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1.
In order to test whether major reductions in acid inputs had improved water quality sufficiently for fish populations to recover, we stocked wild European perch (Perca fluviatilis) in three highly acidified lakes that had previously supported this species, and in one limed lake. The fish, which were introduced from a local lake (donor lake), generally ranged from 12 to 16 cm in total length, and were stocked at densities of 117–177 fish ha?1. The untreated lakes were highly acid, with minimum pH values and maximum inorganic aluminium concentrations (Ali) during the spring of 4.6–4.7 and 118–151 µg L?1 respectively. In the limed lake, the corresponding values for pH and Ali ranged between 5.8 and 6.6 and 5 and 19 µg L?1 respectively. Gill-netting in two subsequent years after the introduction yielded only a few recruits (0+) and one adult in one of the three acidified lakes in one year only. However, stocked perch reproduced successfully in both years in the limed lake. There was a significant linear relationship between the catches (CPUE) of juvenile perch (age 0+) in the different lakes in the autumn and the water quality in May (time of hatching), both in terms of Ali (r 2=0.934, P<0.05) and pH (r 2=0.939, P<0.05). Our data suggest unsuccessful recruitment in waters of pH <5.1 and Ali>60 µg L?1.  相似文献   

2.
Multivariate methods were used to relate microcrustacean (pelagic and littoral) richness and composition (presence/absence) to water quality and other environmental variables. All acidification variables (pH, aluminium, ANC) showed significant correlation with both species richness and composition. The variation in microcrustacean richness was best explained by the combination of dissolved organic carbon (DOC), fish species richness and lake area. Of 16 variables tested, pH showed strongest correlation with the main gradient in the crustacean composition explaining between 13 and 16% of the variance in the species data (CCA). pH, elevation, lake area, average depth, DOC, conductivity and fish species richness explained 30–54% of the total variance. Stronger correlation was obtained between species composition and environmental data in analyses which included the between-year differences than analyses based on the cumulative species records. Analyses based on the pelagic species exclusively gave similarly stronger correlation than analyses based on all crustacean species. Small changes in the species composition during the three years of study may be an indication of recovery of microcrustaceans in Killarney lakes.  相似文献   

3.
Zooplankton has been studied in Lakes Östra Nedsjön and Ömmern (1974–94), two acidified lakes in South-Western Sweden. The former lake was first limed in 1971–73, and secondly in 1982. The first liming increased the pH-level from ca. 5.3 to 6, and the second one from ca. 5.8 to 7–7.5. The pH-value in Lake Ömmern was about 6.1 in 1973, but decreased to 5.3 in 1981, when liming raised the value to 6.5–7. After the first liming in Lake Ö. Nedsjön, the rotatorians represented in average 1% of the total volume of zooplankton. Among the copepods, which made up ca. 22% of the volume, Cyclops was frequent, and both Eudiaptomus gracilis and Heterocope appendiculata were recorded. After the second liming on the other hand the rotatorians increased to in average 28% of the total volume, while the volume of copepods was only ca. 6%. Heterocope disappeared, and Eudiaptomus and Cyclops, usually favoured by liming, were rare. Consequently the supply of larger forms of crustaceans, suitable as fish food was severely reduced. In Lake Ömmern the effects of acidification within the zooplankton were moderate. The species richness was about the same as in unacidified lakes. After liming the development of zooplankton was similar to that in most other limed lakes, i. e. increased frequency of rotatorians, cladocerans and Cyclops spp. In Lake Ö. Nedsjön, however, the small zooplankton volumes and the elimination of copepods was in contrast to the zooplankton development in other limed lakes and in unacidified ones.  相似文献   

