Productivity and rainfall drive bacterial metabolism in tropical cascading reservoirs

Freitas, Roberta Mafra; Vieira, Helena; Moraes, Guilherme Pavan de; Melo, Michaela Ladeira de; Vieira, Armando Augusto Henriques; Sarmento, Hugo

doi:10.1007/s10750-017-3472-0

Cited by 10 publications

(10 citation statements)

References 63 publications

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“…Although bacterial production is expected to be low in the tropics due to constant high temperatures, the dominating presence of bacteria in the study's lakes may have been due to increased nutrient inputs, both anthropogenic or from terrestrial runoff. This has been shown to be the primary guiding factor for bacterial growth in similar environments (Scofield et al, 2015;Freitas et al, 2017), and many studies have acknowledged the critical role of bacterial communities in freshwater food webs (Newton et al, 2011). Based on our results, near bottom POM was characterized more by bacteria-and Type II MOB-specific FAs, while surface POM was associated with cyanobacteria and diatoms (Fig.…”

Section: Discussionsupporting

confidence: 55%

Identification of aquatic consumer trophic pathways in four volcanic tropical lakes using fatty acid biomarkers

et al. 2022

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Food web studies rely heavily on the use of traditional gut content analysis or the fairly popular stable isotope analysis rather than fatty acid analysis (FAA) despite its straightforward process, and ability to identify and characterize more diverse trophic pathways. In this study, we employed fatty acid (FA) biomarkers as a preliminary attempt to trace and characterize trophic pathways in food webs of four tropical lakes of volcanic origin in Luzon Island, Philippines - three clustered maar lakes (Yambo, Pandin and Calibato) and a large caldera lake (Taal). These lakes have a long history of human disturbance but limited ecological data. Knowledge of basal food sources and existing trophic dynamics of organisms are generally non-existent. Particulate organic matter (POM), zooplankton, and fish species were collected in August 2019 from the study lakes as representative of three trophic guilds. Non-metric multidimensional scaling (NMDS) and principal component analysis (PCA) were conducted to analyse FA profiles and characterize trophic relationships between representative organisms. For the POM, within lakes comparison of taxon-specific FA profiles showed a significant difference between the surface and near bottom depths, with the former dominated by photoautorophs and the latter by chemotrophs, suggesting the ability of FAA to effectively delineate between micro-organisms. Between lakes comparison also showed significant difference between the caldera and maar lakes, with the latter containing higher composition of bacterial FA, reminiscent of the considerably smaller lakes’ response to the impact of unmitigated organic loadings from anthropogenic activities. Taken together with the primary consumers’ FA profiles, analysis confirmed the ability of FAA to discriminate between FA profile sources. PCA explained >70% of the variance in the FA compositions for three trophic guilds in the two deepest lakes, which delineated both zooplankton and fish species food selectivity in each lake, alluding to FAA’s capacity to characterize dietary reliance of various species in an environment with numerous food sources. Although certain limitations were encountered, such as the specificity of the sampling depths for POM, and the small sample size of the representative species of the third trophic level, this study demonstrated the effectiveness of FAA as a powerful ecological tool for disentangling intricate lake food webs comprising various food sources. Overall, this study provided baseline information on basal food sources and trophic pathways of representative organisms from four tropical lakes. Taken together, FAA studies have wide application in understanding food webs, including anthropogenically-threatened lake ecosystems.

