Response of protozoan and microbial communities in various coniferous forest soils after transfer to forests with different levels of atmospheric pollution

During recent decades, forest ecosystems have been exposed to high levels of atmospheric pollution, and it has been argued that this affects the composition and activity of decomposer communities and, subsequently, ecosystem functioning. To investigate the effects of atmospheric pollution on protozoa and microflora, a new experimental design was used. Undisturbed soil columns, originating from six coniferous forests across Europe and representing different stages of soil acidification, were transferred to two Scots pine forests (Fontainebleau and Wekerom) with different levels of N and S deposition (NH₄ ⁺-N=4.90 and 42.50?kg ha^–1 year^–1; SO₄ ^–S=10.90 and 30.40?kg ha^–1 year^–1, respectively). The number of protozoa, microbial biomass C and microbial activity were estimated in the organic layer (Of) of the transferred soils at the two host sites after 21 months of incubation. The experiment aimed at answering two questions: (1) Do changes in environmental conditions, studied by transferring soils from one site to another, affect protozoa and microbial communities and, if so, (2) how important are changes in both N and S deposition in explaining the effects of soil transfer on protozoa and microbial communities? The interaction between protozoa and microbial communities was addressed with regard to these changes in environmental conditions. No effect of enhanced N or S deposition on protozoan numbers and microbial biomass C, basal respiration and caloric quotient was revealed. Reciprocal transfer of various soil columns resulted in lower abundance and activity of protozoa and microbes. This reduction could not be explained by differences in N and S deposition, but by differences in microclimate and adaptation. In some cases, protozoa correlated with pH, C/N ratio, P and S content and leached mineral N.     

Illegal and unreported fishing on abalone—Quantifying the extent using a fully integrated assessment model

Illegal, unregulated and unreported (IUU) fishing is a major problem in many of the world's fisheries. The stocks most severely impacted centre on those characterised by high economic value, such as abalone, as well as long lived and slow growing species such as Patagonian toothfish (Dissostichus eleginoides). Effective management of these stocks as well as assessment of the impacts of IUU fishing on the resources is impeded by the technical difficulties associated with determining the magnitude of the IUU catches. The South African abalone Haliotis midae fishery rates as an extreme example of extraordinarily high levels of illegal and unreported (IU) catch. To assess the level and trends in IU catches, we used a combination of approaches that included collation of confiscation records from law enforcement, development of a novel index (the confiscations per unit policing effort—CPUPE), estimation of illegal catches using a spatial and age-structured assessment model, and cross-checking of model outputs through comparison with trade data on abalone imports in destination countries. The model-predicted 2008 IU estimate was 860 tonnes, more than 10 times the total allowable catch (TAC) for that year, and implied that, on average, 14% of all IU catches are confiscated. Associated management responses included the listing of H. midae on Appendix III of CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), and a temporary closure of the commercial fishery. We summarise both technical and management lessons to be learnt from this integrated approach to assess and verify the magnitude of IU fishing.     

Effects of dietary yeast inclusion and acute stress on post-prandial whole blood profiles of dorsal aorta-cannulated rainbow trout

Yeast is a potential alternative to fish meal in diets for farmed fish, yet replacing more than 50 % of fish meal results in reduced fish growth. In a 4-week experiment, 15 rainbow trout (Oncorhynchus mykiss) were cannulated and fed three diets each week: 30 % fish meal as a control (FM); 60 % replacement of fish meal protein, on a digestible basis, with Saccharomyces cerevisiae (SC); and 60 % replacement with Wickerhamomyces anomalus and S. cerevisiae mix (WA). Blood was collected at 0, 3, 6, 12 and 24 h after feeding. In the final week, fish were exposed to a 1-min netting stressor to evaluate possible diet–stress interactions. Significant increases in pH, TCO₂, HCO₃ and base excess were found after fish were fed the SC and WA diets compared with FM, which elevated blood alkaline tides. Yeast ingredients had lower buffering capacity and ash content than fish meal, which explained the increase in alkaline tides. In addition, fish fed the WA diet had significantly reduced erythrocyte area and fish fed SC and WA diets had increased mean corpuscular haemoglobin levels, indicating haemolytic anaemia. Higher levels of nucleic acid in yeast-based diets and potentially higher production of reactive oxygen species were suspected of damaging haemoglobin, which require replacement by smaller immature erythrocytes. Acute stress caused the expected rise in cortisol and glucose levels, but no interaction with diet was found. These results show that replacing 60 % of fish meal protein with yeasts can induce haemolytic anaemia in rainbow trout, which may limit yeast inclusion in diets for farmed fish.     

