Ocean scientists have, for the first time successfully balanced the supply of food to midwater organisms with their demands for this food. The depth at which they consume this sinking material regulates our climate by determining how much carbon is stored by the ocean and how much remains in the atmosphere.
Dr Richard Sanders, Head of Ocean Biology and Ecosystems at the National Oceanography Centre explained: "Phytoplankton -- marine plants -- grow in the surface ocean using CO2 and sunlight to produce biomass in the same way that terrestrial plants do. This links atmospheric CO2 to the processes in the oceans and it is this 'ocean carbon budget' that we are keen to quantify."
When phytoplankton die, they sink to depth and transport atmospheric CO2 into the deep ocean. Massive quantities of CO2 are stored in the deep ocean this way, keeping atmospheric CO2 concentrations much lower than if the oceans were devoid of life.
Most of the food supplied to the deep sea sinks from the upper ocean in the form of marine snow, flakes of marine detritus -- dead plant and animal plankton and plankton faeces. Animals living in the 'twilight zone', a layer between 50-1000 metres depth where light levels are extremely low, eat most of this marine snow.
"We show that a balance between food supply and demand is possible because of intricate linkages between zooplankton and microbes," explained lead author Dr Sarah Giering. "When these microscopic animals eat marine snow, much of it is released as tiny suspended particles that are readily available to bacteria, which in turn convert it into biomass and CO2."
Dr Daniel Mayor from the University of Aberdeen, a co-author of the research, said:"The apparently wasteful process of zooplankton fragmenting, rather than ingesting, sinking detritus is central to understanding how the twilight zone works.
Tell us what you think of Chemistry 2011 -- we welcome both positive and negative comments. Have any problems using the site? Questions?