Lake Trophic Status Research Articles

Trophic status of Missouri River floodplanin lakes in relation to basin type and connectivity

Limnological data were collected over a two-year period from 12 lakes in the Missouri River floodplain in order to evaluate lake trophic status and the influence of basin type and connectivity on nutrient, seston, and phytoplankton dynamics. The lakes were located in west-central Missouri and included eight scour basins formed by levee breaks during a 1993 flood and four older oxbow lakes. The Missouri River was also sampled. Five of the scour basins (connected scours) were inundated by the Missouri River for varying periods during the study. The other lakes (protected lakes) were hydrologically isolated from the river by levees. On the basis of mean total phosphorus (TP-61-282 μg/L), mean total nitrogen (TN-0.7-2.1 mg/L), mean chlorophyll (CHL-22-67 μg/L), and mean suspended solids (TSS-16-93 mg/L), all 12 sites were highly eutrophic compared to other lakes in Missouri. Nutrient fractions and seston composition indicated dominance of inorganic nutrients and abiotic seston in the riverine lakes. Maximum concentrations of nutrients and TSS occurred in oxbow lakes during periods of sediment resuspension and in connected scours during floods in spring 1995 and 1996 when connected sites were inundated by the Missouri River. Algal blooms with peak CHL>200 μg/L occurred sporadically in the oxbow lakes. Similarly large blooms (peak CHL 81–689 μg/L) occurred in connected scours when low river levels reduced exchange with the river. Reduced connectivity was accompanied by rapid loss of dissolved N and P fractions, especially nitrate. Protected scours had lower average TP, TN, and TSS than the other sites and were less temporally variable.

Wintering waterfowl community structure and the characteristics of gravel pit lakes

Wintering waterfowl community structure and their association with lake characteristics were studied in the Cotswold Water Park, a complex of more than 120 gravel pit lakes in southern England. The major distinction in community types was between assemblages dominated by diving waterfowl and those dominated by dabbling waterfowl. The trophic status of lakes was found to be a major determinant of community structure: young lakes in the early stages of a natural process of eutrophication tended to support the most diverse assemblages of diving waterfowl. The abundance of individual species was strongly related to lake size and assemblage type. Some effects of food supply and the recreational use of lakes were also apparent. The relevance of the findings for the sustainable value of the lakes for wintering waterfowl is discussed.

Comparing past and present trophic states of seven Central Volcanic Plateau lakes, New Zealand

Data on seven lakes in the Rotorua District were examined to determine trophic state changes in these lakes. The method of data analysis was specifically designed to find small changes in the trophic state of lakes. For each variable, the P‐value from 12 monthly paired sample Student t‐test comparisons was calculated and a change of trophic state value (CTS) was assigned, based on the P‐value. The CTS values for all the variables examined for a single lake were averaged (C) with a standard error (CV). The resulting Change/ Confidence Value index (C/CV) indicated the nature of the trophic change observed and the degree of confidence that could be placed in the stated change. This study finds that in recent years Lakes Rotorua and Rotoiti have become less eutrophic; Lakes Okareka and Rotoma may have become less eutrophic; Lakes Okataina and Rotokakahi have not changed in trophic state in the last 22 years, and Lake Tikitapu may have become more eutrophic.

On the comprehensive evaluation methods for lake eutrophication

从对湖泊富营养化评价的一般方法入手,综述了国内外有关湖泊富营养化综合评价的一些方法.提出:营养状态指数法(TSI)由于可对湖泊营养状态进行连续的数值化的分级,从而为湖泊富营养化机理的定量研究提供了坚实的基础,应是今后湖泊富营养化评价中的主要方法.文中对综合评价指标的定权方法亦作了分析,认为层次分析法较理想.并给出了TSI及其修正方法中的权重分配.最后.文中讨论了综合评价与其他分析方法如聚类分析等的关系问题.;On the basis of general methods for evaluating lake cutrophicalion, the anthor summarized some comprehensive assessment methods for lake eutrophication reported at home and abroad. It is pointed out that the trophic state index should be the major method for evaluating lake eutrophication status, since it could provide a continuous numerical class of lake trophic state and a rigorous foundation of quantitative studies of eutrophication mechanism. After analyzing some determination methods of weight distribution in lhe comprehensive indices, ihe anthor insists that the hierarchical analysis bo quite perfect to determine weights. This paper shows the weight distribution of TSI and its modifiers. Additionally, il is discussed in brief the relations between comprehensive evaluation and other statistical methcxls such as cluster analysis in the last part of this paper.

