Monday, November 7, 2011

Whale Pump Research

Discussions have been going on for a couple of years to begin a collaboration with Dr. Joe Roman.  Joe Roman is a researcher at the University of Vermont and the author of “Listed: Dispatches from America’s Endangered Species Act” (Harvard) and “Whale” (Reaktion). This summer saw all of that work come to fruition.  Joe has provided the background information about the project:

A few years ago, I was writing an article about the work that Scott Baker and his colleagues were doing in Japan, uncovering the sale of illegal whale meat in the marketplace using DNA. At the time, Japan was arguing for whaling, largely for two reasons. One, whales eat “our” fish, so they should be culled. And, two, certain whales, such as minkes, are so numerous that they are inhibiting the ability of rare species, such as fins and blues, to recover.
Dr. Joe Roman, University of Vermont
This argument might have been in the back of my mind while I was taking marine ecology one spring at the University of Florida. I was learning about one of the basic process in the oceans, known as the biological pump, which causes the downward flow of carbon and nitrogen and can reduce marine productivity. Zooplankton feed on phytoplankton at the surface at night and then migrate deep in the water column by day, presumably to escape predators. This movement, and the downward flux of zooplankton fecal matter, takes nutrients away from the surface, where photosynthesis can occur, to the bottom of the ocean.

As I sat in the back of the class, I drew a diagram based on what I had seen the previous summer in the Bay of Fundy. In contrast to the biological pump, right whales were diving deep to feed--they are sometimes observed with mud on their heads--and quite often defecating at the surface.

A few years later, Jim McCarthy, at Harvard, and I put together a model that showed that whales could have an impact on primary productivity in coastal waters. They increase nutrients at the surface and enhance the growth of algae. This summer, I finally got back to the Bay of Fundy to study the right whale, which forms feeding aggregations just to the east of Grand Manan in an area called the Basin. Of all the ways to collect poop--we typically used a plankton net, patiently following whales until they defecated--perhaps the most dramatic is skirting the edge of a right whale courtship group: one female and several males actively swimming and roiling in the waters. It seemed almost inevitable, the female while swimming on her back would release a thick brown or red fecal plume. We’d wait for the group to swim off--the whales were much larger than our boat--and move in with our net.
Patch of reddish-brown defaecation from a fin whale. 
The colour indicates the whale was probably eating krill. 
Greenish defaecation is most likely from fish consumption.
Two colleagues from Harvard helped analyze the data. John Nevins, a researcher at the Museum of Comparative Zoology, examined the nitrogen levels, and Annabel Beichman, an undergrad, prepped samples to later uncover the microbes that live in whale gastrointestinal tracts. Heather Koopman, of University of North Carolina, lead the search for whales at the wheel of the research vessel Phocoena.
Annabel Beichman, Harvard University
What we have found is that whales, along with seals and seabirds, play an important role in recycling nitrogen in the Gulf of Maine. They release more of this nutrient into the gulf than all rivers combined and even more than point source pollution from sewage effluent. By excreting nitrogen at the surface of their traditional feeding grounds, whales play an important role in maintaining prey aggregations, such as copepods, krill, or herring, which, in a positive feedback loop, supports their tendency to aggregate in feeding areas. They are not eating our fish, as whaling nations claim, but helping increase productivity in areas where they are found. We can have more whales, and more fish, copepods, and krill.

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