The role of sediment microbial food webs in the recovery of acidified lakes (original) (raw)

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Impact of Water Column Acidification on Protozoan Bacterivory at the Lake Sediment-Water Interface

Applied and Environmental Microbiology, 1991

Although the impact of acidification on planktonic grazer food webs has been extensively studied, little is known about microbial food webs either in the water column or in the sediments. Protozoon-bacterium interactions were investigated in a chronically acidified (acid mine drainage) portion of a lake in Virginia. We determined the distribution, abundance, apparent specific grazing rate, and growth rate of protozoa over a pH range of 3.6 to 6.5. Protozoan abundance was lower at the most acidified site, while abundance, in general, was high compared with other systems. Specific grazing rates were uncorrelated with pH and ranged between 0.02 and 0.23 h-1, values similar to those in unacidified systems. The protozoan community from an acidified station was not better adapted (P = 0.95) to low-pH conditions than a community from an unacidified site (multivariate analysis of variance on growth rates for each community incubated at pHs 4, 5, and 6). Both communities had significantly lower (P < 0.05) growth rates at pHs 4 and 5 than at pH 6. Reduced protozoan growth rates coupled with high grazing rates and relatively higher bacterial yields (ratio of bacterial-protozoan standing stock) at low pH indicate reduced net protozoan growth efficiency and a metabolic cost of acidification to the protozoan community. However, the presence of an abundant, neutrophilic protozoan community and high bacterial grazing rates indicates that acidification of Lake Anna has not inhibited the bacterium-protozoon link of the sediment microbial food web.

Bacterial activity in sediments of lakes receiving acid precipitation

Environmental Pollution Series A, Ecological and Biological, 1984

A BS TRA C T Bacteriological dataJor water and sediment coresJrom some oJ the lakes receiving acid precipitation near Sudbury, Ontario, show a strong relationship between lake acidification and bacteria, pH values below about 5"5 appear to be critical for respiring and aerobic heterotrophic bacteria. Total bacteria in the waters of these lakes existed in the 10 6 ml-l range while the viable or activepopulations were approximately two orders oJ magnitude lower. In the sediments, a relationship was demonstrated between pH, bacterial populations, sediment microbial activity, and total organic matter. In the acid-stressed Silver Lake (pH 3"8) the sediment respiration was 10-20 % oJ that in the non-acidstressed McFarlane Lake (pH 7.2). Associated with this, a strong correlation was demonstrated between pH and total organic matter in surficial sediments.

Bacterial Community Structure of Acid-Impacted Lakes: What Controls Diversity?

Applied and Environmental Microbiology, 2008

Although it is recognized that acidification of freshwater systems results in decreased overall species richness of plants and animals, little is known about the response of aquatic microbial communities to acidification. In this study we examined bacterioplankton community diversity and structure in 18 lakes located in the Adirondack Park (in the state of New York in the United States) that were affected to various degrees by acidic deposition and assessed correlations with 31 physical and chemical parameters. The pH of these lakes ranged from 4.9 to 7.8. These studies were conducted as a component of the Adirondack Effects Assessment Program supported by the U.S. Environmental Protection Agency. Thirty-one independent 16S rRNA gene libraries consisting of 2,135 clones were constructed from epilimnion and hypolimnion water samples. Bacterioplankton community composition was determined by sequencing and amplified ribosomal DNA restriction analysis of the clone libraries. Nineteen bacterial classes representing 95 subclasses were observed, but clone libraries were dominated by representatives of the Actinobacteria and Betaproteobacteria classes. Although the diversity and richness of bacterioplankton communities were positively correlated with pH, the overall community composition assessed by principal component analysis was not. The strongest correlations were observed between bacterioplankton communities and lake depth, hydraulic retention time, dissolved inorganic carbon, and nonlabile monomeric aluminum concentrations. While there was not an overall correlation between bacterioplankton community structure and pH, several bacterial classes, including the Alphaproteobacteria, were directly correlated with acidity. These results indicate that unlike more identifiable correlations between acidity and species richness for higher trophic levels, controls on bacterioplankton community structure are likely more complex, involving both direct and indirect processes.

