Massive swarm of tunicates tilts ocean's chemical balance

Jan 31, 2012

A surge of nutrients to the warm waters off the southeastern coast of Australia during the highly productive austral spring can spark an explosion in the phytoplankton population. Where phytoplankton bloom, so do the predators that feed on them. Some of these predators, like the globally prevalent, barrel-shaped tunicate salp Thalia democratica, excel at capitalizing on the transient nature of phytoplankton blooms.

Salps are tiny gelatinous creatures that feed on and other microorganisms by straining them from the with a fine mesh sieve. A rarity among multicellular animals, salps retain the ability to reproduce by asexual budding, with one salp spawning a clone of itself. This budding, combined with sexual reproduction, enables salp populations to grow by up to 250 percent per day.

During early October 2008 the southbound waters of the East Australian Current entrained a column of nutrient-rich coastal water, spawning a self-contained clockwise-rotating cold water eddy. Within the eddy, nutrient-rich deep water mixed with warm surface waters, sparking a surge in phytoplankton and, consequently, salp populations. Using temperature, salinity, fluorescence, and nutrient concentration measurements, along with concentration detections, Everett et al. describe the highest-density salp population ever recorded.

Concentrated in a 15-kilometer by 20-meter (9-mile by 66-foot) disk, the authors estimate that roughly 40 trillion salps gorged on , with a peak density of more than 6,000 salps per cubic meter. Samples from the swarm showed individuals ranging from 0.5 to 5 millimeters (0.02 to 0.2 inches) in length. Stretched end to end, the swarm would stretch halfway to the Sun. Salp swarms can have a powerful temporary effect on localized biology, impinging other species' survivability by limiting carbon and nitrogen supplies.

The authors estimate that this swarm would have tied up 264 metric tons (582,000 pounds) of carbon and 72 metric tons (159,000 pounds) of nitrogen.

Explore further: NASA balloons begin flying in Antarctica for 2014 campaign

More information: Three-dimensional structure of a swarm of the salp Thalia democratica within a cold-core eddy off southeast Australia, J. D. Everett and I. M. Suthers, Journal of Geophysical Research-Oceans, doi:10.1029/2011JC007310 , 2011

add to favorites email to friend print save as pdf

Related Stories

Spring bloom brings 'jelly balls' to NSW coast

Nov 03, 2008

(PhysOrg.com) -- An unusual abundance of jelly-like creatures has been discovered in waters along the NSW coast from Sydney to Newcastle during a marine survey of the region by a team of scientists from the ...

Study sheds light on tunicate evolution

Jul 01, 2011

(PhysOrg.com) -- Woods Hole Oceanographic Institution (WHOI) researchers have filled an important gap in the study of tunicate evolution by genetically sequencing 40 new specimens of thaliaceans, gelatinous, ...

Earth from Space: A southern summer bloom

Jan 16, 2012

(PhysOrg.com) -- In this Envisat image, a phytoplankton bloom swirls a figure-of-8 in the South Atlantic Ocean about 600 km east of the Falkland Islands.   During this period in the southern hemisphere, ...

Coccolithophore blooms in the southwest Atlantic

Oct 21, 2010

A study led by Dr Stuart Painter of the National Oceanography Centre helps explain the formation of huge phytoplankton blooms off the southeast coast of South America during the austral summer (December-January). ...

Recommended for you

Scientists make strides in tsunami warning since 2004

8 hours ago

The 2004 tsunami led to greater global cooperation and improved techniques for detecting waves that could reach faraway shores, even though scientists still cannot predict when an earthquake will strike.

Trade winds ventilate the tropical oceans

8 hours ago

Long-term observations indicate that the oxygen minimum zones in the tropical oceans have expanded in recent decades. The reason is still unknown. Now scientists at the GEOMAR Helmholtz Centre for Ocean Research ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Squirrel
not rated yet Feb 01, 2012
264 metric tons (582,000 pounds) of carbon equals the amount of carbon in 165,000 people (wikipedia composition of the human body, a 70 kg human contains 14 kg of carbon).

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.