Rainforests at the beginning of the 21st century

Rainforests are situated at low latitude where forests enjoy steady and strong radiation. Biodiversity in rainforests has been very high, for historical and climatic reasons. The number of species is very high and tends to increase with precipitation and decrease with seasonality. Disturbance, soil fertility and forest stature also influence the species richness and high turnover of species contribute to diversity. Field observation and studies revealed that large scale deforestation could alter the regional and global climate significantly. Deforestation alters the surface albedo which leads to climate change. Regional land use contributes to climate change through surface-energy budget, as well as the carbon cycle. Forest fragmentation, logging, overhunting, fire and the expanding agriculture threaten the biodiversity. Rainforest covered area has significantly shrunk in the last decades. It is hard to protect the forests because of the growing demand for agricultural area and forest-derived products. Most measures proved ineffective to slow down the destruction. Hence, more forest will be lost in the future. Conservationists should take into consideration the secondary forests because biodiversity can be high enough and it is worth protecting them.

Variation and Uncertainty in Evaporation from a Subtropical Estuary: Florida Bay

Variation and uncertainty in estimated evaporation was determined over time and between two locations in Florida Bay, a subtropical estuary. Meteorological data were collected from September 2001 to August 2002 at Rabbit Key and Butternut Key within the Bay. Evaporation was estimated using both vapor flux and energy budget methods. The results were placed into a long-term context using 33 years of temperature and rainfall data collected in south Florida. Evaporation also was estimated from this long-term data using an empirical formula relating evaporation to clear sky solar radiation and air temperature. Evaporation estimates for the 12-mo period ranged from 144 to 175 cm yr21, depending on location and method, with an average of 163 cm yr21 (6 9%). Monthly values ranged from 9.2 to 18.5 cm, with the highest value observed in May, corresponding with the maximum in measured net radiation. Uncertainty estimates derived from measurement errors in the data were as much as 10%, and were large enough to obscure differences in evaporation between the two sites. Differences among all estimates for any month indicate the overall uncertainty in monthly evaporation, and ranged from 9% to 26%. Over a 33-yr period (1970–2002), estimated annual evaporation from Florida Bay ranged from 148 to 181 cm yr21, with an average of 166 cm yr21. Rainfall was consistently lower in Florida Bay than evaporation, with a long-term average of 106 cm yr21. Rainfall considered alone was uncorrelated with evaporation at both monthly and annual time scales; when the seasonal variation in clear sky radiation was also taken into account both net radiation and evaporation were significantly suppressed in months with high rainfall.

Physiological energetics of the thick shell mussel Mytilus coruscus exposed to seawater acidification and thermal stress

Anthropogenic CO2 emissions have caused seawater temperature elevation and ocean acidification. In view of both phenomena are occurring simultaneously, their combined effects on marine species must be experimentally evaluated. The purpose of this study was to estimate the combined effects of seawater acidification and temperature increase on the energy budget of the thick shell mussel Mytilus coruscus. Juvenile mussels were exposed to six combined treatments with three pH levels (8.1, 7.7 and 7.3) * two temperatures (25 °C and 30 °C) for 14 d. We found that clearance rates (CRs), food absorption efficiencies (AEs), respiration rates (RRs), ammonium excretion rates (ER), scope for growth (SFG) and O:N ratios were significantly reduced by elevated temperature sometimes during the whole experiments. Low pH showed significant negative effects on RR and ER, and significantly increased O:N ratios, but showed almost no effects on CR, AE and SFG of M. coruscus. Nevertheless, their interactive effects were observed in RR, ER and O:N ratios. PCA revealed positive relationships among most physiological indicators, especially between SFG and CR under normal temperatures compared to high temperatures. PCA also showed that the high RR was closely correlated to an increasing ER with increasing pH levels. These results suggest that physiological energetics of juvenile M. coruscus are able to acclimate to CO2 acidification with a little physiological effect, but not increased temperatures. Therefore, the negative effects of a temperature increase could potentially impact the ecophysiological responses of M. coruscus and have significant ecological consequences, mainly in those habitats where this species is dominant in terms of abundance and biomass.

