Humic substances modulate bacterial communities and mitigate adverse effects of temperature stress in coral reef organisms

Journal of Applied Microbiology, vol. 136

Abstract

AIMS: In the present study, we tested whether terrestrially derived humic substances (HS) could mitigate the adverse effects of elevated temperature and ultraviolet B (UVB) radiation on the bacterial communities of two hard corals (Montipora digitata and M. capricornis), one soft coral (Sarcophyton glaucum), sediment and water. We also examined the impact of temperature, UVB radiation, and HS supplementation on coral photosynthetic activity, a proxy for coral bleaching. METHODS AND RESULTS: We performed a multifactorial experiment using a randomized-controlled microcosm setup. Coral photosynthetic efficiency was measured in vivo using a pulse amplitude modulation fluorometer. Bacterial communities were analyzed using 16S rRNA gene sequencing. Corals in HS-supplemented microcosms had significantly higher photosynthetic activities than those in microcosms subjected to elevated temperature and UVB radiation. Additionally, HS supplementation significantly influenced the composition of sediment, water, and host-associated bacterial communities. Reef organisms in HS supplemented microcosms contained distinct bacterial communities enriched with groups of potentially beneficial bacteria. In the hard coral M. digitata, we observed an interactive effect of HS supplementation, UVB radiation, and temperature. CONCLUSION: Our findings indicate that HS significantly modulates coral reef bacterial communities and support the hypothesis that these substances contribute to improved reef resistance to the adverse effects of elevated temperature and UVB radiation.

Authors 9

1. T.M. Stuij

   Centro de Estudos do Ambiente e do Mar · University of Aveiro

   Affiliation as printed

   Centre for Environmental and Marine Studies (CESAM), University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Department of Biology, University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Aveiro, Portugal

2. Daniel F. R. Cleary corresponding

   Centro de Estudos do Ambiente e do Mar · University of Aveiro

   Affiliation as printed

   Centre for Environmental and Marine Studies (CESAM), University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Department of Biology, University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Aveiro, Portugal

3. Nicole Joy de Voogd corresponding Aachen Institute of Biology Naturalis Biodiversity Center

   Leiden University · Naturalis Biodiversity Center

   Affiliation as printed

   Institute of Biology (IBL), Leiden University , Sylviusweg 72, 2333 BE, Leiden ,

   Naturalis Biodiversity Center , Darwinweg 2, 2333 CR, Leiden ,

   Institute of Biology (IBL), Leiden University, Leiden, The Netherlands

   Naturalis Biodiversity Center, Leiden, The Netherlands

4. Rui J. M. Rocha

   Centro de Estudos do Ambiente e do Mar · University of Aveiro

   Affiliation as printed

   Centre for Environmental and Marine Studies (CESAM), University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Department of Biology, University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Aveiro, Portugal

5. Ana R. M. Polónia

   Centro de Estudos do Ambiente e do Mar · University of Aveiro

   Affiliation as printed

   Centre for Environmental and Marine Studies (CESAM), University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Department of Biology, University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Aveiro, Portugal

6. Davide Silva

   Centro de Estudos do Ambiente e do Mar · University of Aveiro

   Affiliation as printed

   Centre for Environmental and Marine Studies (CESAM), University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Department of Biology, University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Aveiro, Portugal

7. Jörg C. Frommlet

   Centro de Estudos do Ambiente e do Mar · University of Aveiro

   Affiliation as printed

   Centre for Environmental and Marine Studies (CESAM), University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Department of Biology, University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Aveiro, Portugal

8. António Louvado

   Centro de Estudos do Ambiente e do Mar · University of Aveiro

   Affiliation as printed

   Centre for Environmental and Marine Studies (CESAM), University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Department of Biology, University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Aveiro, Portugal

9. Newton C. M. Gomes corresponding

   Centro de Estudos do Ambiente e do Mar · University of Aveiro

   Affiliation as printed

   Centre for Environmental and Marine Studies (CESAM), University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Department of Biology, University of Aveiro , Campus Universitário Santiago, 3810-193, Aveiro ,

   Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Aveiro, Portugal