Males are attracted by their own courtship signals

Courting male fiddler crabs Uca terpsichores (1 cm carapace width) sometimes build mounds of sand called hoods at the entrances to their burrows. Males wave their single enlarged claws to attract females to their burrows for mating. It was shown previously that burrows with hoods are more attractive to females and that females visually orient to these structures. In this study, we test whether males also use their hoods to find their burrows. We first determined the maximum distance that males can see and find a burrow opening without a hood. Males were removed from their burrows and placed on the sand at a range of distances from a burrow opening. If they were more than about 8 cm (seven units of eye-height) away, they were unable find the burrow. In contrast, males that were burrow residents used a non-visual path map to return to their burrows from much greater distances. To determine if hoods help males find their burrows when there are errors in their path maps, we moved residents 1–49 cm on sliding platforms producing errors equal to the distances they were moved. Males with self-made hoods or hood models at their burrows relocated their burrows at significantly greater distances than did males with unadorned burrows. Hood builders also relocated their burrows faster. Hence, hoods have two functions: they attract females and they provide a visual cue that males use to find their burrows quickly and reliably when their path maps fail. An erratum to this article can be found at     

Recycled and virgin plastic carriers in hybrid reactors for wastewater treatment.

The reduction of organic and nitrogen pollution of wastewater was investigated in two hybrid reactors and compared with the reduction obtained by using a conventional activated sludge reactor (ASR) run as a control. Both HR-1 and HR-2 were activated sludge systems where a low-density carrier, P1 (polyethylene) for HR-1 and P2 (recycled plastics) for HR-2, was added. Firstly, the three reactors were operated at 10 days Suspended Solid Retention Time (SRT(SS)), leading to a complete nitrification. Secondly, the SRT(SS) for each reactor was lowered to 3 days. Nitrification was lost for the ASR but remained complete for HR's. Respirometric techniques were used to measure fixed or suspended biomass activities for heterotrophic and autotrophic biomass. More than 90% of the autotrophic activity was found on the supports whatever the SRT(SS) used. The results may underline the role of the carrier geometry or surface characteristics on the autotrophic/heterotrophic microorganism distribution.     

Monitoring of copper,arsenic and antimony levels in agricultural soils impacted and non-impacted by mining activities,from three regions in Chile

This paper reports a comparative study of the concentration of three important environmental elements that are often found together in mineral deposits and then associated with mining activities; copper, arsenic and antimony. These elements were determined in 26 different agricultural soils from regions I, II and V in Chile, zones where the most important and biggest copper industries of this country are located. As background levels of these elements in soils have not been well established, in this study, both, impacted and non-impacted agricultural soils from different regions were considered. The relationships between the concentrations of these elements in soils were also examined. The concentration ranges for copper, arsenic and antimony were 11-530; 2.7-202 and 0.42-11 mg kg(-1) respectively. The copper concentrations in non-polluted soils from the north and central zone of Chile were similar. However, three sites from the north region have copper concentration as higher as 100 mg kg(-1), values that exceed the critical concentration for copper in soils. The concentration of arsenic and antimony in the north soils were higher than in non-impacted ones and, in the case of arsenic, greatly exceeded the world average concentration reported for this element in soils. The highest arsenic and antimony concentrations were found in Calama and Quillagua soils, two different sites in the Loa valley. The arsenic/antimony concentration ratio was higher in Quillagua soil. The high concentrations of three elements determined in impacted soils from region V (Puchuncaví and Catemu valleys) clearly shows the impact produced in this zone by the industrial and mining activities developed in their proximities. At Puchuncaví valley a clear decrease was observed in copper, arsenic and antimony concentrations in soils on the function of the distance from the industrial complex "Las Ventanas", and all concentrations exceeded the reported critical values for this matrix. Instead at Catemu valley, only the copper concentration was higher than this value. Statistically significant correlation was found for Cu-Sb in all soils; more significant Cu-As, Cu-Sb and Sb-As correlations were evaluated for soils from Puchuncaví and Catemu valleys, corroborating that high concentrations of copper, arsenic and antimony in these soils coming from the same pollution sources, the copper industry and the thermoelectric power plant.     

