Risk assessment in Nile tilapia (Oreochromis niloticus) and African mud catfish (Clarias gariepinus) exposed to cassava effluent

Toxicity of cassava effluent in water on aquatic lives was examined via acute and chronic bioassay experiments on Clarias gariepinus (I) and Oreochromis niloticus (II) under laboratory conditions, using standard procedures. The effluent cyanide concentration exceeded the WHO limit for wastewater. Fish body weights and haematological parameters (HMP) significantly decreased with increasing effluent concentration at p≤0.05. Toxicity on HMP for the respective (I) and (II) varied from 5.4 to 52.8; 4.8 to 51.9% for packed cell volume, 4.1 to 43.9; 5.3 to 64.0% for red blood count, 0.0 to 15.7; 0.0 to 61.4% for white blood count, 3.6 to 45.9; 5.2 to 49.5% for haemoglobin, 11.6 to 71.9; 28.4 to 63.8% for total protein, 11.5 to 75.5; 15.0 to 58.2% for albumin and 11.8 to 75.0; 46 to 83.9% for globulin. Acute exposure yielded 96-h LC₅₀ values of 0.45% for (I) and 0.25% for (II) and chronic exposure caused reduced growth and poor blood quality.     

Financing Marine Protected Areas Through Visitor Fees: Insights from Tourists Willingness to Pay in Chile

Tourism is a financing mechanism considered by many donor-funded marine conservation initiatives. Here we assess the potential role of visitor entry fees, in generating the necessary revenue to manage a marine protected area (MPA), established through a Global Environmental Facility Grant, in a temperate region of Chile. We assess tourists’ willingness to pay (WTP) for an entry fee associated to management and protection of the MPA. Results show 97 % of respondents were willing to pay an entrance fee. WTP predictors included the type of tourist, tourists’ sensitivity to crowding, education, and understanding of ecological benefits of the MPA. Nature-based tourists state median WTP values of US$ 4.38 and Sun-sea-sand tourists US$ 3.77. Overall, entry fees could account for 10–13 % of MPA running costs. In Chile, where funding for conservation runs among the weakest in the world, visitor entry fees are no panacea in the short term and other mechanisms, including direct state/government support, should be considered.     

Skewed Riskscapes and Environmental Injustice: A Case Study of Metropolitan St. Louis

This article presents a case study of Toxics Release Inventory (TRI) air pollution exposure risks across metropolitan St. Louis. The first section critically reviews environmental justice research and related barriers to environmental risk management. Second, the paper offers a conventional analysis of the spatial patterns of TRI facilities and their surrounding census block group demographics for metropolitan St. Louis. Third, the article describes the use of an exposure risk characterization for 319 manufacturers and their air releases of more than 126 toxic pollutants. This information could lead to more practical resolutions of urban environmental injustices. The analysis of TRIs across metropolitan St. Louis shows that minority and low-income residents were disproportionately closer to industrial pollution sources at nonrandom significance levels. Spatial concentrations of minority residents averaged nearly 40% within one kilometer of St. Louis TRI sites compared to 25% elsewhere. However, one-fifth of the region's air pollution exposure risk over a decade was spatially concentrated among only six facilities on the southwestern border of East St. Louis. This disproportionate concentration of some of the greatest pollution risk would never be considered in most conventional environmental justice analyses. Not all pollution exposure risk is average, and the worst risks deserve more attention from environmental managers assessing and mitigating environmental injustices.     

Über ein langlebiges Zwischenprodukt der photochemischen Reaktion zwischen Jod und Oxalat

The Science of Nature -     

An interlaboratory comparison of sediment elutriate preparation and toxicity test methods

Elutriate bioassays are among numerous methods that exist for assessing the potential toxicity of sediments in aquatic systems. In this study, interlaboratory results were compared from 96-h Ceriodaphnia dubia and Pimephales promelas static-renewal acute toxicity tests conducted independently by two laboratories using elutriate samples prepared from the same sediment. The goal of the study was to determine if the results from the elutriate tests were comparable between two U.S. Environmental Protection Agency (USEPA) laboratories when different elutriate preparation procedures were employed by each lab. Complete agreement in site characterization was attained in 22 of the 25 samples for both bioassays amongst each lab. Of the 25 samples analyzed, 10 were found to be toxic to at least one of the species tested by either laboratory. The C. dubia elutriate tests conducted by the National Exposure Research Laboratory (NERL) indicated that 7 of the 25 sediment samples were toxic, while 8 sediment samples were characterized as such in testing conducted by USEPA Region 6 (Region 6). The P. promelas elutriate tests conducted by NERL determined 8 samples as toxic, while Region 6 tests displayed toxicity in 5 of the samples. McNemar's test of symmetry for C. dubia (S?=?0.33, p?=?0.5637) and P. promelas (S?=?3.0, p?=?0.0833) tests indicated no significant differences in designating a site toxic between NERL and Region 6 laboratories. Likewise, Cohen's kappa test revealed significant agreement between NERL and Region 6 C. dubia (K?=?0.7148, p?<?0.01) and P. promelas (K?=?0.6939, p?<?0.01) elutriate tests. The authors conclude that differences in interlaboratory elutriate preparation procedures have no bearing on the ability of either the C. dubia or P. promelas bioassay testing methods to detect toxicity while yielding similar results.     

