Bacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in Nigerian contaminated systems

Samples of soil, water, and sediments from industrial estates in Lagos were collected and analyzed for heavy metals and physicochemical composition. Bacteria that are resistant to elevated concentrations of metals (Cd^2?+?, Co^2?+?, Ni^2?+?, Cr^6?+?, and Hg^2?+?) were isolated from the samples, and they were further screened for antibiotic sensitivity. The minimum tolerance concentrations (MTCs) of the isolates with dual resistance to the metals were determined. The physicochemistry of all the samples indicated were heavily polluted. Twenty-two of the 270 bacterial strains isolated showed dual resistances to antibiotics and heavy metals. The MTCs of isolates to the metals were 14 mM for Cd^2?+?, 15 mM for Co^2?+? and Ni^2?+?, 17 mM for Cr^6?+?, and 10 mM for Hg^2?+?. Five strains (Pseudomonas aeruginosa, Actinomyces turicensis, Acinetobacter junni, Nocardia sp., and Micrococcus sp.) resisted all the 18 antibiotics tested. Whereas Rhodococcus sp. and Micrococcus sp. resisted 15 mM Ni^2?+?, P. aeruginosa resisted 10 mM Co^2?+?. To our knowledge, there has not been any report of bacterial strains resisting such high doses of metals coupled with wide range of antibiotics. Therefore, dual expressions of antibiotics and heavy-metal resistance make the isolates, potential seeds for decommissioning of sites polluted with industrial effluents rich in heavy metals, since the bacteria will be able to withstand in situ antibiosis that may prevail in such ecosystems.     

Do cod form spawning leks? Evidence from a Newfoundland spawning ground

Catch and acoustic telemetry data were used to test three predictions of lekking behaviour in Atlantic cod (Gadus morhua L.) at a small-scale spawning ground (∼25 km²) in Placentia Bay, Newfoundland: (1) that cod form male-skewed aggregations during spawning; (2) spawning arenas occur at consistent sites; and (3) on the arenas, there will be higher proportions of spawning fish. Forty-two fishing sets from 1998 to 2003 indicated male-skewed sets early in the spawning season (April) in 5 of 6 survey years. Male-skewed sets were consistently distributed at depths < 50 m and mostly in one part of the ground. The proportions of spawning females and spent males were significantly higher in male-skewed sets, whereas sets with equal sex ratios had significantly higher proportions of immature males and spent females. In addition, cod of both sexes were significantly larger in male-skewed sets. Telemetric tracking of 25 cod in 2002 and 2003 (12 males, 13 females) indicated that both males and females were highly mobile while present on the spawning ground. Overall, our results add support to the hypothesis that cod employ a lekking mating system.     

Improving inferences about private land conservation by accounting for incomplete reporting

Private lands provide key habitat for imperiled species and are core components of function protectected area networks; yet, their incorporation into national and regional conservation planning has been challenging. Identifying locations where private landowners are likely to participate in conservation initiatives can help avoid conflict and clarify trade-offs between ecological benefits and sociopolitical costs. Empirical, spatially explicit assessment of the factors associated with conservation on private land is an emerging tool for identifying future conservation opportunities. However, most data on private land conservation are voluntarily reported and incomplete, which complicates these assessments. We used a novel application of occupancy models to analyze the occurrence of conservation easements on private land. We compared multiple formulations of occupancy models with a logistic regression model to predict the locations of conservation easements based on a spatially explicit social–ecological systems framework. We combined a simulation experiment with a case study of easement data in Idaho and Montana (United States) to illustrate the utility of the occupancy framework for modeling conservation on private land. Occupancy models that explicitly accounted for variation in reporting produced estimates of predictors that were substantially less biased than estimates produced by logistic regression under all simulated conditions. Occupancy models produced estimates for the 6 predictors we evaluated in our case study that were larger in magnitude, but less certain than those produced by logistic regression. These results suggest that occupancy models result in qualitatively different inferences regarding the effects of predictors on conservation easement occurrence than logistic regression and highlight the importance of integrating variable and incomplete reporting of participation in empirical analysis of conservation initiatives. Failure to do so can lead to emphasizing the wrong social, institutional, and environmental factors that enable conservation and underestimating conservation opportunities in landscapes where social norms or institutional constraints inhibit reporting.     

Efficacy of stable isotope ratios in assigning endangered migrants to breeding and wintering sites.

A primary constraint on effective conservation of migratory animals is our inability to track individuals through their annual cycle. One such animal is the endangered southwestern subspecies of the Willow Flycatcher, which is difficult to distinguish from conspecifics. Identifying wintering regions used by the endangered subspecies would be an important step in formulating an effective conservation strategy. Our objective was to use stable isotope ratios as a means of identifying wintering sites of Southwestern Willow Flycatchers. We analyzed stable isotope ratios of carbon, nitrogen, and hydrogen from feathers of breeding and wintering Willow Flycatchers. Based on winter samples, we document a positive trend in hydrogen isotope ratios across latitude. We also found that Willow Flycatchers use C4 food webs south of 8 degrees N latitude, but we found no evidence of use of C4 food webs farther north. Nitrogen stable isotope ratios of feathers showed no discernable geographic variation. Discriminant function analyses, based on stable isotope ratios of wintering Willow Flycatchers, were only useful (>50% accurate) for assigning individuals to winter regions if the regions were large and the threshold probability for assignment was relatively high. When using these discriminant functions, most breeding samples of Southwestern Willow Flycatchers were assigned to two wintering regions: central Mexico and Ecuador. We think that assignment of Southwestern Willow Flycatchers to Ecuador is unrealistic. Given the large percentages of samples that could not be classified with certainty, we are not confident that these two regions are truly more likely to harbor wintering Southwestern Willow Flycatchers than other winter regions. We think our inconclusive results are due primarily to weak and nonlinear gradients in isotope ratios across the winter range of Willow Flycatchers.     

