Featured Research

from universities, journals, and other organizations

Whale poop pumps up ocean health

Date:
October 12, 2010
Source:
University of Vermont
Summary:
Whales carry nutrients, especially nitrogen, from the depths where they feed back to the surface via their feces. This waste strongly enhances productivity of fisheries, scientists have found. They've called their discovery a "whale pump," reversing the assumption that whales accelerate loss of nutrients to the bottom. This nitrogen input in the Gulf of Maine is more than the input of all rivers combined, 23,000 metric tons annually.

A conceptual model of the whale pump. In the common concept of the biological pump, zooplankton feed in the euphotic zone and export nutrients via sinking fecal pellets, and vertical migration. Fish typically release nutrients at the same depth at which they feed. Excretion for marine mammals, tethered to the surface for respiration, is expected to be shallower in the water column than where they feed.
Credit: Peter Roopnarine, Joe Roman, James J. McCarthy. The Whale Pump: Marine Mammals Enhance Primary Productivity in a Coastal Basin. PLoS ONE, 2010; 5 (10): e13255 DOI: 10.1371/journal.pone.0013255

Whale feces -- should you be forced to consider such matters -- probably conjures images of, well, whale-scale hunks of crud, heavy lumps that sink to the bottom. But most whales actually deposit waste that floats at the surface of the ocean, "very liquidy, a flocculent plume," says University of Vermont whale biologist, Joe Roman.

And this liquid fecal matter, rich in nutrients, has a huge positive influence on the productivity of ocean fisheries, Roman and his colleague, James McCarthy from Harvard University, have discovered.

Their discovery, published Oct. 11 in the journal PLoS ONE, is what Roman calls a "whale pump."

Whales, they found, carry nutrients such as nitrogen from the depths where they feed back to the surface via their feces. This functions as an upward biological pump, reversing the assumption of some scientists that whales accelerate the loss of nutrients to the bottom.

And this nitrogen input in the Gulf of Maine is "more than the input of all rivers combined," they write, some 23,000 metric tons each year.

Nitrogen limits

It is well known that microbes, plankton, and fish recycle nutrients in ocean waters, but whales and other marine mammals have largely been ignored in this cycle. Yet this study shows that whales historically played a central role in the productivity of ocean ecosystems -- and continue to do so despite diminished populations.

Despite the problems of coastal eutrophication -- like the infamous "dead zones" in the Gulf of Mexico caused by excess nitrogen washing down the Mississippi River -- many places in the ocean of the Northern Hemisphere have a limited nitrogen supply.

Including where Roman and McCarthy completed their study: the once fish-rich Gulf of Maine in the western North Atlantic. There, phytoplankton, the base of the food chain, has a brake on its productivity when nitrogen is used up in the otherwise productive summer months. (In other parts of the ocean, other elements are limiting, like iron in some regions of the Southern oceans.)

"We think whales form a really important direct influence on the production of plants at the base of this food web," says McCarthy.

"We found that whales increase primary productivity," Roman says, allowing more phytoplankton to grow, which then "pushes up the secondary productivity," he says, of the critters that rely on the plankton. The result: "bigger fisheries and higher abundances throughout regions where whales occur in high densities," Roman says.

"In areas where whales were once more numerous than they are today, we suggest that they were more productive," say McCarthy.

The numbers of whales that swam the oceans before human harvests began is a question of some controversy. "Conservative estimates are that large whales have been cut to 25 percent," says Roman, "though the work done on whale genetics shows that we're probably closer to 10 percent," of historical levels. To cover the range of possibilities, Roman and McCarthy's study considered several scenarios, estimating current whale stocks as 10, 25, or 50 percent of historical levels.

"Anyway you look at it, whales played a much bigger role in ecosystems in the past than they do now," says Roman, a conservation biologist in the University of Vermont's Rubenstein School of Environment and Natural Resources and the author of a book on whales.

"And everything that we do to enhance recovery and restoration of the great whales to something like pre-harvest levels works against other deleterious effects that humans are causing in the oceans," says McCarthy, like the decline of overall ocean productivity as climate change drives up water temperatures, which, in turn, causes a decline in nutrients for phytoplankton.

Save the whales, save the fishermen

A further implication of the new study is that ongoing calls by some governments to relax international whaling restrictions are ill-considered. Culls and bounty programs would reduce nitrogen and "decrease overall productivity," Roman and McCarthy note.

"For a long time, and still today, Japan and other countries have policies to justify the harvest of marine mammals," says Roman. These countries argue that whales compete with their commercial fisheries.

"Our study flips that idea on its head," Roman says, "Not only is that competition small or non-existent, but actually the whales present can increase nutrients and help fisheries and the health of systems wherever they are found. By restoring populations we have a chance to glimpse how amazingly productive these ecosystems were in the past."


Story Source:

The above story is based on materials provided by University of Vermont. The original article was written by Joshua E. Brown. Note: Materials may be edited for content and length.


Journal Reference:

  1. Joe Roman, James J. McCarthy. The Whale Pump: Marine Mammals Enhance Primary Productivity in a Coastal Basin. PLoS ONE, 2010; 5 (10): e13255 DOI: 10.1371/journal.pone.0013255

Cite This Page:

University of Vermont. "Whale poop pumps up ocean health." ScienceDaily. ScienceDaily, 12 October 2010. <www.sciencedaily.com/releases/2010/10/101012101255.htm>.
University of Vermont. (2010, October 12). Whale poop pumps up ocean health. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2010/10/101012101255.htm
University of Vermont. "Whale poop pumps up ocean health." ScienceDaily. www.sciencedaily.com/releases/2010/10/101012101255.htm (accessed July 30, 2014).

Share This




More Plants & Animals News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Otters Enjoy Water Slides at Japan Zoo

Raw: Otters Enjoy Water Slides at Japan Zoo

AP (July 30, 2014) River otters were hitting the water slides to beat the summer heatwave on Wednesday at Ichikawa City's Zoological and Botanical Garden. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com
Rodents Rampant in Gardens Around Louvre

Rodents Rampant in Gardens Around Louvre

AP (July 29, 2014) Food scraps and other items left on the grounds by picnickers brings unwelcome visitors to the grounds of the world famous and popular Louvre Museum in Paris. (July 29) Video provided by AP
Powered by NewsLook.com
Jane Goodall Warns Great Apes Face Extinction

Jane Goodall Warns Great Apes Face Extinction

AFP (July 29, 2014) The world's great apes face extinction within decades, renowned chimpanzee expert Jane Goodall warned Tuesday in a call to arms to ensure man's closest relatives are not wiped out. Duration: 00:58 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins