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Thermal discharge-created increasing temperatures alter the bacterioplankton composition and functional redundancy

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ABSTRACT

Elevated seawater temperature has altered the coupling between coastal primary production and heterotrophic bacterioplankton respiration. This shift, in turn, could influence the feedback of ocean ecosystem to climate warming. However, little is known about how natural bacterioplankton community responds to increasing seawater temperature. To investigate warming effects on the bacterioplankton community, we collected water samples from temperature gradients (ranged from 15.0 to 18.6 °C) created by a thermal flume of a coal power plant. The results showed that increasing temperatures significantly stimulated bacterial abundance, grazing rate, and altered bacterioplankton community compositions (BCCs). The spatial distribution of bacterioplankton community followed a distance similarity decay relationship, with a turnover of 0.005. A variance partitioning analysis showed that temperature directly constrained 2.01 % variation in BCCs, while temperature-induced changes in water geochemical and grazing rate indirectly accounted for 4.03 and 12.8 % of the community variance, respectively. Furthermore, the relative abundances of 24 bacterial families were linearly increased or decreased (P < 0.05 in all cases) with increasing temperatures. Notably, the change pattern for a given bacterial family was in concert with its known functions. In addition, community functional redundancy consistently decreased along the temperature gradient. This study demonstrates that elevated temperature, combined with substrate supply and trophic interactions, dramatically alters BCCs, concomitant with decreases in functional redundancy. The responses of sensitive assemblages are temperature dependent, which could indicate temperature departures.

Electronic supplementary material: The online version of this article (doi:10.1186/s13568-016-0238-4) contains supplementary material, which is available to authorized users.

No MeSH data available.


Principal coordinates analysis (PCoA) of the bacterioplankton communities derived from the weighted UniFrac distance matrix. Samples were coded by sampling sites (a) and temperature departures (b)
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Fig2: Principal coordinates analysis (PCoA) of the bacterioplankton communities derived from the weighted UniFrac distance matrix. Samples were coded by sampling sites (a) and temperature departures (b)

Mentions: After quality control, we obtained 1,412,135 clean sequences, and 18,392–33,296 reads per sample (mean 25,675 ± 3742). The dominant phyla or classes across the samples were Alphaproteobacteria (mean relative abundance, 31.4 %), followed by Bacteroidetes (22.7 %), Gammaproteobacteria (24.7 %) and Actinobacteria (8.0 %) (data not shown). The BCCs were substantially different (P < 0.001 for all comparisons, sequential Bonferroni significance) among the sampling sites (Fig. 2a). The cluster pattern was more visible when samples were coded by temperature departures (Fig. 2b). Consistently, the BCCs were distinct (P < 0.01) between each pair temperature departures (Table 1). In addition, seawater temperature highly ranked in splitting the first (31.2 %) and second (18.6 %) branch of the MRT, confirming the primary of temperature in controlling bacterial diversity (Additional file 1: Figure S2).Fig. 2


Thermal discharge-created increasing temperatures alter the bacterioplankton composition and functional redundancy
Principal coordinates analysis (PCoA) of the bacterioplankton communities derived from the weighted UniFrac distance matrix. Samples were coded by sampling sites (a) and temperature departures (b)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016491&req=5

Fig2: Principal coordinates analysis (PCoA) of the bacterioplankton communities derived from the weighted UniFrac distance matrix. Samples were coded by sampling sites (a) and temperature departures (b)
Mentions: After quality control, we obtained 1,412,135 clean sequences, and 18,392–33,296 reads per sample (mean 25,675 ± 3742). The dominant phyla or classes across the samples were Alphaproteobacteria (mean relative abundance, 31.4 %), followed by Bacteroidetes (22.7 %), Gammaproteobacteria (24.7 %) and Actinobacteria (8.0 %) (data not shown). The BCCs were substantially different (P < 0.001 for all comparisons, sequential Bonferroni significance) among the sampling sites (Fig. 2a). The cluster pattern was more visible when samples were coded by temperature departures (Fig. 2b). Consistently, the BCCs were distinct (P < 0.01) between each pair temperature departures (Table 1). In addition, seawater temperature highly ranked in splitting the first (31.2 %) and second (18.6 %) branch of the MRT, confirming the primary of temperature in controlling bacterial diversity (Additional file 1: Figure S2).Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

Elevated seawater temperature has altered the coupling between coastal primary production and heterotrophic bacterioplankton respiration. This shift, in turn, could influence the feedback of ocean ecosystem to climate warming. However, little is known about how natural bacterioplankton community responds to increasing seawater temperature. To investigate warming effects on the bacterioplankton community, we collected water samples from temperature gradients (ranged from 15.0 to 18.6&nbsp;&deg;C) created by a thermal flume of a coal power plant. The results showed that increasing temperatures significantly stimulated bacterial abundance, grazing rate, and altered bacterioplankton community compositions (BCCs). The spatial distribution of bacterioplankton community followed a distance similarity decay relationship, with a turnover of 0.005. A variance partitioning analysis showed that temperature directly constrained 2.01&nbsp;% variation in BCCs, while temperature-induced changes in water geochemical and grazing rate indirectly accounted for 4.03 and 12.8&nbsp;% of the community variance, respectively. Furthermore, the relative abundances of 24 bacterial families were linearly increased or decreased (P&nbsp;&lt;&nbsp;0.05 in all cases) with increasing temperatures. Notably, the change pattern for a given bacterial family was in concert with its known functions. In addition, community functional redundancy consistently decreased along the temperature gradient. This study demonstrates that elevated temperature, combined with substrate supply and trophic interactions, dramatically alters BCCs, concomitant with decreases in functional redundancy. The responses of sensitive assemblages are temperature dependent, which could indicate temperature departures.

Electronic supplementary material: The online version of this article (doi:10.1186/s13568-016-0238-4) contains supplementary material, which is available to authorized users.

No MeSH data available.