In situ application of a cellulose bag and an ion exchanger for differentiation of labile and inert metal species in aquatic systems

This work involved the development and application of a new analytical procedure for in-situ characterization of the lability of metal species in aquatic systems by using a system equipped with a diffusion membrane and cellulose organomodified with p-aminobenzoic acid groups (DM-Cell-PAB). To this end, the DM-Cell-PAB system was prepared by adding cellulose organomodified with p-aminobenzoic acid groups (Cell-PAB) to pre-purified cellulose bags. After the DM-Cell-PAB system was sealed, it was examined in the laboratory. The in-situ application involved immersing the DM-Cell-PAB system in two different rivers, enabling us to study the relative lability of metal species (Cu, Cd, Fe, Mn, and Ni) as a function of time and quantity of exchanger. The procedure is simple and opens up a new perspective for understanding environmental phenomena relating to the complexation, transport, stability, and lability of metal species in aquatic systems rich in organic matter.

Tropical dermatology: Marine and aquatic dermatology

Dermatoses caused by marine organisms are frequently seen in dermatology clinics worldwide. Cutaneous injuries after exposure to marine environments include bacterial and fungal infections and lesions caused by aquatic plants and protists. Some of these diseases are well known by dermatologists, such as Vibrio vulnificus septicemia and erysipeloid, but others are uncommon, such as envenomation caused by ingestion or contact with certain dinoflagellates or cyanobacteria, which are associated with rashes that can begin Within minutes after exposure. Many marine/aquatic invertebrates, such as sponges, cnidarians, echinoderms, crustaceans, and mollusks, are associated with different kinds of dermatologic lesions that call vary from irritant or allergic contact dermatitis to physical trauma and envenomations. These cutaneous lesions May result in mild local reactions or can be associated with severe systemic reactions. Invertebrate animals, such as cnidarians, sea urchins, and worms, and aquatic vertebrates, such as venomous fishes and stingrays, are commonly associated with skin lesions in many countries, where they call constitute occupational dermatoses among fishermen and scuba divers, but they can also be observed among persons who contact these animals in kitchens or beaches. The presence of unusual lesions, a recent travel history, and/or a report of contact with an aquatic environment (including ownership of a marine or freshwater aquarium) should alert the dermatologist to the etiology of the cutaneous problems. (J Am Acad Dermatol 2009;61:733-50.)

Injuries and envenoming by aquatic animals in fishermen of Coxim and Corumbá municipalities, state of Mato Grosso do Sul, Brazil: identification of the causative agents, clinical aspects and first aid measures

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Oxidative stress biomarkers and aggressive behavior in fish exposed to aquatic cadmium contamination

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aquatic insects as the main food resource of fish the community in a Neotropical reservoir

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

New analytical procedure based on a cellulose bag and ionic exchanger with p-aminobenzoic acid groups for differentiation of labile and inert metal species in aquatic systems

A new procedure was developed for the in situ characterization of the lability of metal species in aquatic systems by using a system equipped with a diffusion membrane and cellulose organomodified with p-aminobenzoic acid groups (DM-Cell-PAB). To this end, the DM-Cell-PAB system was prepared by adding cellulose organomodified with p-aminobenzoic acid groups (Cell-PAB) to pre-purified cellulose bags. After the DM-Cell-PAB system was sealed, it was examined in the laboratory to evaluate the influence of complexation time, mass of exchanger, pH, metal ions (Cu, Cd, Fe, Mn, and Ni), and concentration of organic matter on the relative lability of metal species. It was found that the pH and kinetics strongly influence the process of metal complexation by the DM-Cell-PAB system. At all pH levels, Cd, Mn, and Ni showed lower complexation with Cell-PAB resin than Cu and Fe metals. Note that relative lability of metals complexed to aquatic humic substances (AHS) in the presence of Cell-PAB resin showed the following order: Cu congruent to Fe >> Ni > Mn=Cd. The results presented here also indicate that increasing the AHS concentration decreases the lability of metal species by shifting the equilibrium to AHS-metal complexes. Our results indicate that the system under study offers an interesting alternative that can be applied to in situ experiments for differentiation of labile and inert metal species in aquatic systems.

Diet and trophic groups of an aquatic insect community in a tropical stream

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Composition of the aquatic invertebrate fauna associated to the mangrove vegetation of a coastal river, analyzed through a manipulative experiment.

The present study analyzed the composition of the aquatic fauna associated to the mangrove forest in a southeastern Brazilian river. The composition of the macrofauna in the roots of the marginal vegetation located at three different salinity stretches was analyzed by sampling pieces of the submerged branches of the vegetation (natural substrate) and pieces of sisal rope (artificial substrate), installed close to the natural vegetation and sampled after a period of 14 colonization days. In both types of substrate, twelve taxonomic groups were sampled, representing three phyla (Cnidaria, Annelida and Arthropoda). The crustaceans, corresponding to the most diversified group, were represented by Copepoda, Tanaidacea, Isopoda, Amphipoda and Decapoda. The highest salinity stretch showed the highest abundance, with a progressive decrease from high to low salinity for both substrates. Copepoda and Tanaidacea predominated on both substrates, although the artificial substrate exhibited the highest total abundance and species richness. Considering the relative abundance of the taxonomic groups on both substrates, the majority of groups predominated in the highest salinity range. Significant differences on the longitudinal distribution of abundance were associated to the variation on salinity and with the complexity of the substrate.

