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15 recordsLinked to original sources

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↗

PubMed1975

Inexpensive device for the aerobic and anaerobic sampling of microorganisms in lake and shallow ocean waters.

An inexpensive device suitable for sampling microorganisms in water and easily constructed from readily available laboratory equipment is described. The need to transfer subsamples to culturing flasks after collection is eliminated by partly filling the sampling vessels with growth medium prior to sampling. The device is readily adapted for sampling different volumes, is simple and quick to operate, and is suitable for use with prereduced media. Contamination from layers others than that being sampled is insignificant.

Aerobiosis↗

PubMed2026

Littoral and wetland vegetation decrease carbon emissions from dry inland waters.

Lakes are recognized as active components of the inland water carbon (C) cycle, as organic matter is processed by microbial respiration, inducing large carbon dioxide (CO2) and methane (CH4) emissions. In the context of long-lasting drought periods, large uncertainties remain about: (1) the influence of wet-dry cycle on CO2 and CH4 fluxes in littoral zones and lacustrine wetlands; and (2) the contribution of emergent vegetation to C fluxes in dry inland waters. At the water-land interface of two shallow lakes, this study focuses on CO2 and CH4 fluxes from vegetated and bare dry inland waters in relation to hydrological fluctuations. Three seasonal campaigns were conducted to measure daytime CO2 and CH4 fluxes in pelagic, littoral and wetland surface waters, as well as in temporarily air-exposed sediments, using floating and static chambers, respectively. Our results reveal that wet-dry cycle in the littoral zone and wetlands strongly influence gaseous C fluxes through contrasting patterns, especially in late summer, when the biological processes are most active (primary production and respiration). In air-exposed littoral zones, organic-poor sandy sediments presented the lowest CO2 and CH4 emissions, whereas in air-exposed lacustrine wetlands, water-saturated sediments accumulated high amounts of plant-derived organic matter, promoting intense microbial activity and the highest C emissions. However, amphiphytes and helophytes vegetation in exposed littoral zones and wetlands reversed the direction of C fluxes, inducing the highest CO2 uptake due to high photosynthesis rates. This study underlines the relevance of considering vegetation in dry inland waters, particularly in lacustrine littoral zones and wetlands, to obtain comprehensive lake C budgets, especially under climate change scenarios.

Wetlands↗

PubMedDate not supplied

[Diplostomiasis in fishes in lake farms and the ways for its control].

Diplostomosis is the most common disease affecting Coregonidae in lakes of Karelia where intensive fish farming is conducted. The most acute form of diplostomosis, cercariosis, is especially dangerous for larvae introduced into small water bodies. Depending on a season or weather conditions a shift in the infection rate of fishes with metacercariae takes place. Some ways for diplostomatosis prophylaxis are being suggested. Relatively shallow lakes with low miniralisation of water of sulphate type have been found to be most suitable for Coregonidae nurseries. The very specificity of the intensive use of lakes for fish farming offers possibilities for diplostomosis development. In lakes-nurseries with a regulated water regime the abundance of Lymnaeidae can be reduced by winter draining off the water. The chemical control of mollusks, local use of copper sulphate, is also possible under lake conditions.

Animals↗

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↗

PubMedDate not supplied

Respiratory health effects of alkali dust in residents near desiccated Old Wives Lake.

Several years of drought have contributed to the desiccation of Old Wives Lake, a shallow, alkaline lake in southern Saskatchewan. The prevailing northwest wind, which blows across the 177-km2 dry lake bed, has generated airborne sodium sulfate, silt, and clay. Residents have reported nasal, eye, and respiratory irritation. A cross-sectional design that included 300 controls and 300 exposed subjects elucidated the potential adverse respiratory health effects of exposure to blowing alkali salt and dust. An increased prevalence of current cough, current wheeze, chronic cough, chronic wheeze, chronic eye irritation, and chronic nasal irritation was identified in the exposed population. Smoking-adjusted odds ratios were consistent with the prevalence ratios. Lung function did not differ between the exposed and the control populations. Rainfall during the study period reduced airborne dust levels and may have precluded demonstration of previously reported adverse effects.

Adult↗

PubMed1989

Environmental stress in five aquatic ecosystems in the floodplain of the River Rhine.

