Flow cytometric measurement of the clearance rate in the blue mussel Mytilus edulis and the development of a new individual exposure system for aquatic immunotoxicological studies

Animals in poor health condition are not relevant biological models. The current study focused on the use of the clearance rate of Mytilus edulis to assess the gross physiological condition of individuals maintained in stressful experimental conditions. This approach was developed in a new, highly controlled experimental exposure device designed to investigate individual responses in aquatic ecotoxicological studies. Both clearance rate values and immune parameters analysis indicated that the health condition of mussels kept in 50ml tubes for 24h or 48h was not altered compared to controls, while most parameters were depressed after 72h. Moreover, this study confirms the relevance of flow cytometric for the measurement of clearance rate compared to techniques utilizing microscopy. Current results prompted us to perform further 24h chemical exposure using this "in tubo" device.     

An environmental justice perspective on ecosystem services

Mainstreaming of ecosystem service approaches has been proposed as one path toward sustainable development. Meanwhile, critics of ecosystem services question if the approach can account for the multiple values of ecosystems to diverse groups of people, or for aspects of inter- and intra-generational justice. In particular, an ecosystem service approach often overlooks power dimensions and capabilities that are core to environmental justice. This article addresses the need for greater guidance on incorporating justice into ecosystem services research and practice. We point to the importance of deep engagement with stakeholders and rights holders to disentangle contextual factors that moderate justice outcomes on ecosystem service attribution and appropriation in socio-political interventions. Such a holistic perspective enables the integration of values and knowledge plurality for enhancing justice in ecosystem services research. This broadened perspective paves a way for transformative ecosystem service assessments, management, and research, which can help inform and design governance structures that nourish human agency to sustainably identify, manage, and enjoy ecosystem services for human wellbeing.     

Enumeration of 2,4-D-degrading microorganisms in soils and crop plant rhizospheres using indicator media; high populations associated with sugarcane (Saccharum officinarum)

Population of microorganisms able to degrade 2,4-D (2,4-dichlorophenoxyacetate) were estimated in 4 non-rhizosphere and 5 rhizosphere soils in Natal by a most probable number (MPN) method using 2,4-D-bromocresol purple media to show 2,4-D degradation with the formation of HC1. Confirmation of herbicide degradation in acid 2,4-D tubes was required by subculturing into fresh 2,4-D-and control indicator media. The MPN estimates of 2,4-D-degrading organisms per g of corresponding rhizosphere/control soils were 6100/212 with African clover ($\text{Trifolium africanum}$ L.) soils, and $\text{46400}\text{178}$, $\text{156000}\text{1480}$ and $\text{40700}\text{6170}$ with sugarcane ($\text{Saccharum officinarum}$ L.) soils. The high, stimulated populations of 2,4-D-degrading microorganisms in the sugarcane rhizospheres suggest the possibility of rapid degradaton in the rhizosphere as an additional mechanism for the protection of certain plants against soil-applied herbicides.     

Influence of pore size and membrane surface properties on arsenic removal by nanofiltration membranes

Four NF membranes were compared regarding arsenate rejection and their properties. Rejection of arsenate had no relationship with membrane pore size. A more negative surface charge was favorable for arsenate rejection at neutral pH. A severe membrane fouling could lead to a great reduction of arsenic rejection. Nanofiltration (NF) has a great potential in removing arsenate from contaminated water. The performance including arsenate rejection, water permeability and resistance to fouling could however differ substantially among NF membranes. This study was conducted to investigate the influence of membrane pore size and surface properties on these aspects of membrane performance. Four fully-aromatic NF membranes with different physicochemical properties were adopted for this study. The results showed that surface charge, hydrophobicity, roughness and pore size could affect water permeability and/or arsenate rejection considerably. A more negative surface charge was desirable to enhance arsenate rejection rates. NF90 and a non-commercialized membrane (M#1) demonstrated the best performance in terms of arsenate rejection and water permeability. The M#1 membrane showed less membrane fouling than NF90 when used for filtration of real arsenic-containing groundwater. This was mainly due to its distinct chemical composition and surface properties. A severe membrane fouling could lead to a substantial reduction of arsenic rejection. The M#1 membrane showed the best performance, which indicated that membrane modification could indeed enhance the overall membrane performance for water treatment.     

Application of rough sets analysis to identify polluted aquatic sites based on a battery of biomarkers: a comparison with classical methods

The evaluation of toxicological effects at the cellular and molecular levels in organisms are often used to determine sites subjected to contamination problems that pose a threat to the long-term survival of organisms. However, the integration of multiple measurements on the health status of organisms into a model for site discrimination is challenging. This study compares two discrimination methods which are based on rule inference: rough sets (RS) analysis and classification trees (CT) with classical multivariate discriminant analysis (DA). Site classification was attempted with six biomarkers of effects: metallothionein levels, lipid peroxidation, DNA damage, levels of lipophosphoproteins (i.e., vitellins), phagocytosis activity and haemocyte cell viability on clam (Mya arenaria) populations from the Saguenay River fjord (Quebec, Canada). Rule based methods have the advantage of complete independence from data distribution constraints in contrast to the classification methods from multivariate analysis that are more commonly used in ecotoxicology. Results show that RS and CT gave better classifications than DA because they do not require strong distributional assumptions. Moreover, RS provided classification rules that could identify the most important biomarker(s) for site discrimination. RS and CT were shown to be simple and efficient methods for classifying multivariable ecotoxicological data. This methodology would be especially useful when freedom from distributional assumptions is required.