A comparison of impoundments and natural drainage lakes in the Northeast USA*

We classified 235 randomly selected lentic waterbodies (>1 ha) in the Northeast USA as human created, or natural. We compared geographic extent and distribution, morphology and hydrology, trophic state, and fish assemblage metrics of impoundments and natural drainage lakes. We estimated that 46% of the 10 608 (±1695; 95% CI) lentic waterbodies in the region were impoundments or quarries; 68% of Uplands lakes and 26% of Lowlands lakes were natural. Impoundments were smaller, shallower, had shorter water residence times, and were in watersheds with greater human activity than were natural drainage lakes. More than half (55%) of Lowlands impoundments were eutrophic, accounting for 67% of eutrophic or hypereutrophic lentic waterbodies in the Northeast. An estimated 90% of eutrophic lakes and impoundments were <23 ha. Impoundments had greater proportions of fish species and individuals tolerant of human disturbance, and greater proportions of non-native species and individuals than did natural drainage lakes. We discuss some management implications of the differences between impoundments and natural drainage lakes.     

Influence of groundwater on the evaporative evolution of saline lakes in the Wimmera of south-eastern Australia

A hydrogeochemical study conducted in the southern Wimmera of western Victoria, south-eastern Australia reveals a small group of lakes that possess a range of chemical character so diverse that it compares to that recorded for lakes from the entire region of western Victoria and south-eastern South Australia. Principal Components Analysis and reaction path modelling using PHRQPITZ confirm that the chemical diversity of the lakes is largely inherited from the groundwater system. Three end-members (in the Eugster–Jones–Hardie framework) were identified: (i) Path 1B groundwaters transmitted via the fractures of a sandstone monolith; (ii) Path 2A-1A groundwaters derived, in part, from a limestone aquifer; and (iii) groundwaters that carry an essentially meteoric, Path 2A signature. The relative contribution of these path 1B and/or path 2A end-members largely determines the evaporative pathway (1B or 2A) that is subsequently followed, and creates a broad spread in the data. Sulphate reduction, ion exchange, silicate hydrolysis and carbonate mineral solubility also play important roles locally, in some cases displacing lake waters from one evaporation field to another. The chemical processes identified likely contribute to aquatic biodiversity in the region, due to the strong control on the ionic composition of the lakes.

A survey on water chemistry and plankton in high mountain lakes in northern Swedish Lapland

A helicopter survey was carried out on 56 water bodies in the Abisko mountains, Swedish Lapland, in August 1981. Water chemistry was found to be highly correlated with bedrock quality in the drainage area of the lakes. Low pH values (down to 5.1) appeared in the neighbourhood of sulphuric iron-ores. Natrium and chloride concentrations showed large scale patterns which can be explained by orographic rainfall. Biologically, northern high mountain conditions are reflected in species composition rather than in biomass or possibly in diversity. Small chrysomonades and dinoflagellates, as well as Keratella hiemalis and Cyclops scutifer characterize the most ‘arctic’ waters. A comparison with data from earlier investigations did not confirm expected signs of acidification.     

Mongolian salt lakes: some features of their geography,thermal patterns,chemistry and biology

There are >3500 lakes of area >0.1 km² in Mongolia. Most have salinities >1 g 1^–1 Of these saline lakes, 12 have areas > 50 km² each, 10, areas > 100 km², and 2, areas > 1000 km². Limnological investigations of salt lakes include morphometric studies, and investigations of bottom sediments, thermal regimes, chemical features, and biological (including fish) characteristics. Data from these investigations now provide a much clearer picture of the limnology of saline lakes in central Asia.     

Multivariate analysis of diatoms and water chemistry in Bolivian saline lakes

Diatom assemblages are described from surface sediments in thirteen salt lakes located in the southern Bolivian Altiplano. Factor analysis of correspondences and cluster analysis are used to classify the diatom assemblages. New methods are proposed to establish the qualitative and quantitative relationships between diatom floras and ecological parameters. Diatom assemblages are linked more to the ionic elements than to the salinity, pH, depth, temperature or elevation. Environmental variables are divided into three modalities which allow considerations of many different variables not under the same units.     

