Organic ligands in whale excrement support iron availability and reduce copper toxicity to the surface ocean
Abstract Nutrient recycling by marine megafauna is a key ecosystem service that has been disturbed by anthropogenic activity. While some hypotheses attribute Southern Ocean ecosystem restructuring to disruptions in micronutrient cycling after the elimination of two million great whales, there is little knowledge of trace metal lability in whale excrement. Here we measured high concentrations of dissolved iron and copper in five baleen whale fecal samples and characterized micromolar levels of organic metal-binding ligands as a proxy for their availability. The iron-ligand pool consisted of weakly-binding ligands and intermediate-binding ligands which enhanced iron stability and potential bioavailability. In comparison, 47 novel strongly-binding metallophores dominated copper-binding, curtailing its potential toxicity. These results illustrate how marine megafauna transform prey biomass into highly-labile micronutrients that they inject directly into the surface ocean, a mechanism whaling reduced by over 90%. Thus, the rapid restructuring of pelagic ecosystems through overharvesting may cause large biogeochemical feedbacks, altering primary productivity and carbon sequestration processes in the ocean.
Authors
- Patrick J. Monreal (ORCID: https://orcid.org/0000-0001-5343-4142)
- Laura E. Moore (ORCID: https://orcid.org/0000-0002-7146-2267)
- Donald L. Hull
- Jeremy A. Goldbogen (ORCID: https://orcid.org/0000-0002-4170-7294)
- John Calambokidis (ORCID: https://orcid.org/0000-0002-5028-7172)
- Joseph A. Resing (ORCID: https://orcid.org/0000-0002-7334-4176)
- Ari S. Friedlaender (ORCID: https://orcid.org/0000-0002-2822-233X)
- Ross Nichols (ORCID: https://orcid.org/0000-0003-2890-3079)
- Randelle M. Bundy (ORCID: https://orcid.org/0000-0002-0600-3953)
- Lydia Babcock‐Adams (ORCID: https://orcid.org/0000-0001-6545-4917)
- Angel Ruacho
- Logan J. Pallin (ORCID: https://orcid.org/0000-0001-8024-9663)
- Matthew S. Savoca (ORCID: https://orcid.org/0000-0002-7318-4977)
Institutions
- Florida State University (US)
- National Oceanic and Atmospheric Administration (US)
- Cooperative Institute for Research in Environmental Sciences (US)
- University of California, Santa Cruz (US)
- NASA Astrobiology Institute (US)
- University of Washington (US)
- NOAA Pacific Marine Environmental Laboratory (US)
- National High Magnetic Field Laboratory (US)
- Pacific University (US)
- Cascadia Research Collective (US)
- Stanford University (US)
Publication Details
- Journal
- Communications Earth & Environment
- Published
- 2025-01-10
- DOI
- https://doi.org/10.1038/s43247-024-01965-9
- Citations
- 3
- Primary Topic
- Mercury impact and mitigation studies
- Type
- article
- Field-Weighted Citation Impact
- 3.60
Funders
- National Science Foundation
- Ford Foundation
- University of Washington
- National High Magnetic Field Laboratory
- National Oceanic and Atmospheric Administration
- Stanford Woods Institute for the Environment
- Division of Materials Research
- Office of Polar Programs
- Division of Chemistry
- High Magnetic Field Laboratory, Chinese Academy of Sciences