Aquatic macrophyte distribution in relation to water and sediment conditions in the Itaipu Reservoir, Brazil

Aquatic macrophyte community distribution along the eastern shoreline of the Itaipu Reservoir (one of the South America's largest impoundments) is described in relation to limnological and sedimentological factors. The central body of the reservoir is mesotrophic, while the arms (flooded influent river valleys) along the eastern shore may be oligo-mesotrophic to eutrophic, depending on time of year and sub-catchment characteristics. Macrophyte community composition and species cover were surveyed at 30 sites in four arms, in relation to sediment total P and organic matter; underwater light regime; and water total P and Kjeldahl N concentration, alkalinity, conductivity, depth and pH. Seventeen euhydrophyte and six emergent macrophyte species were recorded. Large stands of Egeria najas dominated the euhydrophyte vegetation, together with free-floating weed species (Pistia stratiotes Linn., Salvinia auriculata Aublet and Eichhornia crassipes (Mart.) Solms.). Canonical Correspondence Analysis of the data showed that two sets of variables were important predictors of aquatic macrophyte community structure. Floating macrophyte assemblage was closely related to concentration of nutrients in both water and sediment, while light penetration was the strongest predictor of submerged species occurrence. Although a large number of potential nuisance species were present, dense growths were restricted to shallower areas of the Itaipu Reservoir, causing localised problems. The possibility of increasing interference by these plants with fisheries, recreational use, transport and hydroelectricity generation suggests a need for continued monitoring of weed distribution and abundance, and investigation of appropriate management measures.

Growth of free-floating aquatic macrophytes in different concentrations of nutrients

The objective of the study was to evaluate the effect of different concentrations of nitrogen and phosphorus on the growth of the free-floating aquatic macrophytes Eichhornia crassipes, Pistia stratiotes, and Salvinia molesta. The plants were cultured in 2,000-l outdoor concrete tanks. Triplicate tanks, with a continuous flow of effluent from culture ponds containing Nile tilapia, were used for each plant type (n = 3). The plant material was collected monthly from 0.25 m(2) floating quadrats, at the two ends of the tanks (higher nutrient concentrations near the inflow and lower nutrient concentrations near the outflow). In low nutrient concentrations, the maximum relative growth rates (RGRs) for E. crassipes (0.016/day) and P. stratiotes (0.016/day) were significantly lower (P <= 0.05) than for S. molesta (0.029/day). There were no significant differences between the RGRs of S. molesta in the different nutrient concentrations. Eichhornia crassipes and P. stratiotes had their growth limited by nitrogen and phosphorus concentrations. The increase in plant density during the experiment probably also affected the growth of these species. In this context, E. crassipes and P. stratiotes can cause problems in nutrient-rich waterbodies, but under these experimental conditions their growth was limited by nitrogen and/or phosphorus concentrations. The growth of S. molesta was not influenced by the different nutrient concentrations.

Fish assemblage structure and aquatic pollution in a Brazilian stream: some limitations of diversity indices and models for environmental impact studies

The aim of this study was to describe and quantify the effect of aquatic pollution on the fish assemblage structure of the Corumbatai River (Brazil), by comparing two sites with different water quality characteristics. The results revealed that abundance of individuals was low at the polluted site (B). However, the two sites did not differ significantly in species richness (total and average). This fact contradicts theories stating that portions where the transverse area of the channel is larger should present a higher biological richness. It was also observed that the ichthyofauna of site B had higher evenness, and, consequently, a tendency to a higher diversity than that at site A. This demonstrates that diversity estimates should be used cautiously in environmental impact studies, as they do not necessarily indicate better conditions of communities living in more preserved environments.

Habitat Split as a Cause of Local Population Declines of Amphibians with Aquatic Larvae

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Solar Radiation Effect on the Complexation Capacity of Aquatic Humic Substances with Metals

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Water quality index as a simple indicator of aquaculture effects on aquatic bodies

This paper proposes a water quality index (WQI) to subsidize management actions in the Medio Paranapanema Watershed in São Paulo State, Brazil, as a simple pollution indicator for aquaculture activity. Water quality of the Macuco and Queixada rivers was investigated for 2 years (from May 2003 to May 2005). The index proposed in this work is composed of three measurable environmental parameters-turbidity, total phosphorus and dissolved oxygen. Concentrations of these three variables were normalized on a scale from 0 to 100 and translated into statements of water quality (excellent, good, regular, fair and poor). The index was applied to seventeen monitoring points in the aquatic bodies described above and compared to others, one being that used by the Environmental Protection Agency of United States and proposed for the National Sanitation Foundation, other employing minimal index and the last one considering the minimum operator concept. The results show that the degradation in this watershed from aquaculture activity can be easily inferred with this index, which is more restricted than the others routinely used to infer water quality. (C) 2007 Elsevier Ltd. All rights reserved.

Development of a simple and versatile ultrafiltration system for the fractionation of aquatic humic substances

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)