Quantifying population declines based on presence‐only records for red‐list assessments

Accurate trend estimates are necessary for understanding which species are declining and which are most in need of conservation action. Imperfect species detection may result in unreliable trend estimates because this may lead to the overestimation of declines. Because many management decisions are based on population trend estimates, such biases could have severe consequences for conservation policy. We used an occupancy‐modeling framework to estimate detectability and calculate nationwide population trends for 14 Swiss amphibian species both accounting for and ignoring imperfect detection. Through the application of International Union for Conservation of Nature Red List criteria to the different trend estimates, we assessed whether ignoring imperfect detection could affect conservation policy. Imperfect detection occurred for all species and detection varied substantially among species, which led to the overestimation of population declines when detectability was ignored. Consequently, accounting for imperfect detection lowered the red‐list risk category for 5 of the 14 species assessed. We demonstrate that failing to consider species detectability can have serious consequences for species management and that occupancy modeling provides a flexible framework to account for observation bias and improve assessments of conservation status. A problem inherent to most historical records is that they contain presence‐only data from which only relative declines can be estimated. A move toward the routine recording of nonobservation and absence data is essential if conservation practitioners are to move beyond this toward accurate population trend estimation.     

Application of membrane bioreactor technology for wastewater treatment and reuse in the Mediterranean region: Focusing on removal efficiency of non-conventional pollutants

The Mediterranean Region is a semi-arid area whose land is facing serious erosion, causing adverse impacts on agriculture. To improve the water availability, researchers have proposed the reclamation and reuse of treated wastewater. In this paper, we report the main findings of 10 years of research on the efficiencies of a conventional activated sludge process and a submerged membrane bioreactor, with particular emphasis on the removal of non-conventional pollutants. The studies showed that the membrane bioreactor produced a virtually solids-free, high-quality permeate: most nutrients, heavy metals, and persistent organic pollutants were removed, and in particular, dioxins, furans, and polychlorinated biphenyls were typically present at concentrations below the detection limit. Moreover, the total coliforms count decreased by 4–5 log and Escherichia coli was absent from the membrane bioreactor permeate. These results, combined with the continuing reduction of the capital and operating costs for this approach, suggest that membrane bioreactors are an increasingly cost-effective technology to produce treated effluents that are suitable for reuse.     

Groundwater Management in Coastal Areas through Landscape Scale Planning: A Systematic Literature Review

Environmental Management - Groundwater is one of the main resources for social-ecological systems. As part of the total water cycle and deeply connected with land use, groundwater management faces...     

What stops the ‘diploid male vortex’?—A simulation study for species with single locus complementary sex determination

The survival of hymenopteran populations especially that of ecologically and economically important pollinators and parasitoids, has become a major topic for empirical and theoretical studies. Complementary sex determination (CSD) in Hymenoptera may impose a substantial genetic load through the production of inviable or sterile diploid males. Modelling and laboratory studies have indicated that this genetic load may trigger a ‘diploid male vortex’ leading to rapid extinction of populations.Here we take a broader theoretical approach to analyze why populations exhibiting CSD persist in nature, even if they contain large proportions of homozygous diploid individuals. Using an individual-based model of spatially structured hymenopteran populations, we show that (i) inviability or reduced fertility of homozygous individuals, (ii) female-biased sex ratio, and (iii) strong intra-specific competition can mitigate the negative influence of CSD on population persistence and that (iv) already extremely low dispersal rates will result in long term survival. These findings underline the importance of life history traits for population survival and demonstrate that rather specific conditions must be met to initiate the ‘diploid male vortex’.