Response of plankton communities in freshwater pond and stream mesocosms to the herbicide metazachlor

Metazachlor is a frequently used herbicide with concentrations in surface waters up to 100 microg L(-1). A long-term mesocosm study was performed in order to investigate effects on stream and pond communities also regarding recovery. Single metazachlor doses of 5, 20, 80, 200, and 500 microg L(-1) were given and the aquatic communities monitored for 140 days. In this paper, special attention is paid to the plankton response and the results of the entire study are summarised. Metazachlor strongly affected the stream and pond mesocosm communities at concentrations higher than 5 microg L(-1). Direct negative effects were most prominent for chlorophytes whereas diatoms and cryptophytes seemed insensitive. The effects on zooplankton were caused by changes in habitat structure due to the strong decline of macrophytes. The slow degradation of metazachlor combined with the absence of recovery in both chlorophytes and macrophytes is likely to cause long-lasting effects on aquatic ecosystems.     

Analysis of perfluorooctanoate (PFOA) and other perfluorinated compounds (PFCs) in the River Po watershed in N-Italy

C7-C11 perfluorinated carboxylates (PFACs) and perfluorooctansulfonate (PFOS) were analysed in selected stretches of the River Po and its major tributaries. Analyses were performed by solid-phase extraction (SPE) with Oasis HLB cartridges and methanol elution followed by LC-MS-MS detection using 13C-labelled internal standards. High concentration levels ( approximately 1.3 microg l(-1)) of perfluorooctanoate (PFOA) were detected in the Tánaro River close to the city Alessandria. After this tributary, levels between 60 and 337 ng l(-1) were measured in the Po River on several occasions. The PFOA concentration close to the river mouth in Ferrara was between 60 and 174 ng l(-1). Using the river discharge flow data in m3 s(-1) at this point (average approximately 920 m3 s(-1) for the year 2006), a mass load of approximately 0.3 kg PFOA per hour or approximately 2.6 tons per year discharged in the Adriatic Sea has been calculated. PFOS concentration levels in the Po River at Ferrara were approximately 10 ng l(-1).     

Insights on plant interaction between dominating species from patterns of plant association: expected covariance of pin-point cover measurements of two species

It has been suggested that in order to infer ecological processes from observed patterns of species abundance we need to investigate the covariance in species abundance. Consequently, an expression for the expected covariance of pin-point cover measurements of two species is developed. By comparing the observed covariance with the expected covariance we get a new type of information on the spatial arrangement of two species. Here the discrepancy between the observed and expected covariance may be thought of as a measure of the spatial configuration of the two species that may indicate underling ecological processes. The method is applied in a case study of Calluna vulgaris and Deschampsia flexuosa on dry heathland sites. The observed covariance of Calluna and Deschampsia at the level of the sites was positively and significantly correlated with the expected covariance. Negative covariance was observed on sites where both Calluna and Deschampsia had a high cover, which is in agreement with the notion that both species form distinct patches. Oppositely, at sites where both species have a low cover, we found that both the expected and observed covariance were positive. The proposed measure for the expected covariance of two species does capture information on the combined spatial configuration of the two species if the species are common. We show how this may be relevant for understanding the underlying ecological processes leading to the observed covariance.     

Multi-year, seasonal genotypic surveys of coral-algal symbioses reveal prevalent stability or post-bleaching reversion

This report documents the extent to which coral colonies show fluctuations in their associations with different endosymbiotic dinoflagellates. The genetic identity of Symbiodinium from six coral species [Acropora palmata (Lamarck), A. cervicornis (Lamarck), Siderastrea siderea (Ellis and Solander), Montastrea faveolata (Ellis and Solander), M. annularis (Ellis and Solander), and M. franksi (Gregory)] was examined seasonally over five years (1998 and 2000–2004) in the Bahamas and Florida Keys at shallow (1 to 4 m) fore-reef/patch reef sites and at deeper fore-reef (12–15 m) locations. Symbionts were identified genetically using denaturing gradient gel electrophoresis (DGGE) fingerprinting of the internal transcribed spacer region 2 (ITS2) of ribosomal RNA gene loci. Repetitive sampling from most labeled colonies from the Bahamas and the Florida Keys showed little to no change in their dominant symbiont. In contrast, certain colonies of M. annularis and M. franksi from the Florida Keys exhibited shifts in their associations attributed to recovery from the stresses of the 1997–1998 El Niño southern oscillation (ENSO) event. Over several years, a putatively stress-tolerant clade D type of Symbiodinium was progressively replaced in these colonies by symbionts typically found in M. annularis and M. franksi in Florida and at other Caribbean locations. Greater environmental fluctuations in Florida may explain the observed changes among some of the symbioses. Furthermore, symbiotic associations were more heterogeneous at shallow sites, relative to deep sites. The exposure to greater environmental variability near the surface may explain the higher symbiont diversity found within and between host colonies.     

