The influence of solid matrices on arsenic toxicity to Corophium orientale

In marine ecosystems, benthic organisms are really important because they are the first step in the transfer of contaminants from environment to biota. To this end, this study focused on biological assays with the amphipod Corophium orientale exposed to two different molecules of arsenic: arsenate (As^V), the most abundant form in sediments, and dimethyl-arsinate (DMA), expected to be moderately toxic as an intermediate in the process of detoxification. The toxicity of arsenic compounds was measured after exposure to three different matrices: water, spiked natural sediment and inert spiked quartz sand. LC₅₀ values were calculated for each exposure, and the results confirmed the highest toxicity of As^V, in addition to underlining the importance of matrix of exposure. Water exposure was the matrix which presented the highest toxicity for inorganic arsenic (As^V LC₅₀=3.51 mg L^?1 vs DMA LC₅₀=54.65 mg L^?1), spiked natural sediment demonstrated its capability to chelate arsenate toxicity (As^V LC₅₀=34.27 mg kg^?1 vs. DMA LC₅₀=52.19 mg kg^?1) and spiked quartz sand presented intermediate values for As^V (LC₅₀=25.26 mg kg^?1), whereas for DMA a lower toxicity was registered (LC₅₀=872.35 mg kg^?1). This study can provide some useful data linked with chemical speciation of arsenic and exposure matrix, for improving the correct management of contaminated sediment.     

Polybrominated diphenyl ether (PBDE) levels in the blood of pure vegetarians (vegans)

Intake of many persistent organic pollutants (POPs) including dioxins, dibenzofurans and PCBs is almost exclusively from gastrointestinal ingestion of animal fats in the diet. With polybrominated diphenyl ether (PBDE) brominated flame retardants (BFRs), no consensus exists at present as to the extent of intake from food, from indoor dust or other routes of intake. Vegans, or pure vegetarians, were previously found to have low body burden of dioxins and dibenzofurans in blood. Data reported here for the first time show a trend towards lower PBDE levels with longer time periods without ingestion of food of animal origin in 8 adult residents of the United States. A stronger relationship between lower PBDE levels and time without meat, specifically, is consistent with substantial PBDE intake from meat relative to fish or dairy products in Americans. These vegans had somewhat lower PBDE levels with a range 12.4–127 and a median 23.9?ppb than published reports of US general population samples which had a range of 4–366 and median of 26?ppb. Our findings suggest that food of animal origin may be a major but not the sole contributor to human body burden of PBDEs.     

Sustainable development as freedom

There has been considerable debate about how best to define sustainable development. In this commentary, I argue that Amartya Sen's concept of 'development as freedom' is the appropriate theoretical framework for understanding sustainable development. Environmentalists should consider defining their goal as 'sustainable development as freedom,' the achievement of the greatest possible level of freedom without restricting the access of future generations to these same freedoms. The adoption of this framework has implications for the work of environmental NGOs, which are briefly discussed.     

Development of clade-specific Symbiodinium primers for quantitative PCR (qPCR) and their application to detecting clade D symbionts in Caribbean corals

We developed quantitative PCR (qPCR) assays to distinguish each of the four clades (A–D) of dinoflagellate endosymbionts (genus Symbiodinium) commonly found in Caribbean corals. We applied these primer sets, which target portions of the multi-copy ribosomal DNA (rDNA) gene family, to assess the presence/absence of symbionts in clade D (as indicated by the detection of clade D DNA). We detected these symbionts in five of six Caribbean host species/genera (21% of samples analyzed, N = 10 of 47 colonies), from which clade D had rarely or never been observed. This suggests that Symbiodinium in clade D are present in a higher diversity of coral species than previously thought. This qPCR-based approach can improve our understanding of the total microbial diversity associated with corals, particularly in hosts thought to be relatively specific, and has many other potential applications for studies of coral reef ecology and conservation.     

Young-boy networks without kin clusters in a lek-mating manakin

I use 10 years of data from a long-term study of lek-mating long-tailed manakins to relate the social network among males to their spatial and genetic structure. Previously, I showed that the network connectivity of young males predicts their future success. Here, I ask whether kinship might shape the organization of this “young-boy network”. Not surprisingly, males that were more socially distant (linked by longer network paths) were affiliated with perch zones (lek arenas) that were further apart. Relatedness (r) among males within the network decreased as social distance increased, as might be expected under kin selection. Nevertheless, any role for indirect inclusive fitness benefits is refuted by the slightly negative mean relatedness among males at all social distances within the network (overall mean r = −0.06). That is, relatedness ranged from slightly negative (−0.04) to more negative (−0.2). In contrast, relatedness in dyads for which at least one of the males was outside the social network (involving at least one blood-sampled male not documented to have interacted with other banded males) was slightly above the random expectation (mean r = 0.05). The slight variations around r = 0 among males of different categories likely reflect dispersal dynamics, rather than any influence of kinship on social organization. Relatedness did not covary with the age difference between males. These results, together with previous results for lack of relatedness between alpha and beta male partners, refute any role for kin selection in the evolution of cooperative display in this lek-mating system. This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau, and R. James).     

