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Results for “eutrophication”

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At least 19 recordsLinked to original sources
PubMedDate not supplied

Phosphorus and the eutrophication of lakes--a personal view.

The availability and abundance of biologically-active forms of phosphorus in natural waters are briefly reviewed in relation to the requirements, growth and development of algal populations. The consequences of artificial enrichment of lakes with agricultural, domestic and industrial effluents ('eutrophication') attributed to increased phosphorus loading are compared with evidence from a selection of natural lakes and experimental systems in the UK. The suggestion is made that increased loadings on richer lakes make relatively less impact than does mild eutrophication of unproductive waters. Within limits the effects of eutrophication are reversible.

Chlorophyll↗
PubMed2025

Agricultural land use and ensuing eutrophication both shape parasitic trematode communities in rural African lakes.

Land use is a major driver of biodiversity loss, but how it impacts parasite communities is scarcely documented. Crater lakes and their catchments in rural western Uganda greatly vary in their intensity of anthropogenic disturbance, thus providing an opportunity to assess the effects of land use on snail-borne parasitic trematodes. We applied state-of-the-art molecular biomonitoring to 2385 Bulinus tropicus snails from 34 lakes to detect and genotype trematode infections. The 45 trematode taxa recovered infect a wide range of final vertebrate hosts, and some can cause health burdens of significant public importance. Using constrained ordinations and generalized additive models, we found that B. tropicus reaches peak abundance in lakes with catchments partly under agriculture, whereas trematode infections increase with B. tropicus abundance and peak at intermediate aquatic productivity. Trematode diversity also increases with aquatic productivity, levelling off only in the most productive lakes. These relationships likely reflect the higher abundance and variety of final hosts sustained by more productive lakes. Finally, we found that land use affects trematode community composition, with more livestock parasites and less bird parasites occurring in agricultural catchments. Our results indicate that both land use and lake eutrophication affect the distribution of hotspots for parasitic disease transmission.

Lakes↗
PubMedDate not supplied

[Molecular nitrogen fixation in eutrophic Beloye Ozero].

The rate of production and mineralization of organic matter and the rate of fixation of molecular nitrogen were assayed in th eutrophic lake Beloye (near Moscow) at the end of summer stagnation (1976). The content of hydrogen sulphide reached 6.8 mg per litre which resulted in a change of the ecological environment in the lake. The fixation of molecular nitrogen in water layers was characterized by three maxima: 5.0 mcg N per litre per 4 hours (surface); 4.2 mcg N per litre per 4 hours (metalimnion) and 2.8 mcg N per litre per 4 hours (at bottom). The fixation of nitrogen in the trophogenous layer involved mainly the blue-green alga Anabaena. In the sulphide zone, molecular nitrogen was fixed by butyric and sulphate-reducing bacteria.

Cyanobacteria↗
PubMed2025

Depth-dependent multi-kingdom microbial interactions and biogeochemical cycling genes in eutrophic shallow lake sediments.

Microorganisms are pivotal to lake ecosystem biogeochemical cycles, yet existing research often focuses on single microbial kingdoms or surface sediments, neglecting multi-kingdom interactions and depth-resolved dynamics. To address these gaps, we used metagenomic sequencing to characterize microbial communities and their functional associations across overlying water and 0-45 cm sediments in four shallow lakes of the middle Yangtze River basin, China. Despite increasing bacterial and fungal diversity with depth, the 0-9 cm surface sediments exhibited the strongest multi-kingdom network connectivity and the greatest microbial stability. Functional genes exhibited clear depth-dependent patterns: nitrogen cycling genes, including those involved in dissimilatory nitrate reduction to ammonium, were most enriched in the upper 0-9 cm of sediment; methane cycling genes were positively correlated with depth; phosphorus cycling genes and some sulfur cycling genes, such as assimilatory sulphate reduction, declined with depth. Sediment microbial assembly was dominated by deterministic processes, in which the vertical distribution of functional genes was primarily dictated by heavy metals and conventional environmental indicators. These findings highlight depth-specific multi-kingdom microbial interactions and their associations with biogeochemical cycling, advancing lacustrine microbial ecology understanding and providing references for lake conservation under environmental change.

Lakes↗
PubMed1977

Eutrophication.

Explore the source record for details and available documents.

Animals↗
PubMed2025

Intraspecific divergence within Microcystis aeruginosa mediates the dynamics of freshwater harmful algal blooms under climate warming scenarios.

