The DOI matches its Crossref record; 82 of the 82 references it cites were found in a registry or an index; none of the 50 sources its claims cite is checked for support yet.
Global nutrient transport in a world of giants
Open accessAbstract
Significance: Animals play an important role in the transport of nutrients, but this role has diminished because many of the largest animals have gone extinct or experienced massive population declines. Here, we quantify the movement of nutrients by animals in the land, sea, rivers, and air both now and prior to their widespread reductions. The capacity to move nutrients away from hotspots decreased to 6% of past values across land and ocean. The vertical movement of phosphorus (P) by marine mammals was reduced by 77% and movement of P from sea to land by seabirds and anadromous fish was reduced by 96%, effectively disrupting an efficient nutrient distribution pump that once existed from the deep sea to the continental interiors.
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31 Not checked yet · 27 Own result · 18 Own interpretation · 8 No basis given · 2 Own method
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“they now move ∼ 75 million (54 -110 million; SI Appendix , Table 2) kg of P per year”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“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.”
- Also stated in: § Results · p. 4 · plain
“Current mean, km 2 · y - 1 | 1.6e4 | 3.2e4 | 6.67e4 | 467 | 1.13e4 | 0.42e4 | 0.17e4 | 0.22e5 |”
plain- Asserted: passes — The authors put it forward as true.
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- Also stated in: § Results · p. 4 · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“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).”
- Also stated in: § Results · p. 3 · plain
“they moved a global total of ∼ 340 million (260 -430 million; SI Appendix , Table 2) kg of P per year from the depth to the surface waters before widespread hunting”
plain- Asserted: passes — The authors put it forward as true.
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- Also stated in: § Results · p. 3 · plain
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In the paper
“currently 16,000 km 2 · y -1”
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In the paper
“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).”
- Also stated in: § Results · p. 3 · plain
“representing a decrease to 23% of original capacity (Fig. 2 D -F and Table 1).”
plain- Asserted: passes — The authors put it forward as true.
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- Also stated in: § Results · p. 3 · plain
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“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”
plain- Asserted: passes — The authors put it forward as true.
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- The authors state this as an assumption: 20% of seabird guano produced reaches coastal land, with a range of 5% to 35%.
- The authors state this as an assumption: Seabird population calculations are representative of past, not current, populations because they are based on theoretical population densities.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“averaged 180,000 km 2 · y -1 on the land surface”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“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.”
- Also stated in: § Significance · p. 2 · plain
“movement of P from sea to land by seabirds and anadromous fish was reduced by 96%”
plaindirect- Asserted: passes — The authors put it forward as true.
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- The authors state this as an assumption: 20% of seabird guano produced reaches coastal land, with a range of 5% to 35%.
- Also stated in: § Significance · p. 2 · plain
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The capacity to move nutrients away from hotspots decreased to 6% of past values across land and ocean.”
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“and the North Atlantic (28%)”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“However, currently, with the largest animals in South America only weighing up to ∼ 300 kg, continental nutrient distribution capacity has dropped to ∼ 0.01% of its original value in some regions.”
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“Every continent outside Africa (Africa is at 46% of its lateQuaternary value) is at less than 5% of the original value”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“Using range maps for 42 of these species, and an additional 47 closely related species as proxies for the missing range maps, we estimate that, historically, anadromous fish may have moved at least an order of magnitude more P from ocean to land [140 million (71 -430 million) km 2 · y -1 ; SI Appendix , Table 2] than seabirds [6.3 million (1.5 -16 million) km 2 · y -1 ; SI Appendix , Table 2]”
- Also stated in: § Discussion · p. 5 · hedged
“Possibly, a more important form of sea-to-land nutrient transport comes from the migratory behavior of anadromous fish, which we estimate to bring at least an order of magnitude more nutrients from oceans to land than do seabirds.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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- Also stated in: § Discussion · p. 5 · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“and the North Atlantic (14%)”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“Africa is at 46% of its lateQuaternary value”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“estimated that the capacity in the Southern Ocean is 2% of its historical value”
hedged- Asserted: passes — The authors put it forward as true.
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In the paper
“we estimate that without the range reduction of large species (excluding all extinctions) the capacity would be 37% higher compared with today ' s baseline.”
hedgeddirect- Asserted: passes — The authors put it forward as true.
