Daphnia magna and ecotoxicogenomics: gene expression profiles of the anti-ecdysteroidal fungicide fenarimol using energy-, molting- and life stage-related cDNA libraries

In the present study, the existing life stage-specific cDNA library was extended with energy- and molting-related genes using Suppression Subtractive Hybridization PCR and a microarray for the aquatic test organism Daphnia magna was created. A gene set of 2455 fragments was produced belonging to different pathways such as carbohydrate and lipid metabolism, O2 transport and heme metabolism, immune response, embryo development, cuticula metabolism and visual perception pathways. Using this custom microarray, gene expression profiles were generated from neonates exposed to three concentrations of the anti-ecdysteroidal fungicide fenarimol (0.5, 0.75, 1 microg/ml) during 48 h and 96 h. In total, 59 non-redundant genes were differentially expressed, of which more genes were down- than up-regulated. The gene expression data indicated a main effect on molting specific pathways. At the highest concentration, a set of proteolytic enzymes - including different serine proteases and carboxypeptidases - were induced whereas different cuticula proteins were down-regulated (48 h). Moreover, effects on embryo development were demonstrated at the gene expression as well as at the organismal level. The embryo development related gene vitellogenin was differentially expressed after 96 h of exposure together with a significant increase in embryo abnormalities in the offspring. This study suggests that this Daphnia magna microarray is of great further value for the elucidation of molecular mechanisms of toxicity and for the future development of specific biomarkers for hazard characterization.     

How does a nature-based solution for flood control compare to a technical solution? Case study evidence from Belgium

The strategy of reconnecting rivers with their floodplains currently gains popularity because it not only harnesses natural capacities of floodplains but also increases social co-benefits and biodiversity. In this paper, we present an example of a successfully implemented nature-based solution (NBS) in the Dijle valley in the centre of Belgium. The research objective is to retrospectively assess cost and benefit differences between a technical solution (storm basins) and an alternative NBS, here the restoration of the alluvial floodplain. The method is a comparative social cost–benefit analysis. The case study analysis reveals similar flood security, lower costs, more ecosystem services benefits and higher biodiversity values associated with the NBS option in comparison to the technical alternative. However, the business case for working with NBS depends substantially on the spatial and socio-ecological context. Chances for successful NBS implementation increase in conditions of sufficient space to retain flood water, when flood water is of sufficient quality, and when economic activity and housing in the floodplain is limited.Supplementary InformationThe online version of this article contains supplementary material available at (10.1007/s13280-021-01548-4).     

Assessment of the effluent quality from a gold mining industry in Ghana

The physical and chemical qualities of the process effluent and the tailings dam wastewater of AngloGold-Ashanti Limited, a gold mining company in Ghana, were studied from June to September, 2010. The process effluent from the gold extraction plant contains high amounts of suspended solids and is therefore highly turbid. Arsenic, copper and cyanide were identified as the major pollutants in the process effluent with average concentrations of 10.0, 3.1 and 21.6 mg?L^?1, respectively. Arsenic, copper, iron and free cyanide (CN^?) concentrations in the process effluent exceeded the Ghana EPA discharge limits; therefore, it is necessary to treat the process effluent before it can be discharged into the environment. Principal component analysis of the data indicated that the process effluent characteristics were influenced by the gold extraction process as well as the nature of the gold-bearing ore processed. No significant correlation was observed between the wastewater characteristics themselves, except for the dissolved oxygen and the biochemical oxygen demand. The process effluent is fed to the Sansu tailings dam, which removes 99.9 % of the total suspended solids and 99.7 % of the turbidity; but copper, arsenic and cyanide concentrations were still high. The effluent produced can be classified as inorganic with a high load of non-biodegradable compounds. It was noted that, though the Sansu tailings dam stores the polluted effluent from the gold extraction plant, there will still be serious environmental problems in the event of failure of the dam.     

Removal of estrone, 17α-ethinylestradiol,and 17ß-estradiol in algae and duckweed-based wastewater treatment systems

Background, aim, and scope  

Many pollutants have received significant attention due to their potential estrogenic effect and are classified as endocrine disrupting compounds (EDCs). Because of possible ecological effects and increased attention for water reuse schemes, it is important to increase our understanding of the EDC removal capacities of various wastewater treatment systems. However, there has so far been little research on the fate and behavior of EDCs in stabilization pond systems for wastewater treatment, which represent an important class of wastewater treatment systems in developing countries because of their cost-effectiveness. The aim of this work is to study the fate and behavior of EDCs in algae and duckweed ponds. Because the synthetic hormone 17α-ethinylestradiol (EE2) and the natural hormones estrone (E1), as well as 17β-estradiol (E2), have been detected in effluents of sewage treatment plants and been suggested as the major compounds responsible for endocrine disruption in domestic sewage; E1, E2, and EE2 were therefore chosen as target chemicals in this current work.     

