Non-consumptive effects of predator presence on copepod reproduction: insights from a mesocosm experiment

Reproduction in planktonic animals depends on numerous biotic and abiotic factors. One of them is predation pressure, which can have both direct consumptive effects on population density and sex ratio, and non-consumptive effects, for example on mating and migration behaviour. In copepods, predator vulnerability depends on their sex, motility pattern and mating behaviour. Therefore, copepods can be affected at multiple stages during the mating process. We investigated the reproductive dynamics of the estuarine copepod Eurytemora affinis in the presence and absence of its predator the mysid Neomysis integer in a mesocosm experiment. We found that the proportion of ovigerous females decreased in the presence of predators. This shift was not caused by differential predation as the absolute number of females was unaffected by mysid presence. Presence of predators reduced the ratio of males to non-ovigerous females, but not by predation of males. Our combined results suggest that the shift from ovigerous to non-ovigerous females under the presence of predators was caused by either actively delayed egg production or by shedding of egg sacs. Nauplii production was initially suppressed in the predation treatment, but increased towards the end of the experiment. The proportion of fertilized females was similar in both treatments, but constantly fell behind model predictions using a random mating model. Our results highlight the importance of non-consumptive effects of predators on copepod reproduction and hence on population dynamics.     

Life cycle modelling of environmental impacts of application of processed organic municipal solid waste on agricultural land (EASEWASTE).

A model capable of quantifying the potential environmental impacts of agricultural application of composted or anaerobically digested source-separated organic municipal solid waste (MSW) is presented. In addition to the direct impacts, the model accounts for savings by avoiding the production and use of commercial fertilizers. The model is part of a larger model, Environmental Assessment of Solid Waste Systems and Technology (EASEWASTE), developed as a decision-support model, focusing on assessment of alternative waste management options. The environmental impacts of the land application of processed organic waste are quantified by emission coefficients referring to the composition of the processed waste and related to specific crop rotation as well as soil type. The model contains several default parameters based on literature data, field experiments and modelling by the agro-ecosystem model, Daisy. All data can be modified by the user allowing application of the model to other situations. A case study including four scenarios was performed to illustrate the use of the model. One tonne of nitrogen in composted and anaerobically digested MSW was applied as fertilizer to loamy and sandy soil at a plant farm in western Denmark. Application of the processed organic waste mainly affected the environmental impact categories global warming (0.4-0.7 PE), acidification (-0.06 (saving)-1.6 PE), nutrient enrichment (-1.0 (saving)-3.1 PE), and toxicity. The main contributors to these categories were nitrous oxide formation (global warming), ammonia volatilization (acidification and nutrient enrichment), nitrate losses (nutrient enrichment and groundwater contamination), and heavy metal input to soil (toxicity potentials). The local agricultural conditions as well as the composition of the processed MSW showed large influence on the environmental impacts. A range of benefits, mainly related to improved soil quality from long-term application of the processed organic waste, could not be generally quantified with respect to the chosen life cycle assessment impact categories and were therefore not included in the model. These effects should be considered in conjunction with the results of the life cycle assessment.     

A Review of Waste Tyre Utilisation in the Marine Environment

Waste tyres pose a major disposal problem on land creating a fire hazard and, in warmer climates, providing breeding pools for mosquitoes. the void space in tyres makes them unsuitable for land burial. Schemes to use shredded tyres for road bases and asphalt filler are being pursued in the USA. Tyre combustion for electricity production is being investigated in the UK.

The widespread availability and durability of tyres has led to their use in the marine environment for breakwaters/coastal defence structures and as artificial reefs for promoting fisheries.

Tyres have a low density and have been used in floating breakwaters. Schemes have been proposed to protect and strengthen shorelines with tyre structures.