Trophic State of Clear and Colored, Soft- and Hardwater Lakes with Special Consideration of Nutrients, Anoxia, Phytoplankton and Fish

ABSTRACT Idiosyncrasies, erroneous assumptions and gaps are still hampering lake evaluations, despite several decades of defining the trophic state of lakes. I reevaluated nutrient and algal biomass limits that group lakes into oligo-, meso-, eu- and hyper eutrophic lakes at transition concentrations of 10, 30 and 100 μg · L−1 average total phosphorus concentration of the summer epilimnion. I investigated the direct and indirect effects of general lake characteristics like morphometry and geochemistry (water hardness and color) on lake trophic state and formulated models to deal with their significant influences. Nutrient and biomass concentrations as well as quantitative measures of anoxia were used to determine the trophic state. I demonstrated that the number of coldwater fish species may be used to classify the lower trophic levels in geographically constraint areas. Limits and models were established with data from well-studied lakes and verified with literature data from worldwide lakes. Trophic sta...

Predictability of Phosphorus Load, Hydrological Load and Lake Total Phosphorus Concentration

ABSTRACT One goal for eutrophication research is to predict lake trophic state without extensive field programs. However, existing comparisons of predicted:observed TP (total phosphorus) concentration calculate the former from measured watershed characteristics that require field sampling. Predictions of lake TP based on estimated rather than measured components are probably much less powerful, but this possibility should be quantitatively assessed. To assess the predictive power of current mass-balance models of eutrophication, measured estimates of volumetric water discharge (Qobs: m3·yr−1, n=110) and phosphorus load (Lobs: mg·m−2·yr−1, n=96) from lakes in the OECD (Organization for Economic and Cooperative Development) eutrophication data set were compared to calculated values of Q (Qcal) and 16 different variants of calculated phosphorus loading (Lcal, respectively. For the entire data set, Qcal was unbiased and strongly correlated with Qobs. In regional comparisons, some Lcal variants correlated well with Lobs, but others did not, and no single variant was significantly better than all of the others. In these comparisons, up to 95% of the variance in Lobs was explained by a single regional Lcal variant, but the best regression of a single variant against Lobs for the entire data set explained only 58% of its variance. Stepwise multiple regression to improve prediction of Lobs produced the following model; Log Lobs = 1.23 + 0.81 (log Lbest) + 0.19(G) − 0.42(%F) − 0.38(%U)− 0.11 (log Ad); R2 = 0.75, S xy = 0.37, P < 0.001 where; Lbest – a composite variable consisting of the best performing Lcal variables in geographically limited regressions, G – watershed geology (1-igneous, 1.5-mixed igneous-sedimentary, 2-sedimentary), %F and %U – percentage of the watershed covered by forest and urban areas, respectively, and Ad – drainage basin area (m2). Finally, when a phosphorus budget model was used to predict lake TP concentration with (A) estimated components, (B) estimated components where Lcal, was adjusted for bias with the above equation, and (C) measured components, predictions of lake TP from all three estimates were of equal accuracy indicating that no estimate was better than the others.

Compositional variations in sedimentary lacustrine organic matter and their implications for high Alpine Holocene environmental changes: Lake St. Moritz, Switzerland

Organic matter accumulation and preservation in lakes with different geomorphological and climatic regimes, is directly influenced not only by local but also by regional and more global climatic conditions. Thus, compositional variations in lacustrine organic matter can be used as good indicators of paleoenvironmental conditions of deposition. Relatively high average TOC (1.0–6.5 wt%) and good lamination characterize most of the Holocene sequence of Lake St. Moritz, an Alphine lake located in SE Switzerland. However, variations in the type and quality of the organic matter at discrete intervals have been distinguished using bulk parameters and biomarker distributions. The most prominent change occurs at the Late Glacial-Holocene boundary, where δ 13C (OM), Hydrogen Index and lipid concentrations indicate a substantial increase in primary productivity. Organic matter production and preservation appear to dominate from the early Holocene until approximately 3.8 Ka BP, although variations in sterol contents and fatty acid distributions indicate superimposed fluctuations, such as between 8.3 and 8.1 Ka BP and 5.1 to 4.8 Ka BP. These variations in the lake trophic-state can be correlated with other proglacial lakes in the region, as well as with similar lacustrine records on both sides of the Alps. The result of this comparison indicates a synchronous character of major to medium-amplitude climatic shifts on a European scale.

