Ecological risk assessment of pesticide residues in coastal lagoons of Nicaragua

A detailed investigation on the contamination with chlorinated hydrocarbons and organophosphorous pesticides of the coastal lagoon system of Chinandega district, Nicaragua, allowed the identification of contaminant sources and lagoon areas currently more contaminated. The discharge of rivers into the lagoons is the main transport pathway of pesticide residues; whereas atmospheric depositions are likely to be the main pathway for the introduction of PCBs into the lagoons. Analysis of water samples indicates widespread contamination with soluble organophosphorous compounds, such as dichlorvos, up to 410 ng L(-1), diazinon, up to 150 ng L(-1), and chlorpyrifos, up to 83 ng L(-1). Analyses of suspended matter for low solubility organochlorine (OC) compounds revealed very high concentrations of toxaphene, up to 17,450 ng g(-1) dry weight (dw), total DDTs up to 478 ng g(-1), Aroclor 1254, up to 119 ng g(-1) (dw), and lower concentrations for other compounds. Lagoon sediments contain high concentrations also of toxaphene, from 7.9 to 6,900 ng g(-1) (dw), and DDTs, from 1.5 to 321 ng g(-1) (dw), and lower concentrations of chlorpyrifos, hexachlorocyclohexanes, chlordane and other residues. Concentrations of OCs in soft tissues of clams are statistically correlated with the concentrations of the same compounds in bottom sediments, indicating that sediments are a source of contaminants to biota. In some areas of the lagoon system, concentration of residues in sediments are far above recommended threshold guideline values for protection of aquatic life, and may cause acute and chronic toxic effects on more sensitive aquatic species. Despite the ban on the use of toxaphene and DDT, residues of these compounds are still entering the lagoons due to erosion of, and leaching from, agriculture soils in the region. Measures for protection of the lagoon ecosystem are discussed.     

Positive correlation between helpers at nest and nestling immune response in a cooperative breeding bird

In cooperatively breeding species, helpers may contribute to the success of the brood by increasing the number of independent offspring, but also, they may affect offspring condition and, hence, their survival and recruitment into the breeding population. This second type of benefits is rarely included in theoretical models or assessed in field studies. Immune response is a good proxy of individual quality and fitness, and there is good evidence that the performance of the immune system of chicks during the nestling phase is related to their chances of survival and future reproduction. However, no study has so far explored whether helpers at the nest might contribute to enhance immune functioning of nestlings in species with a cooperative breeding system. Here we investigate this issue in the azure-winged magpie (Cyanopica cyanus) and found for the first time a positive correlation between the number of helpers at nest and the cell-mediated immune response of nestlings. This effect was not explained by a general improvement of body condition of chicks because it was independent of individual variation in body mass or tarsus length. Our results suggest that helping can have subtle effects on the quality of offspring that may influence their survival and future reproduction.     

Testosterone and helping behavior in the azure-winged magpie (Cyanopica cyanus): natural covariation and an experimental test

In this study, we investigated patterns of natural covariation between testosterone and reproductive status in a cooperatively breeding bird species, the azure-winged magpie (Cyanopica cyanus). To assess the relationship between testosterone and breeding behavior, we also manipulated testosterone (T) levels early in the season (before breeding started) using testosterone-filled or empty implants. Our results do not support the hypothesis that circulating testosterone levels affect the occurrence of helping behavior in the azure-winged magpie. Helping males had similar T levels to breeding males. Furthermore, experimentally augmented plasma T did not affect the likelihood of becoming either a helper or a breeder. Overall, these results are consistent with previous findings in other bird species and only give some support to the behavioral suppression hypothesis, suggesting that helping in the azure-winged magpie is a flexible behavioral option moderated in the short-term by social and ecological factors. Experimentally elevated testosterone levels, however, reduced the reproductive success of male breeders because of markedly lower levels of paternal care, had similar effects on their mates, but had the contrary effect on helpers, which raised levels of parental effort. We suggest increases in the share of paternity and in social prestige as possible explanations for these results.Communicated by: A. Cockburn     

Bird Populations in Shade and Sun Coffee Plantations in Central Guatemala

We studied the avifauna of sun and shade coffee plantations and associated mid-elevation habitats during the dry season of 1995. The three plantation types (Inga, Gliricidia, and sun) showed high faunistic similarities with each other and were both distinct and depauperate compared to matorral and forest patch habitats. Of all the coffee plantation habitats, Inga shade had the highest diversity. Species associated with wooded vegetation were more common in shade plantations, particularly in Inga. A second census showed a decline in bird numbers that was more pronounced in sun and Gliricidia than in Inga plantations. Overall, differences between the plantation types were small and all coffee plantations were less diverse than traditional coffee farms previously studied in nearby Chiapas, México. The relatively low bird diversity was probably due to the low stature, low tree species diversity, and heavy pruning of the canopy. These features reflect management practices that are common throughout Latin America. The most common species of birds in all coffee plantation habitats were common second-growth or edge species; more specialized forest species were almost completely absent from plantations. Furthermore, many common matorral species were rare or absent from coffee plantations, even sun plantations with which matorral shares a similar superficial structure. Coffee plantations probably will only be important for avian diversity if a tall, taxonomically and structurally diverse canopy is maintained. We suggest this is most likely to occur on farms that are managed for a variety of products rather than those designated entirely for the production of coffee.     

