Global nutrient transport in a world of giants.
The past was a world of giants, with abundant whales in the sea and large animals roaming the land. However, that world came to an end following massive late-Quaternary megafauna extinctions on land and widespread population reductions in great whale populations over the past few centuries. These losses are likely to have had important consequences for broad-scale nutrient cycling, because recent literature suggests that large animals disproportionately drive nutrient movement. We estimate that the capacity of animals to move nutrients away from concentration patches has decreased to about 8% of the preextinction value on land and about 5% of historic values in oceans. For phosphorus (P), a key nutrient, upward movement in the ocean by marine mammals is about 23% of its former capacity (previously about 340 million kg of P per year). Movements by seabirds and anadromous fish provide important transfer of nutrients from the sea to land, totalling ∼150 million kg of P per year globally in the past, a transfer that has declined to less than 4% of this value as a result of the decimation of seabird colonies and anadromous fish populations. We propose that in the past, marine mammals, seabirds, anadromous fish, and terrestrial animals likely formed an interlinked system recycling nutrients from the ocean depths to the continental interiors, with marine mammals moving nutrients from the deep sea to surface waters, seabirds and anadromous fish moving nutrients from the ocean to land, and large animals moving nutrients away from hotspots into the continental interior.
Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, United Kingdom; chris.doughty@ouce.ox.ac.uk.
Christopher E
CE
Doughty
Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138; Gund Institute for Ecological Economics, University of Vermont, Burlington, VT 05445;
Joe
J
Roman
Section of Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark;
Søren
S
Faurby
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544;
Adam
A
Wolf
Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, United Kingdom;
Alifa
A
Haque
Department of Aquatic Ecology, Netherlands Institute of Ecology, 6708 PB Wageningen, The Netherlands;
Elisabeth S
ES
Bakker
Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, United Kingdom;
Yadvinder
Y
Malhi
Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907.
John B
JB
Dunning
Section of Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark;
Jens-Christian
JC
Svenning
D063147:Animal Distribution; D000818:Animals; D059001:Aquatic Organisms; D001522:Behavior, Animal; D001717:Birds; D049628:Body Size; D004058:Diffusion; D017753:Ecosystem; D053476:Extinction, Biological; D005247:Feeding Behavior; D005399:Fishes; D005502:Food; D005523:Food Supply; D049690:History, Ancient; D006702:Homing Behavior; D008322:Mammals; D009792:Oceans and Seas; D011156:Population Density
anadromous fish; biogeochemical cycling; extinctions; megafauna; whales