Dataset Information

Salinity as a Determinant Structuring Microbial Communities in Coastal Lakes.

ABSTRACT: The response of bacterioplankton structure to salinity level in coastal lakes (n = 9) along the southern Baltic Sea coastline was studied. In terms of mean salinity levels (0.2-5.2 PSU), the lakes represented freshwater, transitional, and brackish types. Results showed that salinity determines the spatial and seasonal distribution patterns of microorganisms in costal lakes. Increased salinity contributed to a significant decline in total bacterial numbers (TBN). The TBN was lowest in brackish lakes in autumn (4 × 10⁶ cells/mL) and highest in freshwater lakes in summer (7.11 × 10⁶ cells/mL). The groups of Proteobacteria are appropriate bioindicators in any classifications of coastal ecosystems, particularly at low-haline stress. Alpha- and Gamma- subclasses of Proteobacteria are identifiers for brackish habitats, while Betaproteobacteria, due to their intolerance to haline stress, prefer freshwater habitats. Counts of euryhaline Actinobacteria, the dominant group of bacterioplankton (31.8%), decreased significantly with increased salinity. Actinobacteria and Deltaproteobacteria were identifiers of transitional lakes. Cytophaga-Flavobacteria showed affinity with freshwater ecosystems, but this relation was not statistically significant (p > 0.05). The bacteria groups correlated with other physico-chemical parameters of water, such as oxygenation (Actinobacteria) or organic carbon (Betaproteobacteria, Deltaproteobacteria). The impact of hydrological connectivity and salt-water interference on the microbiota structure and biogeochemistry of coastal waters should be considered in the assessment of the ecological status of coastal lakes.

SUBMITTER: Lew S

PROVIDER: S-EPMC9028135 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

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Salinity as a Determinant Structuring Microbial Communities in Coastal Lakes.

Lew Sylwia S Glińska-Lewczuk Katarzyna K Burandt Paweł P Kulesza Klaudia K Kobus Szymon S Obolewski Krystian K

International journal of environmental research and public health 20220411 8

The response of bacterioplankton structure to salinity level in coastal lakes (n = 9) along the southern Baltic Sea coastline was studied. In terms of mean salinity levels (0.2−5.2 PSU), the lakes represented freshwater, transitional, and brackish types. Results showed that salinity determines the spatial and seasonal distribution patterns of microorganisms in costal lakes. Increased salinity contributed to a significant decline in total bacterial numbers (TBN). The TBN was lowest in brackish la ...[more]

PMID: 35457457

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Project description:Soil salinization is a growing environmental problem caused by both natural and human activities. Excessive salinity in soil suppresses growth, decreases species diversity, and alters the community composition of plants; however, the effect of salinity on soil microbial communities is poorly understood. Here, we characterize the soil microbial community along a natural salinity gradient in Gurbantunggut Desert, Northwestern China. Microbial diversity linearly decreased with increases in salinity, and community dissimilarity significantly increased with salinity differences. Soil salinity showed a strong effect on microbial community dissimilarity, even after controlling for the effects of spatial distance and other environmental variables. Microbial phylotypes (n = 270) belonging to Halobacteria, Nitriliruptoria, [Rhodothermi], Gammaproteobacteria, and Alphaproteobacteria showed a high-salinity niche preference. Out of nine potential phenotypes predicted by BugBase, oxygen-related phenotypes showed a significant relationship with salinity content. To explore the community assembly processes, we used null models of within-community (nearest-taxon index [NTI]) and between-community (βNTI) phylogenetic composition. NTI showed a significantly negative relationship with salinity, suggesting that the microbial community was less phylogenetically clustered in more-saline soils. βNTI, the between-community analogue of NTI, showed that deterministic processes have overtaken stochastic processes across all sites, suggesting the importance of environmental filtering in microbial community assembly. Taken together, these results suggest the importance of salinity in soil microbial community composition and assembly processes in a desert ecosystem. IMPORTANCE Belowground microorganisms are indispensable components for nutrient cycling in desert ecosystems, and understanding how they respond to increased salinity is essential for managing and ameliorating salinization. Our sequence-based data revealed that microbial diversity decreased with increasing salinity, and certain salt-tolerant phylotypes and phenotypes showed a positive relationship with salinity. Using a null modeling approach to estimate microbial community assembly processes along a salinity gradient, we found that salinity imposed a strong selection pressure on the microbial community, which resulted in a dominance of deterministic processes. Studying microbial diversity and community assembly processes along salinity gradients is essential in understanding the fundamental ecological processes in desert ecosystems affected by salinization.