Sorption of cobalt and nickel on anaerobic granular sludges: isotherms and sequential extraction

The objective of this study was to investigate the sorption capacity and the fractionation of sorbed nickel and cobalt onto anaerobic granular sludges. Two different anaerobic granular sludges (non-fed, pH=7) were loaded with nickel and cobalt in adsorption experiments (monometal and competitive conditions). The combination of sequential extraction with the sorption isotherm analysis allowed the assessment of the sorption capacity of individual fractions present in the anaerobic granular sludges. The operational fractionation of the sorbed heavy metals was determined using a modified Tessier sequential extraction procedure. The sorption characteristics of each extracted fraction (exchangeable, carbonates, organic matter/sulfides and residual fractions) fitted well to the Langmuir model. The organic matter/sulfides fraction showed the highest affinity for cobalt and nickel in both sludges investigated compared to the other operationally defined fractions. The presence of iron negatively affected cobalt and nickel accumulation in this organic matter/sulfides fraction. The trace metals-iron sulfide interactions are likely to be the key process in controlling the distribution of cobalt and nickel during sorption onto non-fed methanogenic granules due to the high affinity of iron sulfides towards the metals studied.     

Individual variation in mate care by alpha males in crested tit winter flocks

Summary Winter flocks of crested tits Parus cristatus, typically consisting of two adults and one or two non-kin 1st-year birds, were observed to split up into subflocks in a way related to ambient temperature. On warm days, when they were foraging in subflocks without 1 st-year birds, alpha males always occupied the most preferred upper foraging sites, as expected from their top dominance rank. On cold days, when foraging in flocks with 1st-year birds, 8 out of 13 alpha males shifted to lower (less preferred) positions below their alpha mates while allowing the latter to forage at the best sites. As enhanced access to preferred microsites on days with high energy stress is believed to increase overwinter survival probability, this shifting behaviour of alpha males can be considered as a form of mate care. Out of 13 alpha males, however, 5 did not shift and always occupied the best foraging sites irrespective of flock composition. As (i) these non-shifting males were in poorer physical condition than shifting males, (ii) they scanned significantly less for predators than either females or shifting males when foraging in the uppermost tree parts, and (iii) four out of five non-shifting males were replaced by immigrants in early spring, absence of mate care during winter may be caused by constraints due to condition. High-quality-territory owners in poor condition at the end of autumn were most vulnerable to replacement by immigrants. Therefore, as four out of five replacements affected high-quality territories, selective intrusion by immigrants is suggested. Correspondence to: L. Lens     

Long-term trends in the trophic structure of the North Sea fish community: evidence from stable-isotope analysis, size-spectra and community metrics

Fishing has wide-ranging impacts on marine ecosystems. One of the most pervasive signs of intensive fishing is "fishing down the food web", with landings increasingly dominated by smaller species from lower trophic levels. Decreases in the trophic level of landings are assumed to reflect those in fish communities, because size-selective mortality causes decreases in the relative abundance of larger species and in mean body size within species. However, existing analyses of fishing impacts on the trophic level of fish communities have focused on the role of changes in species composition rather than size composition. This will provide a biased assessment of the magnitude of fishing impacts, because fishes feed at different trophic levels as they grow. Here, we combine body size versus trophic level relationships for North Sea fishes (trophic level assessed using nitrogen stable-isotope analysis) with species-size-abundance data from two time-series of trawl-survey data (whole North Sea 1982-2000, central and northern North Sea 1925-1996) to predict long-term trends in the trophic structure of the North Sea fish community. Analyses of the 1982-2000 time-series showed that there was a slow but progressive decline in the trophic level of the demersal community, while there was no trend in the trophic level of the combined pelagic and demersal community. Analyses of the longer time-series suggested that there was no trend in the trophic level of the demersal community. We related temporal changes in trophic level to temporal changes in the slopes of normalised biomass size-spectra (which theoretically represent the trophic structure of the community), mean log₂ body mass and mean log₂ maximum body mass. While the size-based metrics of community structure showed long-term trends that were consistent with the effects of increased fishery exploitation, these trends were only correlated with trophic level for the demersal community. Our analysis suggests that the effects of fishing on the trophic structure of fish communities can be much more complex than previously assumed. This is a consequence of sampled communities not reflecting all the pathways of energy transfer in a marine ecosystem and of the absence of historical data on temporal and spatial changes in the trophic level of individuals. For the North Sea fish community, changes in size structure due to the differential effects of fishing on species and populations with different life histories are a stronger and more universal indicator of fishing effects than changes in mean trophic level.