期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 840, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2022.156591
关键词
Green tides; Macroalgae; Marine heatwaves; Nitrogen; Photosynthesis; Seaweed cultivation
资金
- National Natural Science Foundation of China [42076154]
- National Key Research and Development Program of China [2018YFD0900703]
- MEL Internal Research Program [MELRI2004]
This study investigated the physiological and genetic responses of two macroalgae species, Ulva intestinalis and Gracilariopsis lemaneiformis, to simulated marine heatwaves under different nitrate conditions. The results showed that Ulva intestinalis was able to survive heatwaves by shifting to micropropagules under nitrogen limited conditions and protecting its photosynthesis under nitrogen replete conditions. In contrast, Gracilariopsis lemaneiformis died of bleaching regardless of nitrogen availability.
Marine heatwaves (MHWs) are affecting the survival of macroalgae. However, little is known regarding how the im-pacts of MHWs are regulated by nitrogen availability. In this study, we investigated the physiological and genetic re-sponses of a green-tide macroalga Ulva intestinalis Linnaeus and a commercially cultivated macroalga Gracilariopsis lemaneiformis (Bory) E.Y. Dawson, Acleto & Foldvik under different nitrate conditions to simulated MHWs. Under ni-trogen limited conditions (LN), heatwaves did not significantly affect biomass or Fv/Fm of U. intestinalis although it led to an earlier biomass decline due to more reproduction events, and meanwhile an upregulation in genes related to TCA cycle and oxidative phosphorylation was detected, supporting sporulation. Under nitrogen replete conditions (HN), heatwaves did not change biomass, Fv/Fm or photosynthetic pigments but reduced reproduction rate along with insig-nificant change of oxidative phosphorylation and TCA cycle related genes. Meanwhile, genes related to photosynthesis and glutathione metabolism were upregulated. Regarding G. lemaneiformis, heatwaves reduced its Fv/Fm and photo-synthetic pigments content, leading to bleaching and death, and photosynthesis-related genes were also downregu-lated at LN. Fv/Fm was improved and photosynthesis-related genes were up-regulated by the combination of nitrogen enrichment and heatwaves, whereas G. lemaneiformis remained bleached and died by day 12. Therefore, U. intestinalis could survive heatwaves through shifting to micropropagules at LN and protecting its photosynthesis at HN. In contrast, G. lemaneiformis died of bleaching when suffering heatwaves regardless of nitrogen availability. These findings suggest that in future oceans with eutrophication and MHWs, the harmful alga U. intestinalis may have more advantages over the economic alga G. lemaneiformis.
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