M. Beklioğlu, Aysegul Cetin, P. Zorlu, Duygu Ay-Zog
{"title":"Role of planktonic bacteria in biodegradation of fish-exuded kairomone in laboratory bioassays of diel vertical migration","authors":"M. Beklioğlu, Aysegul Cetin, P. Zorlu, Duygu Ay-Zog","doi":"10.1127/0003-9136/2006/0165-0089","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0089","url":null,"abstract":"Daphnia, freshwater crustaceans that graze algae, often rely on predatory chemical cues termed kairomones as signals for predator-avoidance. Using laboratory bioassays, we studied how planktonic bacteria may modify kairomone activity. We measured the amplitude of diel vertical migration (DVM) of Daphnia pulex DE GEER among treatments with different amounts of bacteria. We used temperature incubation to increase bacterial densities and filtration to reduce abundance. Daphnids exposed to fish cue (F) and filtrate of fish cue (FF) (i. e. 3.0 fold decrease in the planktonic bacteria) exhibited a strong DVM response. In addition, the strength of the response remained the same for both treatments. However, daphnids exposed to an incubated fish cue (IF), which had higher bacterial densities, showed similar migration to daphnids in the control treatment. This IF treatment showed a 3-fold enrichment of bacteria. Besides observing a gradient in DVM response with bacterial density, we also found that DVM response varied seasonally in our experiments. DVM response to fish cue developed quickly in the experiments carried out in March and May compared to a delayed response that we observed in a similar experiment in January. A seasonal shift also occurred in the population sizes of cultivable planktonic bacteria. Responsiveness of D. pulex to predator cues may vary seasonally, possibly due to higher vulnerability during seasons with high fish production. Kairomone concentrations may also fluctuate due to varied release or degradation rates. Our results suggest that the in-situ, tight coupling between production and degradation of kairomone appears to be the cause of DVM response for daphnids during summer.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"36 1","pages":"89-104"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91176676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Cruces, R. Urrutia, O. Parra, A. Araneda, H. Treutler, S. Bertrand, N. Fagel, L. Torres, R. Barra, L. Chirinos
{"title":"Changes in diatom assemblages in an Andean lake in response to a recent volcanic event","authors":"F. Cruces, R. Urrutia, O. Parra, A. Araneda, H. Treutler, S. Bertrand, N. Fagel, L. Torres, R. Barra, L. Chirinos","doi":"10.1127/0003-9136/2006/0165-0023","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0023","url":null,"abstract":"Galletue Lake (38° 41'S; 71° 17'W,IX Region-Chile) is located in an area that is highly influenced by eruptive activity of the Lonquimay and Llaima volcanoes. As a consequence, during the last century tephra was deposited into the lake. Sedimentary diatom assemblages were reconstructed in order to establish the tephra effect on their composition and productivity. This was done by taking a sediment core from Galletue Lake at 40m depth and sectioning it in 1 cm intervals. The core age was obtained with 210 Pb and 137 Cs activities and the mineral composition of the tephra was determined with mineralogical analyses. Furthermore, sedimentological analyses were performed and total organic matter was determined in the profile. The diatom assemblages were analysed using light and electronic microscopy. The results showed that the diatom stratigraphy can be separated in three zones recognizing the periods before and after tephra input. Aulacoseira granulata decreased during the tephra influx and was replaced by Cyclotella aff. glomerata. When the tephra disappeared from the sedimentary record, A. granulata returned to pre-volcanic event levels. At the same time, Cyclotella aff. glomerata decreased within the assemblages. Asterionella formosa and Urosolenia eriensis increased after the tephra input, with values surpassing earlier ones. These results indicate that, after the tephra input, the lake recovered its previous nutrient levels, which agrees with the organic matter content in the sedimentary matrix. Finally, the results reveal that the volcanic disturbance changed the structure and productivity of diatom assemblages in Galletue Lake.