Chorionic mosaicism: Association with fetal loss but not with adverse perinatal outcome

Cytogenetic data from the United States NICHD collaborative study of chorionic villus sampling (CVS) were used to evaluate the clinical significance of chorionic mosaicism. The 10 754 patients with normal cytogenetic results were compared wtih 108 patients (1.0 per cent) with placental mosaicism and 181 patients (1.6 per cent) with pseudomosaicism. Of the pregnancies intended to continue, the pregnancy loss rate was significantly greater in patients with placental mosaicism than in the cytogenetically normal cohort (8.6 vs. 3.4 per cent, p <0.05). However, there was no difference in the frequencies of abruptio placenta, preterm labour or delivery, small-for-gestational-age newborns, pregnancy-induced hypertension, or neonates with Apgar scores less than 7.     

Modelling above-ground herbage mass for a wide range of grassland community types

Whereas it is recognized that management of plant diversity can be the key to reconciling production and environmental aims, most grassland models are tailored for high-value grass species. We proposed to adapt a mono-specific grass model to take into account specific features of species-rich permanent grasslands, especially over the reproductive phase. To this end, we used the concept of plant functional type (PFT), i.e. the grouping of plant species according to plant traits determined by the response of plant species to different management practices (land use and fertilization) and characterizing of agronomic properties of the corresponding species. In the model, weather and nutrient availability act upon rates of biophysical processes (radiation capture and use, plant senescence). These rates are modified over times due to PFT-specific parameters determined experimentally which represent the different strategies of plant species regarding growth. The integration of these parameters into the model made it possible to predict herbage biomass accumulation rate under different management practices for a wide range of plant communities differing in their PFT composition. The model was evaluated in two steps, first by analyzing separately the effects of PFT and an indicator of nutrient availability on herbage accumulation and then by conducting a sensitivity analysis. It was validated using two independent datasets; a cutting experiment running over the whole growing season to examine the consistency of the model outputs under different cutting regimes, and a monitoring of meadows and pastures in spring over a whole growth cycle to assess the model’s ability to reproduce growth curves. Although a good fit was observed between the simulated and observed data, the few discrepancies noticed between field data and predicted values were attributed mainly to the potential presence of non-grass species. More specifically, we noticed that nutrient (mainly nitrogen) availability is the main driver of plant growth rate, and that PFT determines the times at which this rate changes in relation to the phenological characteristics of species present. We concluded that integration of the PFT concept into the initial mono-specific growth model is especially suited to evaluating the consequences of management practices on species-rich permanent grasslands to meet feed production targets.     

226Ra and 228Ra in scale and sludge samples and their correlation with the chemical composition

In order to contribute to a future waste management policy related to the presence of technologically enhanced natural occurring radioactive material (TENORM) in the Brazilian petroleum industry, the present work presents the chemical composition and the (226)Ra and (228)Ra content of sludge and scales generated during the offshore E and P petroleum activities in the Campos Basin, the primary offshore oil production region in Brazil. The (226)Ra and (228)Ra content on 36 sludge and scales samples were determined by gamma-spectrometry. Based on X-ray diffractometry results, a chemical analysis schema for these samples was developed. The results have shown that scales are 75% barium and strontium sulfates, with a mean (226)Ra and (228)Ra content of 106 kBq kg(-1) and 78 kBq kg(-1), respectively. On the other hand, sludge samples have a much more complex chemical composition than the scales. The (226)Ra and (228)Ra content in sludge also varies much more than the content observed in the scales samples and ranged from 0.36 to 367 kBq kg(-1) and 0.25 to 343 kBq kg(-1), respectively.     

Male Enchenopa treehoppers (Hemiptera: Membracidae) vary mate-searching behavior but not signaling behavior in response to spider silk

Finding and attracting mates can impose costs on males in terms of increased encounters with, and attraction of, predators. To decrease the likelihood of predation, males may modify mate-acquisition efforts in two main ways: they may reduce mate-searching efforts or they may reduce mate-attraction efforts. The specific behavior that males change in the presence of predator cues should depend upon the nature of risk imposed by the type of predator present in the environment. For example, sit-and-wait predators impose greater costs to males moving in search of mates. Here, we test whether cues of the presence of a sit-and-wait predator lead to a reduction in mate-searching but not mate-acquisition behavior. We used a member of the Enchenopa binotata complex of treehoppers—a clade of vibrationally communicating insects in which males fly in search of mates and produce mate-attraction signals when they land on plant stems. We tested for changes in mate-searching and signaling behaviors when silk from a web-building spider was present or absent. We found that males delayed flight when spider silk was present but only if they were actively searching for mates. These results suggest that males have been selected to reduce predation risk by adjusting how they move about their environment according to the cues of sit-and-wait predators.     

Arabica-coffee and teobroma-cocoa agro-industrial waste biosorbents,for Pb(II) removal in aqueous solutions

Environmental Science and Pollution Research - Agro-industrial waste biosorbents of arabica–coffee (WCA) and theobroma–cocoa (WCT) have been characterized and tested to remove Pb(II)...