Information system for monitoring environmental impacts of genetically modified organisms

Background, aim and scope  

European legislation stipulates that genetically modified organisms (GMO) have to be monitored to identify potential adverse environmental effects. A wealth of different types of monitoring data from various sources including existing environmental monitoring programmes is expected to accumulate. This requires an information system to efficiently structure, process and evaluate the monitoring data.     

Low-disturbance manure incorporation effects on ammonia and nitrate loss

Low-disturbance manure application methods can provide the benefits of manure incorporation, including reducing ammonia (NH3) emissions, in production systems where tillage is not possible. However, incorporation can exacerbate nitrate (NO3?) leaching. We sought to assess the trade-offs in NH3 and NO3? losses caused by alternative manure application methods. Dairy slurry (2006-2007) and liquid swine manure (2008-2009) were applied to no-till corn by (i) shallow (<10 cm) disk injection, (ii) surface banding with soil aeration, (iii) broadcasting, and (iv) broadcasting with tillage incorporation. Ammonia emissions were monitored for 72 h after application using ventilated chambers and passive diffusion samplers, and NO3? leaching to 80 cm was monitored with buried column lysimeters. The greatest NH3 emissions occurred with broadcasting (35-63 kg NH3-N ha?), and the lowest emissions were from unamended soil (<1 kg NH-N ha?1). Injection decreased NH-N emissions by 91 to 99% compared with broadcasting and resulted in lower emissions than tillage incorporation 1 h after broadcasting. Ammonia-nitrogen emissions from banding manure with aeration were inconsistent between years, averaging 0 to 71% that of broadcasting. Annual NO3? leaching losses were small (<25 kg NO3-N ha?1) and similar between treatments, except for the first winter when NO3? leaching was fivefold greater with injection. Because NO3? leaching with injection was substantially lower over subsequent seasons, we hypothesize that the elevated losses during the first winter were through preferential flow paths inadvertently created during lysimeter installation. Overall, shallow disk injection yielded the lowest NH3 emissions without consistently increasing NO3? leaching, whereas manure banding with soil aeration conserved inconsistent amounts of N.     

Effects of the pharmaceuticals gemfibrozil and diclofenac on biomarker expression in the zebra mussel (Dreissena polymorpha) and their comparison with standardised toxicity tests

Pharmaceuticals, including the lipid regulator gemfibrozil and the non-steroidal anti-inflammatory drug diclofenac have been identified in waste water treatment plant effluents and receiving waters throughout the western world. The acute and chronic toxicity of these compounds was assessed for three freshwater species (Daphnia magna,Pseudokirchneriella subcapitata, Lemna minor) using standardised toxicity tests with toxicity found in the non-environmentally relevant mid mg L⁻¹ concentration range. For the acute endpoints (IC₅₀ and EC₅₀) gemfibrozil showed higher toxicity ranging from 29 to 59 mg L⁻¹ (diclofenac 47-67 mg L⁻¹), while diclofenac was more toxic for the chronic D. magna 21 d endpoints ranging from 10 to 56 mg L⁻¹ (gemfibrozil 32-100 mg L⁻¹). These results were compared with the expression of several biomarkers in the zebra mussel (Dreissena polymorpha) 24 and 96 h after exposure by injection to concentrations of 21 and 21,000 μg L⁻¹ corresponding to nominal concentrations of 1 and 1000 μg L⁻¹. Exposure to gemfibrozil and diclofenac at both concentrations significantly increased the level of lipid peroxidation, a biomarker of damage. At the elevated nominal concentration of 1000 μg L⁻¹ the biomarkers of defence glutathione transferase and metallothionein were significantly elevated for gemfibrozil and diclofenac respectively, as was DNA damage after 96 h exposure to gemfibrozil. No evidence of endocrine disruption was observed using the alkali-labile phosphate technique. Results from this suite of biomarkers indicate these compounds can cause significant stress at environmentally relevant concentrations acting primarily through oxidation pathways with significant destabilization of the lysosomal membrane and that biomarker expression is a more sensitive endpoint than standardised toxicity tests.     

Hydrogen peroxide stabilization in one-dimensional flow columns

Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H(2)O(2) propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO.