Metal ion-induced enhanced oxidation of organic contaminants by ferrate: a review

Environmental Chemistry Letters - The global contamination of water resources by organic contaminants such as pharmaceuticals and pesticides is calling for advanced remediation techniques, yet...     

Wastewater technology attenuates the toxicity of shisha smoking

Environmental Chemistry Letters -     

Importance of timely metadata curation to the global surveillance of genetic diversity

Genetic diversity within species represents a fundamental yet underappreciated level of biodiversity. Because genetic diversity can indicate species resilience to changing climate, its measurement is relevant to many national and global conservation policy targets. Many studies produce large amounts of genome-scale genetic diversity data for wild populations, but most (87%) do not include the associated spatial and temporal metadata necessary for them to be reused in monitoring programs or for acknowledging the sovereignty of nations or Indigenous peoples. We undertook a distributed datathon to quantify the availability of these missing metadata and to test the hypothesis that their availability decays with time. We also worked to remediate missing metadata by extracting them from associated published papers, online repositories, and direct communication with authors. Starting with 848 candidate genomic data sets (reduced representation and whole genome) from the International Nucleotide Sequence Database Collaboration, we determined that 561 contained mostly samples from wild populations. We successfully restored spatiotemporal metadata for 78% of these 561 data sets (n = 440 data sets with data on 45,105 individuals from 762 species in 17 phyla). Examining papers and online repositories was much more fruitful than contacting 351 authors, who replied to our email requests 45% of the time. Overall, 23% of our email queries to authors unearthed useful metadata. The probability of retrieving spatiotemporal metadata declined significantly as age of the data set increased. There was a 13.5% yearly decrease in metadata associated with published papers or online repositories and up to a 22% yearly decrease in metadata that were only available from authors. This rapid decay in metadata availability, mirrored in studies of other types of biological data, should motivate swift updates to data-sharing policies and researcher practices to ensure that the valuable context provided by metadata is not lost to conservation science forever.     

Biotechnological intervention for societal development (BioSangam 2020)

Environmental Science and Pollution Research -     

Tropical forest soil microbial communities couple iron and carbon biogeochemistry

We report that iron-reducing bacteria are primary mediators of anaerobic carbon oxidation in upland tropical soils spanning a rainfall gradient (3500-5000 mm/yr) in northeast Puerto Rico. The abundant rainfall and high net primary productivity of these tropical forests provide optimal soil habitat for iron-reducing and iron-oxidizing bacteria. Spatially and temporally dynamic redox conditions make iron-transforming microbial communities central to the belowground carbon cycle in these wet tropical forests. The exceedingly high abundance of iron-reducing bacteria (up to 1.2 x 10(9) cells per gram soil) indicated that they possess extensive metabolic capacity to catalyze the reduction of iron minerals. In soils from the higher rainfall sites, measured rates of ferric iron reduction could account for up to 44% of organic carbon oxidation. Iron reducers appeared to compete with methanogens when labile carbon availability was limited. We found large numbers of bacteria that oxidize reduced iron at sites with high rates of iron reduction and large numbers of iron reducers. The coexistence of large populations of iron-reducing and iron-oxidizing bacteria is evidence for rapid iron cycling between its reduced and oxidized states and suggests that mutualistic interactions among these bacteria ultimately fuel organic carbon oxidation and inhibit CH4 production in these upland tropical forests.     

Life history traits predict relative abundance in an assemblage of forest caterpillars

Species in a given trophic level occur in vastly unequal abundance, a pattern commonly documented but poorly explained for most taxa. Theoretical predictions of species density such as those arising from the metabolic theory of ecology hold well at large spatial and temporal scales but are not supported in many communities sampled at a relatively small scale. At these scales ecological factors may be more important than the inherent limits to energy use set by allometric scaling of mass. These factors include the amount of resources available, and the ability of individuals to convert these resources successfully into population growth. While previous studies have demonstrated the limits of macroecological theory in explaining local abundance, few studies have tested alternative generalized mechanisms determining abundance at the community scale. Using an assemblage of forest moth species found co-occurring as caterpillars on a single host plant species, we tested whether species abundance on that plant could be explained by mass allometry, intrinsic population growth, diet breadth, or some combination of these traits. We parameterized life history traits of the caterpillars in association with the host plant in both field and laboratory settings, so that the population growth estimate was specific to the plant on which abundance was measured. Using a generalized least-squares regression method incorporating phylogenetic relatedness, we found no relationship between abundance and mass but found that abundance was best explained by both intrinsic population growth rate and diet breadth. Species population growth potential was most affected by survivorship and larval development time on the host plant. Metabolic constraints may determine upper limits to local abundance levels for species, but local community abundance is strongly predicted by the potential for population increase and the resources available to that species in the environment.     

