Interactions between sewage sludge-amended soil and earthworms—comparison between <Emphasis Type="Italic">Eisenia fetida</Emphasis> and <Emphasis Type="Italic">Eisenia andrei</Emphasis> composting species

Vermicomposting is an eco-friendly technology, where earthworms are introduced in the waste, inter alia sewage sludge, to cooperate with microorganisms and enhance decomposition of organic matter. The main aims of the present study was to determine the influence of two different earthworm species, Eisenia fetida and Eisenia andrei, on the changes of selected metallic trace elements content in substratum during vermicomposting process using three different sewage sludge mainly differentiated by their metal contents. Final vermicompost has shown a slight reduction in Cd, Cu, Ni, and Pb, while the Zn concentration tends to increase. Accumulation of particular heavy metals in earthworms’ bodies was assessed. Both species revealed high tendency to accumulate Cd and Zn, but not Cu, Ni, and Pb, but E. andrei has higher capabilities to accumulate some metals. Riboflavin content, which content varies depending on metal pollution in several earthworms species, was measured supravitaly in extruded coelomocytes. Riboflavin content decreased slightly during the first 6 weeks of exposure and subsequently restored till the end of the 9-week experiment. Selected agronomic parameters have also been measured in the final product (vermicompost) to assess the influence of earthworms on substratum.     

The Moral Status of Fish. The Importance and Limitations of a Fundamental Discussion for Practical Ethical Questions in Fish Farming

As the world population is growing and government directives tell us to consume more fatty acids, the demand for fish is increasing. Due to declines in wild fish populations, we have come to rely more and more on aquaculture. Despite rapid expansion of aquaculture, this sector is still in a relatively early developmental stage. This means that this sector can still be steered in a favorable direction, which requires discussion about sustainability. If we want to avoid similar problems to the ones we have experienced with livestock farming, we need to generate knowledge of the biology, profitability, environmental aspects, consumer awareness, and product appreciation of particular fish species. However, the discussion about a sustainable aquaculture also raises the question how we should treat fish. This moral question is regularly addressed as a problem of applied ethics with a focus on tailoring ethical principles to practical questions. In this article we do not deny the importance of the practical accounts, but we start from the fundamental question whether and why fish matter in our moral deliberations, i.e., from the discussion on moral status. We elaborate the distinction between moral considerability and moral significance in order to show both the importance and the limitations of the discussion about moral status for practical problems in aquaculture. We illustrate these points with a case-study about the farming of a specific fish species, the African catfish.     

Accumulation,speciation and localization of silver nanoparticles in the earthworm Eisenia fetida

Environmental Science and Pollution Research - The use of silver nanoparticles (AgNPs) in agriculture and many consumer products has led to a significant release of Ag in the environment. Although...     

Water and Sediment Quality in the Clinch River,Virginia and Tennessee,USA, over Nearly Five Decades

The Clinch River, in eastern United States, supports a diverse freshwater fauna including endangered mussels. Although mussel populations are stable in the Clinch's northeastern Tennessee segment, long‐term declines have been documented upstream in Virginia. We analyzed water and sediment quality data collected by government agencies from the 1960s through 2013 in an effort to inform current management. The river was divided into sections considering data availability and major tributaries. We tested for spatial differences among river sections and for temporal trends, and compared measured values to potentially protective levels if available. Ammonia concentrations approaching and exceeding protective levels were recorded, most often during the 1970s and 1980s in upstream sections. Sediment metals occurred at levels potentially causing biological effects, mainly during the 1980s and 1990s. In the 2000s, water‐column metals have been well below protective levels for general aquatic life. Dissolved solids (DS) increased in most river sections over the study period but mussel‐specific protective levels are not known. Analysis of water pH, total N, and total P did not generate conservation concern. Enhanced monitoring for sediment metals, water‐column metals, and ionic composition of DS; closer alignment of agency water monitoring practices in the two states; and research to determine biological effects of DS at current and anticipated levels can aid future conservation management.     

Harvesting the sun: New estimations of the maximum population of planet Earth

The maximum population, also called Earth's carrying capacity, is the maximum number of people that can live on the food and other resources available on planet Earth. Previous investigations estimated the maximum carrying capacity as large as about 1 trillion people under the assumption that photosynthesis is the limiting process. Here we use a present state-of-the-art dynamic global vegetation model with managed planetary land surface, Lund-Potsdam-Jena managed Land (LPJmL), to calculate the yields of the most productive crops on a global 0.5° × 0.5° grid. Using the 2005 crop distribution the model predicts total harvested calories that are sufficient for the nutrition of 11.4 billion people. We define scenarios where humankind uses the whole land area for agriculture, saves the rain forests and the boreal evergreen forests or cultivates only pasture to feed animals. Every scenario is run in an extreme version with no allowance for urban and recreational needs and in two soft versions with a certain area per person for non-agricultural use. We find that there are natural limits of the maximum carrying capacity which are independent of any increase in agricultural productivity, if non-agricultural land use is accounted for. Using all land planet Earth can sustain 282 billion people. The save-forests-scenario yields 150 billion people. The scenario that cultivates only pasture to feed animals yields 96 billion people. Nevertheless, we should always have in mind that all our calculated numbers for the carrying capacity refer to extreme scenarios where humankind may only vegetate on this planet. Our numbers are considerably higher than the general median estimate of upper bounds of human population found in the literature in the order of 10 billion.