The ability of macroalgae to mitigate the negative effects of ocean acidification on four species of North Atlantic bivalve
Coastal ecosystems can experience acidification via upwelling, eutrophication, riverine discharge, and climate change. While the resulting increases in p CO 2 can have deleterious effects on calcifying animals, this change in carbonate chemistry may benefit some marine autotrophs. Here, we report on...
| Published in: | Biogeosciences |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Copernicus Publications
2018
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/bg-15-6167-2018 https://doaj.org/article/72ec83595a4f4378915638bf60ca034e |
| Summary: | Coastal ecosystems can experience acidification via upwelling, eutrophication, riverine discharge, and climate change. While the resulting increases in p CO 2 can have deleterious effects on calcifying animals, this change in carbonate chemistry may benefit some marine autotrophs. Here, we report on experiments performed with North Atlantic populations of hard clams ( Mercenaria mercenaria ), eastern oysters ( Crassostrea virginica ), bay scallops ( Argopecten irradians ), and blue mussels ( Mytilus edulis ) grown with and without North Atlantic populations of the green macroalgae, Ulva . In six of seven experiments, exposure to elevated p CO 2 levels ( ∼ 1700 µatm) resulted in depressed shell- and/or tissue-based growth rates of bivalves compared to control conditions, whereas rates were significantly higher in the presence of Ulva in all experiments. In many cases, the co-exposure to elevated p CO 2 levels and Ulva had an antagonistic effect on bivalve growth rates whereby the presence of Ulva under elevated p CO 2 levels significantly improved their performance compared to the acidification-only treatment. Saturation states for calcium carbonate (Ω) were significantly higher in the presence of Ulva under both ambient and elevated CO 2 delivery rates, and growth rates of bivalves were significantly correlated with Ω in six of seven experiments. Collectively, the results suggest that photosynthesis and/or nitrate assimilation by Ulva increased alkalinity, fostering a carbonate chemistry regime more suitable for optimal growth of calcifying bivalves. This suggests that large natural and/or aquacultured collections of macroalgae in acidified environments could serve as a refuge for calcifying animals that may otherwise be negatively impacted by elevated p CO 2 levels and depressed Ω. |
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