EFFECT OF pH ON THE GROWTH AND ACTIVITY OF HETEROTROPHIC SEDIMENT MICROORGANISMS

Low pH markedly reduced heterotrophic microbial activity in sediment-lake water systems. A marked reduction in both the rate and the total amount of oxygen consumed occurred as pH decreased. In addition, low pH and also low temperature (O°C) resulted in longer turnover times (Tn) and also smaller V values when the kinetics of 14C-glucose, 14C-glycine, and 4C_g I max I utamic acid utilization were examined. When the response of the microorganisms to heavy metals was examined, mercury was generally more toxic than lead over the pH range of 4.5 to 7.5 but both metals were more toxic at pH 4.5 than at higher pH levels. Mercury also inhibited oxygen utilization and 14C-glucose mineralization more than lead at all pH levels. Bisulfite reduced microbial activity at all pH levels although it was always more toxic to the sediment microorganisms at pH values of 4 and 5 than at pH 7. INTRODUCTION Acid precipitation has decreased the pH of many poorly buffered lakes, rivers, and streams in North American and in Scandinavian countries (I). In many lakes, pH values of 4 to 4.5 are not uncommon (2). If the present trends of acidification continue, or increase, many more waters will be seriously affected (3-5). Although some of the biological aspects of acidification

Cultivable Microbial Diversity in An Acidic Temperate Lake, Lake Phelps, NC

Journal of North Carolina Academy of Science, 2013

Despite the immense benefit of freshwater habitats to the day to day activities of humans, their biological diversity remains understudied. Microbial diversity and community structure is critical to the study of ecological processes in these habitats. The naturally acidic oligotrophic lake, Lake Phelps, NC, was studied within the context of understanding sediment dwelling meiofauna using the cultivable microbial communities at three sites in the water column and sediment. Twenty-six bacterial isolates were cultivated, biochemically tested and sequenced. DNA sequence analyses of the 16S ribosomal subunit revealed 26 taxa representing three phyla (12 Proteobacteria, 12 Firmicutes, and 2 Bacteroidetes), four classes (12 Bacilli, 6 β-proteobacteria, 4 γ-proteobacteria, and 2 Flavobacteria), and six bacterial orders (12 Bacillales, 6 Neisseriales, 2 Burkholderiales, 4 Enterobacteriales, and 2 Flavobacteriales). Bacterial communities at the three sampling sites were distinct and this may ...

Heterotrophic microbial activity in lake sediments: effects of organic electron donors

Biogeochemistry, 2010

Allochthonous and autochthonous organic matter deposited in benthic sediments are mineralized by microbial communities, resulting in release of nutrients to the water column. Lakes with different trophic states may have sediments with different carbon and nutrient concentration with consequently different microbial communities. Microbial diversity of surface sediments of three subtropical lakes of different trophic state was investigated by measuring catabolic response to a wide variety of carbon-substrates. Basal carbon dioxide and methane production rates were highest in Lake Apopka (hypereutrophic), followed by Lake Annie (oligo-mesotrophic) and Lake Okeechobee (eutrophic) sediments. The oligo-mesotrophic Lake Annie showed the highest metabolic quotient (qCO 2 ; proportion of basal respiration per unit of microbial biomass, 0.008 ± 0.001) indicating inefficient use of energy. The low qCO 2 found in Lake Apopka sediment indicated higher efficiency in using energy. Lake Okeechobee sediments had intermediary values of qCO 2 (M9 0.005 ± 0.001; M17 0.006 ± 0.0003; KR 0.004 ± 0.001) as compared with other lakes (lake Apopka 0.004 ± 0.14). Lake Apopka's sediment catabolic diversity was higher than that observed in other sediments. Addition of organic electron donors to sediment samples from all lakes stimulated heterotrophic activity; however, the extent of the response varied greatly and was related to microbial biomass. The hypereutrophic Lake Apopka sediments had the highest respiration per unit of microbial biomass with the addition of electron donors indicating that these sediments respired most of the C added. These results showed that sediments with different biogeochemical properties had microbial communities with distinct catabolic responses to addition of the C sources.