The void space in tyres facilitates the construction of artificial reefs to attract fish. the most intensive use is in the south west Pacific and Australia. Tyre surfaces are colonised by algae and a wide range of faunal species, including corals and shellfish. the wide acceptance of tyres as a suitable reef construction material appears to be based largely on these observations. Experience of initial poor deployment practices in the USA led to tyres washing ashore after storms and resulted in the banning or restriction of their use in coastal states of the USA. A review of the scientific literature has yielded limited information on the environmental impact of tyres and in particular the leaching of heavy metals and organic compounds from tyres into sea water.

Preliminary results of tyre dust/sea water leaching studies are presented. These identify zinc as the major leachate (totalling 10mg/tyre after 3 months). Diluted leachates have not shown significant effects of the growth of the phytoplankton Phaeodactylum and Isocrysis.

Further work to characterise the sea water leaching of tyre compounds is recommended.     

Eu3+ uptake by calcite: preliminary results from coprecipitation experiments and observations with surface-sensitive techniques

A lack of information in databases for contamination risk assessment about the transport behaviour of the trivalent f-orbital elements in groundwater systems where calcite is at equilibrium motivated this study of Eu(3+) uptake. The free drift technique was used to examine the effects of Eu(3+) concentration, presence of Na(+) or K(+) and temperature, as well as calcite nucleation and precipitation kinetics, on the partitioning of calcite. Changes in surface composition and morphology resulting from exposure of single crystals of Iceland spar to Eu(3+)-bearing solutions were observed with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). First results confirm that calcite has high affinity for Eu(3+). Rates of nucleation and precipitation strongly affect the extent of uptake but the presence of Na(+) and K(+) has no effect, suggesting formation of solid solution as CaCO(3)-EuOHCO(3). Surface-sensitive techniques prove that Eu(3+) is adsorbed to calcite even when the surface is dissolving and adsorption is not accompanied by precipitation of a separate Eu(3+)-solid phase. Adsorbed Eu modifies calcite's dissolution behaviour, roughening terraces and rounding step edges, and producing surface morphology where some surface sites appear blocked. Results imply that Eu(3+) concentrations in natural calcites are limited by Eu(3+) availability rather than by a lack of ability to fit into calcite's atomic structure. This behaviour can probably be expected for other trivalent rare Earth elements (REE), actinides and fission products whose behaviour is similar to that of Eu(3+). These elements are likely to be incorporated within the calcite bulk in systems where it is precipitating and the demonstrated strong partitioning ensures some uptake even where calcite is at or under saturation.     

Regulation of aquaculture production

Environmental Economics and Policy Studies - In this paper, we investigate the economically optimal regulation of aquaculture production. The time between releasing and harvesting fish (rotation...     

Land-use and agriculture in Denmark around year 1900 and the quest for EU Water Framework Directive reference conditions in coastal waters

The EU Water Framework Directive (WFD) aims to protect the ecological status of coastal waters. To establish acceptable boundaries between good and moderate ecological status, the WFD calls for reference conditions practically undisturbed by human impact. For Denmark, the nitrogen (N) concentrations present around year 1900 have been suggested to represent reference conditions. As the N load of coastal waters relates closely to runoff from land, any reduction in load links to agricultural activity. We challenge the current use of historical N balances to establish WFD reference conditions and initiate an alternative approach based on parish-level land-use statistics collected 1896/1900 and N concentrations in root zone percolates from experiments with year 1900-relevant management. This approach may be more widely applicable for landscapes with detailed historic information on agricultural activity. Using this approach, we find an average N concentration in root zone percolates that is close to that of current agriculture. Thus, considering Danish coastal waters to be practically unaffected by human activity around year 1900 remains futile as 75% of the land area was subject to agricultural activity with a substantial potential for N loss to the environment. It appears unlikely that the ecological state of coastal waters around year 1900 may serve as WFD reference condition.     