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"165 1","pages":"23-35"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87003197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Influence of fine sediments on meiofauna colonization densities in artificial stream channels","authors":"A. J. Radwell, Arthur V. Brown","doi":"10.1127/0003-9136/2006/0165-0063","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0063","url":null,"abstract":"Excessive fine sediments have been shown to adversely affect abundance and diversity of stream macroinvertebrates, but effects on meiofauna have been only minimally and indirectly assessed. We used 12 artificial channels in a 4 th order Ozark stream to investigate the influence of silt (particle diameter 63 μm to 2 mm) and gravel (particle diameter 2 to 16 mm) on meiofauna colonization. Four channels were filled with gravel, four with 1/2 gravel and 1/2 sand, and four with 1/3 gravel, 1/3 sand, and 1/3 topsoil, referred to as gravel, sand, and silt treatments, respectively. Substrate cores were taken from the natural and artificial channels for analysis of meiofauna (80 μm to 1 mm) and substrate composition. Rotifera, Copepoda, Chironomidae, Nematoda, Oligochaeta, and Mollusca (principally juvenile Corbicula fluminea) comprised the major meiofauna taxa. Total meiofauna density in the artificial channels differed significantly among treatments. Density was lower in the silt treatment than in gravel or sand treatments, but overall densities in the gravel and sand treatments did not differ. Responses to treatments varied among specific taxa; densities of rotifers, copepods, nematodes, and oligochaetes were lower in the silt than the gravel treatment, but chironomids and nematodes were equally abundant in gravel and sand treatments, while lower in the silt treatment. Total meiofauna density did not differ between the natural channel and the gravel treatment but was lower in the sand and silt treatments. Copepod density was higher in the gravel treatment, and nematode, oligochaete, and mollusk densities were lower for all three treatments compared to the natural channel. The lower density of total meiofauna associated with high concentrations of silt suggests that excessive silt reduces habitat space and/or quality for meiobenthic organisms, while a sand and gravel mix is suitable for some meiofauna taxa.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"98 1","pages":"63-75"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74168292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Löhr, Rutger Sluik, M. Olaveson, N. Ivorra, C. V. van Gestel, N. V. van Straalen
{"title":"Macroinvertebrate and algal communities in an extremely acidic river and the Kawah Ijen crater lake (pH < 0.3), Indonesia.","authors":"A. Löhr, Rutger Sluik, M. Olaveson, N. Ivorra, C. V. van Gestel, N. V. van Straalen","doi":"10.1127/0003-9136/2006/0165-0001","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0001","url":null,"abstract":"Acidic aquatic ecosystems are mainly characterized by low pH and high concentrations of metals and other elements with evident effects on local community structure. Acidity effects on benthic communities in one of the world's largest extremely acidic crater lakes, the Kawah Ijen (East Java, Indonesia) (pH <0.3), and the acidic Banyupahit-Banyuputih river (pH 0.7-3.3) originating from it, had not been investigated. Therefore, macroinvertebrate and algal community structure in the acidic river were studied and compared to the neutral rivers Kali Sat and Kali Sengon in the same catchment. The aquatic foodweb of the Banyupahit-Banyputih river was poorly developed and a complete lack of macroinvertebrate species was observed at pH values below 2. At two sampling stations with pH 2.69-3.47 and pH 2.26-2.89 only chironomids were found and other acid-tolerant macroinvertebrate taxa from acidic aquatic systems reported in the literature were absent. No statistically significant differences of metal body burden in chironomids could be detected between locations. In contrast, algal communities were more diversified and the number of taxa increased with increasing pH. Remarkably, high densities of an unknown green alga were found in samples from the acidic crater lake. Diatom communities were characterized by dominance of the acid tolerant Pinnularia acoricola at the most acidic sites, and a gradual replacement by other species with increasing pH. Particular features of the river, such as the lack of aquatic macrophytes and the presence of acid-tolerant algal species (e. g. Euglena mutabilis, Achnanthes minutissima), revealed not only the strength of the acid selection on these communities, but also the role of indirect physical and chemical factors (e. g. high Al, low P concentrations). It is concluded, therefore, that the ability of the studied macroinvertebrates and algal species to withstand the acid circumstances is not only due to their resistance to low pH, but also to the consequences of it.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"8 1","pages":"1-21"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79133020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Lecerf, P. Usseglio-Polatera, J. Charcosset, D. Lambrigot, Boris Bracht, É. Chauvet
