Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tiny Marine Organisms Reflect Ocean Warming

06.01.2006


Image credit: (c) 2002 David Field
Foraminifera (forams) are small, amoeba-like organisms that live inside shells ("tests") such as those shown here. These forams were collected from the waters overlying the Santa Barbara Basin.


Sediment cores collected from the seafloor off Southern California reveal that plankton populations in the Northeastern Pacific changed significantly in response to a general warming trend that started in the early 1900s. As ocean temperatures increased, subtropical and tropical species of small marine organisms called foraminifera (forams) became more abundant. Forams that live in cooler waters decreased, especially after the mid-1970s. These changes are unlike anything seen during the previous 1,400 years. Oceanographer David Field discovered these dramatic changes during his Ph.D. work at Scripps Institution of Oceanography at the University of California, San Diego. He currently works as a postdoctoral fellow at the Monterey Bay Aquarium Research Institute (MBARI). Field and his co-authors describe their findings in the current issue of Science magazine.

Foraminifera are small, amoeba-like organisms that live inside tiny shells ("tests") several of which might fit on the head of pin. Most forams live near the surface of the world’s oceans. Different species of forams live in ocean waters of different temperatures. When forams die, they sink to the seafloor, where their shells are often preserved as fossils in seafloor sediments.

Field studied fossilized forams in one- to three-meter-long sediment cores collected at the bottom of the Santa Barbara Basin, off Southern California. In this area, dead plankton and sediments settle onto the seafloor to form distinct annual layers similar to growth rings in a tree. At 600 meters beneath the ocean surface, seawater in the Santa Barbara Basin contains very little oxygen, so few bottom-dwelling animals disturb the sediments and the annual layers remain relatively intact.



In conducting this study, Field worked with Timothy Baumgartner and Vicente Ferreira-Bartrina of Centro de Investigación Científica y de Educación Superior de Ensenada, Mexico and with Christopher Charles and Mark Ohman of Scripps Institution of Oceanography at the University of California, San Diego.

Field and his coauthors examined yearly sediment layers that were formed up to 1,400 years ago. Counting the different species of foraminifera in each layer, they discovered that many species of tropical and subtropical forams became more abundant after about 1925. Although previous studies have shown an ocean warming trend beginning at about this time, scientists have debated how much of this warming trend was due to natural variability. In order to address this issue, scientists needed more long-term data. Field’s data set extends far enough back in time to demonstrate that the 20th century warming trend surpassed the range of natural variability.

Many previous studies have shown that a rapid warming and a dramatic change in eastern North Pacific ecosystems occurred in the mid-1970s. At this time, species of plankton, kelp, fish and seabirds that prefer warmer waters increased and species favoring colder conditions decreased. Most scientists agree that part of the warming of the global oceans and atmosphere since the mid-1970s has been caused by human emissions of greenhouse gases. However, it has been unclear whether the ecosystem changes at this time were associated with anthropogenic warming. Field’s sediment cores show that tropical and subtropical species of forams became even more abundant during this period while forams that prefer cooler waters decreased. The resulting foram community was unlike anything seen during the last 1,400 years. These long-term data indicate that the ecosystem changes since the mid-1970s are best explained by anthropogenic warming.

According to Field, "These data show that ocean warming has been affecting foram populations prior to the late twentieth century. However, changes since the 1970s have been particularly unusual, and show that ocean ecosystems in the northeastern Pacific have passed some threshold of natural variability." He also points out that most scientific data about the ocean have been collected during recent decades, after ocean temperatures and marine ecosystems had already begun to change. As Field notes, "It’s a classic case of ’shifting baselines’—conditions that scientists think of as normal today might actually be very atypical when you look back a few hundred years."

This study provides a long-term context for many other studies of oceanographic and ecological conditions off the California coast. It was conducted as part of the National Science Foundation’s Long-Term Ecological Research (LTER) program. The LTER program supports ecological research over long time periods in a variety of terrestrial and marine ecosystems. The research was supported by the Achievement Rewards for College Students-Los Angeles division, the University of California ship funds and Coastal Initiatives, the National Oceanic and Atmospheric Administration, S. and B. Kimmich, the National Science Foundation and the California Current Ecosystem LTER.

Mario Aguilera | EurekAlert!
Further information:
http://scrippsnews.ucsd.edu/article_detail.cfm?article_num=709
http://scripps.ucsd.edu

More articles from Ecology, The Environment and Conservation:

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

nachricht Value from wastewater
16.08.2017 | Hochschule Landshut

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>