Interactive effects of increasing atmospheric CO 2 and copper exposure on the growth and photosynthesis in the young sporophytes of Sargassum fusiforme (Phaeophyta)

• Published in: Chemosphere (Oxford) 2021-04, Vol.269, p.129397
• Main Authors: Wen, Jiayi, Zou, Dinghui
• Format: Article
• Language: English
• Subjects: Carbon Dioxide - toxicity; Copper - toxicity; Hydrogen-Ion Concentration; Photosynthesis; Sargassum; Seawater
• ISSN: 1879-1298
• DOI: 10.1016/j.chemosphere.2020.129397

Little attention has been given to the combined effects of elevated atmospheric CO -induced ocean acidification (OA) and heavy metal pollution on marine macroalgae at the young stage. This study investigated the mutual effects of copper (Cu) and elevated CO on the young sporophytes of brown macroalgae Sargassum fusiforme. A matrix of four copper concentrations, 0, 0.025, 0.075 and 0.15 mg‧L , and two levels of CO (ambient CO : 400 μatm; elevated CO : 1,000 μatm) were used. High concentration of copper exposure greatly depressed photosynthesis and growth of the young sporophytes of S. fusiforme by reducing the apparent photosynthetic efficiency (ɑ), maximum net photosynthetic oxygen evolution rate (P ), maximum photochemical quantum yield (F /F ) and pigments content (Chl a and Car). While elevated CO alone had obscure impact on this alga. However, the inhibition of Cu stress on F /F was weakened by elevated CO , which also decreased the light compensation point (I ). Meanwhile, the Cu -induced ascent in the dark respiration rate (Rd) and superoxide dismutase (SOD) activity was mitigated under the growth with elevated CO , suggesting an alleviated oxidative stress. Overall, we propose that, under CO enrichment condition, the young sporophytes of S. fusiforme may increase photosynthesis efficiency and synthesize less enzymatic antioxidants in face of increasing Cu stress.