Whale feces can explain the mysterious decline of the ocean after mass whaling

A new study shows that whale waste contains an exact chemical cocktail that may have fertilized the entire marine ecosystem, suggesting that mass killings of whales in the 20th century not only destroyed whales populations. The study, published in Communication Earth and the Environment, provides new evidence on how the loss of 2 million large whales may have triggered the cascade effect that is still visible to today’s oceans.

By analyzing the feces of blue and humpback whales, the researchers found very high bioavailability of iron—a crucial but scarce nutrient that marine plants need to grow. The study marks the first detailed analysis of how trace metals in whale excretion interact with marine chemistry.

“We have conducted new measurements of whale feces to assess the importance of whales to the important nutrition of phytoplankton,” said Patrick Monreal, chief author and doctoral student at the University of Washington Oceanography. “Our analysis It shows that decomposition of Baleen whales from historical whaling may have greater biogeochemical significance for the Southern Ocean, which is crucial for the global carbon cycle.”

These findings help explain a long-standing ecological puzzle: When industrial whaling removes 90% of the large whales from the Southern Ocean, their prey – krill as small as shrimp – unexpectedly descends rather than in absences thrives below. Scientists now suspect that whales’ excretion provides the necessary nutrients to support the entire food web.

The team analyzed five samples – two humpback whales from near Antarctica and three blue whales from near California. They found that iron concentrations were as high as 100,000 times higher than typical ocean levels, and that the amount of copper bound to organic molecules is nontoxic to marine life.

“We were really shocked at how much copper there was in the whale boat. We initially thought, “Oh no, is the whale’s feces actually poisonous? “Assistant Professor of Oceanography at the University of Washington. Further analysis showed that special compounds called ligands convert copper into safe, usable forms.

The study identified nearly 50 previously unknown copper-binding compounds that may be produced by bacteria in the whale’s digestive system. “I think animals play a bigger role in the chemical cycle than many experts have given, especially when thinking on ecosystem scales,” Morel notes. “When I say animals, I mean Their gut microbiome. According to what we see, it seems that the bacteria of whales may be important.”

The meaning is profound. During peak feeding hours, an Antarctic baleen whale can consume several tons of krill per day. When they process this food, they release nutrient-rich feces near the sea surface, which is exactly what marine plants need most. This nutrient’s “whale pump” may be crucial to maintaining productivity in the Southern Ocean.

Calculations show that before industrial whaling, Baleen whales in the Southern Ocean may be recovered from 35,100 to 239,000 moles of bioavailable iron each year. This volume is comparable to other major iron sources in the region, such as dust, ice melting and glacial sediments.

These findings arrive as scientists work to restore damaged marine ecosystems. Although some whales populations are beginning to recover, warm temperatures and an expanded krill fishery threaten this recovery. Understanding the complex relationship between whales, nutrients and ocean productivity is crucial for marine conservation efforts.

The study also opens up new problems for the role of animal gut bacteria in the global nutrition cycle. The team’s discovery of novel copper-bound compounds suggests that whales’ digestive system may be an important molecular source for marine chemistry.