Moulting patterns drive within-individual variations of stable isotopes and mercury in seabird body feathers: implications for monitoring of the marine environment

One major limitation in the use of body feathers of seabirds as a monitoring tool of the trophic structure and contamination levels of marine ecosystems is the degree of heterogeneity in feather chemical composition within individuals. Here, we tested the hypothesis that moulting patterns drive body feather heterogeneity, with synchronous moult minimizing within-individual variations, in contrast to asynchronous feather growth. Chicks of white-chinned petrels Procellaria aequinoctialis (representative of bird chicks) and adults of king penguins Aptenodytes patagonicus (representative of adult penguins) that moult their body feathers synchronously showed very low within-individual variations in their feather δ¹³C and δ¹⁵N values and mercury (Hg) concentrations. By contrast, body feathers of adults of Antarctic prions Pachyptila desolata (representative of adult seabirds with asynchronous feather growth during a protracted moult) presented much higher within-individual variances for the three parameters. These findings have three important implications for birds presenting a synchronous body moult. (1) They suggest that all body feathers from the same individual have identical δ¹³C and δ¹⁵N values and Hg content. (2) They predict negligible within-individual variations in the body feather values of other useful stable isotopes, such as δ²H and δ³⁴S, as well as in the concentrations of other compounds that are deposited in the keratin structure. (3) Analysis of one or any number of pooled body feathers is equally representative of the individual. In conclusion, we recommend that long-term routine monitoring investigations focus on birds presenting synchronous rather than asynchronous moult of body feathers both in marine and terrestrial environments. This means targeting chicks rather than adults and, for seabirds, penguins rather than adults of flying species.     

Intra-sexual variability in feeding behaviour of a mountain ungulate: size matters

Many studies comparing the behaviour of individuals of different genders or species showed that animal body mass and forage quality/quantity are key elements of the foraging ecology of herbivores. Since body mass could also influence the animal’s sensitivity to predation risk, its vigilance behaviour should consequently be affected. Alpine ibex (Capra ibex) is characterised by a strong dimorphism among males of different ages, thus representing an ideal case study for testing the Jarman-Bell principle, avoiding possibly misleading effects resulting from the comparison between different species or genders. We analysed the fine-scale foraging behaviour of male ibex in order to assess the effect of body mass and the effects of vegetation quality/quantity on both foraging and vigilance behaviour. Our results showed that smaller males were more selective than larger ones, on account of their lower capability of digesting plant. Smaller males scanned the environment more frequently than larger ones. Male ibex grazed more selectively in sites with high quality forage and their bite rate increased as forage biomass decreased. Vigilance frequency increased with increasing forage biomass as, under these circumstances, ibex are able to prolong anti-predator vigilance while chewing bites that have already been cropped. Our findings highlight the effects of body mass per se on both foraging and anti-predator behaviours in herbivores, thus supporting the Jarman-Bell principle. Foraging can arguably be considered a very flexible behaviour with high evolutionary relevance as it enables herbivores to optimally adjust their total energy intake under varying conditions of food resources.     

Elimination of antibiotic resistance genes and control of horizontal transfer risk by UV-based treatment of drinking water: A mini review

Antibiotic-resistant bacteria and antibiotic resistance genes are in water bodies. UV/chlorination method is better to remove ARGs than UV or chlorination alone. Research on UV/hydrogen peroxide to eliminate ARGs is forthcoming. UV-based photocatalytic processes are effective to degrade ARGs. Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been recognized as one of the biggest public health issues of the 21st century. Both ARB and ARGs have been determined in water after treatment with conventional disinfectants. Ultraviolet (UV) technology has been seen growth in application to disinfect the water. However, UV method alone is not adequate to degrade ARGs in water. Researchers are investigating the combination of UV with other oxidants (chlorine, hydrogen peroxide (H₂O₂), peroxymonosulfate (PMS), and photocatalysts) to harness the high reactivity of produced reactive species (Clž·, ClOž·ž, Clž₂·ž⁻, žž·OH, and SOž₄ž·⁻€) in such processes with constituents of cell (e.g., deoxyribonucleic acid (DNA) and its components) in order to increase the degradation efficiency of ARGs. This paper briefly reviews the current status of different UV-based treatments (UV/chlorination, UV/H₂O₂, UV/PMS, and UV-photocatalysis) to degrade ARGs and to control horizontal gene transfer (HGT) in water. The review also provides discussion on the mechanism of degradation of ARGs and application of q-PCR and gel electrophoresis to obtain insights of the fate of ARGs during UV-based treatment processes.     

Mediating male–male interactions: the role of the UV blue crest coloration in blue tits

Badges of status, usually color patches, are hypothesized to serve as important signals within natural populations by communicating an individual’s fighting ability or aggressiveness before an interaction ever takes place. These signals, which may evolve via sexual and/or social selection, mediate intra-specific competition by influencing the outcome or escalation of contests between individuals. The last 10 years saw the rise of interest in the role of ultraviolet (UV)-based coloration in intra-sexual communication. However, the rare experimental studies that tested this hypothesis found opposite results, which may originate from the different methodological procedures used to assess the badge of status theory. We present here the results of an experiment testing whether male blue tits (Cyanistes caeruleus) respond differently to unfamiliar conspecifics presenting contrasted UV crest coloration. In an aviary, we simultaneously presented two caged blue tits with enhanced (UV+) or reduced (UV−) crest coloration to a focal bird. We found that focal males acted more aggressively towards the UV− males than UV+ males. In addition, focal males fed more often close to males that were similar in brightness or duller than themselves. We conclude that, in blue tits, UV blue crest coloration affects both social and aggressive responses towards unfamiliar individuals, and thus it has some properties of a badge of status.