El Niño's dramatic impact on ocean biology, carbon dioxide captured by unique monitoring system

December 08, 1999

The 1997-98 El Niño/La Niña had an unprecedented roller-coaster effect on the oceanic food chain across a vast swath of the Pacific, plunging chlorophyll levels to the lowest ever recorded in December 1997 and spawning the largest bloom of microscopic algae ever seen in the region the following summer.

According to new results published in the Dec. 10 issue of the journal Science, El Niño also dramatically reduced the amount of carbon dioxide normally released into the atmosphere by the equatorial Pacific Ocean.

Data from an array of instruments on buoys, ships and in space, including NASA's Sea-viewing Wide Field-of-View Sensor (SeaWiFS), gave researchers an unprecedented view into the extreme biological effects of this El Niño/La Niña event.

"With SeaWiFS in orbit, we were able to see for the first time not only the vast size and intensity of the ocean's biological rebound from El Niño, but also the unbelievable speed of that recovery," said Goddard Space Flight Center (Greenbelt, Md.) oceanographer Dr. Gene Feldman, a co-author of the study. SeaWiFS provides daily views of the world's oceans and land masses.

Over the past decade scientists have been able to observe the development and progression of El Niño warmings, and consequent changes in upwelling of nutrient-rich ocean waters, thanks to data continuously collected in the Pacific by the buoys of the National Oceanic and Atmospheric Administration's Tropical Atmosphere Ocean array.

In 1996 new biological and chemical sensors were added to some of these buoys by the Monterey Bay Aquarium Research Institute (MBARI), allowing researchers for the first time to directly and continuously monitor biological productivity and the concentration of carbon dioxide in the region. The launch of SeaWiFS in 1997 added yet another ocean-monitoring tool capable of detecting subtle changes in ocean color that are directly related to the concentration of chlorophyll, a prime indicator of biological activity in ocean waters. The largest reservoir of chlorophyll in the ocean is in the phytoplankton (a microscopic form of algae), which forms the base of the oceanic food chain.

"This is the first time we've ever had a set of biological measurements from moored instruments and satellites during an intense El Niño, and we've never seen such low chlorophyll concentrations," said MBARI biological oceanographer Francisco Chavez, lead author of the study.

It was the buoy measurements and SeaWiFS data that revealed surprisingly low and then high levels of chlorophyll coinciding with El Niño's strongest phase and the recovery period and transition to La Niña cooling. When the warm-water layer produced by El Niño extended to its greatest depths and the upwelling of nutrients necessary for phytoplankton growth virtually ceased, chlorophyll values plummeted.

The researchers were again surprised in mid-1998 when chlorophyll levels skyrocketed, revealing the largest phytoplankton bloom, in area, ever observed in the equatorial Pacific. In their published results, the researchers suggest that elevated iron concentrations stimulated this intense bloom, a result of the increased upwelling associated with La Nina.

El Niño also drastically reduced the amount of carbon dioxide this ocean region adds to the atmosphere. Unlike most parts of the world's oceans, the equatorial Pacific is normally a major contributor to atmospheric carbon dioxide due to the carbon-dioxide-rich deep ocean waters brought to the surface here and the relatively low levels of biological activity.

The researchers calculate that the amount of carbon dioxide released to the atmosphere by the equatorial Pacific during the year of El Niño conditions was 700 million metric tons of carbon less than the previous year. This is equivalent to half of the United States' total annual carbon dioxide emissions from fossil fuel burning.

SeaWiFS images of the 1997-98 El Niño are available at:
http://svs.gsfc.nasa.gov/imagewall/elnino/elninoimpact.html
-end-
Cynthia O'Carroll
NASA Goddard Space Flight Center
(Phone: 301-614-5563)

Debbie Nail Meyer
Monterey Bay Aquarium Research Center
(Phone: 831-775-1807)

Jana Goldman
National Oceanic and Atmospheric Administration
(Phone: 301-713-2483)

NASA/Goddard Space Flight Center

Related Algae Articles from Brightsurf:

Sprat, mollusks and algae: What a diet of the future might look like
Rethinking what we eat is essential if we hope to nourish ourselves sustainably and mind the climate.

Ocean algae get 'coup de grace' from viruses
Scientists have long believed that ocean viruses always quickly kill algae, but Rutgers-led research shows they live in harmony with algae and viruses provide a 'coup de grace' only when blooms of algae are already stressed and dying.

New science behind algae-based flip-flops
Sustainable flip-flops: A team of UC San Diego researchers has formulated polyurethane foams made from algae oil to meet commercial specifications for midsole shoes and the foot-bed of flip-flops.

Battling harmful algae blooms
In two separate studies, the University of Delaware's Kathryn Coyne is looking at why one species of algae has some strains that can cause fish kills and others that are non-toxic, while examining an algicidal bacterium found in Delaware's Inland Bays that could provide an environmentally-friendly approach to combatting algae blooms.

Algae as living biocatalysts for a green industry
Many substances that we use every day only work in the right 3D structure.

Algae in the oceans often steal genes from bacteria
Algae in the oceans often steal genes from bacteria to gain beneficial attributes, such as the ability to tolerate stressful environments or break down carbohydrates for food, according to a Rutgers co-authored study.

Algae team rosters could help ID 'super corals'
U.S. and Australian researchers have found a potential tool for identifying stress-tolerant ''super corals.'' In experiments that simulated climate change stress, researchers found corals that best survived had symbiotic algae communities with similar features.

Algae shown to improve gastrointestinal health
A green, single-celled organism called Chlamydomonas reinhardtii has served as a model species for topics spanning algae-based biofuels to plant evolution.

How do corals make the most of their symbiotic algae?
Corals depend on their symbiotic relationships with the algae that they host.

Algae as a resource: Chemical tricks from the sea
The chemical process by which bacteria break down algae into an energy source for the marine food chain, has been unknown - until now.

Read More: Algae News and Algae Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.