Biological responses of midge (Chironomus riparius) and lamprey (Lampetra fluviatilis) larvae in ecotoxicity assessment of PCDD/F-, PCB- and Hg-contaminated river sediments

Environmental Science and Pollution Research - We evaluated the utility of chironomid and lamprey larval responses in ecotoxicity assessment of polychlorinated dibenzo-p-dioxins, dibenzofurans...     

Ecosystem consequences of cyanobacteria in the northern Baltic Sea

Cyanobacteria of the Baltic Sea have multiple effects on organisms that influence the food chain dynamics on several trophic levels. Cyanobacteria contain several bioactive compounds, such as alkaloids, peptides, and lipopolysaccharides. A group of nonribosomally produced oligopeptides, namely microcystins and nodularin, are tumor promoters and cause oxidative stress in the affected cells. Zooplankton graze on cyanobacteria, and when ingested, the hepatotoxins (nodularin) decrease the egg production of, for example, copepods. However, the observed effects are very variable, because many crustaceans are tolerant to nodularin and because cyanobacteria may complement the diet of grazers in small amounts. Cyanobacterial toxins are transferred through the food web from one trophic level to another. The transfer rate is relatively low in the pelagic food web, but reduced feeding and growth rates of fish larvae have been observed. In the benthic food web, especially in blue mussels, nodularin concentrations are high, and benthic feeding juvenile flounders have been observed to disappear from bloom areas. In the littoral ecosystem, gammarids have shown increased mortality and weakening of reproductive success under cyanobacterial exposure. In contrast, mysid shrimps seem to be tolerant to cyanobacterial exposure. In fish larvae, detoxication of nodularin poses a metabolic cost that is reflected as decreased growth and condition, which may increase their susceptibility to predation. Cyanobacterial filaments and aggregates also interfere with both hydromechanical and visual feeding of planktivores. The feeding appendages of mysid shrimps may clog, and the filaments interfere with prey detection of pike larvae. On the other hand, a cyanobacterial bloom may provide a refuge for both zooplankton and small fish. As the decaying bloom also provides an ample source of organic carbon and nutrients for the organisms of the microbial loop, the zooplankton species capable of selective feeding may thrive in bloom conditions. Cyanobacteria also compete for nutrients with other primary producers and change the nitrogen (N): phosphorus (P) balance of their environment by their N-fixation. Further, the bioactive compounds of cyanobacteria directly influence other primary producers, favoring cyanobacteria, chlorophytes, dinoflagellates, and nanoflagellates and inhibiting cryptophytes. As the selective grazers also shift the grazing pressure on other species than cyanobacteria, changes in the structure and functioning of the Baltic Sea communities and ecosystems are likely to occur during the cyanobacterial bloom season.     

The Role of Wood Material for Greenhouse Gas Mitigation

Based on an interdisciplinary perspective the role of wood as a carbon sink, as a multi-purpose material, and as a renewable energy source for the net reduction of greenhouse gases is discussed. We synthesize aspects from engineering, natural and social sciences to better understand the role of wood substitution in CO₂ mitigation. We also formulate some recommendations on filling knowledge gaps that could be useful for policy making regarding how wood substitution could be further expanded. There are sufficient wood resources to substantially increase the use of wood for material and energy purposes. However, a number of factors hinder a wider use of wood for energy and material purposes. Furthermore, an analysis of wood substitution is a very complex issue, since the substitution influencing factors are to be found along the entire wood supply chain and involve several industries, socio-economic and cultural aspects, traditions, price dynamics, and structural and technical change. To improve the knowledge about wood as a substitute for other resources and the implications, it would be helpful to better integrate research from different disciplines on the subject and to cover different scales from a project to an economy-wide level.     

Nodularin accumulation during cyanobacterial blooms and experimental depuration in zooplankton

Cyanobacterial blooms are a common phenomenon in the Baltic Sea, and the hepatotoxin nodularin has been frequently detected in certain Baltic Sea fishes and mussels. However, there is no knowledge about the naturally occurring concentrations of nodularin in Baltic Sea zooplankton. The aim of this study was to survey the concentrations of nodularin in natural zooplankton assemblages, and to study the depuration of nodularin in one common copepod species, Eurytemora affinis, experimentally. The nodularin concentrations in common zooplankton species were determined from field-collected samples from the northern Baltic Proper in 2001 and 2002, during cyanobacterial blooms, and the samples were analysed by ELISA immunoassay. Nodularin could be detected from the field-collected zooplankton, suggesting that during a natural bloom event toxins accumulate in their tissues. The concentrations were relatively low (0.07±0.01 μg g⁻¹ ww), ranging from below detection limit to 0.62 μg g⁻¹ ww. Some variation occurred in the concentrations between species and years; generally concentrations were higher in 2001 than in 2002. In the depuration experiment E. affinis copepods were fed with toxic Nodularia spumigena for 24 h, and their toxin contents were monitored for 24 h after transferring them to filtered seawater. A rapid decrease in nodularin concentrations occurred during the first 0.5–3 h after the exposure. However, after a 24-h depuration period in filtered seawater, nodularin could be still detected in E. affinis tissues, indicating that part of the accumulated nodularin, or its derivatives, could be transferred to planktivores.     

Human dietary intake of organochlorines from Baltic herring: implications of individual fish variability and fisheries management

This study examines the extent to which Finnish human dietary intake of organochlorines (PCDD/Fs and PCBs) originating from Northern Baltic herring can be influenced by fisheries management. This was investigated by estimation of human intake using versatile modeling tools (e.g., a herring population model and a bioenergetics model). We used a probabilistic approach to account for the variation in human intake of organochlorines originating from the variation among herring individuals. Our estimates were compared with present precautionary limits and recommendation for use. The results show that present consumption levels and frequencies of herring give a high probability of exceeding recommended intake limits of PCDD/Fs and PCBs. Furthermore, our results clearly demonstrate that in the risk management of dioxinlike organochlorines, regulating fishing (in this case increasing fishing pressure) is a far less effective way to decrease the risk than regulating the consumption of herring. Increased fishing would only slightly decrease organochlorine concentrations of herring in the Finnish fish market.     

Perceived and measured levels of environmental pollution: interdisciplinary research in the subarctic lowlands of northeast European Russia

Using interdisciplinary field research in the Usa Basin, northeast European Russia, we compared local inhabitants' perception of environmental problems with chemical and remote-sensing signatures of environmental pollution and their local impacts. Extensive coal mining since the 1930s around Inta and Vorkuta has left a legacy of pollution, detected by measuring snowpack, topsoil, and lichen chemistry, together with remote-sensing techniques and analysis of lake water and sediments. Vorkuta and its environs suffered the worst impacts, with significant metal loading and alkalization in lakes and topsoils, elevated metals and cations in terricolous (reindeer) lichens, and changes in vegetation communities. Although the coal industry has declined recently, the area boasts a booming oil and gas industry, based around Usinsk. Local perceptions and concerns of environmental pollution and protection were higher in Usinsk, as a result of increased awareness after a major oil spill in 1994, compared with Vorkuta's inhabitants, who perceived air pollution as the primary environmental threat. Our studies indicate that the principal sources of atmospheric emissions and local deposition within 25 to 40 km of Vorkuta were coal combustion from power and heating plants, coal mines, and a cement factory. Local people evaluated air pollution from direct observations and personal experiences, such as discoloration of snow and respiratory problems, whereas scientific knowledge played a minor role in shaping these perceptions.