Lake trophic state and the limnological effects of omnivorous fish

Ecologists have hypothesized that planktivorous fish have greater effects on the plankton and water quality of oligotrophic lakes than eutrophic lakes. We tested this hypothesis in a tank-mesocosm experiment of factorial design in which five biomass levels of filter-feeding omnivorous gizzard shad (Dorosoma cepedianum) were cross-classified with two levels of lake trophic state achieved by filling tank-mesocosms with water and plankton transported by truck from two lakes with different trophic states. The presence of gizzard shad significantly increased total phosphorus, primary productivity, chlorophyll, and particulate phosphorus (PP) 2–20 and 20–200 µm and significantly decreased Secchi depth, cladocerans, copepods and PP > 200 µm. The effects of gizzard shad on chlorophyll, Secchi depth, cladocerans, copepods and PP 2–20 and > 200 µm were dependent on lake trophic state and most intense in the eutrophic lake system. This experiment suggests that filter-feeding omnivorous fish interact synergistically with trophic state so that the limnological effects of omnivorous fish become more intense with increased eutrophication.

Watershed Riparian Management and Its Benefits to a Eutrophic Lake

Sediment and nutrient loads from a 73 km 2 mixed pasture/forested watershed that drains to eutrophic Lake Rotorua (New Zealand) were measured before and after diffuse-source controls were implemented. In the pastoral areas, these controls were exclusion of grazing (“retirement”) from the banks of most perennial streams, erosion-prone hillslopes, and remnant pockets of native forest. After implementation, the loads changed by −85% for sediment, −27% for particulate P, −26% for soluble P, −40% for particulate N, and +26% for dissolved N. Calculated total phosphorus specific yields for the pasture portion of the watershed were 89 kg km −2 yr −1 (preimplementation) and 41 kg km −2 yr −1 (postimplementation). When these findings were applied to the whole Lake Rotorua watershed, we predicted that control measures had reduced TP loads by 20%. This reduction in phosphorus loads was predicted to reduce the chlorophyll a concentration by about 5 mg m −3 , and help shift the lake's trophic state from eutrophic to mesotrophic.

Human disturbance and trophic status changes in Crystal Lake, McHenry County, Illinois, USA

The paleolimnology (sediment chemistry, 210Pb dating, pollen, and diatoms) of Crystal Lake, McHenry County, Illinois, USA was studied to investigate the impact of European settlement on lake trophic status. Pollen clearly indicates a vegetational shift from Quercus dominance to Ambrosia. 210Pb dating suggests that the Ambrosia rise likely occurs around the 1840's, which is consistent with historical records on the European settlement in this area. Coincident with the vegetational shifts, several diatom species, Cyclotella meneghiniana, Fragilaria crotenensis, Asterionella formosa and Tabellaria fenestrata, all increase while C. comta decreases after the settlement. However, C. comta and Aulacoseira ambigua, two dominant species, remain abundant throughout the entire core. Their relative abundances at the surface sediments reach presettlement levels. It is hypothesized that Crystal Lake, a glacial lake rich in CaCO3, may have been able to assimilate increases of phosphorus by coprecipitating phosphorus with CaCO3. Such a 'buffering mechanism’ may be responsible for the lake's resistance to trophic changes or recovery following disturbance.

Optimal sampling period for predicting phosphores and chlorophyll concentrations in north-temperate lakes

Because total phosphorus and chlorophyll a concentrations vary seasonally within north-temperate lakes, estimates of lake trophic status are usually based on several to many sampling visits. However, because such effort is not always logistically possible, the empirical relationships developed between these trophic status indicators may depend upon seasonal patterns of sampling. Clearly, it is desirable to know if some periods of the year are more likely to produce representative estimates of total phosphorus and chlorophyll a, or, alternatively, if sampling in other periods should be restricted or even avoided. Data from north-temperate lakes are used to examine the degree to which single monthly samples for total phosphorus and chlorophyll a represent seasonal means. Analyses indicate that the least precise and least accurate estimates of the means occur when single-visit synoptic surveys are conducted during April. Not until August to September do single sampling visits provide data that approximate those represented by the means garnered through more frequent sampling.

