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Moose Diet Helps Transfer Nitrogen From Water To Land

August 20, 2012
Image Caption: Isle Royale is a perfect place for moose: water in every direction; shores lined with pondweed, water lilies and other aquatic vegetation upon which moose feed; and nearby forests laden with other favored moose foods like the buds and twigs of willow, aspen, red dogwood and balsam fir trees. Credit: John Vucetich

redOrbit Staff & Wire Reports – Your Universe Online

Through their dietary and excretory habits, moose help transfer “significant” amounts of nitrogen from aquatic ecosystems to terrestrial ones, a research project funded by the National Science Foundation (NSF) has discovered.

While land-based vegetation provides some sustenance for moose (Alces alces), it is low in sodium, forcing the creatures to consume aquatic macrophytes (large plants found in lakes, ponds, and wetlands).

Those marine plants are also rich in nitrogen, and after the moose defecate on shore, their waste helps transfer the element into the earth, essentially making them a sea-to-land conduit for nitrogen, Michigan Technological University ecologists Joseph Bump, Rolf Peterson and John Vucetich, as well as Keren Tischler of Common Coast Research & Conservation in Hancock, Michigan, and Amy Schrank of the University of Michigan Biological Station, have discovered.

“Moose transfer significant amounts of aquatic-derived nitrogen to terrestrial [on land] ecosystems. They greatly increase nitrogen in riparian, or shoreline, zones,” Bump said. “Nutrients in salmon, birds, river otters, insects and other animals play a major role in linking aquatic and terrestrial ecosystems.”

Their research, which took place on Isle Royale in Lake Superior and is detailed in the Journal of Animal Ecology, also demonstrates that this form of nutrient transfer can be influenced by predators. For example, when a moose is killed by a wolf, their remains decompose and transfer nitrogen from the aquatic macrophytes they had consumed into the ground.

“It’s hard to imagine what species as diverse as moose, salmon and midges, for example, might have in common,” NSF’s Division of Environmental Biology Program Director Saran Twombly explained. “Yet all three transfer significant quantities of nutrients from aquatic to terrestrial habitats. On Isle Royale, wolves add to this total amount. They kill moose in specific locations and generate ‘hotspots’ where nitrogen is transferred from lake to shore.”

According to the NSF, the moose population of Isle Royale is typically between 700 and 1,200, while the wolf population is currently at just nine. The typical moose, according to the agency, weight nearly 800 pounds, consumes up to 70 pounds of food and nearly 10,000 calories per day as an adult, and tend to migrate to water to cool off when temperatures exceed 59 degrees Fahrenheit (15 degrees Celsius).


Source: redOrbit Staff & Wire Reports - Your Universe Online



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