4.
Increased pH in acid lakes changes the crustacean fauna from communities dominated by acid-tolerant species to communities dominated by more acid-sensitive species. Studies from Canada (Killarney) and southeastern Norway (Østfold county) have demonstrated that planktonic and littoral crustaceans can be used as indicators of such recoveries. In both places the cladocerans Alona rustica and Acantholeberis curvirostris were found in acidic lakes, whereas Alona costata and the copepod Eucyclops macrurus were found in near neutral lakes. The calanoids Diaptomus minutus in North America and Eudiaptomus gracilis in Europe, both dominate in acidic water, and may ecologically be equivalent species. Sometimes the same species occur at different pH in the two continents. Bosmina longirostris and Alonella excisa may serve as examples, but a pertinent question is whether or not they are really the same species.  相似文献   

5.
Ecosystem development in lime-treated waters in Sweden has been followed since 1989 in a programme for integrated studies of the effects of liming acidified waters (ISELAW). Observations after prolonged liming (>10 y) indicate a phosphorus depletion in the limed lakes which contrasts to the increased phosphorus supply often following within the initial years after lime treatment. After prolonged liming, the levels of total phosphorus are lower as compared to neutral reference lakes at identical TOC, and the phosphorus/TOC -ratio is consequently lower in limed lakes. Depletion of dissolved inorganic nitrogen during the summer is also lower in limed as compared to neutral reference lakes. Phytoplankton biomass and species number also lower in the limed lakes as compared to unlimed neutral references. Furthermore the bacterial number per unit TOC is lower in the long term limed lakes, possibly as a result of phosphorus limitation. As to the higher trophic levels, the benthic soft-bottom fauna of limed lakes (specifically the sublittoral fauna) is poorer in terms of species diversity and abundance. Also fish community composition indicates lower productivity in the limed lakes. Taken together there is thus evidence that the long term limed lakes have a lower trophic level than reference lakes.  相似文献   

6.
Alpine lakes of the Tatra Mountains were severely affected by acidification, with minimum recorded values of pH ～4.5 in the mid-1980s. Since the 1990s, a dramatic decrease in the deposition of acidifying compounds has led to a considerable reversal in lake water chemistry (to pH～5 in the most severely affected lakes). We studied changes of planktonic crustaceans and chironomid occurrence during the acidification period and the following period of recovery from acidification in three categories of 50 Tatra Mountain lakes (non-acidified, acidified and strongly acidified, according to their status at the beginning of the 1980s). In acidified and strongly acidified lakes, the planktonic crustaceans completely disappeared already by about 1976 except for a few individuals of ubiquitous species in littoral zone due to acidification-induced oligotrophication. In strongly acidified lakes, the original planktonic crustaceans disappeared and littoral species became more abundant already before 1976 due to acidification-induced eutrophication and aluminium toxicity. These processes were quickly reversed following the increase in lake water pH. Extinct species started to return to several acidified and strongly acidified lakes already in the beginning of 1990s. The process of recovery was delayed in many other lakes of the same categories, however, or it did not even start before 2008 despite the improved water chemistry and feeding resources (concentration of chlorophyll-a). Compared to planktonic crustaceans, the reaction of chironomids to acidification and recent recovery has been less pronounced. An analysis of sediment records showed that fluctuations in relative abundance of the dominant chironomid taxa and a decrease of their density occurred. In spite of the fact that chironomid fauna exhibited clear signs of recovery in the last two decades, the recovered assemblage does not exactly reflect the pre-acidification status in the lake. The occurrence and higher proportion of more thermophilous chironomid species in some alpine lakes of all categories could be correlated with increasing air temperature. The considerable effect of climatic factors may thus prevent the full re-establishment of the original status even when the acidification stress completely ceases. The delayed return of planktonic crustaceans to some recovered lakes could be a consequence of the short water residence time of these lakes. In addition, a shortening of the water residence time in recent decades, probably related to recent climate change, in interaction with the ecology of planktonic crustaceans, may possibly be causing further delays in their return.  相似文献   

