The present paper cites results of studying phytoplankton in the Grosnica Water Reservoir, Serbia (Yugoslavia). Seasonal investigations during 1997 and 1998 enabled us to establish composition and structure of the phytoplankton community, quality of the lake's water, and its trophic status. During the period of investigation, the phytoplankton community was characterized by forms of Cyanophyta, Pyrrophyta, Chrysophyta, Bacillariophyta, Euglenophyta and Chlorophyta. Qualitative analysis indicated that algae of the divisions Bacillariophyta and Chlorophyta are dominant in the phytoplankton, while saprobiological analysis using bioindicatory algal species showed that water of the Grosnica Water Reservoir during the given period was of the 1st and 2nd quality class.

The increased inorganic nitrogen (N) deposition in the last decades has become a major concern for the health of forests. In forest ecosystem, where N might no longer be limiting to primary production, the excess N is thought to be related to forest decline and a concept of ‘N saturation ‘ has been developed. In particular, N, in the form of NH4, in excess to plant and microbial demands could lead to soil acidification if nitrified in the soil and leached, causing loss of base cations or mobilisation of phytotoxic aluminium. As part of the CORE project (CEC), investigating nutrient dynamics in European coniferous forest soils, we studied the effects of continuously increased (NH4)2SO4 deposition and soil characteristics on Norway spruce (Picea abies [L.] Karst) and Scots pine (Pinus sylvestris L.) fine root biomass, vitality and chemistry with an ingrowth core technique. The same experiment was performed in a Norway spruce stand on clay soil (Grizedale, UK) and a Scots pine stand on sandy soil (Wekerom, NL), using soil from each of the two sites. Root-free ingrowth cores reproduced organic and mineral soil horizons to 15 cm depth. They were covered to exclude native throughfall and watered every 2 weeks with throughfall or throughfall with (NH4)2SO4 added to increase deposition by 75 kg ha-1 a-1 NH4+-N. The ingrowth cores were sampled after 19 months, divided into layers, roots washed and analysed for biomass, necromass, root length, root tip number (RTN), root tip vitality and fine root chemistry. A previous field experiment had shown high soil solution Al concentrations at both sites, and an increase in NO3- and Al concentrations in response to increased (NH4)2SO4 deposition at the Grizedale site. The effects of high (NH4)2SO4 deposition depended on tree species, soil type and soil horizon. For Norway spruce, (NH4)2SO4 deposition did not result in any significant changes in root growth or vitality when growing into the native clay soil. However, when growing into the sandy soil, RTN and the proportion of dead roots were increased by N deposition. Norway spruce fine root N content was also increased in the organic horizon of both soil types. For Scots pine, (NH4)2SO4 treatment caused increased fine root Al content and a decreased Mg/Al ratio in the mineral layer of the sandy soil, with opposite effects in the clay soil. This (NH4)2SO4 treatment effect in the sandy soil for Scots pine was the only indication of a potential adverse effect of (NH4)2SO4 deposition on fine roots. Further results demonstrated the dominant importance of inherent soil characteristics and the stratification into soil horizons on fine root growth and chemical composition. For example, a negative correlation between root biomass and fine root Al content was established for Norway spruce.

International audience

Following a number of meetings devoted to knowledge sharing, identification of key issues, and discussing the best ways to move forward, a wide international expert community is now able to provide recommendations regarding the monitoring of seafloor macrolitter through observation and imaging. As the seafloor constitutes a major sink for marine litter including plastics, it is important to acquire robust and extensive data on litter distribution, abundance, types and size ranges across marine habitats. This should be done through widely agreed, harmonised, and non-destructive methods encompassing advanced technologies. Training and capacity building are essential elements in this endeavour. Both new and legacy imagery are needed to establish baseline assessments and trends. Informing policy-making is indispensable for effective action through upstream and targeted measures, with seafloor macrolitter (and megalitter) being a vital part of the evidence base for global mitigation measures.

