Abstract:Recent characterization of the bacterial community structure in beach sands has revealed patterns of biogeography similar to those observed in aquatic environments. Studies to date, however, have mainly focused on subtidal sediments from marine beaches. Here, we investigate the bacterial diversity, using Illumina-based sequencing of the V5-V6 region of the 16S rRNA gene, at 11 beaches representing those next to the Great Lakes, Florida, and the Pacific Ocean. The alpha diversity differed significantly among re… Show more
“…However, although interactions between site and season significantly influenced the sand microbial assemblages ( Table 1), two of the triplicate samples from the supratidal zone of site JL2 tended to cluster with those from the intertidal zone ( Figure S2). This is might be due to the influence of some large tidal events [7]. Nevertheless, these results are in accordance with the findings of previous studies, where salinity was described as a predominant factor in determining microbial biogeography [43][44][45][46][47].…”
Section: Discussionsupporting
confidence: 92%
“…Furthermore, the indigenous microbial sand communities are also one of the most critical factors for preventing the colonization of harmful exogenous microorganisms, such as fecal indicator bacteria and pathogens, on beach sands [5,6]. Thus, increasing attention is being paid to the biogeographic distribution pattern of sand microbial communities and its driving forces [2,4,[7][8][9]. The importance of environmental filtering in shaping the assembly of sand microbial communities has highlighted, and a significant body of literature has demonstrated, that the distance from shoreline, sand grain size, moisture, temperature, nutrients (including organic and inorganic matters), and chemical contaminants are major environmental factors shaping sand microbial communities [2,7,8,10,11].…”
Section: Introductionmentioning
confidence: 99%
“…Thus, increasing attention is being paid to the biogeographic distribution pattern of sand microbial communities and its driving forces [2,4,[7][8][9]. The importance of environmental filtering in shaping the assembly of sand microbial communities has highlighted, and a significant body of literature has demonstrated, that the distance from shoreline, sand grain size, moisture, temperature, nutrients (including organic and inorganic matters), and chemical contaminants are major environmental factors shaping sand microbial communities [2,7,8,10,11]. Therefore, sand microbial assemblages have been proposed as a sensitive bio-indicator for evaluating the environmental health of coastal habitats [10,12].…”
Coastal sands harbor diverse microbial assemblages that play a critical role in the biogeochemical cycling of beach ecosystems. However, little is known about the relative importance of the different ecological processes underlying the assembly of communities of sand microbiota. Here, we employed 16S rDNA amplicon sequencing to investigate the sand microbiota of two coastal beaches, in southern China. The results showed that sand microbial assemblages at intertidal and supratidal zones exhibited contrasting compositions that can be attributed to environmental filtering by electric conductivity. A consistent pattern of habitat generalists and specialists of sand microbiota was observed among different beach zones. Null and neutral model analyses indicated that the environmental filtering was mainly responsible for supratidal microbial communities, while the neutral processes could partially influence the assembly of intertidal communities. Moreover, environmental filtering was found to shape the habitat specialists, while random dispersal played a major role in shaping generalists. The neutral model analysis revealed that the habitat generalists exceeding the neutral prediction harbored a relatively higher proportion of microbial taxa than the specialist counterparts. An opposite pattern was observed for taxa falling below the neutral prediction. Collectively, these findings offer a novel insight into the assembly mechanisms of coastal sand microbiota.
“…However, although interactions between site and season significantly influenced the sand microbial assemblages ( Table 1), two of the triplicate samples from the supratidal zone of site JL2 tended to cluster with those from the intertidal zone ( Figure S2). This is might be due to the influence of some large tidal events [7]. Nevertheless, these results are in accordance with the findings of previous studies, where salinity was described as a predominant factor in determining microbial biogeography [43][44][45][46][47].…”
Section: Discussionsupporting
confidence: 92%
“…Furthermore, the indigenous microbial sand communities are also one of the most critical factors for preventing the colonization of harmful exogenous microorganisms, such as fecal indicator bacteria and pathogens, on beach sands [5,6]. Thus, increasing attention is being paid to the biogeographic distribution pattern of sand microbial communities and its driving forces [2,4,[7][8][9]. The importance of environmental filtering in shaping the assembly of sand microbial communities has highlighted, and a significant body of literature has demonstrated, that the distance from shoreline, sand grain size, moisture, temperature, nutrients (including organic and inorganic matters), and chemical contaminants are major environmental factors shaping sand microbial communities [2,7,8,10,11].…”
Section: Introductionmentioning
confidence: 99%
“…Thus, increasing attention is being paid to the biogeographic distribution pattern of sand microbial communities and its driving forces [2,4,[7][8][9]. The importance of environmental filtering in shaping the assembly of sand microbial communities has highlighted, and a significant body of literature has demonstrated, that the distance from shoreline, sand grain size, moisture, temperature, nutrients (including organic and inorganic matters), and chemical contaminants are major environmental factors shaping sand microbial communities [2,7,8,10,11]. Therefore, sand microbial assemblages have been proposed as a sensitive bio-indicator for evaluating the environmental health of coastal habitats [10,12].…”
Coastal sands harbor diverse microbial assemblages that play a critical role in the biogeochemical cycling of beach ecosystems. However, little is known about the relative importance of the different ecological processes underlying the assembly of communities of sand microbiota. Here, we employed 16S rDNA amplicon sequencing to investigate the sand microbiota of two coastal beaches, in southern China. The results showed that sand microbial assemblages at intertidal and supratidal zones exhibited contrasting compositions that can be attributed to environmental filtering by electric conductivity. A consistent pattern of habitat generalists and specialists of sand microbiota was observed among different beach zones. Null and neutral model analyses indicated that the environmental filtering was mainly responsible for supratidal microbial communities, while the neutral processes could partially influence the assembly of intertidal communities. Moreover, environmental filtering was found to shape the habitat specialists, while random dispersal played a major role in shaping generalists. The neutral model analysis revealed that the habitat generalists exceeding the neutral prediction harbored a relatively higher proportion of microbial taxa than the specialist counterparts. An opposite pattern was observed for taxa falling below the neutral prediction. Collectively, these findings offer a novel insight into the assembly mechanisms of coastal sand microbiota.