Análise da formulação em Monte Carlo dos pacotes de energia multiespectrais aplicada a meios constituídos por vapor d'água

The Monte Carlo method is accurate and is relatively simple to implement for the solution of problems involving complex geometries and anisotropic scattering of radiation as compared with other numerical techniques. In addition, differently of what happens for most of numerical techniques, for which the associated simulations computational time tends to increase exponentially with the complexity of the problems, in the Monte Carlo the increase of the computational time tends to be linear. Nevertheless, the Monte Carlo solution is highly computer time consuming for most of the interest problems. The Multispectral Energy Bundle model allows the reduction of the computational time associated to the Monte Carlo solution. The referred model is here analyzed for applications in media constituted for nonparticipating species and water vapor, which is an important emitting species formed during the combustion of hydrocarbon fuels. Aspects related to computer time optimization are investigated the model solutions are compared with benchmark line-by-line solutions

Carbonate preservation of sediment cores from the Great Bahama Bank

The oceanic carbon cycle mainly comprises the production and dissolution/ preservation of carbonate particles in the water column or within the sediment. Carbon dioxide is one of the major controlling factors for the production and dissolution of carbonate. There is a steady exchange between the ocean and atmosphere in order to achieve an equilibrium of CO2; an anthropogenic rise of CO2 in the atmosphere would therefore also increase the amount of CO2 in the ocean. The increased amount of CO2 in the ocean, due to increasing CO2-emissions into the atmosphere since the industrial revolution, has been interpreted as "ocean acidification" (Caldeira and Wickett, 2003). Its alarming effects, such as dissolution and reduced CaCO3 formation, on reefs and other carbonate shell producing organisms form the topic of current discussions (Kolbert, 2006). Decreasing temperatures and increasing pressure and CO2 enhance the dissolution of carbonate particles at the sediment-water interface in the deep sea. Moreover, dissolution processes are dependent of the saturation state of the surrounding water with respect to calcite or aragonite. Significantly increased dissolution has been observed below the aragonite or calcite chemical lysocline; below the aragonite compensation depth (ACD), or calcite compensation depth (CCD), all aragonite or calcite particles, respectively, are dissolved. Aragonite, which is more prone to dissolution than calcite, features a shallower lysocline and compensation depth than calcite. In the 1980's it was suggested that significant dissolution also occurs in the water column or at the sediment-water interface above the lysocline. Unknown quantities of carbonate produced at the sea surface, would be dissolved due to this process. This would affect the calculation of the carbonate production and the entire carbonate budget of the world's ocean. Following this assumption, a number of studies have been carried out to monitor supralysoclinal dissolution at various locations: at Ceara Rise in the western equatorial Atlantic (Martin and Sayles, 1996), in the Arabian Sea (Milliman et al., 1999), in the equatorial Indian Ocean (Peterson and Prell, 1985; Schulte and Bard, 2003), and in the equatorial Pacific (Kimoto et al., 2003). Despite the evidence for supralysoclinal dissolution in some areas of the world's ocean, the question still exists whether dissolution occurs above the lysocline in the entire ocean. The first part of this thesis seeks answers to this question, based on the global budget model of Milliman et al. (1999). As study area the Bahamas and Florida Straits are most suitable because of the high production of carbonate, and because there the depth of the lysocline is the deepest worldwide. To monitor the occurrence of supralysoclinal dissolution, the preservation of aragonitic pteropod shells was determined, using the Limacina inflata Dissolution Index (LDX; Gerhardt and Henrich, 2001). Analyses of the grain-size distribution, the mineralogy, and the foraminifera assemblage revealed further aspects concerning the preservation state of the sediment. All samples located at the Bahamian platform are well preserved. In contrast, the samples from the Florida Straits show dissolution in 800 to 1000 m and below 1500 m water depth. Degradation of organic material and the subsequent release of CO2 probably causes supralysoclinal dissolution. A northward extension of the corrosive Antarctic Intermediate Water (AAIW) flows through the Caribbean Sea into the Gulf of Mexico and might enhance dissolution processes at around 1000 m water depth. The second