Lime treatment and its effects on the chemistry and biota of hardwater eutrophic lakes

1. The main focus of this study was to investigate the effects of single and multiple moderate doses of lime (slaked lime, Ca(OH)₂, and/or calcite, CaCO₃) on eutrophic hardwater lakes. This information would contribute to strategies to manage phytoplankton and macrophyte biomass in eutrophic lakes.
2. Water chemistry and biota were monitored for up to 7 years after initial lime treatment and results were compared with reference systems.
3. Complementary studies investigated the effect of lime on macrophytes in ponds, irrigation canals and microcosm experiments.
4. When water pH was kept within its natural range (≤ 10), single and multiple lime applications to lakes and ponds controlled macrophyte biomass, without negatively affecting invertebrate communities.
5. Single lime treatments at moderate dosages of lakes and ponds resulted in variable and mostly temporary changes in chlorophyll a (chl a ) and phosphorus (P) concentration. Although sediment P release was reduced in single-dose lakes during the first winter following treatment, reductions appeared temporary.
6. Multiple treatments of lakes and ponds were effective at reducing both chl a and P concentrations over longer periods. Mean winter P release rate was also reduced after initial treatment.
7. In laboratory studies, sediment cores were incubated with eight different treatments to assess P release. Redox-sensitive treatments were no more effective at lowering total P concentration in overlying water than some redox-insensitive treatments. Lime reduced total P concentrations, but was not as effective as treatments with alum.
8. The use of lime in managing macrophyte and phytoplankton biomass in shallow, hardwater lakes and ponds may be preferable over other treatments, because lime is economical and non-toxic as long as pH is kept within a natural range.     

Physical-chemical influences on vernal zooplankton community structure in small lakes and wetlands of Wisconsin,U.S.A.

We sampled zooplankton communities from 54 small water bodies distributed throughout Wisconsin to evaluate whether a snap-shot of zooplankton community structure during early spring could be used for the purpose of differentiating lakes from wetlands. We collected a single set of zooplankton and water chemistry data during a one-month time window (synchronized from south to north across the state) from an open water site in each basin as a means to minimize and standardize sampling effort and to minimize cascading effects arising from predator–prey interactions with resident and immigrant aquatic insect communities. We identified 53 taxa of zooplankton from 54 sites sampled across Wisconsin. There was an average of 6.83 taxa per site. The zooplankton species were distributed with a great deal of independence. We did not detect significant correlations between number of taxa and geographic region or waterbody size. There was a significant inverse correlation between number of taxa and the concentration of calcium ion, alkalinity and conductivity. One pair of taxa, Lynceus brachyurus and Chaoborus americanus, showed a significant difference in average duration of sites of their respective occurrence. All other pairs of taxa had no significant difference in average latitude, waterbody surface area, total phosphorus, total Kjeldahl nitrogen, alkalinity, conductivity, calcium ion, sulfate, nitrate, silicate or chloride. Taxa were distributed at random among the sites – there were no statistically significant pairs of taxa occurring together or avoiding each other. Multivariate analysis of zooplankton associations showed no evidence of distinct associations that could be used to distinguish lakes from wetlands. Zooplankton community structure appears to be a poor tool for distinguishing between lakes and wetlands, especially at the relatively large scale of Wisconsin (dimension of about 500 km). The data suggest that a small body of water in Wisconsin could be classified as a wetland if it persists in the spring and summer for only about 4 months, and if it is inhabited by Lynceus brachyurus, Eubranchipus bundyi, and if Chaoborus americanus and Chydorus brevilabris are absent.     