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In the paper
“in the past, marine mammals could have increased surface concentrations by up to 1% per year in the Southern Ocean”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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In the paper
“Mean nutrient diffusion capacity is larger for the great whales than for terrestrial animals at natural capacity (640,000 km 2 · y -1 for great whales vs. 180,000 km 2 · y -1 for terrestrial mammals).”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“with slightly higher values in the North Pacific (10%)”
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In the paper
“We estimate that the decimation of terrestrial megafauna and whales has reduced the ability of animals to distribute nutrients away from regions of nutrient abundance to ∼ 6%of global natural capacity.”
hedgeddirect- Asserted: passes — The authors put it forward as true.
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In the paper
“These values are not evenly distributed, and there are much higher values in the Northern Hemisphere and at high latitudes than in more tropical latitudes.”
plaincorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“This large number of megaherbivores gave it, before the extinctions, the largest estimated present natural lateral diffusion capacity of anywhere in the world.”
hedgeddirectn = 15- Asserted: passes — The authors put it forward as true.
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In the paper
“On land, large disparities in animal sizes and total animal numbers led to differences in nutrient distribution capacity both before and following the extinctions due to regional disparities in extinctions.”
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“but there are higher values in the North Pacific (34%)”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“Vertical transport capacity in the Southern Ocean is now ∼ 16% of its historical value”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“Here, we have estimated that seabirds can increase P concentrations in coastal environments globally by ∼ 6 million kg · y -1 through the deposition of guano.”
hedgeddirect- Asserted: passes — The authors put it forward as true.
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- The authors state this as an assumption: Twenty percent of guano arrives on land.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“with the largest change in South America ( ∼ 1% of the original value; Table 1).”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“We estimate the total flux of P from sea to land by anadromous fish and seabirds in the past (146 million kg of P per year) is still much less than the total P consumed by humans for fertilizers each year [48,500 million kg of phosphoric acid (as P2O5) in 2010 and growing at 1.9% per year (39)].”
What the sources say
- Not checked yetcites [39] Food and Agricultural Organization of the United Nations (2011) Current world fertilizer trends and outlook to 2015. Available at www.fao.org/3/a-av252e.pdf. Accessed September 4, 2015.
hedged- Asserted: passes — The authors put it forward as true.
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In the paper
“around 150 mammal megafaunal (here, defined as ≥ 44 kg of body mass) species going extinct in the late Pleistocene and early Holocene (1, 2).”
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“Animals play an important role in the transport of nutrients, but this role has diminished because many of the largest animals have gone extinct or experienced massive population declines.”
What the sources say
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“whale densities might have declined between 66% and 99% (4 -6).”
What the sources say
hedged- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Animals play an important role in the transport of nutrients, but this role has diminished because many of the largest animals have gone extinct or experienced massive population declines.”
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“the distribution of nutrients away from a concentration gradient is size-dependent, with larger animals having disproportionally greater importance to this flow of nutrients than smaller animals (20, 21).”
plaincorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“Animal digestion accelerates cycling of nutrients from more recalcitrant forms in decomposing plant matter to more labile forms in excreta after (wild or domestic) herbivore consumption on land (7).”
What the sources say
- Not checked yetcites [7] source
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“in the Southern Hemisphere, blue whales ( Balaenoptera musculus ) have been reduced to 1% of their historical numbers as a result of commercial whaling (4).”
What the sources say
- Not checked yetcites [4]
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“Similarly, at present times, large herbivores enhance nutrient cycling in the grazing lawns of the Serengeti (9).”
What the sources say
- Not checked yetcites [9] source
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“This flux of nutrients has almost certainly decreased through time as seabird populations have decreased [27% of seabirds are classified as threatened (22)] or gone extinct (e.g., the great auk, Pinguinus impennis ) often due to, for instance, invasive mammal predators decimating seabird colonies (36).”
What the sources say
boosteddirect- Asserted: passes — The authors put it forward as true.
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In the paper
“However, in some regions, exotic and mainly domesticated ungulates may have partially taken over this role (33).”
What the sources say
- Not checked yetcites [33] Pires MM, et al. (2014) Reconstructing past ecological networks: The reconfiguration of seed-dispersal interactions after megafaunal extinction. Oecologia 175(4):1247 -1256. source
hedgedconditional- Asserted: passes — The authors put it forward as true.
