Nutrient-enriched Lakes Research Articles

Further data analysis needed to assess the role of pH on the dominance of cyanobacterial blooms in nutrient-enriched lakes—analyze data instead of relying on debates

Further data analysis needed to assess the role of pH on the dominance of cyanobacterial blooms in nutrient-enriched lakes—analyze data instead of relying on debates

Hydrological and Water Quality Trends through the Lens of Historical Operation Schedules in Lake Okeechobee

AbstractWater management operations can drive long-term water quality patterns in nutrient-enriched lakes and reservoirs. This study identified multidecadal trends of rainfall, flow, water levels, ...

Influence of industrial activity and pollution on the paleoclimate reconstruction from a eutrophic lake in lowland England, UK

Reliable estimates of Holocene temperatures are important for understanding past climate dynamics, the response of biota to climate change, and validating climate models. Chironomids in lake sediment cores are used widely to quantify past summer temperatures, for which high-latitude and/or high-altitude lakes, remote from human influence, are usually considered appropriate. Temperature inferences from lowland lakes are likely influenced by other variables, specifically eutrophication and industrial pollution, but their reliability has never been tested. We used a Norwegian chironomid-based transfer function (r 2 = 0.91; RMSEP = 1.01 °C) to infer mean July air temperature over the last 200 years, using chironomid assemblages in a core collected from a polluted, nutrient-enriched lake at Speke Hall, Liverpool, England. The chironomid-inferred temperatures correlate significantly with the local instrumental temperature record and follow long-term national temperature trends. These results show that chironomids can be used to produce reliable estimates of past mean July air temperature, even when other variables have also influenced the composition of the chironomid community. These findings underline the value of chironomids as sensitive and reliable quantitative proxies for summer temperature.

Response of Vallisneria natans to Increasing Nitrogen Loading Depends on Sediment Nutrient Characteristics

High nitrogen (N) loading may contribute to recession of submerged macrophytes in shallow lakes; yet, its influences vary depending on environmental conditions. In August 2013, we conducted a 28-day factorial-designed field mesocosm experiment in Lake Taihu at the Taihu Laboratory for Lake Ecosystem Research (TLLER) to examine the effects of high N loading on the growth of Vallisneria natans in systems with contrasting sediment types. We ran the experiments with two levels of nutrient loading—present-day external nutrient loading (average P: 5 μg·L−1·day−1, N: 130 μg·L−1·day−1) and P: 5 μg·L−1·day−1, and with three times higher N loading (N: 390 μg·L−1·day−1) and used sediment with two contrasting nutrient levels. V. natans growth decreased significantly with increasing N loading, the effect being dependent, however, on the nutrient status of the sediment. In low nutrient sediment, relative growth rates, leaf biomass and root biomass decreased by 11.9%, 18.2% and 23.3%, respectively, at high rather than low N loading, while the decline was larger (44.0%, 32.7% and 41.8%, respectively) when using high nutrient sediment. The larger effect in the nutrient-rich sediment may reflect an observed higher shading of phytoplankton and excess nutrient accumulation in plant tissue, though potential toxic effects of the high-nutrient sediment may also have contributed. Our study confirms the occurrence of a negative effect of increasing N loading on submerged plant growth in shallow nutrient-enriched lakes and further shows that this effect is augmented when the plants grow in nutrient-rich sediment. External N control may, therefore, help to protect or restore submerged macrophytes, especially when the sediment is enriched with nutrients and organic matter.

Natural Climate Variability Can Influence Cyanobacteria Blooms in Florida Lakes and Reservoirs

During the summer, many of Florida's nutrient-enriched lakes and reservoirs experience proliferations of cyanobacteria commonly called “blooms.” Cyanobacteria are natural in Florida lakes and reservoirs, but when they grow to high levels and bloom, they become a big problem. They look awful, smell bad, and can poison fish and other animals in the water. To help resource managers considering costly remediation projects or evaluating the effectiveness of nutrient reduction strategies to manage the problem, this 7-page fact sheet presents the results from 15 years of studies observing three large, nutrient-rich lakes in Florida (Lake Harris, Lake George, and Lake Okeechobee) to study the relationship between rainfall and cyanobacteria blooms and learn causes of year-to-year bloom variability. Written by Karl E. Havens, Mark V. Hoyer, and Edward J. Phlips, and published by the Florida Sea Grant College Program, July 2016. SGEF-234/SG142: Natural Climate Variability Can Influence Cyanobacteria Blooms in Florida Lakes and Reservoirs (ufl.edu)