Dairy manure as a potential source of crop nutrients and environmental contaminants

Although animal manure is applied to agricultural fields for its nutrient value, it may also contain potential contaminants. To determine the variability in such contaminants as well as in valuable nutrients, nine uncomposted manure samples from Idaho dairies collected during 2.5 years were analyzed for macro- and micro-nutrients, hormones, phytoestrogens, antibiotics, veterinary drugs, antibiotic resistance genes, and genetic elements involved in the spread of antibiotic resistance. Total N ranged from 6.8 to 30.7 (C:N of 10 to 21), P from 2.4 to 9.0, and K from 10.2 to 47.7 g/kg manure. Zn (103 – 348 mg/kg) was more abundant than Cu (56 – 127 mg/kg) in all samples. Phytoestrogens were the most prevalent contaminants detected, with concentrations fluctuating over time, reflecting animal diets. This is the first study to document the presence of flunixin, a non-steroidal anti-inflammatory drug, in solid stacked manure from regular dairy operations. Monensin was the most frequently detected antibiotic. Progesterones and sulfonamides were regularly detected. We also investigated the relative abundance of several types of plasmids involved in the spread of antibiotic resistance in clinical settings. Plasmids belonging to the IncI, IncP, and IncQ1 incompatibility groups were found in almost all manure samples. IncQ1 plasmids, class 1 integrons, and sulfonamide resistance genes were the most widespread and abundant genetic element surveyed, emphasizing their potential role in the spread of antibiotic resistance. The benefits associated with amending agricultural soils with dairy manure must be carefully weighed against the potential negative consequences of any manure contaminants.     

Aerobic degradation of di- and trichlorobenzenes by two bacteria isolated from polluted tropical soils

Two polychlorinated biphenyl (PCBs)-degrading bacteria were isolated by traditional enrichment technique from electrical transformer fluid (Askarel)-contaminated soils in Lagos, Nigeria. They were classified and identified as Enterobacter sp. SA-2 and Pseudomonas sp. SA-6 on the basis of 16S rRNA gene analysis, in addition to standard cultural and biochemical techniques. The strains were able to grow extensively on dichloro- and trichlorobenzenes. Although they failed to grow on tetrachlorobenzenes, monochloro- and dichlorobenzoic acids, they were able to utilize all monochlorobiphenyls, and some dichlorobiphenyls as sole sources of carbon and energy. The effect of incubation with axenic cultures on the degradation of 0.9 mM 1,4-dichlorobenzene, 0.44 mM 1,2,3- and 0.43 mM 1,3,5-trichlorobenzene in mineral salts medium was studied. Approximately, 80-90% of these xenobiotics were degraded in 200 h, concomitant with cell increase of up to three orders of magnitude, while generation times ranged significantly (P<0.05) from 17-32 h. Catechol 1,2-dioxygenase and catechol 2,3-dioxygenase activities were detected in crude cell-free extracts of cultures pre-grown with benzoate, with the latter enzyme exhibiting a slightly higher activity (0.15-0.17 micromolmin(-1) mg of protein(-1)) with catechol, suggesting that the meta-cleavage pathway is the most readily available catabolic route in the SA strains. The wider substrate specificity of these tropical isolates may help in assessing natural detoxification processes and in designing bioremediation and bioaugmentation methods.     

Source attribution and quantification of benzene event emissions in a Houston ship channel community based on real-time mobile monitoring of ambient air

A mobile laboratory equipped with a proton transfer reaction mass spectrometer (PTR-MS) operated in Galena Park, Texas, near the Houston Ship Channel during the Benzene and other Toxics Exposure Study (BEE-TEX). The mobile laboratory measured transient peaks of benzene of up to 37 ppb_v in the afternoon and evening of February 19, 2015. Plume reconstruction and source attribution were performed using the four-dimensional (4D) variational data assimilation technique and a three-dimensional (3D) micro-scale forward and adjoint air quality model based on mobile PTR-MS data and nearby stationary wind measurements at the Galena Park Continuous Air Monitoring Station (CAMS). The results of inverse modeling indicate that significant pipeline emissions of benzene may at least partly explain the ambient concentration peaks observed in Galena Park during BEE-TEX. Total pipeline emissions of benzene inferred within the 16-km² model domain exceeded point source emissions by roughly a factor of 2 during the observational episode. Besides pipeline leaks, the model also inferred significant benzene emissions from marine, railcar, and tank truck loading/unloading facilities, consistent with the presence of a tanker and barges in the Kinder Morgan port terminal during the afternoon and evening of February 19. Total domain emissions of benzene exceeded corresponding 2011 National Emissions Inventory (NEI) estimates by a factor of 2–6.

Implications:?Port operations involving petrochemicals may significantly increase emissions of air toxics from the transfer and storage of materials. Pipeline leaks, in particular, can lead to sporadic emissions greater than in emission inventories, resulting in higher ambient concentrations than are sampled by the existing monitoring network. The use of updated methods for ambient monitoring and source attribution in real time should be encouraged as an alternative to expanding the conventional monitoring network.