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In the paper
“It is estimated that there are 110 species of anadromous fish, such as salmon, that migrate from oceans to rivers to breed and eventually die ( SI Appendix , Table 5) (31).”
What the sources say
- Not checked yetcites [31] McDowall RM (1988) Diadromy in Fishes: Migrations Between Freshwater and Marine Environments (Croom Helm, London).
hedged- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“great whales might have once transported nutrients away from concentration gradients more efficiently than terrestrial mammals.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“Regional models found that the transfer of P away from the Amazonian floodplains may have dropped by more than 50% following the extinction of the Amazonian megafauna (20, 21).”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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In the paper
“Previous experimental studies, however, have found that animals move significant quantities of nutrients across concentration gradients despite not necessarily moving dung from fertile to nonfertile areas (11, 14, 19).”
What the sources say
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“Furthermore, a much larger share of primary production in oceans (algae) is consumed compared with terrestrial primary producers (35).”
What the sources say
- Not checked yetcites [35] Cyr H, Pace ML (1993) Magnitude and patterns of herbivory in aquatic and terrestrial ecosystems. Nature 361(6408):148 -150. source
plaincorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“Also, whales and their prey may help in retaining limiting nutrients (N, P, and Fe) in the surface layer and releasing these nutrients slowly into the water (18).”
What the sources say
- Not checked yetcites [18] source
hedgedconditional- Asserted: passes — The authors put it forward as true.
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In the paper
“Marine mammals have seen broad population reductions due to widespread hunting over the past few hundred years (34).”
What the sources say
- Not checked yetcites [34] Branch TA, et al. (2007) Past and present distribution, densities and movements of blue whales Balaenoptera musculus in the Southern Hemisphere and northern Indian Ocean. Mammal Rev 37(2):116 -175. source
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“and due to this faster turnover time, nutrients, especially limiting nutrients, should be converted to primary producer biomass more quickly in the oceans.”
plaindirect- Asserted: passes — The authors put it forward as true.
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- Rests on an assumption: Aquatic algae conduct most of the ocean's photosynthesis and have a much faster turnover time than land plants due to their often single-cellular nature.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“which could result in considerable stock changes in surface P over time.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Seabirds may act as a link connecting nutrient concentrations in the oceans with nutrient concentrations on the land.”
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Anadromous fish seem to be especially important vectors of nutrients because they travel much further inland than seabirds (Fig. 3).”
hedgeddirect- Asserted: passes — The authors put it forward as true.
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In the paper
“Before the widespread extinction of megafauna and hunting of whales, an interlinked system for the recycling of nutrients may have existed, where nutrients flowed against entropy from the ocean depths to continental interiors (Fig. 4).”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Marine mammals moved nutrients vertically to the surface, increasing productivity.”
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“We have shown that a world teeming with large animals may have had an efficient system of redistributing P.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“These processes can regulate atmospheric CO2 levels through the stimulation of new primary production and consequent export of carbon to the deep ocean (16, 44).”
What the sources say
plainconditional- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Although the numbers we have calculated in this paper are exploratory (we explore this uncertainty in SI Appendix , Tables 1 and 2) and subject to further research and quantification, we have demonstrated the plausibility of an animal-mediated chain of nutrient transfer that connects the deep ocean to the continental interiors.”
boostedcorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“However, isotopic evidence indicates that significant quantities of ocean-derived nutrients from anadromous fish do enter terrestrial ecosystems (11).”
What the sources say
- Not checked yetcites [11]
hedgeddirect- Asserted: passes — The authors put it forward as true.
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In the paper
“At current rates of use, the known global stocks of phosphate rock are estimated to run out in as little as 50 y (45).”
What the sources say
- Not checked yetcites [45] Gilbert N (2009) Environment: The disappearing nutrient. Nature 461(7265):716 -718. source
hedgeddirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Each step is potentially a nonlinear positive feedback of increasing productivity.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Finally, on longer time scales, coastal seabird island nutrient hotspots may become exposed to terrestrial fauna and spread toward continental interiors.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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- Rests on an assumption: Guano is generally deposited on steep cliffs or offshore islands that are largely inaccessible to most terrestrial animals.
- Rests on an assumption: Most seabird islands are on continental shelves that become connected to continents during interglacial periods.
