北欧湖泊鱼类状况调查:酸化、富营养化和放养活动对现有鱼类品种组成的影响

1995～1997年间对挪威、瑞典和芬兰的3821个湖泊的鱼类种群状况做了评估.采用分层随机抽样从芬诺斯堪的亚(芬兰、挪威、瑞典、丹麦的总称)所有面积≥0.04km2的126482个湖泊中选择调查湖泊.分析了湖泊的水化学,湖内鱼类状况则从邮件调查问卷中获得.鱼类种群损失发生最为频繁的地区在挪威南部酸化最严重的地区,而在芬诺斯堪的亚东部最少.根据调查问卷,鳟(Salmotrutta)、拟鲤(Rutilus rutilus)、北极红点鲑(Salvelinus alpinus)和鲈鱼(Percafluviatilis)鱼群损失的数量估计超过10000条.这些品种的鱼群潜在地受低碱性湖水影响的数量超过11000条.大约有3300个湖泊显示出总磷高于25μg/L,品种以鲤科鱼为主,这在芬诺斯堪的亚东部、芬兰西南最为明显.这次调查并未显示出鱼类品种由于富营养化而灭绝.1/3的湖泊人工放养了至少一个新的鱼类品种,最常放养的品种有鳟、白鲑(Coregonus lavaretus s.1.)、北极红点鲑、虹鳟(Oncorhynchusmykiss)、梭鲈(Stizostedion lucioperca)、茴鱼(Thymallus thymallus)、狗鱼(Esox lucius)、欧鳊(Abramis brama)、丁 (Tinca tinca)和欧 (Phoxinus phoxinus).在芬诺斯堪的亚湖泊,这些品种的人工放养量估计超过52000群.因此,北欧湖泊现有鱼类品种的数量最近受放养的影响超过了因环境变化如酸化等而损失造成的影响.     

Gas chromatographic separation and determination of chloroanthracene isomers on fly ash

An efficient, reproducible and rapid fused silica capillary column gas chromatographic method, in splitless mode, for analysing of the three chloroanthracene isomers is described. The method affords efficient separation and good linearity for each isomer in the range of 0.2 -200 μg/ml. The method can also be used in separation and determination of another thirty three aromatic and their halosubstituted compounds. This paper also presents the applications of the method in analysing of complex products mixture from reaction of the selected aromatic compounds with hydrogen chloride on fly ash surface from municipal incinerator.     

UV-absorbing compounds in subarctic herbarium bryophytes

The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A280-320 nm) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend.     

Density patterns of gall mites (Acarina:Eriophyidae) in a polluted area

Trends in the densities of six species of gall mites on European aspen (Populus tremula) and on two birch species (Betula pubescens and B. pendula) were compared in an air pollution gradient from the Harjavalta copper-nickel smelter, SW Finland. The densities of gall mites on both birch species decreased towards the smelter and were negatively correlated with the levels of copper and nickel in the birch leaves. In contrast, the densities of aspen mites correlated neither with distance from the pollution source nor with the content of heavy metals in aspen leaves. Both birch and aspen trees tended to produce smaller leaves near the smelter, but a significant correlation between gall mite densities and site-specific leaf areas was only found for one species of mite.     

Reproductive status, blood chemistry, gill histology and growth of perch (Perca fluviatilis) in three acidic lakes

Perch (Perca fluviatilis L.) were sampled soon after spawning in three small acidic lakes (pH 4.3-6.1, Al(lab) 5-106 microg litre(-1), Ca2+ 0.01-0.08 mmol litre(-1)) and in one circumneutral lake (pH 5.9-6.4, Al(lab) 4-12 microg litre(-1), Ca2+ 0.06-0.07 mmol litre(-1)) in southern Finland. Due to the delayed spawning of perch in the acidic lakes, sampling in those lakes was performed later than in the reference lake. In spite of that, the gonadosomatic index (GSI) of males in all the acidic lakes was significantly greater than in the reference lake. Of the two lakes with similar low water pH, the effects on reproduction were more prominent in the lake with higher water Al content. The plasma Ca2+ concentrations of females in the acidic lakes were significantly smaller than in the females of the reference lake. The low female:male plasma Ca2+ ratio (1.0-1.32) depicted delay of spawning. Stress in perch in acidic water was also seen in elevated blood haematocrit values, especially in females. On the other hand, a low plasma Cl- level, a common response to acidic water in salmonids, was not detected in perch in the most acidic lakes. The amount of Al accumulated in the gill epithelium was highest in the most acidified lake with high Al concentration, but was also pronounced in a lake with low pH and low Al concentration.     

Climate Warming and Pikeperch Year-Class Catches in the Baltic Sea

Climate change scenarios concerning the Baltic Sea predict increase in surface water temperatures. Pikeperch (Sander lucioperca (L.)) inhabits the coastal areas of the northern Baltic Sea and is an important fish species for the Finnish fisheries. The year-class strength of pikeperch varies strongly between years and significantly depends on water temperature. We aimed to study the effects of changing temperature conditions on pikeperch fisheries and distribution based on commercial catch data from the period 1980–2008 in the Finnish coastal areas of the Baltic Sea. The results indicated that warmer summers will produce stronger pikeperch year-classes that consequently contribute significantly to the future catches. The average temperature in June–July explained 40% of the variation in the year-class catches in the Gulf of Finland and 73% in July–August in the Archipelago Sea. During the study period, the distribution of pikeperch catches expanded toward north along the coasts of the Bothnian Sea.     