part of this study deals with the preservation of Pliocene to Holocene carbonate sediments from both the windward and leeward basins adjacent to Great Bahama Bank (Ocean Drilling Program Sites 632, 633, and 1006). Detailed census counts of the sand fraction (250-500 µm) show the general composition of the coarse grained sediment. Further methods used to examine the preservation state of carbonates include the amount of organic carbon and various dissolution indices, such as the LDX and the Fragmentation Index. Carbonate concretions (nodules) have been observed in the sand fraction. They are similar to the concretions or aggregates previously mentioned by Mullins et al. (1980a) and Droxler et al. (1988a), respectively. Nonetheless, a detailed study of such grains has not been made to date, although they form an important part of periplatform sediments. Stable isotopemeasurements of the nodules' matrix confirm previous suggestions that the nodules have formed in situ as a result of early diagenetic processes (Mullins et al., 1980a). The two cores, which are located in Exuma Sound (Sites 632 and 633), at the eastern margin of Great Bahama Bank (GBB), show an increasing amount of nodules with increasing core depth. In Pliocene sediments, the amount of nodules might rise up to 100%. In contrast, nodules only occur within glacial stages in the deeper part of the studied core interval (between 30 and 70 mbsf) at Site 1006 on the western margin of GBB. Above this level the sediment is constantly being flushed by bottom water, that might also contain corrosive AAIW, which would hinder cementation. Fine carbonate particles (<63 µm) form the matrix of the nodules and do therefore not contribute to the fine fraction. At the same time, the amount of the coarse fraction (>63 µm) increases due to the nodule formation. The formation of nodules might therefore significantly alter the grain-size distribution of the sediment. A direct comparison of the amount of nodules with the grain-size distribution shows that core intervals with high amounts of nodules are indeed coarser than the intervals with low amounts of nodules. On the other hand, an initially coarser sediment might facilitate the formation of nodules, as a high porosity and permeability enhances early diagenetic processes (Westphal et al., 1999). This suggestion was also confirmed: the glacial intervals at Site 1006 are interpreted to have already been rather coarse prior to the formation of nodules. This assumption is based on the grain-size distribution in the upper part of the core, which is not yet affected by diagenesis, but also shows coarser sediment during the glacial stages. As expected, the coarser, glacial deposits in the lower part of the core show the highest amounts of nodules. The same effect was observed at Site 632, where turbidites cause distinct coarse layers and reveal higher amounts of nodules than non-turbiditic sequences. Site 633 shows a different pattern: both the amount of nodules and the coarseness of the sediment steadily increase with increasing core depth. Based on these sedimentological findings, the following model has been developed: a grain-size pattern characterised by prominent coarse peaks (as observed at Sites 632 and 1006) is barely altered. The greatest coarsening effect due to the nodule formation will occur in those layers, which have initially been coarser than the adjacent sediment intervals. In this case, the overall trend of the grain-size pattern before and after formation of the nodules is similar to each other. Although the sediment is altered due to diagenetic processes, grain size could be used as a proxy for e.g. changes in the bottom-water current. The other case described in the model is based on a consistent initial grain-size distribution, as observed at Site 633. In this case, the nodule reflects the increasing diagenetic alteration with increasing core depth rather than the initial grain-size pattern. In the latter scenario, the overall grain-size trend is significantly changed which makes grain size unreliable as a proxy for any palaeoenvironmental changes. The results of this study contribute to the understanding of general sedimentation processes in the periplatform realm: the preservation state of surface samples shows the influence of supralysoclinal dissolution due to the degradation of organic matter and due to the presence of corrosive water masses; the composition of the sand fraction shows the alteration of the carbonate sediment due to early diagenetic processes. However, open questions are how and when the alteration processes occur and how geochemical parameters, such as the rise in alkalinity or the amount of strontium, are linked to them. These geochemical parameters might reveal more information about the depth in the sediment column, where dissolution and cementation processes occur.

