Environmental Concentrations of Sulfonamides Can Alter Bacterial Structure and Induce Diatom Deformities in Freshwater Biofilm Communities

Since the early 1920s, the intensive use of antibiotics has led to the contamination of the aquatic environment through diffuse sources and wastewater effluents. The antibiotics commonly found in surface waters include sulfamethoxazole (SMX) and sulfamethazine (SMZ), which belong to the class of sulfonamides, the oldest antibiotic class still in use. These antibiotics have been detected in all European surface waters with median concentrations of around 50 ng L–1 and peak concentrations of up to 4–6 μg L–1. Sulfonamides are known to inhibit bacterial growth by altering microbial production of folic acid, but sub-lethal doses may trigger antimicrobial resistance, with unknown consequences for exposed microbial communities. We investigated the effects of two environmentally relevant concentrations (500 and 5,000 ng L–1) of SMZ and SMX on microbial activity and structure of periphytic biofilms in stream mesocosms for 28 days. Measurement of sulfonamides in the mesocosms revealed contamination levels of about half the nominal concentrations. Exposure to sulfonamides led to slight, transitory effects on heterotrophic functions, but persistent effects were observed on the bacterial structure. After 4 weeks of exposure, sulfonamides also altered the autotrophs in periphyton and particularly the diversity, viability and cell integrity of the diatom community. The higher concentration of SMX tested decreased both diversity (Shannon index) and evenness of the diatom community. Exposure to SMZ reduced diatom species richness and diversity. The mortality of diatoms in biofilms exposed to sulfonamides was twice that in non-exposed biofilms. SMZ also induced an increase in diatom teratologies from 1.1% in non-exposed biofilms up to 3% in biofilms exposed to SMZ. To our knowledge, this is the first report on the teratological effects of sulfonamides on diatoms within periphyton. The increase of both diatom growth rate and mortality suggests a high renewal of diatoms under sulfonamide exposure. In conclusion, our study shows that sulfonamides can alter microbial community structures and diversity at concentrations currently present in the environment, with unknown consequences for the ecosystem. The experimental set-up presented here emphasizes the interest of using natural communities to increase the ecological realism of ecotoxicological studies and to detect potential toxic effects on non-target species.

Toxicity testing: ecological relevance and relative efficacy and costs of toxicity tests in the South African context

The Direct Estimation of Ecological Effect Potential (DEEEP) is a suite of toxicological methods that was compiled to facilitate management of effluent discharges. DEEEP used a range of tests to assess different endpoints and test taxa from differing trophic levels. It was used at pilot scale but never adopted in South Africa formally. The use of toxicological testing in managing effluent discharge has been somewhat ad-hoc since. This study examined a range of tests for undertaking toxicological assessments of effluent from the perspectives of ecological realism, test tractability, and cost of testing. The assays assessed include some from DEEEP, some using South African test taxa, and some using commercial toxicity test kits. Results indicate that, in terms of returned endpoints, no clear difference between tests using immobilized and cultured or wild-collected test taxa was present. Culture maintenance was found to be a significant contributor to test costs where cultured test taxa were used (although culture costs are implicit in test kit costs too). Costing analysis looked at scenarios where equipment could be shared and reused, and how these contribute to laboratory costs. The research leads on to suggestions for testing implementation in laboratories while maximizing ecological realism and minimizing costs.

Toxicity testing: ecological relevance and relative efficacy and costs of toxicity tests in the South African context

The Direct Estimation of Ecological Effect Potential (DEEEP) is a suite of toxicological methods that was compiled to facilitate management of effluent discharges. DEEEP used a range of tests to assess different endpoints and test taxa from differing trophic levels. It was used at pilot scale but never adopted in South Africa formally. The use of toxicological testing in managing effluent discharge has been somewhat ad-hoc since. This study examined a range of tests for undertaking toxicological assessments of effluent from the perspectives of ecological realism, test tractability, and cost of testing. The assays assessed include some from DEEEP, some using South African test taxa, and some using commercial toxicity test kits. Results indicate that, in terms of returned endpoints, no clear difference between tests using immobilized and cultured or wild-collected test taxa was present. Culture maintenance was found to be a significant contributor to test costs where cultured test taxa were used (although culture costs are implicit in test kit costs too). Costing analysis looked at scenarios where equipment could be shared and reused, and how these contribute to laboratory costs. The research leads on to suggestions for testing implementation in laboratories while maximizing ecological realism and minimizing costs.

Domination, Power, Supremacy: Confronting Anthropolitics with Ecological Realism

In this article, we study politics as domination. From our point of view, domination, especially in the Anthropocene, has had two vital components—power and supremacy. In order to dominate, one has to have power over others. In addition, the politics of domination, such as colonial oppression of Latin America, has required reasoning, justification, and legitimation, often connected to superiority (because of religion, society, or civilization) from the oppressor’s end. Past and present political ideologies and programs, such as colonialism, imperialism, but also welfare state capitalism, neoliberalism and increasingly popular Green New Deal are examples of what we call “anthropolitics”, an anthropocentric approach to politics based on domination, power, and supremacist exploitation. In contrast to the prevailing anthropolitics, this article discusses post-Anthropocene politics, characterized by localization and decentralization, as well as a steep reduction of matter–energy throughput by introducing a theoretical frame called ecological realism.

Forests in the Czech Public Discourse

Forests are being increasingly studied within the framework of social sciences, especially in relation to environmental problems and global climate change. This article deals with the perception of Czech forests and their management at two basic levels: at the level of sociological analysis of in-depth interviews with experts in the field of forestry and at the level of public opinion research. The main aim of this study was to describe the attitudes of professionals and the general public towards forests and forestry, especially with regard to climate change. Qualitative analysis of interviews with professionals discerned two main categories of opinion: ecological realism and social constructionism. The results of the study show that the Czech public, in agreement with ecological realists, considers it highly important to preserve and support the non-productive environmental functions of forests. The public also prefers close-to-nature forest management practices. Czech Republic is witnessing a fundamental shift in the mindset about forests. Although the public still expects forests to retain their production function, it perceives their environmental functions as increasingly important.