{"title":"Assessment of functional integrity of eutrophic streams using litter breakdown and benthic macroinvertebrates","authors":"A. Lecerf, P. Usseglio-Polatera, J. Charcosset, D. Lambrigot, Boris Bracht, É. Chauvet","doi":"10.1127/0003-9136/2006/0165-0105","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0105","url":null,"abstract":"Currently, interest is growing in evaluating stream functional integrity while river assessment schemes are still exclusively based on structural indicators determined from various aquatic communities. Although some approaches relying on macroinvertebrate functional groups and combinations of traits have been advocated as means to assess ecosystem function, there has been no attempt to test the reliability of these methods with any direct functional indicator even though litter breakdown has been recently proposed as a functional indicator of stream impairment. The purpose of this study was to compare nine benthic macroinvertebrate-based structural metrics with functional metrics based on leaf litter breakdown in coarse and fine mesh bags in nine streams distributed along a eutrophication gradient. In coarse mesh bags, a 10-fold drop in breakdown rate of alder litter indicated a high sensitivity of this functional indicator to the deleterious effects of ammonium and its associated products, ammonia and nitrite. In contrast, microbial breakdown measured in fine mesh bags did not vary substantially along the gradient. Taxonomic and functional structures of macroinvertebrate assemblages were altered in the most eutrophic streams, as shown by drops in IBGN (French biotic index), BMWP (Britain biotic index) and EPTC (Ephemeroptera, Plecoptera, Trichoptera and Coleoptera) richness. Shredder richness and an ecological diversity index calculated from functional groups defined from multiple trait combinations exhibited the highest correlation with litter breakdown rate. Our results indicate that indirect assessment of stream functional integrity by structural indicators is realistic but requires specific metrics not necessarily based on traits or functional groups. Leaf litter breakdown is confirmed as a reliable indicator for direct assessment of streams impacted by eutrophication.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"49 1","pages":"105-126"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83179408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Migrations of soufie (Leuciscus souffia agassizii, VAL. 1844) in a natural river and a tributary determined by mark-recapture","authors":"Hendrik Wocher, R. Rösch","doi":"10.1127/0003-9136/2006/0165-0077","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0165-0077","url":null,"abstract":"From April to October 1998, soufie (Leuciscus souffia agassizii, VAL. 1844) were fished monthly using electrofishing at four sampling sites in the Argen River and in a little tributary. All fish with a body size exceeding 8 cm were tagged individually using micro tags. Additionally the fish were tagged according to sampling site by jet injection using Alcian Blue dye. The main part of the soufie population exhibited a migratory behaviour during the year between winter and summer habitat. Most of the soufie overwintered in a pool of a little tributary of the river, whereas age 0 + soufie remained in the river for the whole year. After spawning in spring in the river, the fish segregated during summer for feeding in the main river system. In the autumn, the fish returned to their winter habitat. It is concluded that the tributary plays an important role as overwintering habitat for the soufie population (except 0 +) of the investigated river section.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"35 1","pages":"77-87"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81693474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Renata Matoničkin Kepčija, I. Habdija, B. Primc-Habdija, M. Miliša
{"title":"Simuliid silk pads enhance tufa deposition","authors":"Renata Matoničkin Kepčija, I. Habdija, B. Primc-Habdija, M. Miliša","doi":"10.1127/0003-9136/2006/0166-0387","DOIUrl":"https://doi.org/10.1127/0003-9136/2006/0166-0387","url":null,"abstract":"Simuliid silk pads and their effect on tufa deposition and biofilm development with respect to current velocity and time of exposure have been studied during the winter on tufa barriers in Plitvice Lakes (Croatia). Analysis of silk pad types on artificial substrates showed that moderate velocity substrates were slightly more favourable for simuliid larvae as landing attachment site, while they strongly preferred high velocity substrates as wandering attachment