O Ensino de ligações químicas por meio do conceito de energia: uma proposta didática para o ensino médio

This work presents discussions on the teaching of Chemical Bonds in high school and some implications of this approach in learning chemistry by students. In general, understanding how the chemicals combine to form substances and compounds, it is a key point for understanding the properties of substances and their structure. In this sense, the chemical bonds represent an extremely important issue, and their knowledge is essential for a better understanding of the changes occurring in our world. Despite these findings, it is observed that the way in which this concept is discussed in chemistry class has contributed, paradoxically, to the emergence of several alternative designs, making the understanding of the subject by students. It is believed that one of the explanations for these observations is the exclusive use of the "octet rule" as an explanatory model for the Chemical Bonds. The use of such a model over time eventually replace chemical principles that gave rise to it, transforming knowledge into a series of uninteresting rituals and even confusing for students. Based on these findings, it is deemed necessary a reformulation in the way to approach this content in the classroom, taking into account especially the fact that the explanations of the formation of substances should be based on the energy concept, which is fundamental to understanding how atoms combine. Thus, the main question of the survey and described here of the following question: Can the development of an explanatory model for the Chemical Bonds in high school based on the concept of energy and without the need to use the "octet rule"? Based on the concepts and methodologies of modeling activity, we sought the development of a teaching model was made through Teaching Units designed to give subsidies to high school teachers to address the chemical bonds through the concept of energy. Through this work it is intended to make the process of teaching and learning of Chemical Bonds content becomes more meaningful to students, developing models that contribute to the learning of this and hence other basic fundamentals of chemistry.

Global surface net-radiation at 5 km from MODIS Terra

Reliable and fine resolution estimates of surface net-radiation are required for estimating latent and sensible heat fluxes between the land surface and the atmosphere. However, currently, fine resolution estimates of net-radiation are not available and consequently it is challenging to develop multi-year estimates of evapotranspiration at scales that can capture land surface heterogeneity and are relevant for policy and decision-making. We developed and evaluated a global net-radiation product at 5 km and 8-day resolution by combining mutually consistent atmosphere and land data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Terra. Comparison with net-radiation measurements from 154 globally distributed sites (414 site-years) from the FLUXNET and Surface Radiation budget network (SURFRAD) showed that the net-radiation product agreed well with measurements across seasons and climate types in the extratropics (Wilmott’s index ranged from 0.74 for boreal to 0.63 for Mediterranean sites). Mean absolute deviation between the MODIS and measured net-radiation ranged from 38.0 ± 1.8 W∙m−2 in boreal to 72.0 ± 4.1 W∙m−2 in the tropical climates. The mean bias was small and constituted only 11%, 0.7%, 8.4%, 4.2%, 13.3%, and 5.4% of the mean absolute error in daytime net-radiation in boreal, Mediterranean, temperate-continental, temperate, semi-arid, and tropical climate, respectively. To assess the accuracy of the broader spatiotemporal patterns, we upscaled error-quantified MODIS net-radiation and compared it with the net-radiation estimates from the coarse spatial (1° × 1°) but high temporal resolution gridded net-radiation product from the Clouds and Earth’s Radiant Energy System (CERES). Our estimates agreed closely with the net-radiation estimates from the CERES. Difference between the two was less than 10 W•m−2 in 94% of the total land area. MODIS net-radiation product will be a valuable resource for the science community studying turbulent fluxes and energy budget at the Earth’s surface.

