scholarly journals Small tropical islands with dense human population: Differences in water quality of near-shore waters are associated with distinct bacterial communities

Author(s):  
Hauke Kegler ◽  
Christiane Hassenrueck ◽  
Pia Kegler ◽  
Tim C Jennerjahn ◽  
Muhammad Lukman ◽  
...  

Water quality deterioration caused by an enrichment in inorganic and organic matter due to anthropogenic inputs is one of the major local threats to coral reefs in Indonesia. However, even though bacteria are important mediators in coral reef ecosystems, little is known about the response of individual taxa and whole bacterial communities to these anthropogenic inputs. The present study is the first to investigate how bacterial community composition responds to small-scale changes in water quality in several coral reef habitats of the Spermonde Archipelago including the water column, particles and back reef sediments, on a densely populated and an uninhabited island. The main aims were to elucidate if a) water quality indicators and organic matter concentrations differ between the uninhabited and the densely populated island of the archipelago, and b) if there are differences in bacterial community composition in back-reef sediments and in the water column, which are associated with differences in water quality. Several key water quality parameters, such as inorganic nitrate and phosphate, chlorophyll a, and transparent exopolymer particles (TEP) were significantly higher at the inhabited than at the uninhabited island. Bacterial communities in sediments and particle attached communities were significantly different between the two islands with bacterial taxa commonly associated with nutrient and organic matter rich conditions occurring in higher proportions at the inhabited island. Within the individual reef habitats, variations in bacterial community composition between the islands are associated with differences in water quality. We also observed that copiotrophic, opportunistic bacterial taxa were enriched at the inhabited island with its higher chlorophyll a, dissolved organic carbon (DOC) and TEP concentrations. Given the increasing strain on tropical coastal ecosystems, this study suggests that effluents from densely populated islands lacking sewage treatment can alter bacterial communities that may be important for coral reef ecosystem function.

2018 ◽  
Author(s):  
Hauke Kegler ◽  
Christiane Hassenrueck ◽  
Pia Kegler ◽  
Tim C Jennerjahn ◽  
Muhammad Lukman ◽  
...  

Water quality deterioration caused by an enrichment in inorganic and organic matter due to anthropogenic inputs is one of the major local threats to coral reefs in Indonesia. However, even though bacteria are important mediators in coral reef ecosystems, little is known about the response of individual taxa and whole bacterial communities to these anthropogenic inputs. The present study is the first to investigate how bacterial community composition responds to small-scale changes in water quality in several coral reef habitats of the Spermonde Archipelago including the water column, particles and back reef sediments, on a densely populated and an uninhabited island. The main aims were to elucidate if a) water quality indicators and organic matter concentrations differ between the uninhabited and the densely populated island of the archipelago, and b) if there are differences in bacterial community composition in back-reef sediments and in the water column, which are associated with differences in water quality. Several key water quality parameters, such as inorganic nitrate and phosphate, chlorophyll a, and transparent exopolymer particles (TEP) were significantly higher at the inhabited than at the uninhabited island. Bacterial communities in sediments and particle attached communities were significantly different between the two islands with bacterial taxa commonly associated with nutrient and organic matter rich conditions occurring in higher proportions at the inhabited island. Within the individual reef habitats, variations in bacterial community composition between the islands are associated with differences in water quality. We also observed that copiotrophic, opportunistic bacterial taxa were enriched at the inhabited island with its higher chlorophyll a, dissolved organic carbon (DOC) and TEP concentrations. Given the increasing strain on tropical coastal ecosystems, this study suggests that effluents from densely populated islands lacking sewage treatment can alter bacterial communities that may be important for coral reef ecosystem function.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4555 ◽  
Author(s):  
Hauke F. Kegler ◽  
Christiane Hassenrück ◽  
Pia Kegler ◽  
Tim C. Jennerjahn ◽  
Muhammad Lukman ◽  
...  