Photodegradation of an azo dye of the textile industry

An advanced oxidation treatment, UV/H2O2, was applied to an azo dye, Hispamin Black CA, widely used in the Peruvian textile industry. Rates of color removal and degradation of the dye have been evaluated. A strongly absorbing solution was completely decolorized after 35 min of treatment, and after 60 min an 82% reduction of the total organic carbon (TOC) was obtained. It has been found that the degradation rate increased until an optimum value, beyond which the reagent exerted an inhibitory effect. The degradation rate was also function of pH.     

Distribution of Pb,Cr, Cu and Zn in the marine-coastal region of Zanzibar (Tanzanian archipelago,East Africa)

In Tanzania, a large amount of domestic and industrial wastes are daily released to the aquatic environment without prior treatment. The present paper establishes the status of distribution and environmental implications of heavy metals in water, sediment, suspended particulate matter and biota (Anadara antiquata) from two marine coasts in Zanzibar, Tanzania. These metals are derived from the industrial areas through rivers and storm water outflows. Heavy metal concentrations in the collected samples were determined using atomic absorption spectrophotometry. Concentrations were significantly higher in the Malindi compared to the Fumba coast (ANOVA, p?=?.001). Calculation of metal partition coefficients shows that the relative importance of the particulate and the water phases varies in response to water parameters and suspended solid content, but that most elements achieve a conditional equilibrium in these coasts. Higher metal concentrations found in Malindi suggest a pollution effect related to anthropogenic activities. Mean metal burdens in the tissues of A. antiquata from both Malindi and Fumba coasts were significantly higher than in other compartments analysed (ANOVA, p?<.05). Maximum values of contamination factor and contamination degree for metals were noticed for sediments from both Malindi and Fumba coasts. It is imperative to understand that metal concentrations of coastal environments depend not only on industrial and household waste inputs but also on the geochemical composition of the area.     

Population differences in predation on Batesian mimics in allopatry with their model: selection against mimics is strongest when they are common

Batesian mimicry evolves when a palatable species, the “mimic,” resembles a dangerous species, the “model,” because both receive protection from predation. Yet, this protection should break down where the model is absent, because predators in such areas would not be under selection to avoid the model. Here, we test this prediction in a coral snake mimicry complex. We exposed plasticine replicas of milk snakes that closely mimic coral snakes to natural predators to determine if good mimetic milk snakes are preferentially attacked in allopatry with their model. Moreover, we evaluated whether attack rates on these replicas varied among three different allopatric regions that differed in the type of mimic found locally (i.e., good mimic, poor mimic, or no mimic). When all three regions were considered together, mimics were not preferentially attacked. When regions were analyzed separately, however, attacks on mimics were significantly greater than randomness only where good mimics were found. These variable levels of predation on good mimics might reflect frequency-dependent (i.e., apostatic) predation. In allopatric regions where good mimics are present, predators might have learned or evolved preferences for conspicuous, palatable prey that they encounter frequently. By contrast, in allopatric regions where good mimics are absent, predators might not have learned or evolved preferences for novel phenotypes. Thus, when predation is frequency-dependent, as long as good mimics are rare, they might not experience elevated levels of predation in allopatry with their model as predicted by the Batesian mimicry hypothesis.     

Nonlinear effects of food aggregation on interference competition in mallards

Previous studies of interference competition have shown an asymmetric effect on intake rate of foragers on clumped resources, with only subordinate individuals suffering. However, the food distributions in these studies were uniform or highly clumped, whereas in many field situations, food aggregation is intermediate. Here we investigated whether food distribution (i.e., uniform, slightly clumped, and highly clumped) affects the behavioral response of mallards foraging alone or competing with another. Although the amount of food was the same in all distributions, the mallards reached higher intake rates, visited fewer patches, and showed longer average feeding times in the highly clumped distribution. Competing mallards had lower intake rates on the slightly clumped than on the uniform or highly clumped food distributions. Subordinates generally visited more patches and had shorter feeding times per patch, but their intake rates were not significantly lower than those of dominants. Therefore, we propose that subordinates do not necessarily suffer from interference competition in terms of intake rate, but do suffer higher search costs. In addition, although dominants had significantly higher average feeding times on the best quality patches of the highly clumped food distribution, such an effect was not found in the slightly clumped distribution. These findings indicate that in environments where food is aggregated to a lesser extent, monopolization is not the best strategy for dominants. Our results suggest that interference experiments should use food distributions that resemble the natural situation animals are faced with in the field.     

Atmospheric carbonaceous aerosols over grasslands of central Europe and a Boreal forest

A labour-intensive analytical technique was applied to atmospheric particulate matter samples collected in a German urban/industrial influenced grassland location (Melpitz) and in a Finnish forest area (Hyyti?l?) in order to achieve a detailed chemical speciation of the organic content. The representative nature of the solvent and water-extractable fractions was determined. The organic compounds identified in the solvent extracts are represented by primary compounds with both anthropogenic and biogenic origin, which mainly derive from the vegetation waxes and from petrogenic sources. Secondary products resulting from the oxidation of volatile organic compounds were also detected. The German meadow presented the highest levels of sugars and acidic compounds in the water extracts, whilst polyols were the most abundant class in the Finnish forest. The major compounds of these classes were malic acid, mannitol, arabitol, glucose and sucrose. Levoglucosan was also found in the water extract.