sites and exclusively as long term attachment sites for feeding. Although silk covered only 0.78% of surface area on glass slides, it accumulated 17% of diatoms and 56% of individual calcite crystals under moderate velocity conditions and 13% of diatoms and 41% of individual calcite crystals under high velocity conditions, thus proving that silk influence periphyton development and serves as biomediator in early stages of tufa formation. Diatom and calcite densities were mainly functions of time, with higher densities of both under moderate velocity. Maximum dimension of calcite crystals wasn’ t affected by the two month time of exposure, with larger crystals found under moderate velocity. We conclude that low winter temperature inhibited intensive calcite precipitation so tufa deposition during winter time happened mainly by trapping and binding microcrystalline calcite. Increased current velocities resulted in a poorer periphyton development and a lesser accumulation of calcite crystals.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"56 1","pages":"387-409"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74046765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Respiration measurements can assess the fitness of Gammarus pulex (L.) after exposure to different contaminants; experiments with wood ash, cadmium and aluminum","authors":"K. Aronsson, N. Ekelund","doi":"10.1127/0003-9136/2005/0164-0479","DOIUrl":"https://doi.org/10.1127/0003-9136/2005/0164-0479","url":null,"abstract":"Wood ash application (WAA) has been recommended mainly for two reasons; i) to avoid depletion of minerals in the soil due to whole tree harvest in the forestry and ii) to mitigate harmful effects of acidification of soil and surface waters. In conclusion, the effects on terrestrial ecosystems and, especially, tree growth, can be attributed to the properties of the ash, the dose applied and the specific site at which the ash is applied. The research conducted on the effects of WAA on limnological ecosystems is very limited, and the major purpose of the present thesis was to gain knowledge of the effects of wood ash to different freshwater organisms, and the more comprehensive, limnological effects of WAA in the first stream in Bispgarden, Sweden. Effects of wood ash solutions on the unicellular alga Euglena gracilis Klebs, the amphipod Gammarus pulex L., and the moss Fontinalis antipyretica Hedw. were investigated under laboratory conditions. Common in all three species was the decline in performance (growth/velocity/respiration/oxygen evolution) when the concentration of wood ash exceeded 5 g/l and no adjustment of pH was done (alkaline solution). In contrast, different movement parameters (motility, upwards swimming and velocity) in E. gracilis (neutral conditions), and increased growth of F. antipyretica with increased concentrations of wood ash indicated that nutrients in the ash was bioavailable for these organisms. There was no evidence of toxic effects on the organisms from metals or other compounds as a result from exposure to wood ash solutions in the present studies. The field study was conducted in a forest area close to Bispgarden, about 100 km NW from Sundsvall, Sweden. The catchment area (50 ha) of the stream Fanbergsbacken was treated with wood ash in September of 2004 (3,000 kg/ha;selfhardened crush-ash). In general, both biological (diatoms) and chemical (pH, alkalinity, and aluminum (Al) measurements) indicators have shown no significant effect on acidification parameters from the addition of wood ash. There was, however, evidence of an increased pH during spring flood, accompanied with a decrease in the frequency of low pH values (<5.6) during spring flood. In addition to this, alkalinity was significantly higher in the period 2005-2006, compared to that of 2003. High concentrations of toxic forms of Al repeatedly occured in the stream Fanbergsbacken, and the WAA did not affect the frequencies of high concentrations of toxic Al forms (<50 μg/l). Both the moss F. antipyretica and the leaves from Alnus incana displayed increased potassium (K) concentrations, although other nutrients did not increase from WAA. In conclusion, no evidence of WAA being effective in restoring or improving the ecological status of freshwater environments has been established, either in the literature or in the present field study. On the other hand, there were no indications of harmful effects due to WAA, either. However, we still do not know the effect","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"55 1","pages":"479-491"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90066983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Development and experimental assessment of an underwater video technique for