Spatial and temporal drivers of zoonotic pathogen contamination of an agricultural watershed

In regions where animal agriculture is prominent, such as southern Alberta, higher rates of gastrointestinal illness have been reported when compared with nonagricultural regions. This difference in the rate of illness is thought to be a result of increased zoonotic pathogen exposure through environmental sources such as water. In this study, temporal and spatial factors associated with bacterial pathogen contamination of the Oldman River, which transverses this region, were analyzed using classification and regression tree analysis. Significantly higher levels of fecal indicators; more frequent isolations of Campylobacter spp., Escherichia coli O157:H7, and Salmonella enterica spp.; and higher rates of detection of pig-specific Bacteroides markers occurred at downstream sites than at upstream sites, suggesting additive stream inputs. Fecal indicator densities were also significantly higher when any one of these three bacterial pathogens was present and where there were higher total animal manure units; however, occasionally pathogens were present when fecal indicator levels were low or undetectable. Overall, Salmonella spp., Campylobacter spp., and E. coli O157:H7 presence was associated with season, animal manure units, and total rainfall on the day of sampling and 3 d in advance of sampling. Several of the environmental variables analyzed in this study appear to influence pathogen prevalence and therefore may be useful in predicting water quality and safety and in the improvement of watershed management practices in this and other agricultural regions.     

Epibenthic macrofaunal community response after a mega-earthquake and tsunami in a shallow bay off central-south Chile

On February 27, 2010, the world’s sixth strongest earthquake on record (8.8 M _w) and tsunami hit central Chile. We assess the response of the epibenthic macrofaunal community following this event in Coliumo Bay, one of the areas most affected by this mega-perturbation. The indicators of aggregate and compositional variability show that 3 years after this event, the community appears to have undergone the following dynamics: (1) At an inter-annual timescale, the community (both in density and biomass) shifted through different structures with apparent directionality; (2) Oceanographic and biological seasonality had a strong cyclical influence on the inter-annual community response; (3) There was spatial homogenization of the community over time (i.e., recovery of diversity), probably promoted by the ecological functionality of scavenger species (i.e., crab Cancer coronatus and snail Nassarius spp.) and by the proportional increase in non-dominant species; (4) Bathymetry and bottom dissolved oxygen also played significant roles in the spatial structure of this community; (5) Three years after the perturbation, total density and total community biomass were still considerably below those described under unperturbed conditions, mainly associated with the decrease in density and biomass of dominant species. Therefore, in spite of this apparent community compositional recovery, the aggregate variability currently remains below the levels reported prior to the effect of the mega-earthquake and tsunami. These results provide evidence that supports both the Cross-Scale Resilience Hypothesis and the Response Diversity Hypothesis.     

Continuous process applied to degradation of triclosan and 2.8-dichlorodibenzene-p-dioxin

Environmental Science and Pollution Research - This study describes the use of a prototype for the continuous photocatalytic reaction process using Fe/Nb2O5-immobilized catalyst for triclosan and...     

How does drought affect native grasses’ photosynthesis on the revegetation of iron ore tailings?

Environmental Science and Pollution Research - The revegetation of areas degraded by iron ore mining is a difficult challenge mainly due to water availability and impoverished metal-rich...     

Acute exposition to Roundup Transorb® induces systemic oxidative stress and alterations in the expression of newly sequenced genes in silverside fish (Odontesthes humensis)

Environmental Science and Pollution Research - Roundup Transorb® (RDT) is a glyphosate-based herbicide commonly used in agricultural practices worldwide. This herbicide exerts negative effects...     

Are the TTAGG and TTAGGG telomeric repeats phylogenetically conserved in aculeate Hymenoptera?

Despite the (TTAGG)_n telomeric repeat supposed being the ancestral DNA motif of telomeres in insects, it was repeatedly lost within some insect orders. Notably, parasitoid hymenopterans and the social wasp Metapolybia decorata (Gribodo) lack the (TTAGG)_n sequence, but in other representatives of Hymenoptera, this motif was noticed, such as different ant species and the honeybee. These findings raise the question of whether the insect telomeric repeat is or not phylogenetically predominant in Hymenoptera. Thus, we evaluated the occurrence of both the (TTAGG)_n sequence and the vertebrate telomere sequence (TTAGGG)_n using dot-blotting hybridization in 25 aculeate species of Hymenoptera. Our results revealed the absence of (TTAGG)_n sequence in all tested species, elevating the number of hymenopteran families lacking this telomeric sequence to 13 out of the 15 tested families so far. The (TTAGGG)_n was not observed in any tested species. Based on our data and compiled information, we suggest that the (TTAGG)_n sequence was putatively lost in the ancestor of Apocrita with at least two subsequent independent regains (in Formicidae and Apidae).     

