Larvacean life: the surprise ocean giants of global carbon capture


The finger-sized 'giant larvaceans' are zooplankton champions, transferring carbon to the deep ocean with trails of mucus, writes Amy Middleton.



Carbon is cycled from the atmosphere to the deep ocean at astonishing rates, and a new study has revealed one of its key carriers: a species of zooplankton called giant larvaceans.

These marine organisms, around the size of a human’s pinky finger, are a type of filter-feeder – an animal that sieves food particles from water to survive.

Giant larvaceans have a particular method for feeding: they construct complex and fragile mucus structures that can reach up to 1 metre in diameter. As the giant larvacean beats its tail, it pushes water through its filtering corridor, to capture floating food particles. The mucus structures are then cast to the sea floor.

Because of the fragility of these structures, researchers have struggled to measure how much carbon is processed from the atmosphere by this unique harvest – a crucial piece of information in understanding how ocean acidification occurs.

As a workaround, a research team led by Kakani Katija at Monterey Bay Aquarium Research Institute in California developed a remote-operated device which visually measures the flow of fluid within these structures, allowing the team to record rates of filtration.

The researchers used this analysis, along with data on species population from the past 22 years, to assess the local grazing impact of the species.

The results, published in Science Advances, reveal giant larvaceans as the record-holders for the most atmospheric carbon transmission into deep ocean of any plankton.

The study represents a crucial step in our understanding of how atmospheric carbon could impact ocean health, and the longer-term effects of climate change.

Amy middleton.jpg?ixlib=rails 2.1
Amy Middleton is a Melbourne-based journalist.
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