Lake Trophic Status Research Articles

Do rotifers have potential as bioindicators of lake trophic state?

(2001). Do rotifers have potential as bioindicators of lake trophic state? SIL Proceedings, 1922-2010: Vol. 27, No. 6, pp. 3497-3502.

Influences of habitat type and environmental variables on littoral macroinvertebrate communities in a large lake system

The community structure of littoral macroinvertebrates was explored by multivariate analyses in three basins of the large Lake Saimaa system (eastern Finland). The basins differed in trophic status and degree of human influence. It was hypothesized that the structure of littoral invertebrate communities is influenced by lake trophic status, as is the case in profundal communities. Three littoral habitat types with different substrate (stony, sandy and vegetated shores) were sampled from the shoreline to a depth of 1.5-3 meters. The habitat type was found to be largely determined by the slope of the shore and the wind exposure. Each habitat type supported fairly characteristic fauna, and detrended correspondence analysis grouped the invertebrate assemblages by habitat type rather than by basin. Within each habitat type, canonical correspondence analysis indicated that species composition changed along the trophic gradient. In the vegetated littoral zone, the greatest change in community structure occurred within the macrophyte beds, varying from the outer edge of macrophytes to the shoreline. Two alternative or complementary explanations are given for this horizontal gradient. First, a horizontal gradient of abiotic characteristics results in a change of community composition. Second, the macrophyte beds may form a horizontal transition zone in predation, from invertebrate predation inshore to fish predators offshore. On the stony and sandy shores, the magnitude of wave action was also important in structuring the communities. As each habitat type harbors characteristic fauna, a variety of habitats needs to be protected in order to conserve littoral macroinvertebrate diversity in large lakes. To make among-lake comparisons of littoral macroinvertebrate assemblages stratification by habitat type is obviously necessary. The effects of eutrophication on invertebrate assemblages were most pronounced in stony habitats.

A one‐year study of the Rostherne Mere ecosystem: seasonal dynamics of water chemistry, plankton, internal nutrient release, and implications for long‐term trophic status and overall functioning of the lake

AbstractA study of Rostherne Mere (Cheshire, UK) was undertaken to reveal relationships among various ecosystem components and assess the progress in lake recovery following sewage diversion. An intensive monitoring programme included measurements of dissolved oxygen, T, pH, electric conductivity, K, Mg, Ca, Si, N and P species, Secchi depth, suspended solids, chlorophyll‐a, phyto‐ and zooplankton counts. Recorded changes and the results of correlation analysis broadly confirmed to the classic limnoecological theory and allowed detailed interpretation of the dynamics observed. The Si level was used to estimate the amount of diatom detritus produced in spring. Chemical profiles were used to estimate the amount of nutrients accumulated in the hypolimnion during the stratified period. These estimates were compared with simulations made using the model of exponential decay, which showed a good performance in the case of Si but considerable underestimation in the case of P. The differences between the values simulated by the model and estimates based on field observations resulted from the additional P release from the sediments. This release could have been stimulated by a combination of factors, including the development of anoxic layers on the sediment–water interface and Si‐induced desorption from Fe, Al and Mn oxides. Internal P loading during the stratified period was thus estimated at about 4–9 g/m2, suggesting that rapid changes in the lake's trophic status are at present unlikely. Certain aspects of this work (including interpretation of interrelationships between ecosystem components, estimation of the decomposition constant, analysis of factors controlling nutrient accumulation in the hypolimnion, and a low‐cost method to estimate internal P release) may be useful for studies of other aquatic systems and have, therefore, general limnological applicability. Copyright © 2001 John Wiley & Sons, Ltd.