- It may state two separate claims as one. 26
- Probably not a substantial claim. 5
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“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.”
- Also stated in: § Results · p. 3 · hedged
“We estimate that the global mean nutrient distribution capacity before the late-Quaternary extinctions averaged 180,000 km 2 · y -1 on the land surface and that it is currently 16,000 km 2 · y -1 , ∼ 8% of its former value (Table 1; detailed methodology is provided in Methods and SI Appendix ).”
hedged- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- Also stated in: § Results · p. 3 · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Therefore global averaged sea-to-land movement of P is 0.19 ± 0.15 kg of P km -2 · y -1 in coastal regions, but varies by an order of magnitude throughout the planet, with peaks in the Southern Hemisphere (Fig. 3 and Table 1).”
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“but this estimated value has decreased to ∼ 4% (5.6 million km 2 · y -1 ) of the original value.”
- Also stated in: § Discussion · p. 5 · hedged
“However, they have also experienced drastic population losses (25 -27), and we estimate that the current nutrient flux is less than 4% of historic values, before overfishing and habitat modification, such as damming of rivers.”
What the sources say
- Not checked yetcites [25] Gresh T, Lichatowich J, Schoonmaker P (2000) An estimation of historic and current levels of salmon production in the Northeast Pacific ecosystem: Evidence of a nutrient deficit in the freshwater systems of the Pacific Northwest. Fisheries (Bethesda, Md) 25(1):15 -21.
- Not checked yetcites [26] de Groot SJ (2002) A review of the past and present status of anadromous fish species in the Netherlands: Is restocking the Rhine feasible? Ecological restoration of aquatic and semi-aquatic ecosystems in the Netherlands (NW Europe). Developments in Hydrobiology 166:205 -218. source
- Not checked yetcites [27] Limburg KE, Waldman JR (2009) Dramatic declines in North Atlantic diadromous fishes. Bioscience 59(11):955 -965. source
hedgeddirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- Also stated in: § Discussion · p. 5 · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Before the extinctions, nutrient distribution capacity was much more evenly spread than it is currently, with most of the current capacity only in Africa, where extensive megafauna remain.”
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“We calculate a global flux of 6.3 million (1.5 -16 million; SI Appendix , Table 2) kg km -2 · y -1 of P from sea to land by the seabirds, with almost half moving onto the Eurasian landmass (Table 1).”
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“in parts of Africa, such as Kruger National Park in South Africa, capacity is still close to 100% of what it once was in the Late Pleistocene, whereas other regions, such as southern South America, are at less than 0.01% of previous values”
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“When averaged by coastal continental area, we find a maximum in Oceania, with 0.31 ± 0.23 kg of P km -2 · y -1 , and lower values in North America, with 0.16 ± 0.12 kg of P km 2 · y -1 .”
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“For instance, South America once had the largest nutrient distribution capacity, but following the Late-Pleistocene extinctions, it experienced the largest drop, to ∼ 1% of its original continent-wide capacity.”
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“27% of all seabirds are classified as threatened (critically endangered, endangered, or vulnerable), and the largest of all seabirds, the albatross, is the most endangered, with up to 75% of albatross species considered threatened or endangered (22 -24)”
What the sources say
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“populations of anadromous fish have declined to less than 10% of their historical numbers in the Pacific Northwest (25) and both the northeastern and northwestern Atlantic (26, 27).”
What the sources say
- Not checked yetcites [25] Gresh T, Lichatowich J, Schoonmaker P (2000) An estimation of historic and current levels of salmon production in the Northeast Pacific ecosystem: Evidence of a nutrient deficit in the freshwater systems of the Pacific Northwest. Fisheries (Bethesda, Md) 25(1):15 -21.
- Not checked yetcites [26] de Groot SJ (2002) A review of the past and present status of anadromous fish species in the Netherlands: Is restocking the Rhine feasible? Ecological restoration of aquatic and semi-aquatic ecosystems in the Netherlands (NW Europe). Developments in Hydrobiology 166:205 -218. source
- Not checked yetcites [27] Limburg KE, Waldman JR (2009) Dramatic declines in North Atlantic diadromous fishes. Bioscience 59(11):955 -965. source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In the past, scavenging birds, such as condors, may also have acted as vectors of nutrients from the sea to the land.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Each value has many uncertainties involved in its calculation, which we explore in a sensitivity study ( SI Appendix , Tables 1 and 2).”