International audience | Studies integrating trophic ecology, physiological condition and accumulation of heavy metals in top predators, such as swordfish, are needed to better understand the links between them and the risk to humans associated with consumption of these fish. This research focuses on the swordfish of the Catalan Sea and follows a multi method approach that considers their diet, their liver lipid content, and mercury accumulation in their bodies as well as in their prey. The aim is to highlight the links between trophic ecology, physiology (fish condition), and ecotoxicology. Results indicate that poor condition of swordfish based on size and the levels of lipid in the liver, and the high Hg levels accumulated to the trophic web (particularly from cephalopods) may indicate potential unfavourable feeding and reproduction conditions for swordfish in the NW Mediterranean and that this warrants further investigation.

International audience | Antibiotics have been increasingly used over the past decades for human medicine, food-animal agriculture, aquaculture, and plant production. A significant part of the active molecules of antibiotics can be released into the environment, in turn affecting ecosystem functioning and biogeochemical processes. At lower organizational scales, these substances affect bacterial symbionts of insects, with negative consequences on growth and development of juveniles, and population dynamics. Yet, the multiple alterations of cellular physiology and metabolic processes have remained insufficiently explored in insects. We evaluated the effects of five antibiotics with different mode of action, i.e. ampicillin, cefradine, chloramphenicol, cycloheximide, and tetracycline, on the survival and ultrastructural organization of the flight muscles of newly emerged blow flies Chrysomya albiceps. Then, we examined the effects of different concentrations of antibiotics on mitochondrial protein content, efficiency of oxidative phosphorylation, and activity of transaminases (Glutamate oxaloacetate transaminase and glutamate pyruvate transaminase) and described the cellular metabolic perturbations of flies treated with antibiotics. All antibiotics affected the survival of the insects and decreased the total mitochondrial protein content in a dose-dependent manner. Ultrastructural organization of flight muscles in treated flies differs dramatically compared to the control groups and severe pathological damages/structures disorganization of mitochondria appeared. The activities of mitochondrial transaminases significantly increased with increased antibiotic concentrations. The oxidation rate of pyruvate + proline from isolated mitochondria of the flight muscles of 1-day-old flies was significantly reduced at high doses of antibiotics. In parallel, the level of several metabolites, including TCA cycle intermediates, was reduced in antibiotics-treated flies. Overall, antibiotics provoked a system-wide alteration of the structure and physiology of flight muscles of the blow fly Ch. albiceps, and may have fitness consequences at the organism level. Environmental antibiotic pollution is likely to have unwanted cascading ecological effects of insect population dynamics and community structure.

Zeolitic tuff constitutes a technical and economical feasible alternative to manage acidic waters in initial phases of generation. A study of cation exchange with two zeolitic tuffs from Ecuador and one from Cuba has been conducted using breakthrough curve methodology. Cations Mn2+, Cd2+, Cr3+, Zn2+, and Al3+ have been chosen owing to their presence in underground water in exploration activities (decline development) in Fruta del Norte (Ecuador). Zeolites characterized by X-ray diffraction and thermal stability after heating overnight as heulandites show a similar exchange behavior for the five cations studied. The clinoptilolite sample Tasajeras shows a relevant cation exchange performance expressed in the important increment of spatial time to reach the breakthrough point in comparison with heulandite samples. The maximum length of unused beds was found for Cr3+ and Zn2+ cations showing, therefore, a lower adsorption performance in relation with Mn2+ and Cd2+. A final disposal method of metal-loaded zeolites with cement is proposed.

peer reviewed | A decision support system (DSS) involving an approach for predicting wheat leaf rust (WLR) infection and progress based on night weather variables (i.e., air temperature, relative humidity, and rainfall) and a mechanistic model for leaf emergence and development simulation (i.e., PROCULTURE) was tested in order to schedule fungicide time spray for controlling leaf rust progress in wheat fields. Experiments including a single fungicide treatment based upon the DSS along with double and triple treatment were carried out over the 2007–2009 cropping seasons in four representative Luxembourgish wheat field locations. The study showed that the WLR occurrences and severities differed according to the site, cultivar, and year. We also found out that the single fungicide treatment based on the DSS allowed a good protection of the three upper leaves of susceptible cultivars in fields with predominant WLR occurrences. The harvested grain yield was not significantly different from that of the double and triple fungicide-treated plots (P < 0.05). Such results could serve as basis or be coupled to cost-effective and environmentally friendly crop management systems in operational context.