Changes in polyphosphate sedimentation: a response to excessive phosphorus enrichment in a hypereutrophic lake

Historic changes in lake phosphorus (P) loading are often determined in paleolimnological investigations by assessing stratigraphic changes in sediment total P. Polyphosphate (poly-P) in sediments may provide additional information on historic lake trophic status, because phytoplankton store surplus P intracellularly as poly-P when supplies exceed growth requirements. We hypothesize that phytoplankton (i.e., cyanobacteria and diatoms) with stored poly-P can remain intact and viable for many decades after sedimentation and that sedimented poly-P is not geochemically reactive. We tested our hypotheses with sediment cores from Lake Apopka, Fla., U.S.A., where P loading has increased ~7-fold since the 1920s and phytoplankton biomass is nitrogen limited owing to excessive P enrichment. We show that sedimented poly-P is mobilized by sample drying (i.e., becomes water soluble, geochemically reactive, and bioavailable); that anthropogenic P enrichment is expressed in the sediment record as increasing concentrations of poly-P; and that, consequently, sedimentary poly-P is a sensitive indicator of historic excessive P enrichment. Sedimentary poly-P is not geochemically reactive; thus, it represents biological attenuation that may partially ameliorate the effects of excessive P loading.

Long-term trends in the profundal chironomid-fauna in nitrogen-limited Lake Esrom, Denmark: a combined palaeolimnological/historical approach

A 90-cm sediment core from Lake Esrom was analysed for subfossil diatoms and Chironomidae. Quantitative diatom-inferred reconstruction of total phosphorus showed an increase in TP levels from 84 μg P/l around 1600 AD (extrapolated 210 Pb chronology) to 200μg P/l in 1975, followed by a decrease to 165 μg P/l at the present day. Chironomid-inferred chlorophyll-a concentration ranged from 5--15 μg chl-a/l 1 throughout the core. Analysis of historical oxygen data and long-term zoobenthic population dynamics from the profundal zone of Lake Esrom suggested that the period of oxygen depletion in the hypolimnion increased during the 20 th century. However, the chironomid record showed only minor variations in the subfossil assemblages over the last ∼400 years and there was no chironomid indication of significant changes in the hypolimnetic (oxygen) conditions. Because primary production in Lake Esrom is nitrogen limited during the stratification period, the chlorophyll concentration is lower than commonly found for Danish lakes with comparable phosphorus concentrations. However, both the diatom-[TP] and chironomid-[chl-a] inferred values for recent periods agree well with monitored data. The two models work because the diatoms are reflecting the ([TP]) spring situation before nitrogen becomes the limiting factor whereas the chironomid fauna is reflecting the average summer (chlorophyll) situation both before and during the period of nitrogen limitation. This study illustrates the importance of multi-proxy analyses for quantitative palaeolimnological reconstruction of lake trophic state, particularly for lakes that behave differently from the more predictable responses to nutrient enrichment.

Regularities in Primary Production, Secchi Depth and Fish Yield and a New System to Define Trophic and Humic State Indices for Lake Ecosystems

General relationships between phytoplankton production, chlorophyll, total, dissolved and particulate phosphorus, Secchi depth, humic level, trophic level, fish production and latitude are described by regression equations using an extensive “Soviet” data base covering a wide domain of lake characteristics and a European data base. New systems for defining lake trophic and humic status are presented. The results may be used for more precise estimates of fundamental lake properties and for many practical issues of lake management, e.g., predictions of fish catch. We have used strict chlorophyll-a concentrations for every trophic class and we have omitted Secchi depth from the trophic classes, since Secchi depth and other variables strongly related to water clarity (like suspended particulate matter and particulate organic carbon) depend on autochthonous production, allochthonous influences and resuspension. We have used the Secchi depth as a simple operational measure of the effective depth of the photic zone. It has also been shown that among these lakes there exist a very strong relationship between primary production and latitude. In fact, 74% of the variability among the lakes in mean summer primary production can be statistically related to variations in latitude. These data also show a strong relationship between primary production and fish yield, which can be used to address many fundamental issues in lake management, like “normal and abnormal fish production”.

Eutrophication of Surface Water in the Arctic Region

The problem of eutrophication of the surface water in the Arctic Regions is discussed. The natural hydrochemical indices of the trophic status of lakes are analyzed in connection with the landscape and physiographic features of the Kola Peninsula. The regular features of changes in the hydrochemical indices of the trophic status of lakes and the development of the process of eutrophication are analyzed in the case of subarctic Lake Imandra, which has been polluted with municipal and industrial (phosphorus-containing waste of the apatite production) wastewater for more than fifty years. Criteria are proposed for establishing and assessing water eutrophication in cold climate.