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“This ability to spread nutrients vertically may be especially important, because once nutrients drop below the photic zone and into the deep ocean sediments, they are generally considered to be lost to the surface biota, and only tectonic movements and limited regions where water is uplifted, will further recycle them (16).”
What the sources say
- Not checked yetcites [16] source
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Such population decreases reduced the lateral distribution capacity and perhaps reduced the vertical distribution, allowing more nutrients to drop below the photic zone.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: unclear — It is unclear why the paper says it holds.
It may state two separate claims as one.
In the paper
“For instance, southern South America once had the largest number of megaherbivores ( > 1,000 kg, n = 15), all of which went extinct (32).”
What the sources say
- Not checked yetcites [32] Owen-Smith N (2013) Contrasts in the large herbivore faunas of the southern continents in the late Pleistocene and the ecological implications for human origins. J Biogeogr 40(7):1215 -1224. source
plainn = 15- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
In the paper
“This flux has certainly greatly decreased as both marine mammals and large scavengers have seen their numbers drop substantially (38).”
What the sources say
- Not checked yetcites [38] Tyrberg T (2008) The Late Pleistocene continental avian extinction -An evaluation of the fossil evidence. Oryctos 7:249 -269.
boosteddirect- Asserted: passes — The authors put it forward as true.
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- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The nutrients transported by whales, or as a consequence of whale activity, should be assimilated more rapidly, and contribute to system productivity more directly than on land.”
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
In the paper
“These estimates are calculated based on theoretical population densities (30), and it is probably closer to theoretical historical values than to actual values today.”
What the sources say
- Not checked yetcites [30] Juanes F (1986) Population-density and body size in birds. Am Nat 128(6):921 -929. source
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
In the paper
“Therefore, a redistribution of P from areas where it is currently found in excess to areas where the soil is naturally P-poor may simultaneously boost global crop production and reduce eutrophication (47).”
What the sources say
- Not checked yetcites [47] Steffen W, et al. (2015) Sustainability. Planetary boundaries: Guiding human development on a changing planet. Science 347(6223):1259855. source
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Given these and many other connections, it is clear that although we can calculate each of these fluxes (marine mammals, seabirds, anadromous fish, and megafauna) separately, the net increase in global productivity is likely more than the sum that we have calculated of the four systems together.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The restoration of whale populations could increase productivity by transferring nutrients to oligotrophic areas and enhancing Fe and N at the ocean surface.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: unclear — It is unclear why the paper says it holds.
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Lateral nutrient distribution capacity was mathematically formulated and found to be strongly size-dependent in two previous papers (20, 21), and this mathematical framework is reformulated in SI Appendix .”
boostedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“P is not well distributed, and it causes eutrophication in some areas, whereas P deficits still affect almost 30% of the global cropland area (46, 47).”
What the sources say
- Not checked yetcites [46] MacDonald GK, Bennett EM, Potter PA, Ramankutty N (2011) Agronomic phosphorus imbalances across the world ' s croplands. Proc Natl Acad Sci USA 108(7):3086 -3091. source
- Not checked yetcites [47] Steffen W, et al. (2015) Sustainability. Planetary boundaries: Guiding human development on a changing planet. Science 347(6223):1259855. source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
In the paper
“This loss of nutrients to these ecosystems from historic highs may have affected the entire ecosystem, including the fish themselves, and ' contributed to the downward spiral of salmonid abundance and diversity in general ' (25).”
What the sources say
- Not checked yetcites [25] Gresh T, Lichatowich J, Schoonmaker P (2000) An estimation of historic and current levels of salmon production in the Northeast Pacific ecosystem: Evidence of a nutrient deficit in the freshwater systems of the Pacific Northwest. Fisheries (Bethesda, Md) 25(1):15 -21.
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“Although the biomass of domestic animals is now much greater than the total biomass of the extinct large terrestrial animals (42), there are two reasons why it is unlikely that they distribute nutrients in the manner that we believe existed in the world of giant megafauna.”
