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Research project

Trophic Diversity in Marine Ecosystems

Project overview

In terrestrial ecosystems, it is quite straightforward to tell the difference between a plant and an animal. This difference seems so clear as to be obvious, but in recent decades, marine scientists have begun to reveal that in the ocean such distinctions are not always appropriate. Among the microscopic but incredibly numerous plankton at the base of marine food-webs, the majority of species defy such strict classifications. These flexible organisms, known as mixotrophs, not only use energy from the sun to take up nutrients and grow, but at the same time they can also kill and eat other plankton.

It is important that we have a good understanding of such processes at the foundation of marine ecosystems - as well as supporting fisheries that provide essential nutrition to more than half the world's population, they play a key role in regulating the global carbon cycle. Photosynthesis by the plankton helps the oceans to absorb massive amounts of carbon dioxide, which is locked away in the deep ocean by the sinking of dead and decomposing biological matter. This process, known as the "biological carbon pump", has been estimated to reduce atmospheric CO2 concentrations by as much as half, and thus plays a critical role in the regulation of global climate.

At present we know that mixotrophy is probably the default lifestyle for most single -celled plankton, and we know that they often dominate marine communities. As yet however, we do not have a concrete understanding of how environmental factors may shape the balance between different sources of nutrition in these communities, and how such changes might affect the ecological role of mixotrophs and their potential effects on the global cycling of climatically important elements, including carbon.


Lead researcher

Dr Ben Ward

Principal Research Fellow

Collaborating research institutes, centres and groups