Ocean acidification and nutrient limitation synergistically reduce growth and photosynthetic performances of a green tide alga <i>Ulva linza</i>
Large-scale green tides have been invading the coastal zones of the western Yellow Sea annually since 2008. Meanwhile, oceans are becoming more acidic due to continuous absorption of anthropogenic carbon dioxide, and intensive seaweed cultivation in Chinese coastal areas is leading to severe regi...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-06-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/15/3409/2018/bg-15-3409-2018.pdf |
| Summary: | Large-scale green tides have been invading the coastal zones of the western
Yellow Sea annually since 2008. Meanwhile, oceans are becoming more acidic
due to continuous absorption of anthropogenic carbon dioxide, and intensive
seaweed cultivation in Chinese coastal areas is leading to severe regional
nutrient limitation. However, little is known about the combined effects of
global and local stressors on the eco-physiology of bloom-forming algae. We
cultured <i>Ulva linza</i> for 9–16 days under two levels of
<i>p</i>CO<sub>2</sub> (400 and 1000 µatm) and four treatments of
nutrients (nutrient repletion, N limitation, P limitation, and N–P
limitation) to investigate the physiological responses of this green tide
alga to the combination of ocean acidification and nutrient limitation. For
both sporelings and adult plants, elevated <i>p</i>CO<sub>2</sub> did not affect the growth rate when cultured under
nutrient-replete conditions but reduced it under P limitation; N or P
limitations by themselves reduced growth rate. P limitation resulted in a
larger inhibition in growth for sporelings compared to adult plants.
Sporelings under P limitation did not reach the mature stage after 16 days of
culture while those under P repletion became mature by day 11. Elevated
<i>p</i>CO<sub>2</sub> reduced net photosynthetic rate for all nutrient treatments
but increased nitrate reductase activity and soluble protein content under
P-replete conditions. N or P limitation reduced nitrate reductase activity
and soluble protein content. These findings indicate that ocean acidification
and nutrient limitation would synergistically reduce the growth of
<i>Ulva</i> species and may thus hinder the occurrence of green tides in a
future ocean environment. |
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| ISSN: | 1726-4170 1726-4189 |