Relative Diazotroph Abundance in Symbiotic Red Sea Corals Decreases With Water Depth
Microbial dinitrogen (N2) fixation (diazotrophy) is a trait critical for coral holobiont functioning. The contribution of N2 fixation to holobiont nitrogen (N) supply likely depends on the ecological niche of the coral holobiont. Consequently, coral-associated diazotroph communities may exhibit dist...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2019-07-01
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| Series: | Frontiers in Marine Science |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fmars.2019.00372/full |
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| author | Arjen Tilstra Claudia Pogoreutz Nils Rädecker Maren Ziegler Maren Ziegler Christian Wild Christian R. Voolstra Christian R. Voolstra |
| author_facet | Arjen Tilstra Claudia Pogoreutz Nils Rädecker Maren Ziegler Maren Ziegler Christian Wild Christian R. Voolstra Christian R. Voolstra |
| author_sort | Arjen Tilstra |
| collection | DOAJ |
| description | Microbial dinitrogen (N2) fixation (diazotrophy) is a trait critical for coral holobiont functioning. The contribution of N2 fixation to holobiont nitrogen (N) supply likely depends on the ecological niche of the coral holobiont. Consequently, coral-associated diazotroph communities may exhibit distinct activity patterns across a water depth gradient. We thus compared relative abundances of diazotrophs in the tissues of two common hard coral species, Podabacia sp. and Pachyserisspeciosa, along their water depth distribution (10–30 m and 30–50 m, respectively) in the Central Red Sea. The relative gene copy numbers of the nifH gene (i.e., referenced against the eubacterial 16S rRNA gene), as a proxy for N2 fixation potential, were assessed via quantitative PCR. We hypothesized that relative nifH gene copy numbers would decrease with water depth, assuming a related shift from autotrophy to heterotrophy. Findings confirmed this hypothesis and revealed that nifH gene abundances for both corals decreased by ∼97% and ∼90% from the shallowest to the deepest collection site. However, this result was not significant for Pachyserisspeciosa due to high biological variability. The observed decrease in nifH gene abundances may be explained by the relative increase in heterotrophy of the coral animal at increasing water depths. Our results underline the importance of interpreting microbial functions and associated nutrient cycling processes within the holobiont in relation to water depth range reflecting steep environmental gradients. |
| first_indexed | 2024-12-11T20:59:15Z |
| format | Article |
| id | doaj.art-19cbef3e5c2d4059b580a4add04f851b |
| institution | Directory Open Access Journal |
| issn | 2296-7745 |
| language | English |
| last_indexed | 2024-12-11T20:59:15Z |
| publishDate | 2019-07-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Marine Science |
| spelling | doaj.art-19cbef3e5c2d4059b580a4add04f851b2022-12-22T00:51:02ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452019-07-01610.3389/fmars.2019.00372446195Relative Diazotroph Abundance in Symbiotic Red Sea Corals Decreases With Water DepthArjen Tilstra0Claudia Pogoreutz1Nils Rädecker2Maren Ziegler3Maren Ziegler4Christian Wild5Christian R. Voolstra6Christian R. Voolstra7Department of Marine Ecology, Faculty of Biology and Chemistry, University of Bremen, Bremen, GermanyRed Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi ArabiaRed Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi ArabiaRed Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi ArabiaDepartment of Animal Ecology and Systematics, Justus Liebig University Giessen, Giessen, GermanyDepartment of Marine Ecology, Faculty of Biology and Chemistry, University of Bremen, Bremen, GermanyRed Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi ArabiaDepartment of Biology, University of Konstanz, Konstanz, GermanyMicrobial dinitrogen (N2) fixation (diazotrophy) is a trait critical for coral holobiont functioning. The contribution of N2 fixation to holobiont nitrogen (N) supply likely depends on the ecological niche of the coral holobiont. Consequently, coral-associated diazotroph communities may exhibit distinct activity patterns across a water depth gradient. We thus compared relative abundances of diazotrophs in the tissues of two common hard coral species, Podabacia sp. and Pachyserisspeciosa, along their water depth distribution (10–30 m and 30–50 m, respectively) in the Central Red Sea. The relative gene copy numbers of the nifH gene (i.e., referenced against the eubacterial 16S rRNA gene), as a proxy for N2 fixation potential, were assessed via quantitative PCR. We hypothesized that relative nifH gene copy numbers would decrease with water depth, assuming a related shift from autotrophy to heterotrophy. Findings confirmed this hypothesis and revealed that nifH gene abundances for both corals decreased by ∼97% and ∼90% from the shallowest to the deepest collection site. However, this result was not significant for Pachyserisspeciosa due to high biological variability. The observed decrease in nifH gene abundances may be explained by the relative increase in heterotrophy of the coral animal at increasing water depths. Our results underline the importance of interpreting microbial functions and associated nutrient cycling processes within the holobiont in relation to water depth range reflecting steep environmental gradients.https://www.frontiersin.org/article/10.3389/fmars.2019.00372/fullcoral reefsdiazotrophyheterotrophyautotrophynitrogen fixationdepth gradient |
| spellingShingle | Arjen Tilstra Claudia Pogoreutz Nils Rädecker Maren Ziegler Maren Ziegler Christian Wild Christian R. Voolstra Christian R. Voolstra Relative Diazotroph Abundance in Symbiotic Red Sea Corals Decreases With Water Depth Frontiers in Marine Science coral reefs diazotrophy heterotrophy autotrophy nitrogen fixation depth gradient |
| title | Relative Diazotroph Abundance in Symbiotic Red Sea Corals Decreases With Water Depth |
| title_full | Relative Diazotroph Abundance in Symbiotic Red Sea Corals Decreases With Water Depth |
| title_fullStr | Relative Diazotroph Abundance in Symbiotic Red Sea Corals Decreases With Water Depth |
| title_full_unstemmed | Relative Diazotroph Abundance in Symbiotic Red Sea Corals Decreases With Water Depth |
| title_short | Relative Diazotroph Abundance in Symbiotic Red Sea Corals Decreases With Water Depth |
| title_sort | relative diazotroph abundance in symbiotic red sea corals decreases with water depth |
| topic | coral reefs diazotrophy heterotrophy autotrophy nitrogen fixation depth gradient |
| url | https://www.frontiersin.org/article/10.3389/fmars.2019.00372/full |
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