The composition,nutritional status and digestibility of the diets of Sarotherodon mossambicus from nine man-made lakes in Sri Lanka

Synopsis The dietary composition and the nutritional status and the digestibility of the diets of Sarotherodon mossambicus from nine reservoirs in Sri Lanka were evaluated. The feeding habits of S. mossambicus were variable from reservoir to reservoir; they ranged from herbivory to total carnivory. The protein, total lipid, carbohydrate and total organic matter content of the ingested material were related to the dietary composition and ranged from 18.53% to 35.15% (x−24.18%), 5.94% to 9.84% (x−7.91%), 11.6% to 34.7% (x−22.34%) and 34.4% to 64.4% (x−45.71%), respectively. Irrespective of the feeding habits, the diet contained a significant proportion of organic material which cannot be accounted for by protein, total lipid and carbohydrate. As much as the ingested material was related to the feeding habit, the digestibility of the nutrient components was related to the food material devoured. For example, the mean digestibility of the total organic matter in S. mossambicus feeding on detritus, plants and animal were 36.85, 33.5 and 29.5 respectively, and compared well with observations from elsewhere. It is hypothesised that the favourable nutrient quality of the available dietary material in the reservoirs of Sri Lanka, which could be and is effectively utilized by S. mossambicus, may have been, at least partially, responsible for its almost unprecedented success in Sri Lanka.     

Phytoplankton structure and dynamics in a volcanic lake in Deception Island (South Shetland Islands,Antarctica)

This work constitutes the first floristic and ecological analysis of the phytoplankton community of a volcanic freshwater lake in Deception Island (62°57′S, 60°38′W, South Shetland Islands, Antarctica). The main limnological features and phytoplankton size fractions were analyzed. Samples were taken during the austral summer of 2002 at two opposite sites. According to ANOVA results performed with abiotic variables, no significant differences between sites were found. The phytoplankton community showed low algal species richness, with an important contribution of the tychoplanktonic taxa. In terms of species number, Bacillariophyceae was the dominant class. Autotrophic picoplankton registered the highest densities from the second sampling date onwards. Nanophytoplankton was represented by unidentified chrysophycean organisms, which showed different distribution patterns between sites. The net phytoplankton abundance remained low during the sampling period and was strongly correlated with chlorophyll a concentration. Both nutrient concentrations and chlorophyll a values indicated oligotrophic conditions.     

Factors influencing the distribution and abundance of diaptomid copepods in high-elevation lakes in the Pacific Northwest, USA

We investigated the impact of abiotic factors and trout density on distribution and abundance of diaptomid copepods in high-elevation lakes in North Cascades National Park Service Complex (NOCA), Washington, USA. The most common large diaptomid, D. kenai (mean length = 1.88 mm), was able to persist over a wide range of abiotic factors, but the small herbivorous diaptomid, D. tyrrelli (mean length = 1.18 mm), was restricted to shallow lakes (maximum depth < ≈ 10 m) with relatively high concentrations of total Kjeldahl nitrogen and total phosphorous. There was a significant negative relationship between the density of D. tyrrelli and the density of large diaptomids ( D. kenai and D. arcticus), which could imply interaction between large and small diaptomids. The abundance of large diaptomids was significantly lower in shallow lakes with high densities of reproducing trout (> 250 fish ha-1) than in fishless lakes, in deep lakes with reproducing trout, or in lakes where trout do not reproduce and are 0periodically stocked with fry at low densities (average 179 fry a-1). In lakes where chemical conditions were suitable for D. tyrrelli, the small diaptomid was often abundant when trout density was high and large diaptomids were either absent or in low abundance. Our research suggests that trout density, nutrient concentration, and lake depth influence the abundance of diaptomid copepods in high lakes in NOCA. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of retrogressive permafrost thaw slumping on sediment chemistry and submerged macrophytes in Arctic tundra lakes

1. Global warming is predicted to cause changes in permafrost cover and stability in the Arctic. Zones of high ion concentration in regions of ice‐rich permafrost are a reservoir of chemicals that can potentially be transferred to fresh waters during thawing. Consequently, input of enriched runoff from the thaw and sediment and vegetation from the landscape could alter lakes by affecting their geochemistry and biological production. 2. Three undisturbed lakes and five lakes disturbed by retrogressive permafrost thaw slumps were sampled during late summer of 2006 to assess the potential effects of thermokarst shoreline slumping on water and sediment chemistry, the underwater light regime, and benthic macrophyte biomass and community structure. 3. Undisturbed lakes had sediments rich in organic material and selected micronutrients, while disturbed lakes had sediments richer in calcium, magnesium and strontium, greater transparency of the water column, and a well‐developed submerged macrophyte community. 4. It is postulated that enriched runoff chemistry may alter nutrient availability at the sediment–water interface and also the degradation of organic material, thus affecting lake transparency and submerged macrophytes. The results suggest that retrogressive permafrost slumping can significantly affect food webs in arctic tundra lakes through an increase in macrophyte biomass and development of a more complex benthic habitat.     

