Carbon and nitrogen accumulation and interspecific competition in two algae species, Pyropia haitanensis and Ulva lactuca, under ocean acidification conditions
If the atmospheric CO2 continues to increase as predicted, Pyropia haitanensis would experience the coupled effects of ocean acidification (OA) and interference from the epiphyte alga Ulva lactuca. In the current study, we evaluated the carbon (C) and nitrogen (N) accumulation in P. haitanensis and U. lactuca under OA conditions, as well as the interspecific competition between these two algae. We found that, under mono-culture conditions, OA significantly enhanced the growth of both P. haitanensis and U. lactuca and markedly increased the soluble carbohydrate (SC) content and C/N ratios in P. haitanensis, but reduced its soluble proteins (SP) content. In U. lactuca, OA reduced its SP content, but increased C/N ratios, while its SC content was not significantly affected. Under biculture conditions, the rapid growth of U. lactuca and its comparatively more efficient use of nutrients resulted in insufficient available N sources for P. haitanensis. Biculture with U. lactuca increased SC but declined SP content. This also resulted in some membrane injuries that were indicated by increased malondialdehyde (MDA) content and depressed growth in P. haitanensis. Biculture with U. lactuca was disadvantageous for carbon and nitrogen accumulation in P. haitanensis. The results demonstrated that under conditions of OA, the negative effects caused by the epiphyte U. lactuca were more pronounced. If the CO2 levels rise as predicted, Ulva algae would severely interfere with maricultivation of P. haitanensis.
KeywordsPyropia haitanensis Ulva lactuca Carbon and nitrogen accumulation Ocean acidification Interspecific competition Climate change
This work was supported by the National Natural Science Foundation of China (Nos. 41706147 and 41876124), the National Natural Science Foundation of Guangdong Province (2018B030311029), and the Fundamental Research Funds for the Central Universities of China (217BQ082).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with animals performed by any of the authors.
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