Effects of copper enrichment on survival, growth and photosynthetic pigment of seedlings and young plants of the eelgrass Zostera marina

ABSTRACT

Copper (Cu²⁺) is an essential nutrient for plants but toxic at high concentrations. We subjected seedlings and young plants of eelgrass Zostera marina to different seawater Cu concentrations (3, 4, 5, 10, 30 and 50 µg l⁻¹) for over 30 days under controlled laboratory conditions. Natural seawater without added Cu (3 µg l⁻¹) was used as reference seawater. We measured plant response in terms of survivorship, morphology, growth, productivity and leaf pigment concentration. Survival analysis combined with morphological, dynamic and productive assessment suggested that the optimum seawater Cu concentration for the establishment of Z. marina seedlings and young plants is 4 μg l⁻¹. The photosynthetic response of young plants to copper enrichment, including an increase in chlorophyll content under low Cu concentration treatment but significant decrease when treated with high concentrations of Cu, is similar to those reported for other seagrass species. NOEC (no observed effect concentration), LOEC (lowest observed effect concentration) and LC₅₀ (lethal concentration that caused an increase in mortality to 50% of that of the control) values of seedlings were significantly lower than those of young plants, implying a reduced Cu tolerance to high concentrations (>10 μg l⁻¹). This study provides data that could prove helpful in the development of successful eelgrass restoration and conservation.

RESPONSIBLE EDITOR:

• Sharon Hook

KEYWORDS:

• Chlorophyll
• Cu concentration
• dynamic properties
• morphology
• survivorship
• Zostera marina

Acknowledgements

We thank Yan-Shan Liu, Qiang Xu and Lezheng Qin for their assistance during sample collection and calculations; two anonymous referees for comments that contributed to improve an earlier version of this manuscript; and the MBRJ Editorial Office for text editing.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCiD

Pei-Dong Zhang http://orcid.org/0000-0003-1564-1807

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (grant no. 41576112); National Basic Research Priorities Program of China (grant no. 2015FY110600); National Marine Public Welfare Research Project (grant no. 201405010); and the Science and Technology Development Program of Shandong Province (grant no. 2014GSF117003).