Intraspecific biodiversity can have ecosystem-level consequences and may affect the accuracy of ecological forecasting. For example, rare genetic variants may have traits that prove beneficial under future environmental conditions. The cyanobacterium responsible for most freshwater harmful algal blooms worldwide, Microcystis aeruginosa, occurs in at least three types. While the dominant type occurs in eutrophic environments and is adapted to thrive in nutrient-rich conditions, two additional types have recently been discovered that inhabit oligotrophic and eutrophic environments and have genomic adaptations for survival under nutrient limitation. Here, we show that these oligotrophic types are widespread throughout the Eastern USA. By pairing an experimental warming study with gene expression analyses, we found that the eutrophic type may be most susceptible to climate warming. In comparison, oligotrophic types maintained their growth better and persisted longer under warming. As a mechanistic explanation for these patterns, we found that oligotrophic types responded to warming by widespread elevated expression of heat shock protein genes. Reduction of nutrient loading has been a historically effective mitigation strategy for controlling harmful algal blooms. Our results suggest that climate warming may benefit oligotrophic types of M. aeruginosa, potentially reducing the effectiveness of such mitigation efforts. In-depth study of intraspecific variation may therefore improve forecasting for understanding future whole ecosystem dynamics.

Microcystis↗
PubMedDate not supplied

The use of phosphate in detergents and possible replacements for phosphate.

About 5% of the total phosphate mined worldwide is used in detergents. The chemical form in which phosphate is used in detergents is predominantly pentasodium triphosphate (PSTP). The most significant feature for the use of PSTP in detergents is its ability to form soluble and strong complexes with calcium and magnesium ions. This provides a strong synergism with regard to detergency when PSTP is used in combination with synthetic surfactants. Other important features of PSTP are its ability to disperse dirt in the washing solution, its weak alkalinity, its crystalline form when dry (which enables production of crisp powders) and, last but not least, its toxicological acceptability. The development of PSTP for use in detergents has a history of over 25 years. In certain areas of highly developed countries where effluents from major centres of population can reach stagnant surface waters a rapid increase of eutrophication of these surface waters is observed. Phosphates are being recognized as one of the essential nutrients contributing to the eutrophication and detergents are one of the many sources of phosphate discharged to the environment. This is now causing demands for reduction in or even banning of the use of phosphates in detergents. Major reserach projects and some practical approaches to meeting these demands are described. The potential environmental impact of removing phosphate from detergents remains, however, doubtful, as it has been demonstrated in Sweden that phosphate removal by sewage treatment is the most effective measure to control phosphate discharges. This makes the case of phosphates in detergents an example of how science and technology can become entangled with politics.

Biodegradation, Environmental↗
PubMed1975

[Biolgical problems of a manmade small lake (author's transl)].

In connection with an intensive hygienic supervision of public bathing facilities and the attempts to draw up a law on bathing hygiene, the lack of contamination standards for small lakes available to the public for bathing was particularly conspicuous. In addition to the current chemical and bacteriological routine examinations, a small bathing lake with a surface area of 3000 square metres containing about 7000 m3 of water and which has been in existence for over 10 years was objected to extensive biological investigations during the months July to September. The results of the analysis show a relatively constant hydrogen ion concentration (pH 8.2), small variations in electrolytic conductivity and 8 German degrees of hardness. The mean phosphourus level was 60 mug/L. the orthophosphate levels ranged between 5.2 and 18.5 mug/L. Oxygen saturation during the entire summer months was more than 100%. Altogether, 49 different kinds of phytoplankton- and 12 kinds of zooplancton-organisms were identified. The total biological mass of phytoplancton organisms was between 8.5 and 16 mg fresh weight per litre, bacterial biomass varied between 4.5 and 9.5 mg/l. Particularly striking for summer conditions was the high proportion of Cyclotella- and Synedra species among the phytoplancton mass, while the algal-bloom producing Microcystis flos aquae attained a maximum proportion of 15%. In spite of the great variety of its forms, green algae were present in small numbers only. The comparison of the described findings with the trophic-systems of HUTCHINSON, NYGAARD and RAWSON indicated an eutrophic type of lake; classification according to the types of the various saprobic systems of NAUMANN, KOLKWITZ and LIEBMANN yielded a predominantly beta-mesosaprobic type of lake. The investigations described show, however, that this is probably a lake rich in nutrients, but that there is a relatively stable biological equilibrium and that, consequently, there is no further threat of progressive eutrophism. Special hygienic parameters, contamination due to visitors and phytoplancton production will be reported in a second communication.

Animals↗
PubMedDate not supplied

The rationale for a ban on detergent phosphate in the Great Lakes Basin.

