nutrient transport method has been used to track the nutrients in the sea, and trace back their sources (river, ocean, and atmosphere). This new model tool is used to assess the current eutrophication status in the Southern North Sea based on existing metrics (OSPAR, MSFD and WFD). This is a first and necessary step before assessing the impacts of realistic nutrient reduction scenarios on eutrophication problems. This work is done in the framework of the EMoSEM EU project (www2.mumm.ac.be/emosem/) that aims at providing support to eutrophication management in the North Atlantic Ocean, using state-of-the-art modelling tools.
Located in Library / RBINS Staff Publications
Conference Reference A modelling approach to trace the origin of jellyfish swarms in the Southern North Sea.
The life cycle, the phenology and the interannual variability of jellyfish (i.e. cnidaria medusozoa scyphozoa) are under study across the world as there is debate on their increasing occurrence under human pressure (overfishing, eutrophication, climate change) (Condon et al. 2012). Beside interference in human activities, jellyfish swarms affect the marine food web as these organisms feed on fish eggs and larvae, and compete for food with adult fish (Lynam et al. 2005, Pauly et al. 2009). Whether jellyfish nuisance can be mitigated remains unclear and depends on our understanding of the causes of outbreaks. Most North Sea jellyfish species have a sessile polyp stage as part of their life cycle, and therefore need solid substrate to fix. While A. aurita polyps are visible along the Belgian and Dutch coasts, the location of other species polyps (e.g. Cyanea, Chrysaora) remains largely unknown. Tracing back the origin of an observed jellyfish swarm in the North Sea could help identifying the potential location of polyps and the timing and temperature of strobilation. A Lagrangian particle tracking model parameterized for jellyfish in the English Channel and the southern North Sea is used in backtracking (15 days) and forecast (3 days; forced by UKMO forecast) modes to study the potential origin and fate of jellyfish swarms. A backtracking simulation was applied on a jellyfish swarm observed in 2013 in the Belgian coastal zone . It allowed identifying potential areas of origin for the outbreak, raising new scientific questions. A first sensitivity study illustrates the wind influence on the backtracking simulation.
Located in Library / RBINS Staff Publications