Copepod Migrations Are Important For The Ocean’s CO2 Uptake

2015-09-10T14:40:32+00:00 September 10, 2015|
Calanus finmarchicus is one of the most abundant copepod species in the North Atlantic and is an extremely important source of food for many commercial fish species. (Credit: Sigrun Jonasdottir/DTUAqua)

(Click to enlarge) Calanus finmarchicus is one of the most abundant copepod species in the North Atlantic and is an extremely important source of food for many commercial fish species. (Credit: Sigrun Jonasdottir/DTUAqua)

Zooplankton no bigger than grains of rice play a much larger role in the transport and storage of CO2in the ocean than previously thought.

(From ScienceDaily) — In a scientific article recently published in Proceedings of the Academy of Sciences (PNAS), researchers from DTU Aqua, the University of Copenhagen and the University of Strathclyde, Scotland, have shown that the ocean’s tiny copepods actively transport carbon down to the deep water in the North Atlantic during their winter hibernation. The discovery means that our understanding of the planet’s carbon cycle, and the ocean’s ability to absorb carbon needs to be revised. Changes in the carbon cycle are the cause of climate change.

“The active transportation of carbon from the atmosphere into the ocean has never been quantified at this scale before, but our calculations indicate that we may be able to double the previous estimate for the North Atlantic carbon capture,” said DTU Aqua’s Senior Researcher Sigrun Jonasdottir, the lead contributor to the article.

The copepod, Calanus finmarchicus, is a small crustacean that lives in the North Atlantic, where it is an important food source for whales, birds and fish alike. In the summer, when food is plentiful, it manages to reproduce faster than it is eaten, but in winter this is not the case. This possibly explains why the animal developed a life cycle whereby it builds up carbon rich lipids during late summer. It then is carried by currents to the middle of the North Atlantic, where it swims down to a depth of about a kilometre. Here the copepod goes into hibernation and lives off its lipid reserves until spring.

The animal’s life cycle has has been known for a long time. But what has not been calculated before is the impact that the copepod’s long journey and hibernation at depth has on the ability of the ocean to store carbon dioxide removed from the atmosphere.

“The trick is that the copepod has to swim down so deep to hibernate that it comes down into water which is not in contact with the atmosphere. This means that the CO2 released at these depths by the copepods burning their carbon-containing lipids into the water will not be exchanged in the atmosphere. In this way, the copepods indirectly remove CO2 from the atmosphere, where it can affect the climate, and deposit it deep down in the ocean, where it can remain for thousands of years,” says Sigrun Jonasdottir.

There are billions of Calanus finmarchicus in the North Atlantic, and the research group’s calculations show that this species of copepod alone actively moves 1-3 million tons of carbon into the North Atlantic every year. And C. finmarchicus is far from being the only animal in the ocean which spends part of its life cycle in deep water.

Read the full article here: http://www.sciencedaily.com/releases/2015/09/150908094120.htm