Phytoplankton taxonomic compositional shifts across nutrient and light gradients in temperate lakes

Nutrient and light availability, and their balance, can modify community composition and structure in pelagic communities. Previous studies have demonstrated contradictory findings about whether total phosphorus (TP) concentrations alone or the ratio of total nitrogen (TN) to TP concentrations (TN:TP) drive Cyanobacteria dominance in freshwater ecosystems, and influences of light availability are often overlooked. Here, we analyzed a 12 year, 137 lake database to test paradigms of phytoplankton compositional patterns across nutrient (TN, TP, TN:TP) and light availability gradients in an agricultural region. We hypothesized that (1) TN:TP ratios would better predict phytoplankton compositional shifts than TP concentrations alone, (2) Cyanobacteria relative abundance would increase at low TN:TP ratios, and (3) Cyanobacteria biomass fluctuations would be the primary driver of light climate. We found that TN:TP ratios better described phytoplankton compositional patterns than TP concentrations, with Cyanobacteria proportions decreasing with increasing TN:TP while other taxa increased. Contrary to expectations, Cyanobacteria always dominated community composition (≥80% biomass), regardless of TP concentrations. Despite these patterns, N-fixing Cyanobacteria proportions were not correlated to TN:TP, suggesting that shifts toward N-fixation were not solely driving phytoplankton compositional patterns. Although Cyanobacteria biomass decreased with increasing light availability, inorganic particles explained more variance in light than total phytoplankton biomass, suggesting that buoyancy-regulating Cyanobacteria may gain an initial competitive advantage in light acquisition before bloom development in turbid systems. These findings suggest that Cyanobacteria strongly influence pelagic community dynamics in nutrient-enriched lakes, and their ability to manipulate light and nutrient environments enable their persistent dominance across large environmental gradients.

Cyanobacterial biodiversity and associated ecosystem services: introduction to the special issue

Cyanobacteria, one of the oldest groups of known organisms, are photosynthetic prokaryotes. They have existed for about 3.5 billion years, from Pre-cambrian times, and played a significant role in oxygen accumulation in the Earth’s early atmosphere making it fit for the survival of aerobic life-forms. Their unique ability, the ability to fix nitrogen and carry out oxygen-evolving photosynthesis and oxygen-labile nitrogen fixation within the same organisms, has always fascinated researchers (Mitsui et al. 1986). During their long evolutionary history, cyanobacteria have been able to adapt to geochemical and climate changes as well as anthropogenic disturbances (Paerl and Otten 2013). They probably exhibit the widest range of diversity in growth habitats of all photosynthetic organisms, and have developed CO2 concentrating mechanisms which adapt them to various environmental limitations (Badger et al. 2006). With an estimated global biomass of 3 9 10 g C, or 10 g wet biomass (Garcia-Pichel et al. 2003), quantitatively they are also some of the world’s most important organisms (Whitton 2012). Many of the species, however, remain to be discovered (Nabout et al. 2013), and cyanobacteria remain a neglected component of biodiversity research (Rejmankova et al. 2004). Global warming will have a profound impact on cyanobacterial biodiversity, probably favouring them over other phytoplankton (Carey et al. 2012), increasing cyanobacterial blooms formation (Wagner and Adrian 2009), and also favour toxin producing species or elevated toxin concentration by extant species with severe consequences for associated ecosystem services (Kleinteich et al. 2012). Lake warming with reduced water turnover and a changed nutrient ratio too will also favour the growth of harmful filamentous cyanobacteria (Posch et al. 2012) and their dominance will affect ecosystem functioning and community turnover in nutrient-enriched lakes (Filstrup et al. 2014). As cyanobacteria have significant ecological roles, their biodiversity need to be fully explored and conserved

Controlling cyanobacterial blooms in hypertrophic Lake Taihu, China: will nitrogen reductions cause replacement of non-N2 fixing by N2 fixing taxa?