General theories of stress ecology were applied to aquatic communities in the floodplain of the polluted River Rhine. These communities inhabited (i) a brackish section of the Ems-Dollard estuary with large intertidal flats, (ii) the coastal waters of the North Sea and the adjacent Wadden Sea, (iii) a former estuary of the Rivers Rhine and Meuse: the newly endiked Lake Grevelingen, (iv) the shallow Loosdrecht Lakes, and (v) the lower River Rhine. These systems are characterized by natural perturbations, such as suspension of sediments and flushing of the shallow waters. Organic pollution, eutrophication and chemical pollution reinforce the natural tendency to severe selection in the communities, in extreme cases leading to an abundance of small and opportunistic species participating in relatively simple food chains. Signs of ecosystem distress, as defined by Rapport et al., were detectable in all five ecosystems. The application of the theory of Odum et al. on stimulation and inhibition of ecosystems helped in identifying the positive impact of man. The role of stress in natural aquatic ecosystems in the delta, together with observations on ecological recovery under reduced man-made perturbation, suggest that there is scope for effective water management that exploits the resilience of these ecosystems.

Animals↗

PubMed1991

[Botulism in birds living in an aquatic environment in Nové Mlýny in the Breclav District].

Epizootic of wild water birds caused by the toxin Clostridium botulinum of C type occurred in extensive shallow artificial lakes of the Nové Mlýny dam system from May to October 1988 and later on from February to early April 1989. In total more than 3,000 dead or dying birds of 44 species were found, the following orders were prevailing: Anseriformes (56%), Lariformes (33%), Charadriiformes (6%) and Ralliformes (4%). Botulotoxin was detected at high concentrations in sarcophagic fly larvae of Calliphora vomitoria and Lucilia sericata which were collected in bird cadavers, but it was not found in different components of the aquatic environment (water, submersed vegetation, phytoplankton, zooplankton, Gastropoda, Crustacea, Oligochaeta, larvae of Odonata, Chironomidae and Ceratopogonidae). Future development of the epizootic situation in the Nové Mlýny artificial lakes will depend on the water level and meterological conditions in the critical period (May to September).

Animals↗

PubMedDate not supplied

Characteristics of three acidic lakes in Kejimkujik National Park, Nova Scotia, Canada.

This report summarizes a study of the chemical and biological characteristics of three oligotrophic lakes located in a region that receives a moderately acidic precipitation (mean annual pH 4.5-4.6), and a sulfate deposition of about 20 kg/ha/yr. The two brownwater lakes are relatively acidic (pH 4.5 and 4.8), and much of their acidity is attributable to organic anions. The brownwater lakes also have a large concentration of aluminum and iron, but these are bound to dissolved organic matter and are relatively non-toxic to biota. Average phytoplankton production was largest in the clearwater lake. This was due to its relatively deep euphotic zone, since the average unit-volume productivity did not differ much among the lakes. In fact, productivity at light optimum was largest in the most acidic brownwater lake, probably because of its larger phosphorus concentration. The clearwater lake had extensive macrophyte vegetation, which covered its bottom to a depth of 6.5 m. In the brownwater lakes, macrophytes were confined to shallow nearshore water because of the limited water transparency. Zooplankton density and biomass were largest in the most acidic brownwater lake, probably because of allochthonous organic particulates and little fish predation. Benthic invertebrates were abundant in all three lakes, and were dominated by insects, especially Chironomids. Lakes in the study area appear to be sustaining fish populations at more acidic pHs than elsewhere. This may be due to the large concentration of dissolved organic matter in many lakes, which complexes and partially detoxifies metals such as aluminum.

Acid Rain↗

PubMed2025

Rapid Divergence of Visual Systems and Signaling Traits to Contrasting Light Regimes During Early Speciation of African Crater Lake Cichlid Fish.

