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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.


The occurrences of the 24 dominant bacterial families over the temperature gradient. The diameters of the circles are proportional to the mean relative abundances of each family at a given temperature departure
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Fig5: The occurrences of the 24 dominant bacterial families over the temperature gradient. The diameters of the circles are proportional to the mean relative abundances of each family at a given temperature departure

Mentions: Here, we focused on the temperature effects on the bacterial assemblages, thus screening the taxa that linearly responded to the increasing temperatures. As a result, 24 bacterial families were identified, whose relative abundances significantly correlated (P < 0.05 in all cases) with temperature (Fig. 5). The relative abundances of bacterial families affiliated with Bacteroidetes were consistently increased along the temperature gradient, while the assemblages belonged to Gammaproteobacteria (with the exception of Alteromonadaceae) showed an opposite pattern. In contrast, the bacterial families affiliated with Alphaproteobacteria and Actinobacteria divergently responded to the increasing temperatures (Fig. 5).Fig. 5


Thermal discharge-created increasing temperatures alter the bacterioplankton composition and functional redundancy
The occurrences of the 24 dominant bacterial families over the temperature gradient. The diameters of the circles are proportional to the mean relative abundances of each family at a given temperature departure
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig5: The occurrences of the 24 dominant bacterial families over the temperature gradient. The diameters of the circles are proportional to the mean relative abundances of each family at a given temperature departure
Mentions: Here, we focused on the temperature effects on the bacterial assemblages, thus screening the taxa that linearly responded to the increasing temperatures. As a result, 24 bacterial families were identified, whose relative abundances significantly correlated (P < 0.05 in all cases) with temperature (Fig. 5). The relative abundances of bacterial families affiliated with Bacteroidetes were consistently increased along the temperature gradient, while the assemblages belonged to Gammaproteobacteria (with the exception of Alteromonadaceae) showed an opposite pattern. In contrast, the bacterial families affiliated with Alphaproteobacteria and Actinobacteria divergently responded to the increasing temperatures (Fig. 5).Fig. 5

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.