The nitrogen phosphorus relationship in mountain lakes: Influence of atmospheric input, watershed, and pH

The impact of high N input on the trophic status of small mountain lakes as modified by the type of watershed and stage of acidification in two central European mountain ranges (the High Tatra Mts. and the Sumava Mts.) is reported. Atmospheric N deposition enhanced nitrate concentrations of lake water, but the type of watershed determined both the share of nitrate in the pool of total N and its concentrations, which increased from forest to meadow to rocky watersheds. Ratios of total N to total P (TN : TP) generally reflected highest nitrate concentrations in alpine lakes, where soils and vegetation were sparse in the watersheds, and were lowest in forest lakes, where the N retention capacities of watersheds have not yet been exceeded. In alpine lakes, TN : TP reached a maximum level at pH values from 4.8 to 6.2, reflecting low TP concentrations in lakes at this stage of acidification. Because atmospheric N deposition may contribute to lake acidification, it may paradoxically also contribute to oligotrophication.

Paleopigment evidence of competition between phytoplankton and a cyanobacterial algal mat in a meromictic lake near Toronto, Ontario Canada

Crawford Lake, a meromictic lake located near Toronto, Canada, was cored to determine if algal pigments preserved in its sediments would make it possible to infer past changes in lake productivity over the last five hundred years. From 1500 to 1910 A.D. the sediments display extremely high levels of oscillaxanthin and myxoxanthophyll while chlorophyll derivatives and total carotenoids were relatively low. As the lake became increasingly more eutrophic in the latter part of the twentieth century, this relationship reversed itself. Competition for light between the deep dwelling cyanobacteria in the algal mat on the lake's bottom (8–14 m) and phytoplankton in the overlying surface layers of the water column (5–7 m) was attributed to the observed reduction in oscillaxanthin and myxoxanthophyll as Crawford Lake eutrophied. Because the major cyanobacteria in Crawford Lake are benthic mat forming Lyngbya and Oscillatoria, and not phytoplankton, competition for light with the overlying phytoplankton is critical in determining the total quantity of oscillaxanthin and myxoxanthophyll preserved in the lake's profundal sediments. These findings have major implications for the use of cyanobacterial pigments as indicators of lake trophic status in lakes where benthic algal mats are present.

PICOPHYTOPLANKTON BIOMASS IN RELATION TO LAKE TROPHIC STATE AND THE TN:TP RATIO OF LAKE WATER IN JAPAN1

ABSTRACTPicophytoplankton biomass and its contribution to total phytoplankton biomass were investigated in relation to the nutrient concentration and total N: total P ratio of the epilimnetic waters of 42 Japanese lakes during the warm season in 1991 (April–October). Picophytoplankton biomass (as chlorophyll a) in meso‐, eu‐, and hypertrophic lakes was significantly higher than those observed in oligotrophic lakes. However, picophytoplankton biomass increased significantly with increased total P concentrations in all systems excluding hypertrophic lakes. Picophytoplankton contribution to total chlorophyll a content was significantly higher in oligo‐ and mesotrophic lakes than in eu‐ and hypertrophic lakes and was inversely correlated with total P concentrations in lake water. Picophytoplankton contribution to the total phytoplankton biomass was positively (r = 0.54, n = 42, P = 0.0003) correlated with the total N: total P ratio of lake waters. Each lake trophic type, with the exception of hypertrophic lakes, showed this trend, although the correlation was not significant. We suggest that picophytoplankton contribution is influenced by the total N: total P ratio rather than lake trophic state; however, picophytoplankton were of little importance in hypertrophic lakes.

Lakeshore Capacity Study: Part I—Test of Effects of Shoreline Development on the Trophic Status of Lakes

ABSTRACT A simple mass balance model, combined with detailed hydrologic and mass balance measurements, yielded accurate predictions of total phosphorus (TP) concentrations in two lakes with no shoreline development. On the other hand, the model based on only natural TP loads predicted TP concentrations lower than observed in four developed lakes; however, in three of the four lakes, predictions and observations were virtually identical if the potential TP contribution from sewage disposal systems associated with shoreline development was included in the budgets. In the exception Harp Lake, the only one of the four with thick deposits of till/soil in its catchment, predicted and observed trophic status were comparable if about a third of the potential TP input from shoreline development reached the lake. The suggestion is that in this case the till/soil was effective in retaining a significant portion of TP transported from septic systems. Lakes with oxic and anoxic hypolimnia were distinguished by using d...