Sensory adaptation is widely hypothesized to drive ecological speciation, yet empirical evidence from natural populations undergoing early stage divergence remains limited. In Lake Masoko, a young crater lake in East Africa, the haplochromine cichlid Astatotilapia calliptera is undergoing early stage sympatric speciation into shallow-water littoral and deep-water benthic ecotypes that experience contrasting light environments. Here, we integrate retinal transcriptomics, phenotypic analyses, and visual modeling to uncover rapid sensory divergence associated with this ecological transition. We find striking shifts in cone opsin expression, with the benthic ecotype exhibiting a switch from short-wavelength sensitive SWS2B to SWS2A and an overall narrowing of cone sensitivity toward the center of the light spectrum, consistent with changes in deep-water light environment. In contrast, coding sequence variation in opsin genes was limited and no significant differences in allele frequencies were detected across nine polymorphic sites, pointing to expression regulation as the primary axis of early divergence in visual systems. In parallel, we observed divergence in male signaling traits, with benthic males displaying deeper red egg-spots, aligning with predictions from visual modeling of signal efficiency in different light environments. These results demonstrate rapid transcriptomic and phenotypic divergence in associated signaling traits-within ∼1,000 years-supporting a potential role for regulatory evolution in sensory adaptation during early ecological speciation.

Animals↗

PubMed1991

Evaluation of gill nets, fyke nets, and mark-recapture methods to estimate the number of Hirudinea and Crustacea on fish.

Twenty species of fishes (n = 20,759) were collected from Dauphin Lake, Manitoba, Canada, to determine the types and numbers of ectoparasites they harbored. Counts of ectoparasites on fishes collected with different gear were compared to evaluate different methods of collection and to estimate rates of recruitment of ectoparasites by fishes. Ectoparasites were found on 11 species of fishes and the majority of these were parasitic leeches (Myzobdella moorei, Cystobranchus verilli, and Placobdella montifera) and parasitic Crustacea (Argulus appendiculosus and Lernaea cyprinacea). Some fishes also were infested by neascus-type metacercariae (blackspot) or had tumors (lymphocystis). The prevalence of ectoparasites was correlated with the abundance, feeding habits, and spatial distribution of fish species. Argulus appendiculosus and blackspot were more prevalent on benthic fishes, whereas M. moorei and tumors were more prevalent on limnetic fishes. Mark-recapture records showed that fishes occupying shallow (less than or equal to 1.5 m) water had a higher prevalence of infestation and 28 of 29 infected fishes caught by gill nets were captured in shallow water. Placobdella montifera was the only ectoparasite found on fishes from deep (1.5-3.5 m) water and the only species that was acquired by fishes previously released with no ectoparasite (2 of 239 fishes). The littoral zone (less than or equal to 1.5 m) comprises only 14% of the surface area and 3% of the volume of Dauphin Lake, yet 72% of all gill-netted fishes harboring ectoparasites were collected there. Intensities of ectoparasites estimated from gill net and pound net samples were similar, but prevalence of ectoparasites estimated from samples obtained with gill nets was lower.

Animals↗

PubMed1979

The epidemiology of schistosomiasis in the vicinity of Lake Sibaya, with a note on other areas of Tongaland (Natal, South Africa).

The epidemiology of human and bovine schistosomiasis in the Lake Sibaya area of Tongaland, South Africa, an undeveloped rural environment, is discussed. The mean prevalence of Schistosoma haematobium infection is 72%, but S. mansoni is absent; possible reasons for this are given and the different types of water habitat are shown to play different roles in transmission. Fear of crocodiles and hippopotami is important because villagers are compelled to use for domestic purposes, the smaller, shallower habitats, where Bulinus (Ph.) globosus occurs but not Biomphalaria pfeifferi, rather than the deeper, larger ones where both snails are found. This discontinuous distribution of B. pfeifferi in the deeper sites, due to the high temperatures in spring, is viewed in relation to local climatic conditions. A human population influx, such as would result from the economic development of Tongaland, would cause not only a decline in crocodile and hippopotamus populations, and thus encourage human contact with the deeper waterbodies, but would favour the introduction of S. mansoni into at least some of these habitats. A similar prevalence pattern of human schistosomiasis exists over the remainder of Tongaland and the lowlands of southern and central Mozambique. The mean prevalence of Schistosoma mattheei in Tongaland cattle is 42% and although data are not available a comparable percentage seems likely in Mozambique.

Adolescent↗

PubMed1976

Temperature limitation of methanogenesis in aquatic sediments.