Changes in polyphosphate sedimentation: a response to excessive phosphorus enrichment in a hypereutrophic lake

Historic changes in lake phosphorus (P) loading are often determined in paleolimnological investigations by assessing stratigraphic changes in sediment total P. Polyphosphate (poly-P) in sediments may provide additional information on historic lake trophic status, because phytoplankton store surplus P intracellularly as poly-P when supplies exceed growth requirements. We hypothesize that phytoplankton (i.e., cyanobacteria and diatoms) with stored poly-P can remain intact and viable for many decades after sedimentation and that sedimented poly-P is not geochemically reactive. We tested our hypotheses with sediment cores from Lake Apopka, Fla., U.S.A., where P loading has increased ~7-fold since the 1920s and phytoplankton biomass is nitrogen limited owing to excessive P enrichment. We show that sedimented poly-P is mobilized by sample drying (i.e., becomes water soluble, geochemically reactive, and bioavailable); that anthropogenic P enrichment is expressed in the sediment record as increasing concentrations of poly-P; and that, consequently, sedimentary poly-P is a sensitive indicator of historic excessive P enrichment. Sedimentary poly-P is not geochemically reactive; thus, it represents biological attenuation that may partially ameliorate the effects of excessive P loading.

Evolution of the trophic state of Lake Annecy (eastern France) since the last glaciation as indicated by iron, manganese and phosphorus speciation

Lake Annecy sediments have been studied to provide an insight into the evolution of the lake trophic state in response to climate changes during the Holocene. Determination of the concentration of carbonate, Fe, Mn, and different forms of P in conjunction with total sediment fluxes derived from 14C ages allows an estimation of yearly fluxes of these sediment components. High fluxes of endogenic carbonate occur during the early to middle Holocene. Non apatitic inorganic phosphorus flux is variable but shows some higher-than-present values during this period. These observations are interpreted as being a result of enhanced productivity by favourable conditions for phytoplankton development. In addition, the low Mn/Fe ratio of the redox-sensitive forms of these elements recorded during this period suggests low oxygen concentrations in the bottom waters. Therefore it appears that the lake may have undergone oxygen depletion in the bottom water during the warmer-than-present periods, due to increased productivity and subsequent oxygen consumption from the decay of organic matter. With future climate changes, this suggests that lake water quality may likely degrade under global warming.

Temporal and geographical variation in lake trophic status in the English Lake District: evidence from (sub)fossil diatoms and aquatic macrophytes

1. A sediment core (representing 250–300 years) was taken from each of three lakes of conservation interest and contrasting trophic status in the English Lake District: Wastwater, Bassenthwaite Lake and Esthwaite Water. Lithostratigraphic analyses, radiometric dating and analysis of fossil diatoms were carried out. 2. Transfer functions, based on the diatoms, were used to reconstruct total phosphorus (TP) and, thus, eutrophication at the study lakes. In Wastwater, changes in lake pH were also reconstructed. 3. The lakes were also classified according to their present macrophyte flora, the latter being compared with previous records. 4. The fossil diatoms of Wastwater were continuously dominated by taxa typical of oligotrophic, circumneutral waters, indicating that the lake has not been enriched or acidified in the last 250 years. The aquatic macrophyte flora has probably remained unchanged since before the Industrial Revolution. 5. The diatom assemblages of both Bassenthwaite Lake and Esthwaite Water began to change in the mid-1800s. Further change occurred from the 1960s, at the onset of a recent period of eutrophication. These two lakes have experienced continued nutrient enrichment throughout the 1970s, 80s and 90s, largely associated with increasing phosphorus inputs from sewage effluent. There is no evidence of any recovery in response to recent reductions in external nutrient loads. 6. Only in Esthwaite Water has the change in aquatic macrophytes been pronounced. 7. Palaeolimnological reconstruction is useful in determining background conditions and natural variation in lake ecosystems.