Excessive anthropogenic nitrogen (N) and phosphorus (P) inputs have caused an alarming increase in harmful cyanobacterial blooms, threatening sustainability of lakes and reservoirs worldwide. Hypertrophic Lake Taihu, China’s third largest freshwater lake, typifies this predicament, with toxic blooms of the non-N2 fixing cyanobacteria Microcystis spp. dominating from spring through fall. Previous studies indicate N and P reductions are needed to reduce bloom magnitude and duration. However, N reductions may encourage replacement of non-N2 fixing with N2 fixing cyanobacteria. This potentially counterproductive scenario was evaluated using replicate, large (1000 L), in-lake mesocosms during summer bloom periods. N+P additions led to maximum phytoplankton production. Phosphorus enrichment, which promoted N limitation, resulted in increases in N2 fixing taxa (Anabaena spp.), but it did not lead to significant replacement of non-N2 fixing with N2 fixing cyanobacteria, and N2 fixation rates remained ecologically insignificant. Furthermore, P enrichment failed to increase phytoplankton production relative to controls, indicating that N was the most limiting nutrient throughout this period. We propose that Microcystis spp. and other non-N2 fixing genera can maintain dominance in this shallow, highly turbid, nutrient-enriched lake by outcompeting N2 fixing taxa for existing sources of N and P stored and cycled in the lake. To bring Taihu and other hypertrophic systems below the bloom threshold, both N and P reductions will be needed until the legacy of high N and P loading and sediment nutrient storage in these systems is depleted. At that point, a more exclusive focus on P reductions may be feasible.

Cyanobacteria dominance influences resource use efficiency and community turnover in phytoplankton and zooplankton communities

Freshwater biodiversity loss potentially disrupts ecosystem services related to water quality and may negatively impact ecosystem functioning and temporal community turnover. We analysed a data set containing phytoplankton and zooplankton community data from 131 lakes through 9years in an agricultural region to test predictions that plankton communities with low biodiversity are less efficient in their use of limiting resources and display greater community turnover (measured as community dissimilarity). Phytoplankton resource use efficiency (RUE=biomass per unit resource) was negatively related to phytoplankton evenness (measured as Pielou's evenness), whereas zooplankton RUE was positively related to phytoplankton evenness. Phytoplankton and zooplankton RUE were high and low, respectively, when Cyanobacteria, especially Microcystis sp., dominated. Phytoplankton communities displayed slower community turnover rates when dominated by few genera. Our findings, which counter findings of many terrestrial studies, suggest that Cyanobacteria dominance may play important roles in ecosystem functioning and community turnover in nutrient-enriched lakes.

Infection level of the Asian tapeworm (Bothriocephalus acheilognathi) in the cyprinid fish, Schizothorax niger, from Anchar Lake, relative to season, sex, length and condition factor

Various studies have shown that the Asian fish tapeworm, Bothriocephalus acheilognathi causes great economic loss in hatcheries, fish farms as well as in lakes. In order to understand the seasonal variation of infection in a nutrient-enriched lake, parasitological investigation was carried out in the indigenous cyprinid fish, Schizothorax niger Heckel 1838 from September, 2008 to August, 2009. Overall, this study revealed definite seasonality of infection (p < 0.05), with greater infection in summer (prevalence = 39.5%) and lesser in winter (prevalence = 8.1%). The prevalence among different seasons revealed significant differences (p < 0.05). Sex was not an important factor influencing the prevalence of the Asian tapeworm. A strong positive correlation (Pearson's correlation, r = 0.7; p = 0.02) between total length of S. niger and number of Asian fish tapeworms was observed. Similarly, a strong positive correlation existed between weight of fish and number of tapeworms (Pearson's correlation, r = 0.7; p = 0.005). Prevalence and mean abundance were positively and significantly correlated with water temperature (r = 0.8, p < 0.01 and r = 0.8, p < 0.01, respectively). Thus seasonal dynamics, total length and weight of the host significantly influenced the tapeworm infection. The above findings will be useful in devising the appropriate control strategies for the Asian tapeworm in wild fish in Kashmir valley as well as in similar climatic zones of other parts of the world. Also, information from this study will be used to assess the spread and extent of B. acheilognathi which is a potential threat to the indigenous fish fauna of Anchar Lake.

Sources and fates of dissolved organic carbon in lakes as determined by whole-lake carbon isotope additions

Four whole-lake inorganic 13C addition experiments were conducted in lakes of differing trophic status. Inorganic 13C addition enriched algal carbon in 13C and changed the $$\delta^{13}$$ C-DOC by +1.5‰ to +9.5‰, depending on the specific lake. This change in $$\delta^{13}$$ C-DOC represented a significant input of algal DOC that was not completely consumed by bacteria. We modeled the dynamics in $$\delta^{13}$$ C-DOC to estimate the fluxes of algal and terrestrial carbon to and from the DOC pool, and determine the composition of the standing stock. Two experiments in lightly stained, oligotrophic lakes indicated that algal production was the source of about 20% of the DOC pool. In the following year, the experiment was repeated in one of these lakes under conditions of nutrient enrichment, and in a third, more humic lake. Algal contributions to the DOC pool were 40% in the nutrient enriched lake and 5% in the more humic lake. Spectroscopic and elemental analyses corroborated the presence of increased algal DOC in the nutrient enriched lake. Natural abundance measurements of the $$\delta^{13}$$ C of DOC in 32 lakes also revealed the dual contributions of both terrestrial and algal carbon to DOC. From these results, we suggest an approach for inferring the contribution of algal and terrestrial DOC using easily measurable parameters.

