Hydrobionts of a freshwater oil-polluted northern lake: bioaccumulation of heavy metals in fish and the rate of ecosystem recovery

The response of phytoplankton, zooplankton, benthic and fish community structure to one of the biggest oil spill in history of Komi Republic (north-west part of Russia) was investigated using data from a long-term survey off the polluted lake. The characteristics of aquatic freshwater communities observed in the study area 10, 11 and 22 years after the spill (1994) were compared to find out the rate of natural recovery of the ecosystem after oil decontamination of bottom sediments. The concentrations of fifteen trace metals (Al, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Pb, U, Bi, Th) were analyzed in the tissues (muscle) of three fish species. The concentrations of Al (3-309 mg/kg), Cr (0,1-3,71 mg/kg), Fe (8,6-317 mg/kg), and Cu (0,09-99 mg/kg) in fishes from polluted lake resulted in most cases higher than reference thresholds. Quantitative and qualitative indicators of aquatic invertebrates from polluted lake reach those one of unpolluted lake but do not fully recover 22 years after the spill, despite that oil concentration in water column and in bottom sediments was lower than reference tresholds. We conclude that natural recovery rate of aquatic freshwater ecosystems in northern regions after oil pollution is extremely low. The purification of water and bottom sediments of oil-polluted northern water bodies is necessary for stimulation of ecosystem restoration

Microstructured optical waveguide-based endoscopic probe coated with silica submicron particles

Microstructured optical waveguides (MOW) are of great interest for chemical and biological sensing. Due to the high overlap between a guiding light mode and an analyte filling of one or several fiber capillaries, such systems are able to provide strong sensitivity with respect to variations in the refractive index and the thickness of filling materials. Here, we introduce a novel type of functionalized MOWs whose capillaries are coated by a layer-by-layer (LBL) approach, enabling the alternate deposition of silica particles (SiO2) at different diameters—300 nm, 420 nm, and 900 nm—and layers of poly(diallyldimethylammonium chloride) (PDDA). We demonstrate up to three covering bilayers consisting of 300-nm silica particles. Modifications in the MOW transmission spectrum induced by coating are measured and analyzed. The proposed technique of MOW functionalization allows one to reach novel sensing capabilities, including an increase in the effective sensing area and the provision of a convenient scaffold for the attachment of long molecules such as protein

Interspecific competition delays recovery of Daphnia spp. populations from pesticide stress

Xenobiotics alter the balance of competition between species and induce shifts in community composition. However, little is known about how these alterations affect the recovery of sensitive taxa. We exposed zooplankton communities to esfenvalerate (0.03, 0.3, and 3 μg/L) in outdoor microcosms and investigated the long-term effects on populations of Daphnia spp. To cover a broad and realistic range of environmental conditions, we established 96 microcosms with different treatments of shading and periodic harvesting. Populations of Daphnia spp. decreased in abundance for more than 8 weeks after contamination at 0.3 and 3 μg/L esfenvalerate. The period required for recovery at 0.3 and 3 μg/L was more than eight and three times longer, respectively, than the recovery period that was predicted on the basis of the life cycle of Daphnia spp. without considering the environmental context. We found that the recovery of sensitive Daphnia spp. populations depended on the initial pesticide survival and the related increase of less sensitive, competing taxa. We assert that this increase in the abundance of competing species, as well as sub-lethal effects of esfenvalerate, caused the unexpectedly prolonged effects of esfenvalerate on populations of Daphnia spp. We conclude that assessing biotic interactions is essential to understand and hence predict the effects and recovery from toxicant stress in communities

Norm setting for oil and petroleum products in bottom sediments and their quality assessment according to Russian hydro chemical parameters

Norm setting for oil and petroleum products concentration in bottom sediments of water bodies in the Russian Federation is very important for the protection of fishery water bodies. The lack of specified content standards for petroleum products in different types of bottom sediments in oil extraction regions impedes projects to rehabilitate water bodies, polluted by oil. The paper discusses regional regulations of the Russian Federation on the norm setting for petroleum products in bottom sediments of water bodies

Norm setting for oil and petroleum products in bottom sediments and their quality assessment according to Russian hydro chemical parameters

Norm setting for oil and petroleum products concentration in bottom sediments of water bodies in the Russian Federation is very important for the protection of fishery water bodies. The lack of specified content standards for petroleum products in different types of bottom sediments in oil extraction regions impedes projects to rehabilitate water bodies, polluted by oil. The paper discusses regional regulations of the Russian Federation on the norm setting for petroleum products in bottom sediments of water bodies

Seasonal changes in the functional diversity of bacterioplankton in contrasting coastal environments of the NW mediterranean

10 pages, 4 figures, 1 tableTo understand the seasonal and intersite variations in the functional diversity of coastal bacterioplankton assemblages, their utilization of 31 different carbon sources was analyzed with Biolog-Ecoplates™ in waters from 3 harbours and 2 oligotrophic coastal environments of the NW Mediterranean. Polymers (α-cyclodextrin and glycogen) and carbohydrates (d-cellobiose and N-acetyl-d-glucosamine) were most utilized in the harbours, while carboxylic acids were mainly used in the coastal areas. Seasonal differences in the patterns of carbon source utilization (the so-called ‘functional diversity’) were investigated in 2 spatially close, but contrasting, coastal stations: the oligotrophic coastal site of Blanes Bay, and the Barcelona inner harbour. The existence of a possible seasonal trend in functional diversity of bacterioplankton in the oligotrophic coastal station, but not in the harbour, suggests that the bacterial assemblage of oligotrophic environments can adapt to changing inputs of nutrients and DOC. In contrast, the low water exchange in the harbour provides a pool of DOC of relatively stable composition throughout the year which could allow few potential bacterial metabolisms to persist. We considered the quantity of substrates used (of all those provided in the Biolog plate) as an index of potential functional diversity. The index calculated for the harbour and the coastal station samples was negatively correlated with chlorophyll a concentration, suggesting that the bacterial assemblages of oligotrophic systems have a higher number of metabolic pathways in order to be able to exploit a wide variety of DOC molecules present at low concentrationsThis work was supported by the projects BIOHAB (EVK3-CT99-00015), BASICS (EVK3-CT2002- 00078) and PROCAVIR (CTM 2004-04404-C02-01/MAR) and by a CSIC-I3P post-doctoral contract funded by the Fondo Social Europeo to M.M.S.Peer reviewe