“…Due to the fact that geochemical characteristics are the main drivers of BCC (Constancias et al., ), and since geochemical characteristics differ only slightly across sampling sites, we suggest that this results in a similar taxonomic community composition at the phylum level. This was not unexpected and confirms observations reported by Staley and Sadowsky () that variation in community composition tends to be smaller within the same region. However, differences in taxonomic community composition between sampling sites were more apparent at the family level.…”
Section: Discussionsupporting
confidence: 93%
“…Due to the fact that geochemical characteristics are the main drivers of BCC (Constancias et al, 2015), and since geochemical characteristics differ only slightly across sampling sites, we suggest that this results in a similar taxonomic community composition at the phylum level. This was not unexpected and confirms observations reported by Staley and Sadowsky (2016) between sampling sites were more apparent at the family level. In conjunction with the results of bacterial diversity, it is most likely that significant differences in diversity estimates across sampling sites are driven by the proportion of rare families, notably for sampling site BB3, where rare families compose approximately 61% of the overall abundance ( Figure 4B).…”
Modern agricultural practices have undeniably increased global food production. On the other hand, agricultural practices not only lead to a degradation of natural ecosystems but also affect the functioning of ecosystems and the related services they provide. Even though impacts of anthropogenic activities vary across ecosystems, freshwater ecosystems are among those affected to a higher degree. In comparison to surface water ecosystems, groundwater ecosystems are less affected by anthropogenic pollutants, as the overlaying soil retains organic and inorganic substances. However, it has become evident that the excessive use of fertilizers has led to the eutrophication of many aquifers. Bacterial communities, which significantly contribute to the cycling of matter due to their metabolic capacities, are prone to environmental perturbations, and structural variation of bacterial communities may consequently affect the functioning of groundwater ecosystems. Our present paper intends to evaluate the impact of anthropogenic activities on environmental conditions as well as on the structural properties of bacterial communities in groundwater. We repeatedly sampled emerging groundwater at five spring sites belonging to different catchments and determined the concentration of abiotic variables as well as the diversity and composition of bacterial communities on a local scale. We hypothesized that anthropogenic activities influence the concentration of abiotic variables, especially of nitrate, as well as the composition and diversity of bacterial communities in groundwater. Our results show that underground spring catchment areas only slightly differ regarding the concentration of abiotic variables as well as the structure of bacterial communities. Furthermore, abiotic variables, presumably influenced by anthropogenic activities, do not correlate with the diversity and composition of bacterial communities. Although supported only by circumstantial evidence, we suggest that upwelling groundwater from the deeper aquifer affects the diversity and composition of bacterial communities, and we argue that bacterial communities act as useful indicators for environmental changes.
Sea turtle hatching success can be affected by many variables, including pathogenic microbes, but it is unclear which microbes are most impactful and how they are transmitted into the eggs. This study characterized and compared the bacterial communities from the (i) cloaca of nesting sea turtles (ii) sand within and surrounding the nests; and (iii) hatched and unhatched eggshells from loggerhead (Caretta caretta) and green (Chelonia mydas) turtles. High throughput sequencing of bacterial 16S ribosomal RNA gene V4 region amplicons was performed on samples collected from 27 total nests in Fort Lauderdale and Hillsboro beaches in southeast Florida, United States. Significant differences were identified between hatched and unhatched egg microbiota with the differences caused predominately by Pseudomonas spp., found in higher abundances in unhatched eggs (19.29% relative abundance) than hatched eggs (1.10% relative abundance). Microbiota similarities indicate that the nest sand environment, particularly nest distance from dunes, played a larger role than the nesting mother's cloaca in influencing hatched and unhatched egg microbiota.Pathogenic bacteria potentially derive from mixed-mode transmission or additional sources not included in this study as suggested by the high proportion (24%-48%) of unhatched egg microbiota derived from unknown sources. Nonetheless, the results suggest Pseudomonas as a candidate pathogen or opportunistic colonizer associated with sea turtle egg-hatching failure.
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