Immediate reduction of phosphorus loadings to the Great Lakes is essential to slow accelerated eutrophication. The Great Lakes National Program Office of the US Environmental Protection Agency now advocates adoption of bans on detergent phosphates as the most practical and feasible means of immediately reducing the phosphorus loadings to the Great Lakes. This change in policy from previous reliance on removal by sewage treatment has been adopted for the following reasons: (1) Bans on phosphates will reduce capital and operating costs of treatment and, were adopted, have met with consumer acceptance. (2) In practice, treatment plants have not met design expectations for phosphate removal. (3) Neither nitrilotriacetic acid nor other substitutes for phosphates have proved to be a public health problem. (4) Reduction of phosphorus loadings to treatment plants avoids increasing levels of chlorides and total dissolved solids in effluents. (5) Water quality has improved in small lakes with phosphorus reduction. In summary, detergent phosphate bans alone will not reduce phosphorus loadings to the Great Lakes sufficiently for the long term but the Environmental Protection Agency has concluded that such action is necessary in addition to continued efforts to control non-point sources.

Detergents↗
PubMed2026

Nitrogen sources and concentrations shape algal odor compounds: Key drivers of β-cyclocitral and β-ionone in water bodies of the lower Yangtze River.

Taste and odor (T&O) compounds derived from cyanobacterial blooms pose escalating threats to freshwater security worldwide, yet the drivers of specific T&O metabolites remain poorly constrained. Here, we investigated the dual effects of nitrogen (N) sources and concentrations on the production of β-cyclocitral and β-ionone, two algal-derived T&O compounds, through integrated field surveys (54 sites across lakes and rivers) in the eutrophic lower Yangtze River, China, and laboratory cultivation of typical cyanobacteria (Microcystis aeruginosa and Pseudanabaena cinerea). Our field data revealed that the concentrations of β-cyclocitral and β-ionone in lakes and rivers were not significantly different, but increased with the trophic level index. Redundancy analysis and Mantel analysis showed that Microcystis and Pseudanabaena were potentially dominant contributors to β-cyclocitral and β-ionone in the water column. Structural equation modeling and variation partitioning analysis showed that enhanced nitrate (NO3--N) significantly promoted the production of these compounds. Laboratory experiments demonstrated that inorganic N (NaNO₃) maximized total T&O yields by promoting algal biomass, whereas organic N (urea and glutamic acid) elevated the T&O production per unit biomass by 1.5- to 9.5-fold. Notably, Pseudanabaena exhibited a 2.3-fold higher β-ionone yield than Microcystis, with greater sensitivity to N concentrations. Our study highlights the critical role of nitrogen pollution, both source and concentration, in the production of T&O compounds by phytoplankton and provides reference data for managing T&O issues in rivers and shallow lakes.

Norisoprenoids↗
PubMed2026

Sedimentary Ancient DNA Tracks Multi-Kingdom Ecosystem Reorganizations Following Sequential Human Land Use at Crawford Lake.

Crawford Lake has an exceptional stratigraphic record that began recording biannual (varved) sedimentation in the lake basin ~750 years ago, preserving evidence of shifting cultural zones and agricultural practices, from Late Woodland Period Indigenous agriculturalists to the impacts of industrialization during the late 19th century. It was selected as the candidate site for the proposed 'Anthropocene' epoch in 2023-a proposal ultimately rejected in 2024-but the lake's significance extends beyond a formal stratigraphic boundary. Its sediments preserve a long record of human-ecosystem entanglement that captures the cumulative, reverberating nature of local human impacts and global change. While many proxies have been studied at the site, the lake's sedimentary ancient DNA (sedaDNA) record has yet to be investigated. Here, we report on sedaDNA preserved at Crawford Lake over the last ~1300 years. Sedentism and agriculture clearly impacted the entire lake ecosystem, with corresponding shifts observable in the sedaDNA of plants, animals, algae, fungi and bacteria. Canada goose (Branta canadensis) roosting on the lake-likely drawn by foraging opportunities in fields cleared for Three/Four Sisters agriculture and sedentism-contributed to repeated eutrophications and algal blooms that permanently shifted the lake's ecological structure. Subsequent impacts during the Euro-Canadian zone furthered anthropogenic succession, although local impacts have been minimal since closure of the sawmill in 1900 ce, allowing for sensitivity to global change. Beyond the molecular ecological history of the lake, we also evaluate the effectiveness of an Arctic/Subarctic bait-set for palaeoecological reconstructions of the Eastern Woodlands, and the preservation of lake sedaDNA.

Lakes↗
PubMedDate not supplied

Reaction of freshwater phyto- and zooplankton to pesticides.