Fluoro‐mobilization of metals in a Slovak forest soil affected by the emissions of an aluminum smelter

Depositions originating from a central Slovak Al smelter may increase metal solubility in adjacent soils because they contain F (mainly HF). The reason for fluoro‐mobilization of metals may be the formation of soluble fluoro‐metal complexes or the mobilization of organic matter and subsequent formation of organo‐metal complexes. The objectives of our work were (1) to assess the extent of metal mobilization by fluoride in a Slovak Lithic Eutrochrept affected by the emissions of an Al smelter and (2) to model the dissolved metal species with the help of a chemical equilibrium model (MINEQL+). The O (Moder), A, and B horizons were equilibrated with solutions at F concentrations of 0, 0.9, 2.7, and 9.0 mmol l^—1. In the extracts, the concentrations of Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Zn, dissolved organic carbon (DOC), free and complexed F, and the pH and electrical conductivity (EC) were determined. The heavy metal concentrations in the O horizon (Cd: 0.99, Cr: 18.0, Cu: 44, Ni: 26, Pb: 110, and Zn: 84 mg kg^—1) were 2.5 to 9 times larger than those in the A and B horizons. The concentrations of H₂O‐soluble F decreased from the O (261 mg kg^—1) to the A (103 mg kg^—1) and B horizon (92 mg kg^—1). In batch experiments increasing addition of F increased the equilibrium concentrations of Al, Cr, Cu, Fe, Ni, Pb, and DOC in all samples, of Cd in the A, and of K in the B horizon. At the same time the concentrations of complexed F and pH increased whereas EC decreased. Chemical equilibrium modelling indicated that the mobilizing effect of F resulted from the formation of fluoro‐Al complexes and organo‐complexes of all other metals.     

Comparative survival and growth performance of European lobster Homarus gammarus post‐larva reared on novel feeds

One approach to ongrow juvenile European lobster, Homarus gammarus, is to utilize land based rearing systems, incorporating automated feeding, individual culture and provision of stable pelleted feeds, preferably using sustainable ingredients. We initiated three feeding experiments to investigate the general suitability of ingredients produced from seafood by‐products as novel feeds for H. gammarus, in terms of promoting survival, development and growth of post‐larval lobsters from post‐larvae (PL) stage IV to the first juvenile stage (stage V). The first experiment was designed to screen an array of candidate, locally produced, novel protein sources on growth performance parameters. This initial experiment revealed that PL reared on a raw (i.e. wet, unprocessed shrimp) feed used as a reference showed superior performance to those reared on experimental feeds containing fishmeal, herring protein isolate or mussel meal; however, a novel type of shrimp meal, produced by flocculation from waste water, promoted the best PL performance of any experimental feed. A second experiment was designed to test the effect of drying method and to optimize the form of a wet shrimp reference feed used by lobster hatcheries. This showed that the performance of PL reared on experimental freeze‐dried shrimp feed was not significantly different to those reared on the wet, unprocessed shrimp used as a reference feed. However, lobsters offered experimental oven‐dried shrimp feed (with or without an immune supplement) resulted in significantly lower survival or growth performance. A third and final experiment was designed in an attempt to improve a candidate herring‐based protein source, by supplementing with nutrients found in shrimp. However, the results showed that PL reared on the wet reference shrimp feed still showed superior growth and survival than those reared on a herring feed alone, or supplemented with additives found in shrimp meal (either glucosamine, astaxanthin or both supplements combined). The high survival and growth, low incidence of moulting problems and high availability of waste shrimp material, suggest that non‐heat‐treated shrimp products are a promising feed ingredient for post‐larval European lobsters.     

Trace elements bioavailability to <Emphasis Type="Italic">Triticum aestivum</Emphasis> and <Emphasis Type="Italic">Dendrobaena veneta</Emphasis> in a multielement-contaminated agricultural soil amended with drinking water treatment residues

Purpose

The in situ stabilization of multielement-contaminated agricultural soils has limited effectiveness when using common single amendments. This study examined the use of drinking water treatment residues (WTR), based on (hydr)oxides of Fe, Al, or Mn, as a cost-effective solution to optimize the immobilization of metals (Cd, Pb, Zn) and As.