Fate and antibacterial potency of anticoccidial drugs and their main abiotic degradation products

The antibacterial potency of eight anticoccidial drugs was tested in a soil bacteria bioassay (pour plate method), EC₅₀-values between 2.4 and 19.6 μM were obtained; however, one compound, nicarbazin exhibited an EC₅₀-value above the maximum tested concentration (21 μM, 9.1 mg L⁻¹). The potency of mixtures of two of the compounds, narasin and nicarbazin, was synergistic (more than additive) with 10-fold greater antibacterial potency of the mixture than can be explained by their individual EC₅₀-values. The influence of pH, temperature, oxygen concentration and light on the transformation of robenidine and salinomycin was investigated. Robenidine was transformed by photolysis (DT₅₀ of 4.1 days) and was unstable at low pH (DT₅₀ of approximately 4 days); salinomycin was merely transformed at low pH, the latter into an unknown number of products. The antibacterial potency of the mixtures of transformation products of robenidine after photolysis and at low pH was comparable with that of the parent compound. Finally five photo-transformation products of robenidine were structural elucidated by accurate mass measurements, i-FIT values (isotopic pattern fit) and MS/MS fragmentation patterns.     

Validation of reliable and selective methods for direct determination of glyphosate and aminomethylphosphonic acid in milk and urine using LC-MS/MS

Simple high-throughput procedures were developed for the direct analysis of glyphosate [N-(phosphonomethyl)glycine] and aminomethylphosphonic acid (AMPA) in human and bovine milk and human urine matrices. Samples were extracted with an acidified aqueous solution on a high-speed shaker. Stable isotope labeled internal standards were added with the extraction solvent to ensure accurate tracking and quantitation. An additional cleanup procedure using partitioning with methylene chloride was required for milk matrices to minimize the presence of matrix components that can impact the longevity of the analytical column. Both analytes were analyzed directly, without derivatization, by liquid chromatography tandem mass spectrometry using two separate precursor-to-product transitions that ensure and confirm the accuracy of the measured results. Method performance was evaluated during validation through a series of assessments that included linearity, accuracy, precision, selectivity, ionization effects and carryover. Limits of quantitation (LOQ) were determined to be 0.1 and 10 µg/L (ppb) for urine and milk, respectively, for both glyphosate and AMPA. Mean recoveries for all matrices were within 89–107% at three separate fortification levels including the LOQ. Precision for replicates was ≤7.4% relative standard deviation (RSD) for milk and ≤11.4% RSD for urine across all fortification levels. All human and bovine milk samples used for selectivity and ionization effects assessments were free of any detectable levels of glyphosate and AMPA. Some of the human urine samples contained trace levels of glyphosate and AMPA, which were background subtracted for accuracy assessments. Ionization effects testing showed no significant biases from the matrix. A successful independent external validation was conducted using the more complicated milk matrices to demonstrate method transferability.     

Method for Evaluating Germicidal Ultraviolet Inactivation of Biocontaminated Surfaces

Safety issues related to work-site conditions often deal with potential worker exposure to infectious airborne microorganisms due to their dissemination in indoor air and contamination of surfaces. Germicidal ultraviolet (GUV) radiation is used in health-care settings and other occupational environments for microbial inactivation. In this study, a new methodology for determining the efficiency of GUV microbial inactivation of surfaces was developed and evaluated. The method utilizes identical chambers in which test microorganisms are irradiated on agar surfaces at different humidity and irradiation intensity levels. The effects of GUV intensity and exposure time on microbial inactivation were examined for Micrococcus luteus and Serratia marcescens. It was found that at low humidity levels (20–25%) both organisms can be inactivated with at least 95% efficiency if the GUV intensity exceeds 50 μW/cm² for at least 3-5 min (corresponding to a dose of ~ 10 mJ/cm²). The radiation dose needed for effective inactivation of S. marcescens, as measured by a UV meter near the microbial sample, was found not to be affected by the humidity level, whereas that of M. luteus increased at higher humidities. The findings of this study can be used to determine sufficient GUV inactivation doses for occupational environments with various microbial contaminations.