The reaction of plankton to the toxic effect of pesticides is considered at four levels: the cell, the organism, the population, and the biocenosis. The basis for the methodological approach to evaluation of response at the cell level was the principle of phase reactions. Depending on concentration, the pesticides may either suppress or stimulate the plankton organisms. Temperature may be decisive intoxic effects (pesticides are effective in a range of 15 to 25 degrees C). Most pesticides having algacidal activity are effective in a range of concentrations of 1-10 mg/liter. Phytoplankton as a whole has a high buffer capacity with respect to pesticides. Changes in ratios of basic components of phytoplankton effected by pesticides most often lead to a change of the dominant. Analogical changes are characteristic also for zooplankton; pesticides lead to the elimination of water fleas from its composition. The stimulating effect of a low concentration of pesticides, changes in the functional activity of the components of bacterial plankton, and changes coupled with this in biogeochemical cycles of nitrogen and phosphorous as well as elimination of water fleas from the plankton promotes the development of "secondary" eutrophication, that is, an increase in the biomass of the phytoplankton.

Animals↗
PubMed1978

[Chemical parameters in coastal waters in correlation with microbiological parameters (author's transl)].

Nearly 4600 samples of coastal water from the Baltic Sea were characterized by microbiological parameters as well as by pH, ammonium, nitrite, nitrate, phosphate, and oxidizability by permanganate. Correlation of E. coli with chemical parameters varies strongly according to parameter, region, and season. Sanitary assessments can only be based on microbiological findings.--As regards eutrophication, we should expect special and more comprehensive chemical test programmes to give us substantial knowledge, whereas chemical tests after the EC guidelines for bathing waters along the Baltic Sea coast would mean considerable work and costs without getting any new results.

Escherichia coli↗
PubMed2025

Coupling of spectroscopy and nitrogen-oxygen isotopes unveils the mechanisms of dissolved organic matter and nitrate pollution in lakes within the agro-pastoral transition zone.

Lakes in arid and semi-arid regions are subjected to severe ecological stress, such as organic pollution, eutrophication, and salinization, due to climate change and human activities. This study investigates Chagannur Lake, a typical arid-region lake that is representative and ecologically sensitive in Northern China's agro-pastoral ecotone, to uncover its pollution characteristics and mechanisms. We employed fluorescence spectroscopy and stable isotope analysis to trace dissolved organic matter (DOM) and nitrate sources. The DOM composition was dominated by microbial metabolic byproducts and protein-like substances, suggesting that microbial processes are key to organic matter transformation. Source apportionment revealed that pollutants primarily originated from livestock and poultry manure (37.6 %), agricultural fertilizers (35.6 %), and soil erosion (24.7 %), with agricultural fertilizers contributing most significantly in the Gogstai River (63.3 %). A structural equation model (SEM) coupling spectral and mass spectrometric data revealed that microbial transformation significantly impairs the lake's self-purification capacity, thereby promoting pollutant accumulation (path coefficient = 0.91,*p < 0.05). Moreover, microbial processes link endogenous and exogenous pollution, a mechanism effectively traced by isotopic and fluorescence indices (path coefficient = 0.55, &#x204e;&#x204e;p < 0.01). These findings enhance the understanding of pollution sources and transformation mechanisms in arid-region lakes and offer foundational theoretical support for policymakers engaged in pollution control strategies.

Lakes↗
PubMed1979

N-formyliminodiacetic acid, a new compound from the reaction of nitrilotriacetic acid and chlorine.

It has been proposed that nitrilotriacetic acid be substituted for trisodium polyphosphates in detergents as a way to reduce the rate of eutrophication in the Great Lake Basin. The reaction of nitrilotriacetic acid with chlorine-containing solutions produces a hitherto unknown degradation production, N-formyliminodiacetic acid, in high yield. The toxicological and environmental implications of this reaction are unclear.

Acetates↗
PubMed1976

Influence of sewage discharge on nitrogen fixation and nitrogen flux from coral reefs in Kaneohe Bay, Hawaii.

Nitrogen fixation was investigated in Kaneohe Bay, Oahu, Hawaii, a subtropical eutrophic estuary, by using the acetylene reduction technique on algal samples. No active, planktonic, N2-fixing blue-green algae or bacteria were observed. However, Calothrix and Nostoc capable of fixing N2 were cultured from navigational buoys and dead coral heads. Nitrogen fixation associated with these structures was greater in the middle sector than in the south and north sectors of the estuary. Experiments demonstrated that the fixation was photosynthetically dependent. Examination of the data showed that there was no significant correlation between rates of nitrogen fixation and concentration of combined nitrogen compounds in the Bay water. Fixation was significantly correlated to the inorganic N/P (atomic) ratio in the south and middle sectors but not in the north sector. The nutrient data indicate there was a flux of combined nitrogen, but not phosphate, from the reef flats.

Acetylene↗