7.
He  Zhiguo  Li  Shuzhen  Wang  Lisha  Zhong  Hui 《Water, air, and soil pollution》2014,225(3):1-10
In the mid-20th century, similar to many lakes in the vicinity of Sudbury, Canada, Middle Lake was severely acidified due to nearby smelting operations. However, this lake is of particular interest because it was limed in 1973, and later fertilized as part of a restoration effort. Here, we use paleolimnological methods to track cladoceran assemblage responses to acidification, liming, and subsequent recovery in a ～250-year lake sediment record. Cladoceran assemblage changes, notably increases in Chydorus brevilabris, coincided with the late 1800s establishment of open-pit ore roasting in the region. As acidification progressed, the Daphnia pulex complex was replaced by the Daphnia longispina complex. At the height of acidification, and with similar timing to the liming, C. brevilabris increased abruptly in relative abundance in the sediment record, followed by a rapid decline. Invertebrate predation was investigated using Bosmina mucro length; however, no significant trends were evident. Our results suggest that complete biological recovery has not occurred. Specifically, species richness (rarefied) is ～64 % lower after the onset of acidification, and many rare species present prior to the onset of acidification have not yet returned to pre-impact levels despite dispersal events of these rare taxa being observed during contemporary zooplankton monitoring. Factors impeding the complete biological recovery of the cladocerans in Middle Lake may include biotic resistance, ongoing metal contamination, and a warming climate.  相似文献   

8.
Sediment profiles from ten excessively limed lakes were used to study the occurrence of lime residues as a result of incomplete lime dissolution and the influence of treatment with very high lime doses on the sequestration of metals in lake sediments. The sediment profiles were subjected to multi-element analysis and compared to sediment profiles from previous studies of lakes limed with normal lime doses and untreated reference lakes. The high lime doses were found to result in large lime residues in the sediment, with lime concentrations of up to 70% of the dry sediment in the studied lakes. Excessive liming, like liming with normal doses, was found to cause increased sequestration in sediments of, e.g. Cd, Co, Ni and Zn, metals where the mobility is known to be highly pH dependent, compared to non-limed reference lakes. No effect of liming on the sequestration of Cu, Cr, Pb and V could be shown. The size of the lime dose did not seem to influence the metal sequestration in the sediment, since no difference between the excessively limed lakes and lakes limed with normal doses was found. On the contrary, the large lime residues were found to cause a dilution of the metal concentrations in the sediments, since lime products used for lake liming generally have lower metal concentrations compared to the sediments.  相似文献   

9.
Responses to low pH of perch, Perca fluviatilis, from a naturally acid and a neutral lake were compared by 24 hr exposures to pH 4.6, 4.1 and 3.8 and by 72 hr exposures to pH 4.5. Plasma osmolality and plasma concentrations of Na and chloride decreased in fish from both lakes during acid exposures. Significant differences between the populations were observed at pH 4.1 and 4.5. Hematocrits of the fish from the acid lake increased rapidly and at higher pH compared with those of fish from the neutral lake. This was interpreted as an adaptation to their normal acidic environment, connected with the maintenance of red cell oxygen affinity. The perch from the acid lake maintained their muscle water balance at lower pH better than did the fish from the neutral lake.  相似文献   

10.
The acidified Lake Hovvatn have been limed in 1981, 1987, 1989 and 1991. After the first liming the lake reacidified close to the prelimed condition. The reliming, which started in 1987, was planned to maintain the pH at a relatively high level for the lake. A detailed monitoring of pH and temperature was performed at depth 0.5, 1, 1,5 and 5 m since spring 1993. Quantitative samples of benthic invertebrates were taken in spring and fall in 1977 and regularly at the same seasons from 1981 at depth 0.5, 2, 5 and 10 m. A reference lake, Lille Hovvatn have been sampled with the same procedure since 1988. The acid tolerant mayfly Leptophlebia vespertina responded quickly to the first liming with a 20 times increase in density after a few months. However, the densities rapidly decreased during the first years of reacidification. The lime treatments in 1987 and 1989, resulted in a second peak in density in 1990. After this, the densities have been reduced in spite of generally good water quality in Hovvatn. During fall the density increase was significant at 0.5 m depth in 1990, at 2 m depth in 1989, 1990 and 1992 and at 5 m depth in 1988 to 1990. No significant increase was observed in the limed localities during spring. It is concluded that acid surface water, prior to ice break, affect the food resources to L. vespenina and reduce the population at all depths during spring and in the littoral zone in fall.  相似文献   