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Section: Discussionsupporting

confidence: 55%

Identification of aquatic consumer trophic pathways in four volcanic tropical lakes using fatty acid biomarkers

et al. 2022

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“…Changes in intra-annual rainfall and long periods of drought can alter the water volume in lakes, and in the Nhecolandia region, some lakes can be completely dry, as occurred in 2017, 2020, and 2021. Hydrology is a key driver of phytoplankton and heterotrophic bacterial communities in tropical freshwater lakes, as well as soda lakes [43,44]. Water dynamics impact nutrient concentration and its flux by modulating the diverse components of the system [45].…”

Section: Discussionmentioning

confidence: 99%

Bacterial Communities Along Environmental Gradients in Tropical Soda Lakes

et al. 2022

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Soda lakes environment is known to be variable and can have distinct differences according to geographical location. In this study, we investigated the effect of different environmental conditions of six adjacent soda lakes on bacterial communities and their functioning using a metagenomic approach combined with flow cytometry and chemical analyses. Ordination analysis using flow cytometry and water chemistry data from two sampling periods (wet and dry) clustered soda lakes in three different profiles: eutrophic turbid (ET), oligotrophic turbid (OT), and clear vegetated oligotrophic (CVO). Analysis of bacterial community composition and functioning corroborated this ordination; the exception was one ET lake, that was similar to one OT lake during the wet season, indicating drastic shifts between seasons. Microbial abundance and diversity increased during the dry period, along with a considerable number of limnological variables, all indicative of a strong effect of the precipitation-evaporation balance in these systems.Cyanobacteria were linked to high electric conductivity, pH, and nutrient availability, whereas Actinobacteria, Alphaproteobacteria, and Betaproteobacteria were correlated with landscape morphology variability (surface water, surface perimeter, and lake volume) and less stressed lake conditions. Stress response metabolism was overrepresented in ET and OT lakes and underrepresented in CVO lakes. Altogether, this study illustrated the sensitivity of tropical soda lakes to climate change, as slight changes in hydrological regimes might produce drastic shifts in community diversity.

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“…The water in this cascade flows toward the interior of the continent, and the anthropogenic waste load is largest in the Barra Bonita reservoir because of influences from the São Paulo metropolitan region. Thus, Barra Bonita is the most eutrophic reservoir, and the productivity decreases throughout the flow of the river because of the gradual nutrient removal/dilution effect, while the trophic state changes from hypereutrophic to eutrophic and mesotrophic ( Freitas et al, 2018 ). Additionally, organisms are moving from Barra Bonita reservoir toward subsequent reservoirs.…”

Section: Methodsmentioning

confidence: 99%

Regional factors as major drivers for microbial community turnover in tropical cascading reservoirs

et al. 2022

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The turnover of microbial communities across space is dictated by local and regional factors. Locally, selection shapes community assembly through biological interactions between organisms and the environment, while regional factors influence microbial dispersion patterns. Methods used to disentangle the effects of local and regional factors typically do not aim to identify ecological processes underlying the turnover. In this paper, we identified and quantified these processes for three operational microbial subcommunities (cyanobacteria, particle-attached, and free-living bacteria) from a tropical cascade of freshwater reservoirs with decreasing productivity, over two markedly different dry and rainy seasons. We hypothesized that during the dry season communities would mainly be controlled by selection shaped by the higher environmental heterogeneity that results from low hydrological flow and connectivity between reservoirs. We expected highly similar communities shaped by dispersal and a more homogenized environment during the rainy season, enhanced by increased flow rates. Even if metacommunities were largely controlled by regional events in both periods, the selection had more influence on free-living communities during the dry period, possibly related to elevated dissolved organic carbon concentration, while drift as a purely stochastic factor, had more influence on cyanobacterial communities. Each subcommunity had distinct patterns of turnover along the cascade related to diversity (Cyanobacteria), lifestyle and size (Free-living), and spatial dynamics (particle-attached).

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Productivity and rainfall drive bacterial metabolism in tropical cascading reservoirs

Cited by 10 publications

References 63 publications

Identification of aquatic consumer trophic pathways in four volcanic tropical lakes using fatty acid biomarkers

Identification of aquatic consumer trophic pathways in four volcanic tropical lakes using fatty acid biomarkers

Bacterial Communities Along Environmental Gradients in Tropical Soda Lakes

Regional factors as major drivers for microbial community turnover in tropical cascading reservoirs

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