Impact of hydrology on the chemistry and phytoplankton development in floodplain lakes along the Lower Rhine and Meuse

The impact of hydrology (floods, seepage) on the chemistry of water and sediment in floodplain lakes was studied by a multivariate analysis (PCA) of physico-chemical parameters in 100 lakes within the floodplains in the lower reaches of the rivers Rhine and Meuse. In addition, seasonal fluctuations in water chemistry and chlorophyll-a development in the main channel of the Lower Rhine and five floodplain lakes along a flooding gradient were monitored. The species composition of the summer phytoplankton in these lakes was studied as well.At present very high levels of chloride, sodium, sulphate, phosphate and nitrate are found in the main channels of the rivers Rhine and Meuse, resulting from industrial, agricultural and domestic sewage. Together with the actual concentrations of major ions and nutrients in the main channel, the annual flood duration determines the physico-chemistry of the floodplain lakes. The river water influences the water chemistry of these lakes not only via inundations, but also via seepage. A comparison of recent and historical chemical data shows an increase over the years in the levels of chloride both in the main channel of the Lower Rhine and in seepage lakes along this river. Levels of alkalinity in floodplain lakes showed an inverse relationship with annual flood duration, because sulphur retention and alkalinization occurred in seepage waters and rarely-flooded lakes. The input of large quantities of nutrients (N, P) from the main channel has resulted, especially in frequently flooded lakes, in an increase in algal biomass and a shift in phytoplankton composition from a diatom dominated community towards a community dominated by chlorophytes and cyanobacteria.     

Anostraca,Cladocera and Copepoda of Spanish saline lakes

A study of 102 samples from almost all salt water bodies in Spain has allowed the preparation of a comprehensive list of anostracans, cladocerans and copepods living in such extreme environments. Among the 26 species recorded, 9 are halobionts, but 17 can exist in less saline waters. Of the halobionts, several are widely distributed throughout arid areas around the Mediterranean (Arctodiaptomus salinus, Cletocamptus retrogressus, Branchinectella media, Branchinella spinosa, Daphnia mediterranea, Moina salina); Branchinecta orientalis ( = B. cervantesi) only appears in Guadiana watershed and toward the east of Hungary, and the Alona belonging to the A. elegans complex is a Spanish endemic. In the second group are many typically freshwater species which also appear occasionally in saline waters, and colonizers of wetlands in steppes, characteristically adapted to a wide range of salinity; one of the formers, Diaphanosoma cf. mongolianum, deserves closer study. The Spanish halobiontic fauna seems to be very old judging by the existence of some isolated species, e.g. B. orientalis may be a Tertiary relic. Persistence through time could have resulted from the continuous aridity of some Iberian localities during the Pleistocene and the ecological constancy of wetlands maintained by regional groundwater discharges.     

Microbiology and chemistry of acid lakes in Florida: I. Effects of drought and post-drought conditions

Short term changes in acid loading and dissolved organic carbon (DOC) content were studied in relation to water column bacteria of ten acid lakes on the Katharine Ordway Preserve, Florida. Five clear oligotrophic lakes and five dark dystrophic lakes were sampled during and after a drought period in July and September, 1985. Water column bacterial densities, light extinction, chlorophyll a, DOC, pH, dissolved oxygen, nutrients, and other chemical variables were measured. Significant positive correlations existed among DOC, chlorophyll a, pH, and water column bacterial densities during the drought period.There were no significant changes in water column bacterial densities or pH of clear lakes in the post-drought period, despite a 4.6 fold increase in acid loading from rainfall. A 3 fold increase of DOC, a decline in pH, and decreased bacterial densities in dark lakes suggested inhibition of bacteria by DOC and pH. A decrease in the relationship of DOC to bacterial numbers in all lakes was also noted. The correlations among DOC, chlorophyll a, and pH were no longer significant.Using data from both time periods significant polynomial regressions were observed between DOC and bacterial density and DOC and chlorophyll a. Maximum bacterial numbers occurred at 20 mg C 1^–1 of DOC. Above this bacterial numbers decreased also suggesting an inhibitory effect of DOC. Because pH was lower after DOC had increased in the dark lakes, the increase in acid conditions may have enhanced this inhibitory effect. The short term effects of DOC on the dark-lake bacteria greatly exceeded the influence of acid loading on clear-lake bacteria.     