11.
This study presents data concerning long-term trends after neutralization of four acidified lakes in two regions on the Swedish west coast. Neutralization was achieved by a di-Ca-silicate with 52% CaO and about 11.5% MgO. Between 61 and 74% of the spread lime product dissolved during a 5 to 7 yr period. The liming increased pH, from a range of 4.5 to 5.2 to near neutral and restored alkalinity in the range of 0.2 to 0.3 meq l?1 and the Ca-content became 3 to 4 times higher than before liming. In two lakes transparency decreased significantly presumably due to changed phytoplankton composition. These changes successively declined due to dilution and continuous acid loading. The changes in water chemistry and development of stocked brown trout (Salmo trutta) populations initiated biotic changes. Phyto- and zooplankton communities reacted both instantly and later with successions in species composition. Changes of benthic macroinvertebrate species occured over several years, but some pelagic species, e.g. corixids were rapidly reduced due to predation of fish. Observed changes were predominantly due to expanding populations of species present at very low abundances even during acid state of the lakes. Some organisms found during preacid state of the lakes did not establish new populations and this process may need a prolonged time with favorable conditions. Reacidification towards the end of the study period significantly stressed the brown trout population and also favored expansion of the filamentous algaMougeotia sp. andSphagnum sp. that almost vanished during the first year after liming. Decreasing concentration of total P was not influenced by neutralization and may be mostly dependent on negative changes in the soils surrounding the lakes. If generally valid, this process may be an important factor for the oligotrophication of lakes in areas where acid deposition is high.  相似文献   

12.
Long-term monitoring, 1973 to 1987, of reactions to liming and reacidification of a forest lake ecosystem near the Swedish west coast is reported in this study. Treatment of Lake Lysevatten with a slag product of limestone in 1974 resulted in neutralization and a positive alkalinity. Prolonged dissolution proceeded for about 7 yr whereby 86% dissolved. During 1984–86 Lake Lysevatten approached maximum reacidification with high Al concentrations and an affected biota. Asellus aquaticus L. decreased and dominance within chironomid groups approached preliming conditions. However, the most obvious biological change was the development of the filamentous algal genus Mougeotia and increased growth of Sphagnum. Populations of both plants increased notably when pH declined to about 5. Our study suggests that extensive reacidification (pH < 6.0) of limed lakes should be avoided by successive treatments to prevent development of destabilized lake ecosystems.  相似文献   

13.
Since the early 1980s, the acidic deposition in the northern Europe has decreased substantially. This has resulted in corresponding improvements of the water quality in some acid sensitive small lakes of southern Finland. Among the fish of these lakes, the first signs of recovery were recorded in the early 1990s, when the European perch (Perca fluviatilis L.) started to reproduce in some sparse populations. Since then, the reproduction of perch has been successful in several years. The appearance of strong year-classes in lakes earlier almost empty of fish indicates recovery. This development has resulted in increased population densities, decreased mean sizes of fish and decreased growth rates. In a more acid sensitive species, roach (Rutilus rutilus (L.)), no clear indications of recovery have been recorded this far. However, schools of small roach (age 1+) were observed in the summer of 1998 in two acidic lakes that were inhabited by sparse roach populations during 1985–1995.  相似文献   