Microbial methanogenesis was examined in sediments collected from Lake Mendota, Wisconsin, at water depths of 5, 10, and 18 m. The rate of sediment methanogenesis was shown to vary with respect to sediment site and depth, sampling date, in situ temperature, and number of methanogens. Increased numbers of methanogenic bacteria and rates of methanogenesis correlated with increased sediment temperature during seasonal change. The greatest methanogenic activity was observed for 18-m sediments throughout the sampling year. As compared with shallower sediments, 18-m sediment was removed from oxygenation effects and contained higher amounts of ammonia, carbonate, and methanogenic bacteria, and the population density of methanogens fluctuated less during seasonal change. Rates of methanogenesis in 18-m sediment cores decreased with increasing sediment depth. The optimum temperature, 35 to 42 C, for sediment methanogenesis was considerably higher than the maximum observed in situ temperature of 23 C. The conversion of H2 and [14C]carbonate to [14C]methane displayed the same temperature optimum when these substrates were added to sediments. The predominant methanogenic population had simple nutritional requirements and were metabolically active at 4 to 45 C. Hydrogen oxidizers were the major nutritional type of sediment methanogens; formate and methanol fermentors were present, but acetate fermentors were not observed. Methanobacterium species were most abundant in sediments although Methanosarcina, Methanococcus, and Methanospirillum species were observed in enrichment cultures. A chemolithotropic species of Methanosarcina and Methanobacterium was isolated in pure culture that displayed temperature optima above 30 C and had simple nutritional requirements.

Cell Count↗

PubMed1988

Schistosomiasis in Kano State, Nigeria. I. Human infections near dam sites and the distribution and habitat preferences of potential snail intermediate hosts.

Stool and urine samples from 813 schoolchildren and adults from the Tomas and Rimin Gado dam areas of Kano State, Nigeria, showed Schistosoma haematobium to be present at both localities with prevalences of 26.6 and 36.8%, respectively. No cases of S. mansoni were found. The prevalence and intensity of S. haematobium was low and similar in both study areas. Statistical analysis revealed a correlation between prevalence and location, but no evident association with professed patterns of water contact. Investigation of 165 freshwater habitats throughout the state revealed the presence of a number of potential snail intermediate host species, namely Bulinus senegalensis, B. forskali, B. globosus, B. rohlfsi and Biomphalaria pfeifferi. The most widespread species was Bulinus senegalensis, which inhabited shallow pools and excavations on a variety of substrata. Its habitats were typically devoid of aquatic vegetation and included those with highly turbid waters and conductivities as low as 11 microseconds. Bulinus forskali was by contrast relatively rare, occurring in more permanent water courses, although it was often found in mixed populations with B. senegalensis. Bulinus globosus also occurred in seasonally rainfilled pools, but was confined to areas south of the 12 degrees N parallel, and its habitats tended to have a well-developed aquatic flora and clear water. The dominant species in man-made lakes was B. rohlfsi, which occurred in both the Tomas and Rimin Gado reservoirs. Biomphalaria pfeifferi was also primarily lake dwelling, although all species save B. senegalensis were found in irrigation canals.

Adolescent↗

PubMed1991

Altered performance of white sucker populations in the Manitouwadge chain of lakes is associated with changes in benthic macroinvertebrate communities as a result of copper and zinc contamination.

White sucker (Catostomus commersoni) collected from the Manitouwadge chain of lakes show a lower growth rate and fecundity in lakes contaminated with copper and zinc from a mixed metal mine. This study evaluated whether the changes in performance of the fish were related to direct impacts of the metals or indirect impacts associated with changes in food availability. Concentrations of metals in the water and sediment of lakes in the Manitouwadge chain were elevated, relative to reference sites. The concentrations of Cu and Zn in the digesta of white sucker were significantly higher, as were the levels of both Cu and Zn in liver, kidney, and gill tissue. Muscle and spleen levels of Cu and Zn were significantly lower or not different from controls. Tissue levels were within the homeostatic range for Cu and Zn. However, the total density of invertebrates varied from greater than 25,000 m-2 at control sites to less than 13,000 m-2 at contaminated sites, and the number of genera recorded was more than 50% lower in shallow water samples. There was almost a complete absence of several invertebrate taxa at contaminated sites, including Plecoptera, Ephemeroptera, Odonata, Trichoptera, Amphipoda, and Unionidae. Diptera accounted for 78 to 96% of the total numbers of individuals at metal-contaminated sites as compared with 40 to 75% at the control sites. An analysis of white sucker stomach contents showed that the contents closely reflected the benthic composition observed in the natural substrate. Changes in food availability and feeding activity were correlated with previous changes documented in the growth, fecundity, and lipid levels of white sucker.

Animals↗