Diversity and complexity in the acoustic behaviour of Dacyllus flavicaudus (Pomacentridae)

Synchronous underwater audio–video recordings and a passive acoustic detector were used to study the behaviour of Dascyllus flavicaudus. These damselfish produced sounds during six different behaviours and showed three different colour patterns while doing so. These sounds can be grouped into three classes: sounds associated with (1) fighting; (2) mating/visiting and (3) chasing and signal jumps. Moreover, the evolution of the different kinds of sound is discussed: the first calls could be a single pulse originating in teeth snapping. Modifications in the rhythm and number of pulses allowed the fish to build new messages. Daily recordings showed that sound production rates were higher at sunrise and sunset than during the day and that no sound was produced during the night. However, the kinds of call were different: sunrise sounds seemed mainly associated with mating/visiting, whereas the sounds associated with chasing and to signal jumps were mainly found at sunset.     

Phylogeography of the diamond turbot (Hypsopsetta guttulata) across the Baja California Peninsula

We compared morphology and sequenced nuclear and mitochondrial genes from 11 populations of a previously genetically unstudied “Baja California disjunct” species, the diamond turbot (Hypsopsetta guttulata). This species exhibits very limited adult movement and restriction to soft-bottom habitats but has a moderately long pelagic larval duration. Therefore, if pelagic larval duration is correlated with gene flow between Gulf of California and Pacific populations, we expect a reduced level of genetic and morphological differentiation. However, if adult habitat and ecology have more effect on gene flow, we expect the populations in the two bodies of water to be more highly differentiated. We used logistic regression to compare morphological features and phylogenetic and population genetic analyses to compare nucleotide sequence data. Gulf of California H. guttulata are different from Pacific populations in morphology and both mitochondrial and nuclear gene sequences. MtDNA shows reciprocal monophyly, and nuclear sequences from the Gulf of California formed a monophyletic group. Population genetic analyses also suggest further population subdivision within the Pacific and within the Gulf of California. We argue that adult ecology has a significant effect on migration rates among populations in the Pacific Ocean and the Gulf of California.     

Application of an evolutionary algorithm to the inverse parameter estimation of an individual-based model

Inverse parameter estimation of individual-based models (IBMs) is a research area which is still in its infancy, in a context where conventional statistical methods are not well suited to confront this type of models with data. In this paper, we propose an original evolutionary algorithm which is designed for the calibration of complex IBMs, i.e. characterized by high stochasticity, parameter uncertainty and numerous non-linear interactions between parameters and model output. Our algorithm corresponds to a variant of the population-based incremental learning (PBIL) genetic algorithm, with a specific “optimal individual” operator. The method is presented in detail and applied to the individual-based model OSMOSE. The performance of the algorithm is evaluated and estimated parameters are compared with an independent manual calibration. The results show that automated and convergent methods for inverse parameter estimation are a significant improvement to existing ad hoc methods for the calibration of IBMs.     

Assessing the parameterisation of the settling flux in a depth-integrated model of the fate of decaying and sinking particles, with application to fecal bacteria in the Scheldt Estuary

The fate of reactive tracers is often modelled by depth-averaged equations. When integrating the depth-resolved equations, it appears that the term describing the settling of particles is dependent on the concentration just above the bottom. Because in a depth-averaged framework this quantity is not available, the settling term needs to be parameterised. The most natural choice is to make the settling flux dependent on the average concentration. This approximation is acceptable if the water column is well mixed, but these conditions are not necessarily met in real applications. Therefore, this study aims at assessing and understanding the error made by using a depth-averaged model in a range of realistic conditions. For the definition of these conditions, typical values for the Scheldt Estuary and the Dutch-Belgian coast were taken. The realistic inspiration for the reactive tracer in this study is the fecal bacterium Escherichia coli, whose own dynamics are characterised by settling and gradual decay by mortality. In an attempt to understand the relative importance of several factors like settling, mortality, mixing and stratification on the error made by a depth-averaged approach, a number of simplified test cases were investigated. It follows that, as expected, the error is acceptable if the situation is mixing-dominated. However, the effect of mortality and stratification was less obvious in advance. For instance, it appeared that errors can also be significant if settling and mortality have the same characteristic timescales. Stratification often has the effect to increase the error made by the depth-averaged model.