Project description:Salinity stress is one of the critical environmental drivers of soil organic matter (SOM) decomposition in coastal ecosystems. Although the temperature sensitivity (Q10) of SOM decomposition has been widely applied in Earth system models to forecast carbon processes, the impact of salinity on SOM decomposition by restructuring microbial communities remains uncovered. Here, we conducted a microcosm experiment with soils collected from the coastal salt marsh in the Yellow River Estuary, which is subjected to strong dynamics of salinity due to both tidal flooding and drainage. By setting a gradient of salt solutions, soil salinity was adjusted to simulate salinity stress and soil carbon emission (CO2) rate was measured over the period. Results showed that as salinity increased, the estimated decomposition constants based on first-order kinetics gradually decreased at different temperatures. Below the 20‰ salinity treatments, which doubled the soil salinity, Q10 increased with increasing salinity; but higher salinity constrained the temperature-related response of SOM decomposition by inhibiting microbial growth and carbon metabolisms. Soil bacteria were more sensitive to salinity stress than fungi, which can be inferred from the response of microbial beta-diversity to changing salinity. Among them, the phylotypes assigned to Gammaproteobacteria and Bacilli showed higher salt tolerance, whereas taxa affiliated with Alphaproteobacteria and Bacteroidota were more easily inhibited by the salinity stress. Several fungal taxa belonging to Ascomycota had higher adaptability to the stress. As the substrate was consumed with the incubation, bacterial competition intensified, but the fungal co-occurrence pattern changed weakly during decomposition. Collectively, these findings revealed the threshold effect of salinity on SOM decomposition in coastal salt marshes and emphasized that salt stress plays a key role in carbon sequestration by regulating microbial keystone taxa, metabolisms, and interactions.

Project description:Coastal lakes are subject to multiple stressors, among which land use, hydrological connectivity, and salinity have the greatest effect on their biodiversity. We studied the effects that various land cover types (CORINE) of coastal lake watersheds had on macrophyte diversity in ten coastal lakes along the southern Baltic coast as characterised by twelve phytocenotic indices: these being a number of communities, Shannon-Wiener diversity, evenness, and indices of taxonomic distinctiveness of plant communities: vegetation coverage; colonisation index; share of the phytolittoral area in the total lake area, as well as shares of nympheides, pondweeds, charophytes, marine, emerged and submerged communities in the total lake area. The effects were checked for three groups of lakes distinguished by differences in salinity-freshwater (F, 5), transitional (T, 4), and brackish (B, 1)-in which a total of 48 macrophyte communities were identified. The most abundant in aquatic phytocoenoses were lakes of T type. A partial least squares regression model (PLS-R) showed a stronger impact of land-use types in immediate vicinities and entire watersheds than the impact of physico-chemical properties of water on phytocenotic indices in the lakes. Macrophyte diversity was relatively low in urban and agricultural catchments and relatively high in forest and wetland areas. Agriculture had a negative impact on the number of macrophyte communities in F lakes and, in T lakes, on the number of macrophyte communities, biodiversity, evenness, and proportion of emerged, submerged, and marine communities. Urban areas contributed to lower values of evenness, vegetation coverage, and share of marine communities in F, but, in T, to lower the number of macrophyte communities, evenness, and proportion of submerged and marine communities. Our results confirm the significant impact of land use on macrophyte diversity in coastal aquatic ecosystems. Combined analysis of anthropogenic and natural descriptors is a prerequisite for analysing human threats to biodiversity in coastal lakes. Macrophyte community-based measures of biodiversity are sensitive indicators of anthropogenic impact on the ecological condition of coastal ecosystems.

Dataset Information

Salinity as a Determinant Structuring Microbial Communities in Coastal Lakes.

Publications

Salinity as a Determinant Structuring Microbial Communities in Coastal Lakes.

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