EXPERIMENTAL STUDY OF PHYTOPLANKTON SPECIES COMPOSITION, ALTERNATE STATES, AND COMMUNITY BREAKPOINTS ALONG A PHOSPHORUS GRADIENT

A model combining algal mortality due to selective zooplankton grazing with the Monod model of phytoplankton growth was used to predict phytoplankton species composition along a gradient of phosphorus (P) concentration and zooplankton grazing pressure. Model predictions were compared to the results of a mesocosm experiment of phytoplankton species composition along a range of P concentrations of five to 115 μg L−1 and potential grazing loss rates of 0.001 to 0.27 day−1. The effect of the P gradient was measured by monitoring phytoplankton and zooplankton species composition and biomass, and physical and chemical parameters for seven weeks in 12 fiberglass tanks (5500 L) filled with lake water and associated plankton. P concentrations were manipulated so that tanks were evenly distributed along the gradient. Using laboratory derived Monod growth constants for P and literature values of phytoplankton selectivity coefficients, zooplankton filtering rates, and zooplankton assimilation efficiencies, the model correctly predicted (1) the existence of alternate community states, (2) breakpoints between the alternate states which are similar to the P concentrations defining Vollenweider's lake trophic states, and (3) phytoplankton species composition along the P gradient in the mesocosm study. These results suggest that the trade‐off between competitive ability for P and edibility is a primary factor structuring phytoplankton communities, and that multiple states exist which may be consistent with the long‐standing P‐based lake trophic classification.

Empirical analysis of the effect of phosphorus limitation on algal food quality for freshwater zooplankton

Herbivorous zooplankton production is often constrained by algal food quality, and variation in algal food quality has been attributed to its phosphorus (P) content. To test the hypothesis that mineral P limitation is an important constraint on freshwater herbivorous zooplankton production, we conducted a quantitative analysis of published data on lake seston carbon to phosphorus (C:P) ratios and daphnid growth responses to P‐limited algal diets. Our summary of 276 observations of mean lake seston C:P ratios showed 38% exceeded a critical threshold of 300, above which daphnid production is often predicted to be limited by algal P content. Our analysis of 91 observations of daphnid growth responses to nutrient‐limited algal diets indicates the true daphnid critical threshold lies within the range of 225–375. Algal food quality is consistently reduced at algal C:P ratios above 300; however, the predicted reduction in algal food quality with P limitation is greater than the observed reduction at critical thresholds <390. Mineral P limitation of Daphnia production may be quite strong in some lakes; however, the production of most zooplankton taxa would not be expected to be limited by mineral P in a large proportion of lakes. After correcting for the algal C:P ratio, large differences in food quality were found between the major algal taxa, with diatoms and cryptophytes high food quality, chlorophytes intermediate food quality, and small ingestible cyanophytes very low food quality. A Monte Carlo simulation indicated that shifts in algal community composition similar to those seen during seasonal succession or across lake trophic state gradients explained four times more variability in daphnid growth rates across a range of seston C:P ratios representative of natural lakes. Overall these results tend to support the mineral P limitation hypothesis for daphnids, but they also suggest other factors will be the primary determinants of algal food quality for most zooplankters in most lakes.

Lake trophic state, community structure and biomass of crustacean plankton

Lake trophic state, community structure and biomass of crustacean plankton

Determination of Chlorophyll Content and Trophic State of Lakes Using Field Spectrometer and IRS-1C Satellite Data in the Mecklenburg Lake District, Germany

Multitemporal data sets of the LISS-III sensor mounted on the Indian Remote Sensing Satellite (IRS-1C) and field reflectance spectra have been evaluated for estimating chlorophyll-a content in lakes. The results were compared to laboratory analyses of in situ water samples. Quantification from field reflectance spectra was carried out using the 678 nm absorption maximum and the 705 nm reflectance peak. For the evaluation of the LISS-III satellite data three approaches were compared: spectral height of the green peak, supervised maximum likelihood classification, and linear spectral unmixing. The latter gave the best results with the highest certainty measure of R 2=0.85 and was applied to all five LISS-III data sets. The results are maps of the chlorophyll-a content in 10 μg/l classes for each of the five dates. For comparison of the accuracy of the different methods for water quality analysis, the trophic state index was calculated based on chlorophyll-a determination from laboratory, field spectra, and satellite data. Regarding the five lakes for which all the data were available, each method shows similar results for the estimation of trophic state.