Data S1. Results of the analyses considering developmental time, supplementary figures and tables & Video S1

Our ability to project the impact of global change on marine ecosystem is limited by our poor understanding on how to predict species sensitivity. For example, the impact of ocean acidification is highly species-specific, even in closely related taxa. The aim of this study was to test the hypothesis that the tolerance range of a given species to decreased pH corresponds to their natural range of exposure. Larvae of the green sea urchin Strongylocentrotus droebachiensis were cultured from fertilization to metamorphic competence (29 days) under a wide range of pH (from pHT = 8.0/pCO2 ~ 480 ?atm to pHT = 6.5/pCO2 ~ 20 000 ?atm) covering present (from pHT 8.7 to 7.6), projected near-future variability (from pHT 8.3 to 7.2) and beyond. Decreasing pH impacted all tested parameters (mortality, symmetry, growth, morphometry and respiration). Development of normal, although showing morphological plasticity, swimming larvae was possible as low as pHT >= 7.0. Within that range, decreasing pH increased mortality and asymmetry and decreased body length (BL) growth rate. Larvae raised at lowered pH and with similar BL had shorter arms and a wider body. Relative to a given BL, respiration rates and stomach volume both increased with decreasing pH suggesting changes in energy budget. At the lowest pHs (pHT <= 6.5), all the tested parameters were strongly negatively affected and no larva survived past 13 days post fertilization. In conclusion, sea urchin larvae appeared to be highly plastic when exposed to decreased pH until a physiological tipping point at pHT = 7.0. However, this plasticity was associated with direct (increased mortality) and indirect (decreased growth) consequences for fitness.

Seawater carbonate chemistry, mass, length and gene expression of Sepia officinalis during experiments, 2011

The specific transporters involved in maintenance of blood pH homeostasis in cephalopod molluscs have not been identified to date. Using in situ hybridization and immuno histochemical methods, we demonstrate that Na+/K+-ATPase (soNKA), a V-type H+-ATPase (soV-HA), and Na+/HCO3- cotransporter (soNBC) are co-localized in NKA-rich cells in the gills of Sepia officinalis. mRNA expression patterns of these transporters and selected metabolic genes were examined in response to moderately elevated seawater pCO2 (0.16 and 0.35 kPa) over a time-course of six weeks in different ontogenetic stages. The applied CO2 concentrations are relevant for ocean acidification scenarios projected for the coming decades. We determined strong expression changes in late stage embryos and hatchlings, with one to three log2-fold reductions in soNKA, soNBCe, socCAII and COX. In contrast, no hypercapnia induced changes in mRNA expression were observed in juveniles during both short- and long-term exposure. However a transiently increased demand of ion regulatory demand was evident during the initial acclimation reaction to elevated seawater pCO2. Gill Na+/K+-ATPase activity and protein concentration were increased by approximately 15% in during short (2-11 day), but not long term (42 day) exposure. Our findings support the hypothesis that the energy budget of adult cephalopods is not significantly compromised during long-term exposure to moderate environmental hypercapnia. However, the down regulation of ion-regulatory and metabolic genes in late stage embryos, taken together with a significant reduction in somatic growth, indicates that cephalopod early life stages are challenged by elevated seawater pCO2.

A novel methodology for analysis of large scale interconnected power and gas systems

The European Union continues to exert a large influence on the direction of member states energy policy. The 2020 targets for renewable energy integration have had significant impact on the operation of current power systems, forcing a rapid change from fossil fuel dominated systems to those with high levels of renewable power. Additionally, the overarching aim of an internal energy market throughout Europe has and will continue to place importance on multi-jurisdictional co-operation regarding energy supply. Combining these renewable energy and multi-jurisdictional supply goals results in a complicated multi-vector energy system, where the understanding of interactions between fossil fuels, renewable energy, interconnection and economic power system operation is increasingly important. This paper provides a novel and systematic methodology to fully understand the changing dynamics of interconnected energy systems from a gas and power perspective. A fully realistic unit commitment and economic dispatch model of the 2030 power systems in Great Britain and Ireland, combined with a representative gas transmission energy flow model is developed. The importance of multi-jurisdictional integrated energy system operation in one of the most strategically important renewable energy regions is demonstrated.

