Sunday, July 27, 2014
YOLO COUNTY NEWS
99 CENTS

Plankton make scents for birds, cooler planet

By
From page A5 | March 25, 2014 |

The top predators of the Southern Ocean, far-ranging seabirds, are tied both to the health of the ocean ecosystem and to global climate regulation through a mutual relationship with phytoplankton, according to newly published work from UC Davis.

When phytoplankton are eaten by grazing crustaceans called krill, they release a chemical signal that calls in krill-eating birds. At the same time, this chemical signal — dimethyl sulfide, or DMS — forms sulfur compounds in the atmosphere that promote cloud formation and help cool the planet. Seabirds consume the grazers, and fertilize the phytoplankton with iron, which is scarce in the vast Southern Ocean.

The work was published March 3 in the journal Proceedings of the National Academy of Sciences.

“The data are really striking,” said Gabrielle Nevitt, professor of neurobiology, physiology and behavior at UCD and co-author on the paper with graduate student Matthew Savoca. This suggests that marine top predators are important in climate regulation, although they are mostly left out of climate models, Nevitt said.

“In addition to studying how these marine top predators are responding to climate change, our data suggest that more attention should be focused on how ecological systems, themselves, impact climate. Studying DMS as a signal molecule makes the connection,” she said.

Nevitt has studied the sense of smell in ocean-going birds for about 25 years, and was the first to demonstrate that marine top predators use climate-regulating chemicals for foraging and navigation over the featureless ocean. DMS is now known to be an important signal for petrels and albatrosses, and the idea has been extended to various species of penguins, seals, sharks, sea turtles, coral reef fishes and possibly baleen whales, she said.

Phytoplankton are the plants of the open ocean, absorbing carbon dioxide and sunlight to grow. When these plankton die, they release an enzyme that generates DMS.

A role for DMS in regulating climate was proposed by Robert Charlson, James Lovelock, Meinrat Andreae and Stephen Warren in the 1980s.

According to the CLAW hypothesis, warming oceans lead to more growth of green phytoplankton, which in turn release a precursor to DMS when they die. Rising levels of DMS in the atmosphere cause cloud formation, and clouds reflect sunlight, helping to cool the planet. It’s a negative feedback loop to control the planet’s temperature.

Savoca and Nevitt looked at 50 years of records on seabirds’ stomach contents, combined with Nevitt’s experimental results of which species use DMS to forage. They found that species that respond to DMS overwhelmingly fed on krill, which graze on phytoplankton.

On land, there are several known examples of plants that respond to attack by insects by producing chemicals that attract predators that eat those insects. Nevitt and Savoca propose the same thing happens in the open ocean: when phytoplankton come under attack by krill, the DMS released as they die attracts predators that eat the krill.

The birds have something else to contribute. The Southern Ocean lacks large land masses, and is relatively poor in iron, which has to be washed out from land by rivers. Krill are rich in iron, but birds can absorb relatively little of it — so the rest is excreted back into the ocean, promoting plankton growth.

The work suggests that by linking predatory seabirds and phytoplankton — the top and bottom levels of the food chain — DMS plays an important role in the ocean ecosystem, which affects climate by taking up carbon, as well as a physical role in generating clouds, Nevitt said.

“Studying how seabirds use scent cues to forage has shown us a mechanism by which the seabirds themselves contribute to climate regulation. That’s not what we expected, but I really think our results will have global significance,” she said.

At the same time, numbers of these birds are declining, with almost half of species listed as vulnerable, endangered or critically endangered. The newly discovered links between top predators and the base of the ocean food web mean that a decline in seabirds could have a significant effect on the marine productivity.

The work was funded by the National Science Foundation.

— UC Davis News

Comments

comments

.