Influence of sugar cane vinasse on the sorption and degradation of herbicides in soil under controlled conditions

This study reports the influence of sugar cane vinasse on the persistence, sorption and leaching potential of diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea), hexazinone (3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4-dione) and tebuthiuron (1-(5-tert-butyl-1,3,4-thiadiazol-2-yl)-1,3-dimethylurea) in both a clay and sandy soil from a tropical area of Brazil. The experiments were conducted out under controlled laboratory conditions. The addition of sugarcane vinasse to soil influenced the persistence and sorption of the herbicides in both the studied clay and sandy soils, with a considerable decrease in the diuron DT₅₀ values in clay soil. The Ground Water Ubiquity Score (GUS) Index classifies the herbicides as leachers in both soils and treatments, with the exception of diuron, which is classified as a non-leacher in clay soil-vinasse and as a transient herbicide in sandy soil. These results suggest that special attention should be given to areas such as those where the sandy soil was collected in this study, which is a recharge area of the Guarani Aquifer and is likely to experience groundwater contamination due to the high leaching potential of the applied pesticides.     

Batch and continuous adsorption of Cu(II) and Zn(II) ions from aqueous solution on bi-functionalized sugarcane-based biosorbent

Environmental Science and Pollution Research - A new one-pot synthesis method optimized by a 23 experimental design was developed to prepare a biosorbent, sugarcane bagasse cellulose succinate...     

Quality of the surface water of a basin affected by the expansion of the agricultural frontier over the native forest in the Argentine Espinal region

Environmental Science and Pollution Research - Land use changes have led to the degradation of multiple ecosystem services and affected the quality of aquatic ecosystems. The aims of this study...     

Radium and uranium levels in vegetables grown using different farming management systems

Vegetables grown with phosphate fertilizer (conventional management), with bovine manure fertilization (organic management) and in a mineral nutrient solution (hydroponic) were analyzed and the concentrations of ²³⁸U, ²²⁶Ra and ²²⁸Ra in lettuce, carrots, and beans were compared. Lettuce from hydroponic farming system showed the lowest concentration of radionuclides 0.51 for ²²⁶Ra, 0.55 for ²²⁸Ra and 0.24 for ²³⁸U (Bq kg⁻¹ dry). Vegetables from organically and conventionally grown farming systems showed no differences in the concentration of radium and uranium. Relationships between uranium content in plants and exchangeable Ca and Mg in soil were found, whereas Ra in vegetables was inversely correlated to the cation exchange capacity of soil, leading to the assumption that by supplying carbonate and cations to soil, liming may cause an increase of U and a decrease of radium uptake by plants. The soil to plant transfer varied from 10⁻⁴ to 10⁻² for ²³⁸U and from 10⁻² to 10⁻¹ for ²²⁸Ra.     

Evaluation of genotoxicity in Rhamdia quelen (Pisces, Siluriformes) after sub-chronic contamination with Fipronil

Diverse genetic biomarkers have been used to evaluate the effects of pollution by mutagenic agents such as metals and pesticides, as well as a large variety of chemical substances derived from human activities. This work researched the effects that an exposure of 60 days to the insecticide Fipronil (concentrations of 0.05, 0.10 and 0.23 μg/L) can cause in the fish Rhamdia quelen using Comet assay with gills, histopathological analysis of gills and the Piscine Micronucleus test and Nuclear Morphological Alterations. The results for the Comet assay and for gills histopathological injuries showed no difference between the control group and the contaminated groups. In the Piscine Micronucleus test, the smallest concentration of Fipronil (0.05 μg/L) was similar as the control group, while concentrations of 0.10 and 0.23 μg/L caused more damage to the DNA. These results suggested that only the highest concentrations of Fipronil tested cause damage in erythrocytes, but none of these concentrations was sufficient to alter the DNA in the gill cells. R. quelen may be a less sensitive bioindicator than other fish that have been tested. On the other hand, the concentrations used may not have been sufficient to detect alterations in the DNA of R. quelen with the chosen tests. Works like this take on great importance given the enormous quantity of substances that are thrown daily into the environment in an uncontrolled way, without evaluation of the consequences. The application of these tests with other concentrations, tissues and exposure times is suggested for future works.     

Exploratory analysis in the evaluation of stress due to aluminum presence in Physalis angulata L. and multielement determination by microwave-induced plasma optical emission spectrometry (MIP OES)

Environmental Science and Pollution Research - The present work aimed to analyze the mineral nutrition of Physalis angulata L. under stress by aluminum in the nutrient solution. The treatments...