Water quality deterioration caused by an enrichment in inorganic and organic matter due to anthropogenic inputs is one of the major local threats to coral reefs in Indonesia. However, even though bacteria are important mediators in coral reef ecosystems, little is known about the response of individual taxa and whole bacterial communities to these anthropogenic inputs. The present study is the first to investigate how bacterial community composition responds to small-scale changes in water quality in several coral reef habitats of the Spermonde Archipelago including the water column, particles, and back-reef sediments, on a densely populated and an uninhabited island. The main aims were to elucidate if (a) water quality indicators and organic matter concentrations differ between the uninhabited and the densely populated island of the archipelago, and (b) if there are differences in bacterial community composition in back-reef sediments and in the water column, which are associated with differences in water quality. Several key water quality parameters, such as inorganic nitrate and phosphate, chlorophylla, and transparent exopolymer particles (TEP) were significantly higher at the inhabited than at the uninhabited island. Bacterial communities in sediments and particle-attached communities were significantly different between the two islands with bacterial taxa commonly associated with nutrient and organic matter-rich conditions occurring in higher proportions at the inhabited island. Within the individual reef habitats, variations in bacterial community composition between the islands were associated with differences in water quality. We also observed that copiotrophic, opportunistic bacterial taxa were enriched at the inhabited island with its higher chlorophylla, dissolved organic carbon and TEP concentrations. Given the increasing strain on tropical coastal ecosystems, this study suggests that effluents from densely populated islands lacking sewage treatment can alter bacterial communities that may be important for coral reef ecosystem function.


2020 ◽  
Vol 96 (2) ◽  
Author(s):  
Ben Ma ◽  
Timothy M LaPara ◽  
Ashley N. Evans ◽  
Raymond M Hozalski

ABSTRACT Spatial patterns of bacterial community composition often follow a distance–decay relationship in which community dissimilarity increases with geographic distance. Such a relationship has been commonly observed in natural environments, but less so in engineered environments. In this study, bacterial abundance and community composition in filter media samples (n = 57) from full-scale rapid biofilters at 14 water treatment facilities across North America were determined using quantitative polymerase chain reaction and Illumina HiSeq high-throughput sequencing targeting the 16S rRNA gene, respectively. Bacteria were abundant on the filter media (108.8±0.3 to 1010.7±0.2 16S rRNA gene copies/cm3 bed volume) and the bacterial communities were highly diverse (Shannon index: 5.3 ± 0.1 to 8.4 ± 0.0). Significant inter-filter variations in bacterial community composition were observed, with weighted UniFrac dissimilarity values following a weak but highly significant distance–decay relationship (z = 0.0057 ± 0.0006; P = 1.8 × 10−22). Approximately 50% of the variance in bacterial community composition was explained by the water quality parameters measured at the time of media sample collection (i.e. pH, temperature and dissolved organic carbon concentration). Overall, this study suggested that the microbiomes of biofilters are primarily shaped by geographic location and local water quality conditions but the influence of these factors on the microbiomes is tempered by filter design and operating conditions.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5508 ◽  
Author(s):  
Yan Li ◽  
Yan Kong ◽  
Dexiong Teng ◽  
Xueni Zhang ◽  
Xuemin He ◽  
...  

BackgroundRecently, researches have begun to investigate the microbial communities associated with halophytes. Both rhizobacterial community composition and the environmental drivers of community assembly have been addressed. However, few studies have explored the structure of rhizobacterial communities associated with halophytic plants that are co-occurring in arid, salinized areas.MethodsFive halophytes were selected for study: these co-occurred in saline soils in the Ebinur Lake Nature Reserve, located at the western margin of the Gurbantunggut Desert of Northwestern China. Halophyte-associated bacterial communities were sampled, and the bacterial 16S rDNA V3–V4 region amplified and sequenced using the Illumina Miseq platform. The bacterial community diversity and structure were compared between the rhizosphere and bulk soils, as well as among the rhizosphere samples. The effects of plant species identity and soil properties on the bacterial communities were also analyzed.ResultsSignificant differences were observed between the rhizosphere and bulk soil bacterial communities. Diversity was higher in the rhizosphere than in the bulk soils. Abundant taxonomic groups (from phylum to genus) in the rhizosphere were much more diverse than in bulk soils. Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and Planctomycetes were the most abundant phyla in the rhizosphere, while Proteobacteria and Firmicutes were common in bulk soils. Overall, the bacterial community composition were not significantly differentiated between the bulk soils of the five plants, but community diversity and structure differed significantly in the rhizosphere. The diversity ofHalostachys caspica,Halocnemum strobilaceumandKalidium foliatumassociated bacterial communities was lower than that ofLimonium gmeliniiandLycium ruthenicumcommunities. Furthermore, the composition of the bacterial communities ofHalostachys caspicaandHalocnemum strobilaceumwas very different from those ofLimonium gmeliniiandLycium ruthenicum. The diversity and community structure were influenced by soil EC, pH and nutrient content (TOC, SOM, TON and AP); of these, the effects of EC on bacterial community composition were less important than those of soil nutrients.DiscussionHalophytic plant species played an important role in shaping associated rhizosphere bacterial communities. When salinity levels were constant, soil nutrients emerged as key factors structuring bacterial communities, while EC played only a minor role. Pairwise differences among the rhizobacterial communities associated with different plant species were not significant, despite some evidence of differentiation. Further studies involving more halophyte species, and individuals per species, are necessary to elucidate plant species identity effects on the rhizosphere for co-occurring halophytes.