Bacterial Growth on Allochthonous Carbon in Humic and Nutrient-enriched Lakes: Results from Whole-Lake 13C Addition Experiments

Organic carbon (C) in lakes originates from two distinct sources—primary production from within the lake itself (autochthonous supply) and importation of organic matter from the terrestrial watershed (allochthonous supply). By manipulating the 13C of dissolved inorganic C, thereby labeling within-lake primary production, we examined the relative importance of autochthonous and allochthonous C in supporting bacterial production. For 35 days, NaH13CO3 was added daily to two small, forested lakes. One of the lakes (Peter) was fertilized so that primary production exceeded total respiration in the epilimnion. The other lake (Tuesday), in contrast, was low in productivity and had high levels of colored dissolved organic C (DOC). To obtain bacterial C isotopes, bacteria were regrown in situ in particle-free lake water in dialysis tubes. The contribution of allochthonous C to bacterial biomass was calculated by applying a two-member mixing model. In the absence of a direct measurement, the isotopic signature of the autochthonous end-member was estimated indirectly by three different approaches. Although there was excess primary production in Peter Lake, bacterial biomass consisted of 43–46% allochthonous C. In Tuesday Lake more than 75% of bacterial growth was supported by allochthonous C. Although bacteria used autochthonous C preferentially over allochthonous C, DOC from the watershed contributed significantly to bacterial production. In combination with results from similar experiments in different lakes, our findings suggest that the contribution of allochthonous C to bacterial production can be predicted from ratios of chromophoric dissolved organic matter (a surrogate for allochthonous supply) and chlorophyll a (a surrogate for autochthonous supply).

Coupling between 210Pb ex and organic matter in sediments of a nutrient-enriched lake: An example from Lake Chenghai, China

Sediment cores were collected from deep-water areas of Lake Chenghai, China in June 1997. The vertical profile of 137Cs activity gives reliable geochronological results. The results also indicate that sediment accumulation rates in deep-water areas of Lake Chenghai were relatively constant in recent decades, averaging 0.43 g cm − 2 y − 1 , despite a variable organic carbon influx. 210Pb eq (= 226Ra) activity was relatively constant also, with an average value of 54.3 ± 3.2 Bq kg − 1 . Vertical profiles of 210Pb ex (= 210Pb total − 226Ra) decreased exponentially, resulting in somewhat lower sediment accumulation rates (0.3 g cm − 2 y − 1 ). These lower rates are likely less reliable, as the relatively large fluctuations in 210Pb ex activities correlate closely to the organic carbon (C org) content of the sediments. For example, the vertical profile of 210Pb ex activity displays peaks at mass depths of 3.7–4.7 g cm − 2 (10–12 cm) and 10–11 g cm − 2 (25–28 cm), similar to the maxima in the vertical profile of C org. This phenomenon must be related to the delivery of particulate organic matter (POM) from the water to the sediments, or to watershed soil erosion. Since the mean atomic ratios of H org / C org and C org / N org in Lake Chenghai sediments are 5.5 and 7.0, respectively, indicating that POM was predominantly derived from the remains of authigenic algae, this eliminates watershed erosion rates as a primary control on lake sedimentation rates as resolved by 210Pb ex. Sedimentation fluxes ( F(C org)) of particulate organic carbon since 1970 varied between 60 to 160 g m − 2 y − 1 , and appeared to closely influence variations in 210Pb ex concentrations. For example, sedimentation fluxes of 210Pb ex (F( 210Pb ex)) showed maxima in the years 1972–1974 and 1986–1989, likely reflecting historical variations of lake biological productivity or carbon preservation.