14.
Limestone dissolution efficiencies and reacidification rates observed in ten small Adirondack Mountain lakes, treated in 1983 to 1984 as part of the Extensive Liming Study (ELS), were compared with Scandinavian model predictions of dissolution (Sverdrup and Bjerle, 1983), and reacidification (Wright, 1985). The standard deviation of predicted initial dissolution was 15.4% of the observed fraction of limestone dissolved. Model predictions of dissolution for the Scandinavian lakes were similarly within 8 to 14% of observed values. Further analysis of the ELS data indicated that of the dissolution model parameters, dose rate alone was the best predictor of initial dissolution efficiency. Dissolution rates declined exponentially with time to undetectable levels within 2 to 3 yr following treatment. Total limestone dissolution efficiencies were in the range of 17 to 59% for the ELS lakes, which are comparable to levels observed in Scandinavian treatments with similar limestone materials (26 to 64%). Analysis of data from other Adirondack lakes limed by private groups and the New York State Department of Environmental Conservation for fisheries management programs, yielded similar estimates of dissolution efficiency for calcite based materials (average 36%). However, some of these lakes which were treated with slaked lime [Ca(OH)2], exhibited initial dissolution efficiencies approaching 100%. The simple two box dilution model of reacidification, satisfactorily predicted Ca loss rates in the ELS lakes, indicating the importance of hydrology (water retention time) as a factor controlling reacidification rates in these small, limed lakes. For the ELS lakes, the ratio of watershed area/lake volume satisfactorily predicted Ca loss rates (R2 = 0.96) and this simplified empirical model was applied to other Adirondack lakes where inadequate water chemistry and hydrologic data were available to utilize the dilution model. Limed Adirondack lakes with mean water retention times less than 4 mo reacidified within 1 yr after treatment. Given the preponderance of acidified lakes in the Adirondack region with retention times less than this threshold value of 4 mo (approximately 80% of lakes <10 ha surface area), simple whole lake liming practices would not be adequate for maintaining water quality suitable for the support of viable fish populations in these lakes.  相似文献   

15.
Occurrence of stratified acidic water is described for five forest lakes situated in the westcoast region of Sweden. Differentiation between two types of acid events is made related to origin; one is caused by heavy rains and the other associated with snowmelt during winter and spring. Acid events are due to incomplete mixing between lake and inflow water. Both mixing forces like wind and density differences are important factors regulating the actual stratification. As observed in the lakes studied, stratification therefore occurs during periods of ice-cover when wind-induced mixing is impeded and generally results in an acidic surface water of varying depth. However, in this study we also describe the stratification of acidic inflow water at the sediment-water interface. This type of inlayering is presumably less frequent as a complex set of conditions must be satisfied for its occurrence. Our study shows that acid events may cause temporal and spatial water chemistry changes even in lakes and streams with relatively high pH and buffer capacity. Thus, early biotic damages can be expected in neutral and limed (soft water) lakes.  相似文献   

16.
Semi-quantitative biomass-size distributions (BSD's) along a joint axis of individual size provided an integrated illustration of aquatic communities sampled at different taxonomic and trophic levels. The approach was applied within the Swedish ISELAW-programme (integrated studies of the effects of liming acidified waters) to test the general hypothesis that aquatic communities in limed lakes are not systematically different from communities in comparable non-limed circumneutral lakes. Input data included pelagic phytoplankton and zooplankton, sublittoral/profundal macroinvertebrates, and benthic fish, within twelve Swedish lakes (six limed, two acidic and four circumneutral reference lakes). The four compartments were sampled on different spatial scales, but each designed for between-lakes comparisons. There were no clear-cut differences in overall size distribution between the three categories of lakes. The mean BSD of limed lakes was indeed more similar to the mean BSD of circumneutral lakes than to that of two acidic lakes. Due to high variation within categories, however, acifidication status alone can not be used for reliable prediction of BSD in a certain lake.  相似文献   

17.
In Sweden, approximately 16 000 of a total of about 85 000 lakes have been acidified due to acidic deposition. Of these about 8000 have been treated with limestone powder in order to detoxify the acidified waters and protect sensitive fauna. The present study was performed in ten lakes in the southern part of the country. The lakes belong to four different catchments and were in different stages of acidification at the time of lime treatment. The composition of the zooplankton and fish communities also differed and three lakes were empty of fish at the beginning of the studies. Quantitative sampling of planktonic crustaceans was performed during the ice free season between 1976–87 in five of the lakes and between 1977–87 in the other five. After treatment the pH increased significantly in all lakes except one. The average number of crustacean taxa found per sampling occasion increased in all lakes. Increases were statistically significant in four of the lakes. In the lakes empty of fish, increased abundances of chaoborids inhibited, by predation, the increase of species richness. Species richness increased after the introduction of fish and the subsequent reduction of the chaoborids. At the end of the study, more taxa were found in the limed study lakes than in non-treated west coast lakes with an alkalinity of 0.04–0.10 meq L-1. Most species normally occurring in oligotrophic forest lakes were found. It was shown that the water quality after liming made the occurrence of sensitive species possible and that predation from fish and interactions within the zooplankton assemblage were of great importance to the species composition and structure of the zooplankton community.  相似文献   

