| 英文摘要: | The ocean is a difficult environment to study due to its vast, remote regions. Climate change is impacting on marine biology and we need to better understand how this will manifest. The ocean is full of life, but most of it is too small for the human eye to see. The microscopic plants of the ocean, made up of many species but known collectively as phytoplankton, produce half of Earth's oxygen through their photosynthetic growth. Phytoplankton are at the base of the ocean food chain and form a critical part of the global carbon cycle by driving the biological carbon pump — transferring carbon from the atmosphere to the deep ocean. Whilst we cannot see individual plankton, when conditions are right they grow at an amazing rate, resulting in a bloom of such high density that it can be seen from space. Their growth relies on the right temperature, sufficient nutrients and minerals (such as iron), and light — meaning they are limited to the upper ocean and the maximum depth to which light can penetrate. Small changes in these properties can disproportionately impact on individual species. But these are not the only changes that can affect the growth and survival of phytoplankton. Anthropogenic greenhouse-gas emissions are increasing and so is the amount of carbon and heat entering the ocean. The result is warming of surface waters and a lower pH, that is, a more acidic environment. It is not just carbon that needs to be considered when talking about emissions. Other compounds should be considered, such as higher emissions of reactive nitrogen (that is, nitrogen compounds that are available for plant growth) from northeastern Asia due to surging population and development. The deposition of this additional nitrogen into the North Pacific Ocean, where photosynthesis is limited by low nitrogen, has the potential to shift it to being a phosphate-limited region (I. Kim et al., Science 346, 1102–1106; 2014).
PENELOPE AJANI
- Corrected online 16 April 2015
- In the Editorial 'Ocean wanderers' (Nature Clim. Change 5, 1; 2015) the image did not show marine phytoplankton. Corrected after print 16 April 2015.
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