What the sources say
- Not checked yetcites [42] Barnosky AD (2008) Colloquium paper: Megafauna biomass tradeoff as a driver of Quaternary and future extinctions. Proc Natl Acad Sci USA 105(Suppl 1):11543 -11548. source
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Rests on an assumption: Most domestic animals in the industrialized world are fenced in or indoors, and fences constrain movement.
- Rests on an assumption: Most pastures contain only a single animal type, such as cattle.
- Rests on an assumption: A single species is more likely to have consistent behavior, eating in one place and defecating in another, concentrating nutrients rather than dispersing them.
- Rests on an assumption: Multiple species have different eating and defecating patterns and are more likely to diffuse nutrients across gradients.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“It is uncertain what quantity of nutrients transported inland by the fish arrives onto terra firma , but it is clearly a function of river size, distance transported inland, and consumption of the fish by scavengers and predators.”
boosteddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This increased surface productivity increased available food for seabirds and anadromous fish, potentially increasing the flux of nutrients from sea to land.”
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The authors state this as an assumption.
No previous study has attempted a global-scale estimate of how nutrient distribution changed from before human-caused extinctions and exploitation to today across oceans, air, rivers, and land.
“There have been many individual site-level studies showing the importance of animals in distributing nutrients, but as far as we are aware, no previous study has attempted to estimate at a global scale how this distribution has changed from the time before humancaused extinctions and exploitation up to today in the oceans, air, rivers, and land.”
The paper relies on this without support.
Phosphorus serves as a proxy for other limiting elements such as nitrogen and iron.
“We calculate nutrient fluxes caused by animals in terms of the frequently limiting nutrient, P, which serves as a proxy for other limiting elements, such as N and Fe.”
The authors state this as an assumption.
20% of seabird guano produced reaches coastal land, with a range of 5% to 35%.
“assume 20% (5 to 35%) of guano reaches land”
“We assume that 20% (ranging between 5% and 35%) of seabird guano produced arrives on coastal land.”
The authors state this as an assumption.
Seabird population calculations are representative of past, not current, populations because they are based on theoretical population densities.
“We assume our calculations for seabird populations are representative of past, not current, populations because they are based on theoretical population densities (43).”
The paper relies on this without support.
Guano is generally deposited on steep cliffs or offshore islands that are largely inaccessible to most terrestrial animals.
“Guano is generally deposited on steep cliffs or offshore islands generally inaccessible to most terrestrial animals.”
The paper relies on this without support.
Most seabird islands are on continental shelves that become connected to continents during interglacial periods.
“For instance, most seabird islands are on the continental shelves, which become connected to the continent during interglacial periods, thus exposing the nutrient hotspots to terrestrial animals.”
The paper relies on this without support.
Most domestic animals in the industrialized world are fenced in or indoors, and fences constrain movement.
“First, most domestic animals in the industrialized world are fenced in (or indoors), and fences constrain movement, thus stopping the diffusion of nutrients (fences are less common in the nonindustrialized world, although the animals may be fenced in at night).”
The paper relies on this without support.
Most pastures contain only a single animal type, such as cattle.
“Second, most pastures have only a single animal type, such as cattle.”
The paper relies on this without support.
A single species is more likely to have consistent behavior, eating in one place and defecating in another, concentrating nutrients rather than dispersing them.
“A single species is more likely to have consistent behavior, eating in one place, defecating in another, and concentrating nutrients instead of dispersing them across gradients.”
The paper relies on this without support.
Multiple species have different eating and defecating patterns and are more likely to diffuse nutrients across gradients.
“By contrast, multiple species have different eating and defecating patterns and are more likely to diffuse nutrients across gradients.”
The paper relies on this without support.
Aquatic algae conduct most of the ocean's photosynthesis and have a much faster turnover time than land plants due to their often single-cellular nature.
“Aquatic algae, which conduct most of the ocean ' s photosynthesis, have a much faster turnover time than land plants due to their often single-cellular nature”
The authors state this as an assumption.
Twenty percent of guano arrives on land.