ECOSYSTEM SUBSIDIES: TERRESTRIAL SUPPORT OF AQUATIC FOOD WEBS FROM13C ADDITION TO CONTRASTING LAKES

Whole-lake additions of dissolved inorganic 13C were used to measure allochthony (the terrestrial contribution of organic carbon to aquatic consumers) in two unproductive lakes (Paul and Peter Lakes in 2001), a nutrient-enriched lake (Peter Lake in 2002), and a dystrophic lake (Tuesday Lake in 2002). Three kinds of dynamic models were used to estimate allochthony: a process-rich, dual-isotope flow model based on mass balances of two carbon isotopes in 12 carbon pools; simple univariate time-series models driven by observed time courses of δ13CO2; and multivariate autoregression models that combined information from time series of δ13C in several interacting carbon pools. All three models gave similar estimates of allochthony. In the three experiments without nutrient enrichment, flows of terrestrial carbon to dissolved and particulate organic carbon, zooplankton, Chaoborus, and fishes were substantial. For example, terrestrial sources accounted for more than half the carbon flow to juvenile and adult largemouth bass, pumpkinseed sunfish, golden shiners, brook sticklebacks, and fathead minnows in the unenriched experiments. Allochthony was highest in the dystrophic lake and lowest in the nutrient-enriched lake. Nutrient enrichment of Peter Lake decreased allochthony of zooplankton from 0.34–0.48 to 0–0.12, and of fishes from 0.51–0.80 to 0.25–0.55. These experiments show that lake ecosystem carbon cycles, including carbon flows to consumers, are heavily subsidized by organic carbon from the surrounding landscape.

Seasonal occurrence of mesophilic Aeromonas spp. as a function of biotype and water quality in temperate freshwater lakes

Densities of mesophilic aeromonads were compared in Virginia freshwater lakes with trophic classifications ranging from mesotrophic to hypereutrophic. Aeromonad concentrations were independent of trophic status and did not correlate statistically with water quality parameters used to measure trophic state (total phosphorus, chlorophyll a and Secchi depth). Bacterial indicators (fecal coliforms and Escherichia coli) used to assess the public health safety of recreational waters correlated with mesophilic aeromonads only when sewage pollution occurred. Overall ( n = 101–107) there were small negative correlations of aeromonad densities with dissolved oxygen ( r = −0.30, P = <0.05), and total dissolved nitrogen ( r = −0.30, P = 0.05). During frequent sampling from April through October 1991, mean mesophilic aeromonad concentrations ranged from 10 3–4 cells 100 ml −1 with the lowest values measured during mid-summer. Over the course of twelve months, 273 aeromonad isolates were identified as belonging to the following biotypes: A. sobria (54%), A. hydrophila (29%), A. caviae (10%), and undetermined (7%). Seasonally, the frequency of isolation of A. sobria, considered the most pathogenic biotype, increased from 17 to 69% when water temperatures exceeded 20°C in a hypereutrophic lake. These temperatures typically occur during periods of peak recreational usage. Phenotypic characteristics associated with virulence were positive in 70% (hemolysis) and 42% (autoagglutination) of glycerol-stored strains ( n = 85), and in 15% (autoagglutination) of strains immediately processed ( n = 73). S-layer proteins associated with invasiveness were not found in 14 strains which autoagglutinated. To evaluate the public health significance of aeromonads in nutrient enriched lakes, our results demonstrate a need to couple investigations of mesophilic aeromonad ecology with virulence and biotype assessments.

Some observations on red-coloured species ofOscillatoria(Cyanophyceae) in nutrient-enriched lakes of southern Norway

(1978). Some observations on red-coloured species of Oscillatoria (Cyanophyceae) in nutrient-enriched lakes of southern Norway. SIL Proceedings, 1922-2010: Vol. 20, No. 2, pp. 776-787.

Changes in the fauna and flora of a nutrient enriched lake

Changes in the flora and fauna at Loch Leven are described. Species associated with oligotrophic conditions such as charr and desmids have declined or disappeared, and prolonged, dense algal blooms, particularly Cyanophyceae, have been a feature of recent years. Much of the macrophytic vegetation has disappeared and there have been changes in the composition of the zooplankton and benthos, several abundant species disappearing (Table II). Possible reasons for these changes are given. Die Veranderungen in der Pflanzen-und Tierwelt von Loch Leven werden beschrieben. Gattungen welche gewohnlich in oligotrophen Gewassern gefunden werden, wie Salvelinus und Desmidiaceae, sind verringert oder ganz verschwunden. In den letzten Jahren sind Cyanophyceae immer haufiger hervorgetreten. Viele hohere Pflanzen sind verschwunden und es hat sich vieles geandert in der Komposition des Zooplanktons und Benthos. Mehrere wichtige Gattungen dieser Gruppen verschwinden allmahlich. Mogliche Grunde fur diese Veranderungen werden gegeben.