Nature: Whales are more important ecosystem "engineers" than previously thought

The researchers said that this contradictory result shows that the dramatic decline of large marine mammals has a negative impact on the health and productivity of marine ecosystems

"Fifty years after we stopped whaling, we are still understanding its impact

The researchers came to disturbing conclusions after asking a very basic question: How much do whales eat?

Modern whale research

Large whales are inherently difficult to study because they cannot be kept in captivity

In this study, the researchers looked at blue whales, fin whales, humpback whales, and minke whales-these whales swallow large amounts of water and then filter it through the baleen plate of the mouth until only prey is left

"All this together really makes us see this amazing sight," said Shirel Kahane-Rapport, a graduate student in Goldbogen's lab and co-author of the paper

After analyzing the data they captured, it was found that whales in the Southern Ocean eat about twice as much krill as previously estimated, while blue whales and humpback whales that eat krill on the coast of California eat about the same amount of krill before.

"As large baleen whales get larger, the anatomy they use to feed has also become relatively larger," Hopkins Marine Station Co-Director, School of Humanities and Sciences (School of Humanities and Sciences) Jeremy Goldbogen, associate professor of biology, said he is the senior author of the paper

The researchers estimated their consumption based on the data on the prey density, swallowing size and stabbing frequency recorded on the label

"We proposed a very complicated process in which we tried to maintain as much uncertainty as possible," said Max Czapanskiy, a graduate student in Goldbogen's lab and co-author of the paper

Based on these new consumption estimates, the researchers calculated that the number of krill in the Southern Ocean in the early twentieth century had to be about five times the current population to feed the pre-whaling whale population

Kahane-Rapport said: "I hope such work can really allow people to consider the impact of human activities on the entire ecosystem, because we are still continuously affecting their environment

Mobile processing plant

The Southern Ocean is one of the most productive ecosystems on the planet, due in large part to a large number of microscopic algae called phytoplankton

Czapanskiy said: "If you don't have phytoplankton, you can't get all the animals and everything we care about

"Think of these large whales as moving krill processing plants," Savoca added

The many twists and turns of these findings show the potential impact of asking simple questions

Goldbergen said: "If you remove the large whales, the productivity will actually decrease, and the krill and fish may also decrease.

Journal Reference :

1. Matthew S.
   Savoca, Max F.
   Czapanskiy, Shirel R.
   Kahane-Rapport, William T.
   Gough, James A.
   Fahlbusch, KC Bierlich, Paolo S.
   Segre, Jacopo Di Clemente, Gwenith S.
   Penry, David N.
   Wiley, John Calambokidis, Douglas P.
   Nowacek, David W.
   Johnston, Nicholas D.
   Pyenson, Ari S.
   Friedlaender, Elliott L.
   Hazen, Jeremy A.
   Goldbogen.
   Baleen whale prey consumption based on high-resolution foraging measurements .
   Nature , 2021; 599 ( 7883): 85 DOI: 10.
   1038/s41586-021-03991-5