Taxonomic and Functional Responses to Fire and Post-Fire Management of a Mediterranean Hymenoptera Community

Fire is one of the commonest disturbances worldwide, transforming habitat structure and affecting ecosystem functioning. Understanding how species respond to such environmental disturbances is a major conservation goal that should be monitored using functionally and taxonomically diverse groups such as Hymenoptera. In this respect, we have analyzed the taxonomic and functional response to fire and post-fire management of a Hymenoptera community from a Mediterranean protected area. Thus, Hymenoptera were sampled at fifteen sites located in three burnt areas submitted to different post-fire practices, as well as at five sites located in peripheral unburnt pine forest. A total of 4882 specimens belonging to 33 families, which were classified into six feeding groups according to their dietary preferences, were collected. ANOVA and Redundancy Analyses showed a taxonomic and functional response to fire as all burnt areas had more Hymenoptera families, different community composition and higher numbers of parasitoids than the unburnt area. Taxonomic differences were also found between burnt areas in terms of the response of Hymenoptera to post-fire management. In general the number of parasitoids was positively correlated to the number of potential host arthropods. Parasitoids are recognized to be sensitive to habitat changes, thus highlighting their value for monitoring the functional responses of organisms to habitat disturbance. The taxonomic and functional responses of Hymenoptera suggest that some pine-forest fires can enhance habitat heterogeneity and arthropod diversity, hence increasing interspecific interactions such as those established by parasitoids and their hosts.     

Parental investment without kin recognition: simple conditional rules for parent–offspring behavior

Species differ widely with regard to parental investment strategies and mechanisms underlying those strategies. The passing of benefits to likely genetic offspring can be mediated through a number of different computational and behavioral systems. We report results from an agent-based model in which offspring maintain proximity with parents and parents transmit benefits to offspring without the capacity of either parent or offspring to “recognize” one another. Instead, parents follow a simple rule to emit benefits after reproducing and offspring follow a simple rule of moving in the direction of positive benefit gradients. This model differs from previous models of spatial kin-based altruism in that individuals are modeled as having different behavioral rules at different life stages and benefits are transmitted unidirectionally from parents to offspring. High rates of correctly directed parental investment occur when mobility and sociality are low and parental investment occurs over a short period of time. We suggest that strategies based on recognition and bonding/attachment might serve to increase rates of correctly directed parental investment under parameters that are shown here to otherwise lead to high rates of misdirected and wasted parental investment.     

Oxidative stress in Nile tilapia (Oreochromis niloticus) and armored catfish (Pterygoplichthys anisitsi) exposed to diesel oil

Considering that diesel oil is one of the most common aquatic contaminants, we compare the oxidative stress between two species of fish with different habitats (Pterygoplichthys anisitsi, benthic and Oreochromis niloticus, nektonic) exposed to diesel oil. Malondialdehyde concentrations (MDA) and the activities of ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase were all analyzed in the fishes' livers and gills after 2 and 7 days of exposure to different concentrations of diesel (0.1 and 0.5 mL/L). In the tilapia, MDA levels and the activities of EROD and GST activity in the liver, as well as MDA levels and the activities of GST and SOD in the gill had statistically significant differences between the treatments and between the times of exposure. For the catfish, the same occurred in the case of MDA, EROD, and SOD in the liver and in CAT and SOD in the gills. There were significant differences in the enzyme activity and lipid peroxidation between the species. Although the activity of most enzymes seemed to be more expressive and responsive to diesel in O. niloticus, diesel oil also caused significant effects on oxidative stress parameters in P. anisitsi, even though this species is benthic and thus has less access to insoluble fractions of diesel oil. Therefore, both species can be used as sentinel organisms in environmental biomonitoring of diesel contamination.     

Sources, transport and reactivity of anionic and non-ionic surfactants in several aquatic ecosystems in SW Spain: a comparative study

Presence, distribution and transport mechanisms of the four major synthetic surfactants -linear alkylbenzene sulfonates (LAS), alkyl ethoxysulfates (AES), nonylphenol ethoxylates (NPEOs) and alcohol ethoxylates (AEOs)- have been simultaneously studied in different aquatic ecosystems. Urban wastewater discharges and industrial activities were identified as the main sources for these compounds and their metabolites. LAS, AES and carboxylic metabolites remained in the dissolved form (87–99%). However, NPEOs and AEOs were mostly associated with particulate matter (65–86%), so their degradation in the water column was limited due to their lower bioavailability. It was also observed that sorption to the particulate phase was more intense for longer homologs/ethoxymers for all surfactants. With respect to surface sediments, AES levels were considerably below (<0.25 mg/kg) the values detected for LAS and NPEOs. Concentrations of AEOs, however, were occasionally higher (several tens of ppm) than those found for the rest of the target compounds in several sampling stations.