18.
The quantitative dynamics of the zooplankton community was studied during a period of 13 years in the manipulated Lake Gårdsjön and an acidified reference lake. Lake Gårdsjön was acid during the first 3 years, limed and fishless the following 4 years and stocked with brown trout for a period of 6 years. During the final 2 years rainbow trout was added. Changes in water chemistry and phytoplankton standing stock are associated with the manipulations. Liming had a positive effect on the overall species richness and diversity among rotifers and cladocerans. Changes in the zooplankton community during the different phases of the lake restoration are discussed in relation to the development of the planktivorous fauna of the lake, phantom midge larvae, aquatic hemipterans and fish. It can be concluded that liming creates a potential for the restoration of the zooplankton diversity, but the actual structure of the zooplankton community in limed lakes is strongly influenced by predatory and competitive interactions.  相似文献   

19.
Ecosystems in Finnish Lapland are threatened by heavy metal pollution and acid deposition derived from emissions of Cu-Ni smelters in Kola Peninsula and to varying extent to pollution from southern Fennoscandian and Central European sources. Extensive chemical analyses of small lake waters collected in Finnish Lapland have demonstrated that a significant number of lakes are acidified (ANC < 0μcq/l) or their buffering capacity is critical (ANC = 0–50μe/l). The relative abundance of mafic, ultramafic and carbonate rock components in the catchment were the chief factors controlling ANC and the main base cation (Ca2+, Mg2+) concentrations of lake waters. Both humic and clearwater lakes with low buffering capacity (ANC < 50μeq/l) were mainly located in the catchment areas identified as sensitive to acidification on the basis of low content of base cations (Ca2+ +Mg2+ +K+ < 500 meq/kg) in till. The ratio of the catchment area to the lake area was distinctly smaller for acidic lakes than for the well-buffered lakes, indicating the importance of catchment processes in determining the ANC and main base cations. The high sulphur concentrations (median 60μeq/1) of acidic lakes in northeastern Lapland, near the Finnish-Norwegian border, were strongly correlated with the highest deposition of sulphur derived from smelters of Kola Peninsula. The anomalously high concentrations of sulphur of well-buffered lakes in the western part of Lapland were due to sulphide minerals of soil and bedrock. The acidity of humic lakes in southern Lapland was in large part due to the organic acidity derived from peatlands.  相似文献   

20.
During the summer of 1981, crustacean plankton was sampled in 249 northeastern Ontario lakes, including a large proportion of acidic lakes. Species cluster analysis showed that a major species group containing B. longirostris, D. minutus, H. gibberum, and M. edax was common to most lakes. Two species subgroups most associated with more productive waters (D. retrocurva, D. oregonensis, T. p. mexicanus, and Diaphanosoma sp.) and less productive waters (D. longiremis, C. scutifer, D. g. mendotae, C. b. thomasi, E. longispina, and E. lacustris) in the study area were identified. Acidic lakes were characterized by reduced numbers of species related to declines in the importance of cyclopoids, Daphnidae, L. kindtii and E. lacustris and high relative abundance of D. minutus. Stepwise multiple linear regression of physico-chemical lake characteristics against percent composition of individual species failed to explain much of the variation in species proportions. However, variables related to lake thermal structure were most frequently the primary correlates with species proportions in near-neutral lakes while in acidic lakes the best statistical predictors of species percent composition were most often variables directly related to lake acidity.  相似文献   

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