Environmental specimen bank samples of Pleurozium schreberi and Hylocomium splendens as indicators of the radiation environment at the surface

Pleurozium schreberi (Brid.) Mitt. and Hylocomium splendens (Hedw.) Schimp. samples from the Finnish Environmental Specimen Bank were used to study the UV-B-absorbing compounds as potential screens of the past radiation environment. The first series from southern and central Finland consisted of samples collected from 18 P. schreberi or H. splendens dominated sites in 1985 and 1995. The second series from four H. splendens dominated sites (two in southern and two in northern Finland) and two P. schreberi dominated sites (one southern and one northern) were from the years 1985, 1990, 1995 and 2000. In the first series, the moss surface area of the analyzed specimens (5 +/- 0.2 mg DW) was smaller in 1995 (40% of both species collected in June) than in 1985 (40% of P. schreberi and 55% of H. splendens collected in September). The methanol-extractable UV-B-absorbing compounds of P. schreberi in 1985 and 1995 measured as absorbance at 10 nm intervals at 280-360 nm per mg DW revealed a negative correlation with reconstructed UV-radiation data. In the second series, the UV-B-absorbing compounds per specific surface area (surface area mm2 per DW) showed significant differences between the years. The highest values in both species were obtained in 1990. In H. splendens, a difference between the southern and northern samples was observed. The preliminary study encouraged the use of environmental specimen bank samples to indicate changes in surface radiation conditions.     

Automated color correction method for Vibrio fischeri toxicity test. Comparison of standard and kinetic assays.

We demonstrate in this study that the toxicity of solid and highly colorful samples can be measured with kinetic bioassay using luminescent bacterium Vibrio fischeri. The Flash assay, named after the test protocol, is performed with a tube luminometer. In this method, each sample acts as a reference for itself, and therefore, the color correction is possible with minimal hands-on-time. The bacteria are dispensed into the sample and the signal is recorded continuously. The maximum signal received after immediately dispensing is compared to the signal after an incubation period. With many chemicals, the toxic effects are obtained after a very short contact time. However, different chemicals have different modes of toxicity. Thus, kinetic data from sample analyses after 15 or 30 min for this bacterium gives an additional dimension for obtaining reliable results. The performance of the test was compared to the standardized photobacteria test protocol with reference chemicals. The repeatability of the test was excellent. The coefficient of variation was normally below 1% with 10 replicates.     

Enteric Viruses in a Large Waterborne Outbreak of Acute Gastroenteritis in Finland

In Nokia city about 450,000 l of treated sewage water was for 2 days allowed to run into the drinking water supplies of the city due to a personal error of one employee. Within the next 5 weeks about 1,000 people sought care at the municipal health centre or regional hospital because of gastroenteritis. Here we report the results of viral analyses performed by gene amplification assays from the earliest water and sewage samples as well as from close to 300 patient samples. The contaminating treated sewage was shown to harbour several enteric viruses known to cause acute gastroenteritis. Likewise, the drinking water sample was positive for noro-, astro-, rota-, entero- and adenoviruses. Noroviruses were also found in 29.8% of stool samples from affected patients, while astro-, adeno-, rota- and enteroviruses were detected in 19.7, 18.2, 7.5 and 3.7% of the specimens, respectively. An erratum to this article can be found at     

Latitudinal gradients in niche breadth and position—regional patterns in freshwater fish

The latitudinal gradient in diversity is widely acknowledged, but the mechanisms contributing to this pattern are still poorly known. Given that the species have environmental optima, a central issue is how species’ niche parameters, i.e. niche breadth and niche position, vary along the latitudinal gradient. In this study, we examined the determinants of fish distribution and the variability in species’ niche breadth and position along latitudinal gradient using a regional data set of boreal lakes. Results of the Outlying Mean Index analysis showed that the fish community structure was jointly controlled by a number of environmental factors, ranging from water chemistry and temperature to local physical factors such as lake area and depth. Corroborating the number of earlier findings, the regional occupancy of species was more strongly governed by the niche position than the niche breadth, although both showed a significant relationship with the regional distribution. When the latitudinal variability in niche parameters of the main taxonomic groups was analysed, both percids and cyprinids, being cool water species, showed significant decrease in niche breadth northwards as we predicted. By contrast, the niche position and latitude were non-significantly correlated in percids and salmonids, and negatively correlated in cyprinids, the latter showing the opposite pattern as we predicted. However, even if only a part of our predictions was supported, the results generally implied that the examination of latitudinal variability in the niche properties is potentially highly rewarding, not only in estimation of present community structure in lakes but also for predictions of species’ responses to climate change.