Similar Bacterial Community Composition in Acidic Mining Lakes with Different pH and Lake Chemistry

Microbial Ecology, 2010

As extreme environmental conditions strongly affect bacterial community composition (BCC), we examined whether differences in pH-even at low pH-and in iron and sulfate concentrations lead to changes in BCC of acidic mining lakes. Thereby, we tested the following hypotheses: (1) diversity of the bacterial community in acidic lakes decreases with reducing pH, (2) BCC differs between epilimnion and hypolimnion, and (3) BCC in extremely acidic environments does not vary much over time. Therefore, we investigated the BCC of three acidic lakes with different pH values (2.3, 2.7, and 3.2) by denaturing gradient gel electrophoresis (DGGE) and subsequent sequencing of DGGE bands as well as catalyzed reporter deposition-FISH (CARD-FISH). BCC did not significantly vary among the studied lakes nor differ much between water layers. In contrast, BCC significantly changed over time, which is contradictory to our hypoth-eses. Bacterial communities were dominated by Alpha-, Beta-, and Gammaproteobacteria, whereas Actino-and Acidobacteria rarely occurred. Cell numbers of both free and attached bacteria were positively related to DOC concentration. Overall, low pH and extreme chemical conditions of the studied lakes led to similar assemblages of bacteria with pronounced temporal differences. This notion indicates that temporal changes in environmental conditions including food web structure also affect unique communities of bacteria thriving at low pH.

Diversity and in situ quantification of Acidobacteria subdivision 1 in an acidic mining lake

FEMS Microbiology Ecology, 2000

Analysis of 16S rRNA gene clone libraries from acidic mining lake water and sediment, and from an enclosure to which organic carbon was added to stimulate microbial alkalinization processes of sulfate and iron reduction revealed the presence of diverse sequences affiliated with the Acidobacteria subdivision 1. A novel oligonucleotide probe, ACIDO228, was designed that covered most sequences of Acidobacteria subdivision 1. The hybridization conditions were optimized using the type strain Acidobacterium capsulatum. The depth distribution and seasonal dynamics of Acidobacteria in the lake and the enclosure were assessed by whole cell hybridization. Sequence analyses and in situ quantification indicated that Acidobacteria accounted for a substantial part of bacterioplankton communities in both compartments. During the summer stratification distinct maxima of acidobacterial abundance were detected in the hypolimnion (up to 13% of total cell numbers), whereas during spring and autumn circulations no clear depth-dependent differences were visible. These data suggest that Acidobacteria thrive best in the hypolimnion, which is characterized by lower temperatures and higher availability of organic substrates. The application of probe ACIDO228 provided quantitative information on the seasonal and depth distribution of Acidobacteria in a lake environment and in particular in a rather extreme habitat, an acidic mining lake. Ã Refers to the phylum Acidobacteria according to the RDP classification. w Number in parentheses includes also RDP sequences referred to as 'unclassified bacteria'.

Influence of acid precipitation on bacterial populations in lakes

Hydrobiologia, 1983

Relative abundance of total, respiring, aerobic heterotrophic, nitrogen cycle and sulfur cycle bacteria was measured in acid stressed and non-acid stressed hard water lakes. Data indicated that bacterial populationsand densities were nearly an order of magnitude less in acid stressed waters than in non-acid stressed waters. Nitrifying bacteria and some sulfur cycle bacteria (Thiobacillus sp.) were very low or absent in acid stressed waters. Surface sediments of acid stressed lakes contained 3 to 4 times more organic matter than the amount found in the relatively more enriched lake. Methodology and data are presented.