“assuming 20% of the guano arrives on land”
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“with an associated loss in ecosystem functions they maintained (1,41)”
From Annual mass drownings of the Serengeti wildebeest migration influence nutrient cycling and storage in the Mara River (2017) · cites this paper as [1]
Experimental — accuracy not yet measured
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
“| % | 8% | 5% | 46%”
Reported 46 · recomputed 52.109375
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Discussion · p. 4
“South America once had the largest nutrient distribution capacity”
§ Results · p. 4
“Land mammals 2.77e5 | Land mammals 2.39e5 | Land mammals 1.53e5”
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Results · p. 4
“anadromous fish may have moved at least an order of magnitude more P from ocean to land [140 million (71 -430 million) km 2 · y -1 ; SI Appendix , Table 2]”
§ Results · p. 4
“Past total, kg P · y - 1 | A. fish 1.4e8 kg · y - 1 Seabirds 6.3e6 ± 5e6”
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Results · p. 4
“We calculate a global flux of 6.3 million (1.5 -16 million; SI Appendix , Table 2) kg km -2 · y -1 of P from sea to land by the seabirds”
§ Results · p. 4
“Past total, kg P · y - 1 | A. fish 1.4e8 kg · y - 1 Seabirds 6.3e6 ± 5e6”
Citations
Cites
IUCN Red List of Threatened Species
(2012) · Choice Reviews Online · doi:10.5860/choice.49-6872 · Cited by 12,829
Planetary boundaries: Guiding human development on a changing planet
Steffen, W., Richardson, K., Rockström, J., Cornell, S. E., Fetzer, I., Bennett, E. M., Biggs, R., Carpenter, S. R., de Vries, W., de Wit, C. A., et al. (2015) · Science · doi:10.1126/science.1259855 · Cited by 12,527
Defaunation in the Anthropocene
Dirzo, R., Young, H. S., Galetti, M., Ceballos, G., Isaac, N. J. B., & Collen, B. (2014) · Science · doi:10.1126/science.1251817 · Cited by 4,474 · cited 2×
“These extinctions and range declines continued up through historical times and, in many cases, into the present (3).”
BackgroundTrophic Downgrading of Planet Earth
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“Seabirds transport nutrients from the sea to their breeding colonies onshore (13, 14).”
Background
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Self-citationAnimals and the zoogeochemistry of the carbon cycle
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Metadata
- Authors
- Doughty, C. E., Roman, J., Faurby, S., Wolf, A., Haque, A., Bakker, E. S., Malhi, Y., Dunning, J. B., & Svenning, J.-C.
- Affiliations
- University of Oxford (GB)
- University of Vermont (US)
- Aarhus University (DK)
- Princeton University (US)
- Netherlands Institute of Ecology (NL)
- Purdue University West Lafayette (US)
- ORCID
- Venue
- Proceedings of the National Academy of Sciences
- Publisher
- National Academy of Sciences
- Published
- 2015-10-26
- Volume
- 113
- Issue
- 4
- Pages
- 868-873
- ISSN
- 0027-8424 (ISSN-L)
- 1091-6490
- PMC
- PMC4743783
- OpenAlex
- W1826044145
- Semantic Scholar
- 73ec212cf94b82ed41724cc153e72b1e98c69f2b
- Cited by
- 470
- References
- 82
- Citations by year
- 2026: 27 · 2025: 46 · 2024: 50 · 2023: 63 · 2022: 46 · 2021: 49 · 2020: 63 · 2019: 47 · 2018: 26 · 2017: 32 · 2016: 17 · 2015: 3
- FWCI
- 23.57
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Proceedings of the National Academy of Sciences (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- KNAW Research Portal (The Royal Netherlands Academy of Arts and Sciences) (publishedVersion, other-oa)
- Data Archiving and Networked Services (DANS) (submittedVersion, other-oa)
- Funders
- Danmarks Grundforskningsfond
- Topics
- Physical Sciences › Environmental Science › Ecology › Marine animal studies overview
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Marine Plankton and Biogeochemistry
- Physical Sciences › Environmental Science › Ecology › Animal Ecology and Behavior Studies
- Keywords
- nutrient cycling, megafaunal extinction, marine mammals, whales, seabirds, anadromous fish, phosphorus, nutrient transport, nutrient hotspots, large animals
- MeSH terms
- Animals, Behavior, Animal, Birds, Diffusion, Feeding Behavior, Fishes, Food, Food Supply, Homing Behavior, Mammals, Oceans and Seas, Population Density, Ecosystem, Body Size, History, Ancient, Extinction, Biological, Aquatic Organisms, Animal Distribution
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-10-04, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-10-04 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
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