Stable isotope analysis of the origins of zooplankton carbon in lakes of differing trophic state.

Carbon stable isotope analysis was carried out on zooplankton from 24 United Kingdom lakes to examine the hypothesis that zooplankton dependence on allochthonous sources of organic carbon declines with increasing lake trophy. Stable isotope analysis was also carried out on particulate and dissolved organic matter (POM and DOM) and, in 11 of the lakes, of phytoplankton isolates. In 21 of the 24 lakes, the zooplankton were depleted in 13C relative to bulk POM, consistent with previous reports. δ13C for POM showed relatively little variation between lakes compared to high variation in values for DOM and phytoplankton. δ13C values for phytoplankton and POM converged with increasing lake trophy, consistent with the expected greater contribution of autochthonous production to the total organic matter pool in eutrophic lakes. The difference between δ13C for zooplankton and that for POM was also greatest in oligotrophic lakes and reduced in mesotrophic lakes, in accordance with the hypothesis that increasing lake trophic state leads to greater dependence of zooplankton on phytoplankton production. However, the difference increased again in hypertrophic lakes, where higher δ13C values for POM may have been due to greater inputs of 13C-enriched organic matter from the littoral zone. The very wide variation in phytoplankton δ13C between lakes of all trophic categories made it difficult to detect robust patterns in the variation in δ13C for zooplankton.

Helminth communities of yellow perch (Perca flavescens (Mitchill)): determinants of pattern

Twenty-eight parasite species were recorded from 504 yellow perch (Perca flavescens) collected from Dauphin Lake and Beaufort Lake, Manitoba, and Lake Winnebago, Green Bay, and Lake Michigan, Wisconsin. Four parasite species, Diplostomum spp., Urocleidus adspectus, Proteocephalus pearsei, and Raphidascaris acus, occurred in perch from all localities. Infracommunities and component communities were low in richness. The Dauphin Lake and Beaufort Lake samples had the richest parasite communities, while those in the Green Bay and Lake Michigan samples were the least rich. The effect of host size and age on parasite community structure was equivocal. A positive association between P. pearsei and Bothriocephalus cuspidatus and more multispecies infracommunities than expected provide evidence of nonrandom associations in the Manitoba samples, while the Wisconsin infracommunities were random associations. Significant infracommunity nestedness in all samples indicated nonrandom community organization and structure. Parasite faunas were richer in samples with complex invertebrate communities than in samples with complex fish communities. The trophic status of the aquatic system indirectly affected the parasite communities by limiting the variety of potential intermediate hosts. Predictions regarding relationships between parasite community structure and lake trophic status were not supported. We show that predictable patterns at the fine-scale local level of the parasite infracommunity and component communities of perch are best explained by a rich invertebrate community upon which the host feeds.

First Observations on the Effect of a Complete, Exceptional Overturn of Lake Maggiore on Plankton and Primary Productivity

This manuscript presents some results of a monitoring of the planktonic communities of Lago Maggiore during the complete overturn of the lake in the winter of 1998/1999. These results are of particular interest not only because holomixy is a rare event in this well-known water body, but also because these are the first such results obtained after a significant change in the lake's trophic status. Holomixy can be regarded as a “whole lake experiment” sensu Edmondson (1993): irrespective of the mechanisms underlying the process, it produces an internal enrichment of algal nutrients, and particularly of phosphorus. The increase in biomass and productivity of phytoplankton seems to be driven more by the increase in phosphorus than by a decrease in potential grazers. However, once the luxury amount of nutrients supplied by the overturn was exhausted, the photosynthetic productivity decreased to values more typical of a “normal” spring productivity, in accordance with the present trophic condition of the lake. Similarly, the enhancement of phytoplankton growth seems likely to have stimulated the numerical increase of zooplankton, and especially of small, fast reproducing rotifer species. Moreover, the spring pulse of primary productivity and the phosphorus enrichment represent a crucial phase for the storage of the potential energy necessary for the development of the zooplankton population, particularly of cladocera, in summer.

