What can whale poop teach us about ocean nutrients? This is what a recent study published in Communications Earth & Environment hopes to address as a team of researchers investigated a link between a decrease in blue whales and krill throughout Earth’s oceans, as previous hypotheses stated the two had an inverse relationship, meaning when one’s population decreased the other would increase, but this new study challenges that longstanding notion. This study has the potential to help scientists better understand the close relationship between ocean species and the steps that can be taken to mend this relationship.
For the study, the researchers analyzed whale poop obtained from the surface of the Southern Ocean and Pacific Ocean and compared these findings with values based on past studies. In the end, the researchers found high concentrations of iron and copper, which correspond to nutrients that krill use to survive, the latter of which is a large food source for blue whales. Since the study challenges longstanding notions that krill populations would flourish without blue whales while noting the opposite is occurring, the team emphasizes the importance of the imbalance in marine ecosystems due to blue whale hunting that leads to negative impacts on other ecosystems.
Diagram from the study depicting the relationship between increases and decreases in blue whale and krill populations. (Credit: Monreal et al./University of Washington)
“We made novel measurements of whale feces to assess how important whales are to recycling important nutrients for phytoplankton,” said Dr. Patrick Monreal, a PhD student in oceanography at the University of Washington and lead author of the study. “Our analysis suggests that the decimation of baleen whale populations from historical whaling could have had larger biogeochemical implications for the Southern Ocean, an area crucially important to global carbon cycling.”
While blue whale populations drastically decreased due to whaling in the early 1900s, their populations have slowly started to increase globally while consuming an average of 6 tons of krill daily. This study highlights the importance of conservation efforts to protect both species while addressing the delicate balance between ocean ecosystems globally.
What new connections between whale poop and ocean nutrients will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: Communications Earth & Environment, EurekAlert!, National Oceanic and Atmospheric Administration