Integrated Optimal Power Flow for Distribution Networks in Local and Urban Scales

This paper develops an integrated optimal power flow (OPF) tool for distribution networks in two spatial scales. In the local scale, the distribution network, the natural gas network, and the heat system are coordinated as a microgrid. In the urban scale, the impact of natural gas network is considered as constraints for the distribution network operation. The proposed approach incorporates unbalance three-phase electrical systems, natural gas systems, and combined cooling, heating, and power systems. The interactions among the above three energy systems are described by energy hub model combined with components capacity constraints. In order to efficiently accommodate the nonlinear constraint optimization problem, particle swarm optimization algorithm is employed to set the control variables in the OPF problem. Numerical studies indicate that by using the OPF method, the distribution network can be economically operated. Also, the tie-line power can be effectively managed.

Combined Conduction-Convection-Radiation Heat Transfer of Slip Flow inside a Micro-channel Filled with a Cellular Porous Material

Combined conduction–convection–radiation heat transfer is investigated numerically in a micro-channel filled with a saturated cellular porous medium, with the channel walls held at a constant heat flux. Invoking the velocity slip and temperature jump, the thermal behaviour of the porous–fluid system are studied by considering hydrodynamically fully developed flow and applying the Darcy–Brinkman flow model. One energy equation model based on the local thermal equilibrium condition is adopted to evaluate the temperature field within the porous medium. Combined conduction and radiation heat transfer is treated as an effective conduction process with a temperature-dependent effective thermal conductivity. Results are reported in terms of the average Nusselt number and dimensionless temperature distribution, as a function of velocity slip coefficient, temperature jump coefficient, porous medium shape parameter and radiation parameters. Results show that increasing the radiation parameter (Tr)(Tr) and the temperature jump coefficient flattens the dimensionless temperature profile. The Nusselt numbers are more sensitive to the variation in the temperature jump coefficient rather than to the velocity slip coefficient. Such that for high porous medium shape parameter, the Nusselt number is found to be independent of velocity slip. Furthermore, it is found that as the temperature jump coefficient increases, the Nusselt number decrease. In addition, for high temperature jump coefficients, the Nusselt number is found to be insensitive to the radiation parameters and porous medium shape parameter. It is also concluded that compared with the conventional macro-channels, wherein using a porous material enhances the rate of heat transfer (up to about 40 % compared to the clear channel), insertion of a porous material inside a micro-channel in slip regime does not effectively enhance the rate of heat transfer that is about 2 %.

Ecophysiologie de la maturation sexuelle et de la ponte de l'huître creuse Crassostrea gigas : réponses métaboliques (respiration) et alimentaires (filtration, absorption) en fonction des différents stades de maturation

The study of sexual maturation and spawning in the Pacific oyster (Crassostrea gigas) is part of a vast research programme that endeavours to understand the causes of mortality that occur sporadically during the spring and summer seasons in the Marennes-Oléron Bay. Thermal and diet conditioning were used to obtain oysters at each stage of maturity simultaneously. Using the measured rates of clearance, consumption, absorption and respiration provided estimates of growth potential and gave the energetic budget of oysters at different stages of sexual maturity. Physiological responses were similar for males and females. Filtration decreased from 2.4 to 2.6 l.h (-1) to 1.8 l.h (-1) with increasing maturity. Weight gain was associated with gonad development and did not appear to have an effect on the clearance rate. Oysters 2.5 years old showed a negative energy budget (-15 J h (-1)) at later maturity stages. This deficit was confirmed (90 J.h (-1)) in oysters 1.5 years old at the same stage of maturity. On the contrary, immature oysters, in the early stages of maturity or post-spawning, had a growth potential of 110 to 170 J.h (-1). The energy deficit observed at later stages of maturity was primarily due to absorption, which decreased sharply during peak gametogenesis. Using measured respiration rates, an allometric relationship specific to gonad growth was determined with a coefficient of 0.574. Low physiological performance of oysters, observed at later stages of sexual maturity, must be taken into account in research on the factors responsible for spring and summer mortalities affecting oyster farms in Marennes-Oléron.

