Megafauna moves nutrients uphill Michael Gross  Current Biology  Volume 26, Issue 1, Pages R1-R5 (January 2016) DOI: 10.1016/j.cub.2015.12.028 Copyright © 2016 Terms and Conditions

Nutrient delivery: Seabirds provide an important flow of nutrients from sea to land, acting against the draining that occurs through rivers and runoff from the land. The image shows guillemots, shags and kittiwakes breeding on the Farne Islands. (Photo: Jamumiwa/Wikimedia Commons.) Current Biology 2016 26, R1-R5DOI: (10.1016/j.cub.2015.12.028) Copyright © 2016 Terms and Conditions

Good catch: Another nutrient stream from sea to land, comparable in magnitude to that caused by sea birds, is the migration of fish species like salmon. (Photo: Jennifer Allen, http://dx.doi.org/10.1371/journal.pbio.1001304.g001.) Current Biology 2016 26, R1-R5DOI: (10.1016/j.cub.2015.12.028) Copyright © 2016 Terms and Conditions

Big beasts: Megafauna like the woolly mammoth, which became extinct in Siberia only a few thousand years ago, provide crucial ecosystem services, including nutrient distribution and soil stabilisation. Researchers have argued that returning a mammoth-like elephant breed to Siberia could help to save the carbon sequestered in permafrost soils. (Image: Mauricio Anton, http://dx.doi.org/10.1371/journal.pbio.0060099.g001.) Current Biology 2016 26, R1-R5DOI: (10.1016/j.cub.2015.12.028) Copyright © 2016 Terms and Conditions

Flow patterns: Unlike megafauna, humans tend to dispose of their excretions through the hydrological cycle, meaning that valuable nutrients are washed down to the oceans and may be lost to the biosphere. (Photo: Annabel/Wikimedia Commons.) Current Biology 2016 26, R1-R5DOI: (10.1016/j.cub.2015.12.028) Copyright © 2016 Terms and Conditions

Recycling rules: In ecological cycles, one species’ waste is another’s valuable resource. Our civilisation has yet to learn to operate in such circular patterns rather than in a linear flow from (overexploited) resource to (polluting) waste. (Photo Kay-africa/Wikimedia Commons.) Current Biology 2016 26, R1-R5DOI: (10.1016/j.cub.2015.12.028) Copyright © 2016 Terms and Conditions