Animals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 701 ◽  
Author(s):  
Fengling Zhang ◽  
Xingjia Xiang ◽  
Yuanqiu Dong ◽  
Shaofei Yan ◽  
Yunwei Song ◽  
...  

Intestinal bacterial communities form an integral component of the organism. Many factors influence gut bacterial community composition and diversity, including diet, environment and seasonality. During seasonal migration, birds use many habitats and food resources, which may influence their intestinal bacterial community structure. Hooded crane (Grus monacha) is a migrant waterbird that traverses long distances and occupies varied habitats. In this study, we investigated the diversity and differences in intestinal bacterial communities of hooded cranes over the migratory seasons. Fecal samples from hooded cranes were collected at a stopover site in two seasons (spring and fall) in Lindian, China, and at a wintering ground in Shengjin Lake, China. We analyzed bacterial communities from the fecal samples using high throughput sequencing (Illumina Mi-seq). Firmicutes, Proteobacteria, Tenericutes, Cyanobacteria, and Actinobacteria were the dominant phyla across all samples. The intestinal bacterial alpha-diversity of hooded cranes in winter was significantly higher than in fall and spring. The bacterial community composition significantly differed across the three seasons (ANOSIM, P = 0.001), suggesting that seasonal fluctuations may regulate the gut bacterial community composition of migratory birds. This study provides baseline information on the seasonal dynamics of intestinal bacterial community structure in migratory hooded cranes.


2020 ◽  
Vol 17 (7) ◽  
pp. 2085-2106
Author(s):  
Dario Fussmann ◽  
Avril Jean Elisabeth von Hoyningen-Huene ◽  
Andreas Reimer ◽  
Dominik Schneider ◽  
Hana Babková ◽  
...  

Abstract. Despite advances regarding the microbial and organic-molecular impact on nucleation, the formation of dolomite in sedimentary environments is still incompletely understood. Since 1960, apparent dolomite formation has been reported from mud sediments of the shallow, oligohaline and alkaline Lake Neusiedl, Austria. To trace potential dolomite formation or diagenetic alteration processes in its deposits, lake water samples and sediment cores were analyzed with respect to sediment composition, hydrochemistry and bacterial community composition. Sediments comprise 20 cm of homogenous mud with 60 wt % carbonate, which overlies dark-laminated consolidated mud containing 50 wt % carbonate and plant debris. Hydrochemical measurements reveal a shift from oxic lake water with pH 9.0 to anoxic sediment pore water with pH 7.5. A decrease in SO42- with a concomitant increase in ΣH2S and NH4+ from 0 to 15 cm core depth indicates anaerobic heterotrophic decomposition, including sulfate reduction. The bacterial community composition reflects the zonation indicated by the pore water chemistry, with a distinct increase in fermentative taxa below 15 cm core depth. The water column is highly supersaturated with respect to (disordered) dolomite and calcite, whereas saturation indices of both minerals rapidly approach zero in the sediment. Notably, the relative proportions of different authigenic carbonate phases and their stoichiometric compositions remain constant with increasing core depth. Hence, evidence for Ca–Mg carbonate formation or ripening to dolomite is lacking within the sediment of Lake Neusiedl. As a consequence, precipitation of high-magnesium calcite (HMC) and protodolomite does not occur in association with anoxic sediment and sulfate-reducing conditions. Instead, analytical data for Lake Neusiedl suggest that authigenic HMC and protodolomite precipitate from the supersaturated, well-mixed aerobic water column. This observation supports an alternative concept to dolomite formation in anoxic sediments, comprising Ca–Mg carbonate precipitation in the water column under aerobic and alkaline conditions.