Materials and methods

Trace elements (TE) bioavailability was assessed under semi-controlled conditions in a pot study cultivating winter wheat (Triticum aestivum L. cv. Tiger) until maturity. An Fe-based WTR and a Mn-based WTR, applied at rates of 0.5 and 1% (m/m), were related to effects of lime marl (LM) application. Additionally, a bioassay with earthworms (Dendrobaena veneta) was conducted. Both bioassays were compared with measurements of NH₄NO₃-soluble, diffusive gradients in thin film (DGT)-available and soil solution TE concentrations, representing well-established surrogates for mimicking the bioavailable element fractions in soil.

Results and discussion

The application of the Fe-based WTR reduced As accumulation in vegetative wheat tissues (by up to 75%) and earthworms (by up to 41%), which corresponded with the findings from soil chemical analyses and improved plant growth and earthworm body weight. However, As concentrations in cereal grains were not affected, Cd or Pb accumulation by wheat was not mitigated, and Zn uptake was enhanced. By contrast, the Mn-based WTR effected the greatest reduction in Pb uptake, and lowered Cd transfer to wheat grain (by up to 25%). Neither the NH₄NO₃-soluble nor DGT-available concentrations matched with Cd and Zn accumulation in plants or earthworms, indicating interferences due to competition for binding sites according to the biotic ligand model.

Conclusions

The results obtained in this study suggest that a bioassay with key species prior to field application should be mandatory when designing in situ stabilization options. The application of WTR to an agricultural soil strongly affected TE bioavailability to plants and earthworms. Low application rates tended to improve biomass production of biota. Higher application rates involved risks (e.g., P fixation, TE inputs), and none of the amendments tested could immobilize all targeted elements.

     

A data-driven fuzzy approach to simulate the critical shear stress of mixed cohesive/non-cohesive sediments

Purpose

The critical shear stress of cohesive and mixed cohesive/non-cohesive sediments is affected by multiple interacting physical, chemical and biological parameters. There are various mathematical approaches in the scientific literature for computing critical shear stress. However, processes that influence sediment stability are still not fully understood, and available formulas differ considerably. These discrepancies in the literature arise from random system behaviour (natural variability of the sediments), different definitions of the critical shear stress, different measurement techniques and different model frameworks (scope of the parameters, undisturbed versus artificial sediment samples). While analytical approaches fail to address the involved uncertainties, fuzzy logic-based models integrate uncertainty and imprecision.

Materials and methods

With this in mind, a data-driven neuro-fuzzy model (ANFIS) was used to determine the critical shear stress based on sediment characteristics such as wet bulk density and grain size distribution. In order to select model predictors systematically, an automated stepwise regression algorithm was applied. The database for this analysis consisted of 447 measurements of the critical shear stress originating from 64 undisturbed sediment samples.

Results and discussion

The study identified clay content as the primarily controlling variable for erosion resistance. Depending on the characteristics of the sampling location, the bulk density was also selected as a model predictor. In comparison to analytical models that are available in the scientific literature, the fuzzy model achieved higher correlation coefficients between measured and predicted data.

Conclusions

The neuro-fuzzy-model includes uncertainties of input variables and their interactions directly. Thus, it provides a reliable method for the prediction of erosion thresholds of cohesive/non-cohesive mixtures. It was also shown that this approach requires fewer measured variables as well as fewer assumptions than the models it was compared to.

     

Pesticide diversity in rice growing areas of Northern Vietnam

Pesticide use in developing countries increases rapidly. In many regions, we miss knowledge of how frequently pesticides are applied and which active ingredients are used. We present a new cost-efficient and rapid assessment method of recording pesticides diversity in rice-dominated landscapes and present some evidence of the misuse of active ingredients in our study regions. We investigated 17 rice fields in two regions of Northern Vietnam in 2014 and 2015. At each region, we explore the abundance of pesticides used with three methods including (1) the novel approach of collecting pesticide packages close to our target rice fields, (2) observations of farmers spraying pesticides in the surrounding and (3) interviewing local farmers. By collecting pesticide packages, we found 811 packages containing 74 different active ingredients. On average, 19 active ingredients (ranging from four to 40 active ingredients) were applied with an average content of 275.3 g of active ingredients per site. Insecticide packages (39%) were most abundant followed by those of fungicides (31%), herbicides (16%) and other active ingredients (14%). On all sites, active ingredients banned in the European Union were applied by the farmers. Collecting pesticide packages proved to be an efficient and rapidly implemented method to obtain some baseline information about pesticide application (for Northern Vietnam). We suspect that improved agricultural extension services could contribute to good agricultural practices in pest management. Generally, better information and education for local farmers for appropriate use of pesticides seem a necessity.