First Observations on the Effect of a Complete, Exceptional Overturn of Lake Maggiore on Plankton and Primary Productivity

This manuscript presents some results of a monitoring of the planktonic communities of Lago Maggiore during the complete overturn of the lake in the winter of 1998/1999. These results are of particular interest not only because holomixy is a rare event in this well-known water body, but also because these are the first such results obtained after a significant change in the lake's trophic status. Holomixy can be regarded as a “whole lake experiment” sensu Edmondson (1993): irrespective of the mechanisms underlying the process, it produces an internal enrichment of algal nutrients, and particularly of phosphorus. The increase in biomass and productivity of phytoplankton seems to be driven more by the increase in phosphorus than by a decrease in potential grazers. However, once the luxury amount of nutrients supplied by the overturn was exhausted, the photosynthetic productivity decreased to values more typical of a “normal” spring productivity, in accordance with the present trophic condition of the lake. Similarly, the enhancement of phytoplankton growth seems likely to have stimulated the numerical increase of zooplankton, and especially of small, fast reproducing rotifer species. Moreover, the spring pulse of primary productivity and the phosphorus enrichment represent a crucial phase for the storage of the potential energy necessary for the development of the zooplankton population, particularly of cladocera, in summer.

Factors governing nutrient status of mountain lakes in the Tatra Mountains

1. Nutrient and chlorophyll a levels, and bacterial numbers of 84 glacial lakes in the Tatra Mountains (Slovakia and Poland, Central Europe) were determined to assess the impact of catchment vegetation and water acidity on lake trophic status.2. Catchment vegetation was the crucial factor governing nutrient content of lakes.3. Concentrations of organic carbon, organic nitrogen, and chlorophyll a, and bacterial numbers were tightly correlated with total phosphorus (TP) content. Their levels were the highest in forest lakes, then decreased in alpine lakes with decreasing amount of catchment vegetation and soil cover, and were the lowest in lakes situated in bare rocks.4. The above pattern was further modified by lake water acidity. Concentrations of TP, organic carbon, and chlorophyll a were lower in alpine lakes with pH between 5 and 6 than in more or less acid alpine lakes. Zooplankton was absent in all alpine lakes with pH between 5 and 6.5. Nitrate concentrations followed an inverse trend to TP; lowest values were in forest lakes, then increased with decreasing amount of catchment soils and vegetation. Within the lakes of the same type of catchment vegetation, nitrate concentrations were negatively correlated to TP. N‐saturation of catchment areas and lake primary production were dominant processes controlling nitrate levels in lakes and nitrate contribution to lake acidification.

The last ca 2000 years palaeolimnology of Lake Candia (N. Italy): inorganic geochemistry, fossil pigments and temperature time-series analyses

The palaeoenvironmental history of Lake Candia, a small, shallow, eutrophic lake in Northern Italy, is described for the last ca 2000 years. Sediment samples from a sediment core collected in autumn 1995 were analysed for a range of palaeolimnological indicators, which included the principal algal and sulphur photosynthetic bacterial pigments, as well as magnetic susceptibility, organic matter, carbonates, organic carbon, total nitrogen, total sulphur and various forms of phosphorus. An accurate sediment chronology was determined using 210Pb, 137Cs and 14C. The results show that throughout a first, long phase of the history of this period (from ca AD 100 to 1830; zone 1) the sediments have an organic carbon content of ca 10% d.w. and low concentrations of algal pigments, suggesting a moderately productive environment. Sedimentary carotenoids unique to anaerobic photosynthetic bacteria indicate a seasonally hypolimnetic anoxia during the whole ca 2000 year period. Clear effects of climate changes on lake productivity were inferred from the carotenoid, ß-carotene, okenone and organic carbon estimates. Values were higher in the warm periods before AD ca 660 and during the so-called Little Optimum of the Medieval Warm Epoch (AD ca 1100-1300), and lower during cold moist periods, such as the main phase of the Little Ice Age (AD ca 1550-1700). After AD ca 1830 (zone 2), anthropogenic impacts resulted in a sharp increase in lake trophic state, leading first to a decoupling of the trophic state from natural (climate) variability, and then to "cultural" eutrophication. The onset of this latter process in the Turin area has been set around 1830, when a sharp increase of sedimentary sulphur concentration took place.