Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates
<p>High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic <span class="inline-formula">CO<sub>2</sub></span> emissions continue. Marine microbes are an essential part of the marine food web and are a critic...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-08-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/17/4153/2020/bg-17-4153-2020.pdf |
| Summary: | <p>High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic <span class="inline-formula">CO<sub>2</sub></span> emissions continue. Marine microbes are an essential part of the marine food web and are a critical link in biogeochemical processes in the ocean, such as the cycling of nutrients and carbon. Despite this, the response of Antarctic marine microbial communities to ocean acidification is poorly understood. We investigated the effect of increasing <span class="inline-formula"><i>f</i></span><span class="inline-formula">CO<sub>2</sub></span> on the growth of heterotrophic nanoflagellates (HNFs), nano- and picophytoplankton, and prokaryotes (heterotrophic Bacteria and Archaea) in a natural coastal Antarctic marine microbial community from Prydz Bay, East Antarctica. At <span class="inline-formula">CO<sub>2</sub></span> levels <span class="inline-formula">≥634</span> <span class="inline-formula">µ</span>atm, HNF abundance was reduced, coinciding with increased abundance of picophytoplankton and prokaryotes. This increase in picophytoplankton and prokaryote abundance was likely due to a reduction in top-down control of grazing HNFs. Nanophytoplankton abundance was elevated in the 634 <span class="inline-formula">µ</span>atm treatment, suggesting that moderate increases in <span class="inline-formula">CO<sub>2</sub></span> may stimulate growth. The taxonomic and morphological differences in <span class="inline-formula">CO<sub>2</sub></span> tolerance we observed are likely to favour dominance of microbial communities by prokaryotes, nanophytoplankton, and picophytoplankton. Such changes in predator–prey interactions with ocean acidification could have a significant effect on the food web and biogeochemistry in the Southern Ocean, intensifying organic-matter recycling in surface waters; reducing vertical carbon flux; and reducing the quality, quantity, and availability of food for higher trophic levels.</p> |
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| ISSN: | 1726-4170 1726-4189 |