Recent carbonate sedimentation and brine evolution in the saline lake basins of the Cariboo Plateau,British Columbia,Canada

There are more than 100 closed, saline lakes in the semiarid, intermontane plateaus of British Columbia. They range from shallow perennial lakes to ephemeral playas. Most are groundwater-fed and lie within glaciofluvial deposits and till. Some have permanent salts. Where underlain by basalts, sodium carbonate brines predominate. Magnesium sulphate brines occur where catchments lie within Paleozoic sedimentary rocks, metasediments and basic volcanics. A few sodium sulphate brines are also present.A reconnaissance study of the sediments and mineralogy of 21 lake basins has shown that carbonates, including extensive magnesite and hydromagnesite deposits, and several occurrences of protodolomite, are widely precipitated in lake basins of each brine type. Analyses of stream, spring, ground and lake waters from the Cariboo Plateau region demonstrate that carbonate precipitation probably constitutes the major chemical divide responsible for producing the two dominant types of brine.     

Island biogeography, diversity and dominance of zooplankton in crater lakes on the Azores

In July and August 1988 samples of zooplankton were collected from 17 lakes on four islands. Five species of Cladocera, three species of Copepoda and 30 species of Rotifera were found. The maximum numbers of species in any one lake were four planktonic Cladocera, two Copepoda and seven planktonic Rotifera (with up to six additional non-planktonic species). The smallest, most distant island had fewer species than the largest island nearest to the mainland, but the number of species in each lake was determined more by the size of the lake than by its location. This results in the most distant island having lakes containing the same number of species as lakes of similar size on islands nearer to the mainland. The numbers of zooplankton species in each of these lakes are significantly lower than the world average, and the dominance ratios are significantly higher.     

Interannual variation and climatic regulation of the CO2 emission from large boreal lakes

We studied the interannual variation of surface water partial pressure of CO₂ (pCO₂) and the CO₂ emissions from the 37 large Finnish lakes linking them to the water quality, catchment and climate attributes in 1996–2001. The lake water CO₂ was measured three times a year in the study lakes in 1998 and 1999 and for the rest of the years the CO₂ was modeled by measured alkalinity. The median annual CO₂ emission to the atmosphere ranged between 1.49 and 2.29 mol m^?2 a^?1. The annual CO₂ emission followed closely the annual precipitation pattern with the highest emission during the years when the precipitation was highest (r²=0.81–0.97, P<0.05). There was a strong negative correlation (r²=0.50–0.82, P<0.001) between O₂ and CO₂ saturation in the lake water during stratification suggesting effective decomposition of organic matter in the lakes. Furthermore, total phosphorus and the proportion of agricultural land in the catchment had significant positive correlations with CO₂ saturation.     

Primary production in three lakes of differing salinity in Victoria,Australia

Lakes Purrembete, Bullenmerri and Gnotuk are relatively deep lakes with salinities of 0.4, 8 and 58 respectively. From Carbon-14 experiments conducted monthly over a year annual primary production was 96.2, 182.1 and 90.1 gCm^-2. These values correlate well with chlorophyll-a in Purrumbete and Bullenmerri, but not in Gnotuk. There is considerable dark fixation in both the saline lakes.     

Acidification of small mountain lakes in the High Tatra Mountains,Poland

A hydrochemical investigation was carried out on eight small High Tatra mountain lakes (Poland). When comparing recent data with those from the period 1935–1965, a constant process of acidification of the lakes is found. The average pH of precipitation is 4.8 in the study area, but the lakes are in two stages of acidification: weak (pH 6.0–6.5) and intermediate (pH 5.5–5.8). The differences are due to differences in water sources.