News

Zombies by rail: It’s not just a show, it’s a trip

By Evan Arnold-Gordon | From Page: A1 | Gallery

 
Fatal Covell Boulevard crash recalled in court

By Lauren Keene | From Page: A1

Humphrey Fellows will host Global Forum

By Enterprise staff | From Page: A1 | Gallery

 
Community gardens stretch food dollars, study finds

By Special to The Enterprise | From Page: A1 | Gallery

Ukraine launches offensive to retake Donetsk

By The Associated Press | From Page: A2

 
Israel extends Gaza truce through Sunday

By The Associated Press | From Page: A2

Wildfire spurs evacuation of 700 homes

By The Associated Press | From Page: A2

 
State can’t say if it’s meeting drought goal

By The Associated Press | From Page: A2

 
Rairdan joins race for Davis school board

By Enterprise staff | From Page: A2

New ordinance aims to prevent nut thefts from orchards

By Anne Ternus-Bellamy | From Page: A4

 
Biggest book sale to date opens Friday at Davis library

By Enterprise staff | From Page: A4

Luna family matriarch turns 100

By Enterprise staff | From Page: A4 | Gallery

 
Mace Innovation Center is focus of meeting

By Enterprise staff | From Page: A5

Freeway crash injures two drivers

By Lauren Keene | From Page: A5

 
Museum wants your old Davis High School yearbooks

By Enterprise staff | From Page: A5

Affordable housing forum planned in Davis

By Special to The Enterprise | From Page: A5

 
 
 
Discussion of oil by rail EIR planned Sunday

By Enterprise staff | From Page: A5

State awards $40,000 for historic property survey

By Lily Holmes | From Page: A8

 
Protesters gather at Primate Center

By Tanya Perez | From Page: A8

Vanguard hosts economic development director

By Enterprise staff | From Page: A9

 
Get a sneak peek at documentary trailer

By Enterprise staff | From Page: A9

Davis Chamber Choir sings short summer program

By Jeff Hudson | From Page: A9

 
Tasting event benefits Yolo Land Trust

By Lily Holmes | From Page: A9

Free blood pressure screenings offered

By Enterprise staff | From Page: A9

 
At the Pond: From Davis, it’s easy to get back to nature

By Jean Jackman | From Page: A10 | Gallery

Tickets on sale now for DHS Hall of Fame dinner

By Enterprise staff | From Page: A11

 
.

Forum

Feels like a million miles away

By Creators Syndicate | From Page: A7

 
Here’s what you need for a perfect wedding

By Marion Franck | From Page: A7

 
Check doctors’ vitals before they check yours

By The Associated Press | From Page: A7

Husband’s let himself go

By Creators Syndicate | From Page: A14

 
So, what’s in a week’s worth of waste?

By Michelle Millet | From Page: A16

Pat Oliphant cartoon

By Debbie Davis | From Page: A16

 
Golf tourney was a big success

By Letters to the Editor | From Page: A16

Questions on water rights

By Letters to the Editor | From Page: A16, 1 Comment

 
Campus turns on the tap

By Our View | From Page: A16

We can do more to help

By Letters to the Editor | From Page: A17

 
New playground is wonderful

By Letters to the Editor | From Page: A17

Just Us in Davis: Little Rock Nine hero to celebrate with Davis youths

By Jann L. Murray-Garcia | From Page: A17 | Gallery

 
.

Sports

Furyk opens 3-shot lead in Canadian Open

By The Associated Press | From Page: B1

 
Gray wins 6th straight, A’s 4 HRs beat Texas 5-1

By The Associated Press | From Page: B1

Kershaw throws 2-hitter as Dodgers beat Giants 5-0

By The Associated Press | From Page: B1

 
Sutherland presents 1st clinic; golf column on its way

By Bruce Gallaudet | From Page: B1 | Gallery

New Korematsu teacher is an American Ninja Warrior

By Bruce Gallaudet | From Page: B1 | Gallery

 
Nibali set to cruise to Tour victory

By The Associated Press | From Page: B2

Area sports briefs: River Cats take Game 1 of doubleheader

By Special to The Enterprise | From Page: B4

 
.

Features

.

Arts

.

Business

Companies will collaborate on crop insect control

By Enterprise staff | From Page: A13

 
Developer’s commitments: affordable and green

By Special to The Enterprise | From Page: A13 | Gallery

UC Davis Health System earns ‘Most Wired’ award

By Charles Casey | From Page: A15

 
Bartholomew hires new associate

By Enterprise staff | From Page: A15

Yolo County real estate sales

By Zoe Juanitas | From Page: A15

 
Go back to school with Great Clips

By Enterprise staff | From Page: A15

Lagerstrom represents Davis at Mary Kay seminar

By Special to The Enterprise | From Page: A15

 
.

Obituaries

Carlton Hope Meister

By Special to The Enterprise | From Page: A4

 
Jonathan Eric Hollander

By Special to The Enterprise | From Page: A4

.

Comics

Comics: Sunday, July 27, 2014

By Creator | From Page: A6