Why in the News?
A new study published in Nature Ecology & Evolution highlights how species mobility, measured as biomass movement, shapes ecosystems and reflects human ecological dominance.
About the Concept of Biomass Movement:
- Overview: Biomass movement is the product of a species’ total biomass and the distance it travels annually, representing the mass of living matter displaced across ecosystems each year.
- Biomass movement = (Total biomass of a species) × (Distance it travels annually).
- Purpose: Quantifies how living organisms contribute to nutrient transport, seed dispersal, and energy flow through movement.
- Comparative Metric: Enables cross-species comparison of ecological influence via mobility, bridging animal ecology and global biogeography.
- Analytical Value: Provides a standardised ecological indicator to study both natural migrations and human-induced mobility patterns.
- Anthropocene Context: Serves as a unified measure of ecological and energetic impact in a human-dominated epoch.
- Scientific Basis: Concept explored in Nature Ecology & Evolution (2025) to assess species-level and anthropogenic movement on a global scale.
Key Highlights with Example:
- Arctic Tern: Weighing ~100 g, travels ~90,000 km annually (Arctic–Antarctica circuit), the longest animal migration known.
- Collective Biomass Movement: Two million terns contribute only 0.016 gt/km/yr, due to low body mass despite vast distances.
- Grey Wolf: Records 0.03 gt/km/yr, higher due to larger body size and wider terrestrial range.
- Serengeti Migration: Over a million wildebeests, gazelles, and zebras generate biomass movement 20× greater than wolves.
- Human Parallel: The total biomass moved in the FIFA World Cup equals that of major animal migrations, highlighting scale disparity between species.
Human Biomass Movement and Its Consequences:
- Magnitude: Humans move an estimated ~4,000 gt/km/yr, the largest on Earth, 40× greater than all wild land mammals combined.
- Mobility Patterns: Average human travels 30 km/day, mostly motorised, 65% by cars/motorcycles, 10% by air, 5% by rail.
- Economic Disparity: Two-thirds of total human mobility occurs in high- and upper-middle-income countries, reflecting global inequality.
- Ecological Effects: Drives carbon emissions, urban sprawl, resource depletion, and land fragmentation.
- Marine Decline: Marine animal mobility has halved since 1850 due to industrial fishing and whaling.
- Livestock Factor: Domesticated cattle show biomass movement comparable to humans, indicating the ecological weight of livestock farming.
- Wildlife Contrast: Combined biomass movement of all wild land mammals (excluding bats) is only 30 gt/km/yr, underscoring human dominance.
- Anthropocene Insight: Demonstrates that human and domesticated animal mobility now defines Earth’s biogeochemical and ecological motion.
