Skip To Content
NSF Logo Search GraphicGuide To Programs GraphicImage Library GraphicSite Map GraphicHelp GraphicPrivacy Policy Graphic
OLPA Header Graphic
 
     
 

NSF Press Release

 


NSF PR 04-004 - January 14, 2004

Media contact: Cheryl Dybas, NSF  (703) 292-7734 cdybas@nsf.gov
Program contact: James Morris, NSF  (703) 292-8481 jmorris@nsf.gov




If We Are What We Eat, Some Lake Fish Are Made of Maple Leaves
Study Shows Fallen Leaves Play a Role in the Food Web.

  image of study lakes.
Image of study lakes.
Credit: IES, Millbrook, New York
Select image for larger version
(Size: 247KB)
 
  scientists conduct research in lakes
Scientists conduct research in study lakes.
Credit: IES, Millbrook, New York
Select image for larger version
(Size: 100KB)
 
  Larger versions of all images from this document
   Note About Images

Arlington, Va.—Aquatic plants form the base of the food web. The energy they create supports aquatic life, from invertebrates to the largest sport fish. Now, a study shows that aquatic plants are receiving a little help from trees. In a paper in this week's issue of the journal Nature, Michael Pace and Jonathan Cole of the Institute of Ecosystem Studies in Millbrook, New York, along with colleagues from Wisconsin and Sweden, indicate that a significant part of the aquatic food chain is supported by terrestrial organic matter that originates on shore.

A building block of life, organic carbon is essential to aquatic food webs. In lakes, aquatic plants produce organic carbon by harnessing the sun's energy (photosynthesis); some of this carbon supports the growth of fish and invertebrate populations. Scientists have long suspected that organic carbon from land is also significant to aquatic life, but the idea is difficult to demonstrate. By tracing the fate of carbon through large-scale lake manipulations, Pace, Cole, and their colleagues have revealed that in some waters terrestrial organic carbon significantly subsidizes the aquatic food web.

"These scientists have found an ingenious method of teasing apart the carbon cycle of lakes," says James Morris, program director in the National Science Foundation (NSF)'s division of environmental biology, which funded the research. "Their study reveals a surprising degree of dependence of lake food webs on sources of organic matter transported into the lakes from the surrounding watershed. These findings reinforce the concept that the ecology of lake ecosystems is tightly coupled with that of the surrounding terrestrial landscape."

That maple tree leaves many eventually become perch, and that the vegetation around a water body can have profound impacts on the animal life within the body of water blur the perceived ecological boundaries between aquatic and terrestrial systems.

The impetus behind the study, which involved manipulating two Michigan lakes, was to better understand the aquatic food chain. Pace explains, "We wanted to reveal what many ecologists have long thought- aquatic life is partly dependent on organic matter produced in the watershed." Using a chemical tracer, Pace and his colleagues set out to quantify this assumption. "The moral of the story," Pace comments, "is, yes, fish are made from algae, but fish are also partly made from maple leaves."

In Lakes Peter and Paul located at the University of Notre Dame Research Center, the scientists tested whether lake plant production was sufficient to support resident aquatic life.

They found that 40-55 percent of particulate carbon and 2250 percent of zooplankton (small animals that live in the water column) in the lakes are derived from terrestrial sources, which confirms that terrestrial carbon fuels aquatic production. The carbon in the zooplankton reflects their dependence on both lake plant production and terrestrial organic matter. Zooplankton are a dietary staple of many fish, especially in very young life stages.

"Our results," notes Cole, "tell us there is not nearly enough aquatic carbon to support these animals. They are dependent on terrestrial inputs."

Pace comments, "We now have direct experimental evidence that confirms that aquatic food chains are supported not just by the production of plants in the water but also by the production of plants on the land surrounding lakes and ponds. The leaves and organic matter that enter lakes are ultimately incorporated into aquatic animals." These findings challenge traditional views of the aquatic food web and may help watershed managers. "Organic matter from the watershed subsidizes lake food webs, allowing more animal life in the lakes than if they were simply isolated water bodies," Pace concludes.


-NSF-


The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of nearly $5.58 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives about 40,000 competitive requests for funding, and makes about 11,000 new funding awards. The NSF also awards over $200 million in professional and service contracts yearly.

Receive official NSF news electronically through the e-mail delivery and notification system, Custom News Service. To subscribe, enter the NSF Home Page at: http://www.nsf.gov/home/cns/#new and fill in the information under "new users."

Useful NSF Web Sites:
NSF Home Page: http://www.nsf.gov
News Highlights: http://www.nsf.gov/od/lpa
Newsroom: http://www.nsf.gov/od/lpa/news/media/start.htm
Science Statistics: http://www.nsf.gov/sbe/srs/stats.htm
Awards Searches: http://www.fastlane.nsf.gov/a6/A6Start.htm


 
 
     
 


National Science Foundation
Office of Legislative and Public Affairs
4201 Wilson Boulevard
Arlington, Virginia 22230, USA
Tel: 703-292-8070
FIRS: 800-877-8339 | TDD: 703-292-5090
 

NSF Logo Graphic