Disruption of amylase genes by RNA interference affects reproduction in the Pacific oyster Crassostrea gigas

Feeding strategies and digestive capacities can have important implications for variation in energetic pathways associated with ecological and economically important traits, such as growth or reproduction in bivalve species. Here, we investigated the role of amylase in the digestive processes of Crassostrea gigas, using in vivo RNA interference. This approach also allowed us to investigate the relationship between energy intake by feeding and gametogenesis in oysters. Double-stranded (ds)RNA designed to target the two α-amylase genes A and B was injected in vivo into the visceral mass of oysters at two doses. These treatments caused significant reductions in mean mRNA levels of the amylase genes: −50.7% and −59% mRNA A, and −71.9% and −70.6% mRNA B in 15 and 75 µg dsRNA-injected oysters, respectively, relative to controls. Interestingly, reproductive knock-down phenotypes were observed for both sexes at 48 days post-injection, with a significant reduction of the gonad area (−22.5% relative to controls) and germ cell under-proliferation revealed by histology. In response to the higher dose of dsRNA, we also observed reductions in amylase activity (−53%) and absorption efficiency (−5%). Based on these data, dynamic energy budget modeling showed that the limitation of energy intake by feeding that was induced by injection of amylase dsRNA was insufficient to affect gonadic development at the level observed in the present study. This finding suggests that other driving mechanisms, such as endogenous hormonal modulation, might significantly change energy allocation to reproduction, and increase the maintenance rate in oysters in response to dsRNA injection.

Determination of thresholds in marine molluscs as an alternative to the Environmental Quality Standards in marine water defined in the Water Framework Directive

The Water Framework Directive (WFD) establishes Environmental Quality Standards (EQS) in marine water for 34 priority substances. Among these substances, 25 are hydrophobic and bioaccumulable (2 metals and 23 organic compounds). For these 25 substances, monitoring in water matrix is not appropriate and an alternative matrix should be developed. Bivalve mollusks, particularly mussels (Mytilus edulis, Mytilus galloprovincialis), are used by Ifremer as a quantitative biological indicator since 1979 in France, to assess the marine water quality. This study has been carried out in order to determine thresholds in mussels at least as protective as EQS in marine water laid down by the WFD. Three steps are defined: - Provide an overview of knowledges about the relations between the concentrations of contaminants in the marine water and mussels through bioaccumulation factor (BAF) and bioconcentration factor (BCF). This allows to examine how a BCF or a BAF can be determined: BCF can be determined experimentally (according to US EPA or ASTM standards), or by Quantitative Activity-Structure Relationship models (QSAR): four equations can be used for mussels. BAF can be determined by field experiment; but none standards exists. It could be determined by using QSAR but this method is considered as invalid for mussels, or by using existing model: Dynamic Budget Model, but this is complex to use. - Collect concentrations data in marine water (Cwater) in bibliography for those 25 substances; and compare them with concentration in mussels (Cmussels) obtained through French monitoring network of chemicals contaminants (ROCCH) and biological integrator network RINBIO. According to available data, this leads to determine the BAF or the BCF (Cmussels /Cwater) with field data. - Compare BAF and BCF values (when available) obtained with various methods for these substances: BCF (stemming from the bibliography, using experimental process), BCF calculated by QSAR and BAF determined using field data. This study points out that experimental BCF data are available for 3 substances (Chlorpyrifos, HCH, Pentachlorobenzene). BCF by QSAR can be calculated for 20 substances. The use of field data allows to evaluate 4 BAF for organic compounds and 2 BAF for metals. Using these BAF or BCF value, thresholds in shellfish can be determined as an alternative to EQS in marine water.