2020 ◽  
Vol 86 (12) ◽  
Author(s):  
Ferran Romero ◽  
Vicenç Acuña ◽  
Sergi Sabater

ABSTRACT Freshwater ecosystems are exposed to multiple stressors, but their individual and combined effects remain largely unexplored. Here, we investigated the response of stream biofilm bacterial communities to warming, hydrological stress, and pesticide exposure. We used 24 artificial streams on which epilithic (growing on coarse sediments) and epipsammic (growing on fine sediments) stream biofilms were maintained. Bacterial community composition and estimated function of biofilms exposed during 30 days to individual and combined stressors were assessed using 16S rRNA gene metabarcoding. Among the individual effects by stressors, hydrological stress (i.e., a simulated low-flow situation) was the most relevant, since it significantly altered 57% of the most abundant bacterial taxa (n = 28), followed by warming (21%) and pesticide exposure (11%). Regarding the combined effects, 16% of all stressor combinations resulted in significant interactions on bacterial community composition and estimated function. Antagonistic responses prevailed (57 to 89% of all significant interactions), followed by synergisms (11 to 43%), on specific bacterial taxa, indicating that multiple-stressor scenarios could lead to unexpected shifts in the community composition and associated functions of riverine bacterial communities. IMPORTANCE Freshwater ecosystems such as rivers are of crucial importance for human well-being. However, human activities result in many stressors (e.g., toxic chemicals, increased water temperatures, and hydrological alterations) cooccurring in rivers and streams worldwide. Among the many organisms inhabiting rivers and streams, bacteria are ecologically crucial; they are placed at the base of virtually all food webs and they recycle the organic matter needed for bigger organisms. Most of these bacteria are in close contact with river substratum, where they form the biofilms. There is an urgent need to evaluate the effects of these stressors on river biofilms, so we can anticipate future environmental problems. In this study, we experimentally exposed river biofilms to a pesticide mixture, an increase in water temperature and a simulated low-flow condition, in order to evaluate the individual and joint effects of these stressors on the bacterial community composition and estimated function.


2020 ◽  
Author(s):  
Yongqin Liu ◽  
Tandong Yao ◽  
Baiqing Xu

<p>Many studies focusing on the physical and chemical indicators of the ice core reflected the climate changes. However, only few biological indicators indicated the past climate changes which are mainly focused in biomass rather than diversity. How the biodiversity response to the climate change during the past hundred years is still unknow. Glaciers in Mt. Muztagh Ata region are influenced by the year-round westerly circulation. We firstly disclosed annual variations of bacterial community compositions in ice core over the past 130 years from Muztagh Glacier, the western Tibetan Plateau. Temporal variation in bacterial abundance was strongly controlled by DOC, TN, δ<sup>18</sup>O, Ca<sup>2+</sup>, SO<sub>4</sub><sup>2</sup><sup>−</sup>, NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>−</sup>. Proteobacteria, Actinobacteria and Firmicutes were the three most abundant bacterial phyla, accounting for 49.3%, 21.3% and 11.0% of the total community, respectively. The abundances of Firmicutes and Bacteroidetes pronouncedly increased over time throughout the entire ice core. UPGMA cluster analysis of the bacterial community composition separated the all ice core samples into two main clusters along the temporal variation. The first cluster consisted of samples from 1951 to 2000 and the second cluster contained main samples during the period of 1869-1950. The stage 1 and stage 2 bacterial community dissimilarities increased linearly with time on the basis of the Bray-Curtis distance, indicating a similar temporal–decay relationship between the stage 1 and stage 2 bacterial communities. Of all the environmental variables examined, only DOC and NH<sub>4</sub><sup>+</sup> exhibited very strong negative correlations with bacterial Chao1-richness. <sup>18</sup>O was another important variable in shaping the ice core bacterial community composition and contributed 1.6% of the total variation. Moreover, DistLM analysis indicated that the environmental variables explained more variation in the stage 1 community (20.1%) than that of the stage 2 community (19.9%).</p>


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