Zoobenthos associated with submerged macrophytes and evaluation of trophic status in lakes

(1993). Zoobenthos associated with submerged macrophytes and evaluation of trophic status in lakes. SIL Proceedings, 1922-2010: Vol. 25, No. 2, pp. 780-783.

The influence of catchment size on lake trophic status during the hemlock decline and recovery (4800 to 3500 BP) in southern Ontario lakes

We investigated the ecological effects of terrestrial ecosystem change during the hemlock decline and recovery (4,800–3,500 BP) on lake communities (diatoms and chrysophytes). This study specifically assessed the role of catchment area and slope in determining the magnitude of lake eutrophication during the hemlock decline by analyzing sediment cores from five alkaline, holomictic lakes in southeastern Ontario, Canada. The study lakes were similar in most limnological aspects, but differed widely in the relative sizes of their catchments. Diatoms were used to quantitatively infer past lake-water total phosphorus (TP) concentrations.

Patterns in the Size Structure of Littoral Zone Macroinvertebrate Communities

A wide range of size spectra was encountered in 11 lakes of the Quebec Eastern Townships; most were bimodal with maximum biomass represented between 1 and 4 mg (wet weight) and between 64 and 256 mg and minimum biomass between 8 and 32 mg. PCA was used to show that the two size modes represented independent size fractions and that they were related to different environmental factors. The biomass of the small size fraction increased strongly with submerged macrophyte biomass and with lake trophic status. The biomass of the large size fraction was independent of the small size fraction and increased with wave exposure at the site. As the macrophyte biomass increased, more of the invertebrates were found upon the plants, and the small size fraction became more dominant. This is probably a result of the animals upon the vegetation being more exposed to fish predators than those hidden within the substrate. Linear regression models are developed to predict the biomass of both size fractions as well as the slope and intercept parameters of the normalized size distribution (NSD). The size-fraction approach (using PCA) complements the simpler NSD approach; it detects functionally independent size fractions in the community that NSD parameters cannot reveal.

DIATOM ASSEMBLAGES AS INDICATORS OF LAKE TROPHIC STATUS IN SOUTHEASTERN ONTARIO LAKES1

ABSTRACTCanonical correspondence analysis (CCA) was used to explore the relationship between measured environmental variables and surficial diatom (Bacillariophyceae) assemblages in alkaline lakes from southeastern Ontario. Total nitrogen (TN), watershed area, alkalinity, and maximum depth each explain significant (P ≤ 0.05) directions of variance in the distribution of diatom taxa.TN was highly correlated to total phosphorus (TP) (r = 0.92), chlorophyll a (r = 0.86), and Secchi depth (r =0.77). When a series of CCAs were run with the first axis constrained to each of these variables in turn, the ratio of the eigenvalue of the first axis to that of the second axis (λ1/λ2) was highest for TN, indicating that TN best explained the distribution of the diatom assemblages in this set of lakes. Furthermore, results of Monte Carlo permutation tests indicated that these four variables did not act independently on the diatom assemblages. Therefore, TN was selected to represent these four closely related variables to infer lake trophic status.Weighted‐averaging regression and calibration (with classical deshrinking) were used to develop transfer functions to infer TN from the relative abundances of 83 diatom taxa recovered from the surficial sediments of 51 lakes. There was a good correlation between diatom‐inferred TN concentrations and measured TN concentrations (r2= 0.75, n = 51).The weighted‐averaging regression and calibration model was used to infer lake trophic status (represented by TN) from diatom assemblages presented in the sediments from Little Round Lake, Ontario. These data were used in conjunction with historical land‐use data in order to quantify the sequence and extent of nutrient enrichment related to human activity in the watershed area.

Relationship of Salmonine Production to Lake Trophic Status and Temperature

Data on trout, char, and salmon from lakes in several geographic areas indicate that salmonine production (P, kilograms per hectare per year) increases with total phosphorus concentration (TP, micrograms per litre) as log10P = 0.47 + 0.95 log10TP (r2 = 0.61). A positive relationship was also found between P and phytoplankton productivity and this relationship suggests that energy transfer efficiencies from phytoplankton to salmonines are reduced in eutrophic lakes. Lake area and mean depth had no significant statistical effect on P but salmonine production was significantly lower in warmer climates. Analysis of these data suggests that projected global increases in air temperatures could lead to about 50% reductions in salmonine production and yield in the north temperate zone.