assessing fish-habitat relationships","authors":"T. Pratt, K. Smokorowski, J. Muirhead","doi":"10.1127/0003-9136/2005/0164-0547","DOIUrl":"https://doi.org/10.1127/0003-9136/2005/0164-0547","url":null,"abstract":"Developing tools that aquatic managers can use to understand the impact of human development on fish habitat is important in an era where our aquatic resources are under increasing pressure. To this end, we examined whether an underwater video camera was useful for quantifying fish habitat use in inland lakes by 1) examining patterns in fish habitat use, residency time and feeding behaviour among habitat types, 2) determining the precision and statistical power of the aforementioned estimates, and 3) assessing whether our habitat-specific camera estimates were reflective of whole-system estimates. Lastly, we used our protocol in an experimental situation to test site-specific fish habitat use at sites where habitats were manipulated (removed or added). We demonstrated that our underwater video protocol could successfully capture site-level habitat use that corresponded with whole-system abundance estimates, addressing the concern that habitat-based surrogates of fish productivity be validated on a whole-system scale. Unfortunately, our underwater video technique was unable to discriminate fish habitat use patterns among simple habitat types and unable to consistently separate differences in among-habitat fish feeding and residency behaviours. Our ability to detect a difference was low in all among-habitat comparisons. In the aquatic systems where habitat was added, we documented a significant shift in fish habitat use towards the addition sites and away from control sites, but no corresponding increase in system-wide fish biomass or production; no changes were apparent in the habitat removal lakes. A combination of longer filming duration, more filming sites or changing to a mobile transect method would likely address the data deficiencies that limited our ability to make site-level inferences about fish habitat use.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"48 1","pages":"547-571"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79453239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The use of chironomid pupal exuviae in river biomonitoring : the importance of sampling strategy","authors":"J. Raunio, T. Muotka","doi":"10.1127/0003-9136/2005/0164-0529","DOIUrl":"https://doi.org/10.1127/0003-9136/2005/0164-0529","url":null,"abstract":"Due to the seasonal variation in the emergence patterns of chironomid taxa, a combination of three monthly samples from spring to autumn has been recommended for biomonitoring of rivers using the Chironomid Pupal Exuvial Technique (CPET). The main purposes of this study were to establish an effective sampling strategy (i. e. strategy that would allow effective discrimination between study sites) for biomonitoring of boreal rivers using the CPET methodology and to estimate the taxonomic coverage of any three monthly sample combinations. First, we collected pupal exuvial samples from three oligo- to mesotrophic study sites in a large boreal River Kymi, southern Finland, in 4-week intervals from the beginning of May to September 2003. The four most effective combinations of three monthly samples resulted in a significant difference between the sites, while the six least powerful combinations indicated no differences in chironomid communities between the sites. A corresponding data set was collected from four oligo- to eutrophic rivers, one sampling site representing each river. In this data set, eight combinations out of ten found significant differences between the rivers. Thus, the sampling strategy seemed more decisive at the within vs. among-river scale of comparison. No single combination of three monthly samples was consistently the most effective one in discriminating among the studied sites and rivers. Nevertheless, a combination of CPET samples from different seasons (i. e. spring, mid-summer and late summer/autumn) clearly constitutes the best sampling strategy for the detection of environmental impacts in boreal rivers. In the studied rivers, and probably in other boreal rivers as well, any combination of three monthly samples from spring to autumn will yield a reasonably high coverage of the available genera (at least 60%). We suggest that the efficiency of different sample combinations and the distribution of the emergence periods of locally abundant intolerant taxa are crucial information when the CPET methodology is used for river biomonitoring.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":"1 1","pages":"529-545"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84658917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}