When sharks nearly disappeared

doi:10.1126/science.abj2088

GSTDTAP > 气候变化

DOI	10.1126/science.abj2088
	When sharks nearly disappeared
	Catalina Pimiento; Nicholas D. Pyenson
	2021-06-04
发表期刊	Science
出版年	2021
英文摘要	Each year, the discovery of new shark species underscores how little we know about ocean biodiversity ([ 1 ][1]). This is alarming not only because human pressures threaten sharks more than other marine lineages ([ 2 ][2]) but also because their fossil record suggests that they were largely resilient to extinction in the past ([ 3 ][3]), with some extant species persisting for tens of million years ([ 4 ][4]). On page 1105 of this issue, Sibert and Rubin ([ 5 ][5]) report an unexpected finding: a wholesale extinction of shark lineages in the pelagic ocean, the largest ecosystem on Earth, about 19 million years ago. Their discovery suggests that some extinctions in the open sea of the past may have been cryptic. More puzzling is that this event in the early Miocene seems to have been hiding in an interval of geologic time that was previously unremarkable. How did they find it, and what does it mean? Our view of the ancient oceans is constrained by the environments recorded in the rock record, which are often limited to shallow-water deposits that provide little insight into the ocean-wide history of pelagic faunas. The study of Sibert and Rubin takes advantage of a system that Sibert largely pioneered ([ 6 ][6]) using ichthyoliths—tiny, hard bits of shark skin and bony fish teeth that naturally fall from their bodies to the seafloor. Once retrieved from deep-sea sediment drill cores (about 5700 m deep), these microscopic fossils provide a rich record of ancient oceanic shark (those living in the open ocean) ecomorphotypes and their abundance, all accumulating in fine succession at the scale of thousands of years. Although this proxy record of diversity has weak phylogenetic control because such samples of skin and teeth do not always correspond directly with host lineages, its power derives from the high temporal resolution and broad geographic coverage that comes with sediment cores. By using cores from multiple regions, the diversity patterns from the microfossils of marine fauna can yield major insights into evolution of the open sea that would be otherwise unknown. ![Figure][7] Oceanic shark loss, then and now Pelagic shark communities never recovered from the early Miocene extinction event discovered by Sibert and Rubin. The parallels between that event and today's crisis driven by human pressures (i.e., overfishing) are striking. Sibert and Rubin quantified the magnitude of a past extinction of sharks, reporting a 90% decline in abundance and >70% drop in morphological diversity. Critically, they make a compelling case for the secular nature of this event by adjusting their counts for the rate of microfossil accumulation in the seafloor sediment and variation in sedimentation rates as well as the preservation potential of these microfossils. This control of geologic factors, along with the finely resolved cores from two distinct sites (hemispheres apart in the Pacific Ocean), points to a real global event. There is also a strong ecological dimension to this faunal turnover: Nearer-shore taxa appear to survive, whereas migratory, ocean-going ones go extinct. The finding of this study is that shark ecology had undergone a widespread extinction that reorganized their communities, in an apparent global manner, in the early Miocene (about 16 million to 20 million years ago). Although the early Miocene marine faunas were roughly similar to those of today, the body size distributions of major ocean predators were askew. Whereas whales lacked extreme gigantism at this time ([ 7 ][8]), the 20-m shark “Megalodon” ([ 8 ][9]) first appeared ([ 9 ][10]), persisting as a top predator until the Pliocene (about 2.5 million to 5.3 million years ago) ([ 3 ][3], [ 10 ][11], [ 11 ][12]). The findings of Sibert and Rubin suggest that there is still much to learn about the ecological roles for these marine predators that likely crossed the interface between the deep ocean and the shallow marine environment (down to 200-m depths, where the continental shelf is located) in the early Miocene. We don't know whether they migrated to seek seasonal prey, as whales and sharks do today, or what the structure was of their feeding ecology over the course of their life history. Sibert and Rubin narrowed the disappearance of pelagic sharks to a window of time under 100,000 years around 19 million years ago, but the causes of this event remain obscure. Because the early Miocene does not stand out as a period of major climatic change, the authors do not attribute environmental factors as an extinction driver. Mechanism aside, this extinction resulted in a permanent suppression of pelagic sharks that affected the ecological composition of shark communities through time to the present day. Despite sharks today being mostly distributed in the continental shelf ([ 2 ][2], [ 12 ][13]), in less than half a century the global abundance of oceanic sharks has declined by more than 70% ([ 13 ][14], [ 14 ][15]). This loss of shark diversity is directly linked to overfishing ([ 12 ][13], [ 13 ][14]), even as the undisputable effects of global heating in the oceans continue to complicate this crisis. The parallels between this ongoing crisis and the extinction of pelagic sharks more than 19 million years ago thus feels like déjà vu, except that this time we know that the decline of sharks is happening at a faster rate than at any other in the history of the planet (see the table). The loss of sharks from the oceans has profound, complex, and irreversible ecological consequences because their presence reflects the stability of marine ecosystems ([ 15 ][16]). Yet, one-quarter of the global diversity of sharks is currently threatened with extinction ([ 2 ][2]), with a substantial risk status increase for all 31 extant oceanic shark species ([ 13 ][14]). Despite recent improvements in conservation actions, few countries impose restrictions that target oceanic sharks ([ 13 ][14]). Pelagic shark communities never recovered from a mysterious extinction event 19 million years ago; the ecological fate of what remains is now in our hands. 1. [↵][17]1. H. S. Randhawa, 2. R. Poulin, 3. M. Krkošek , Ecography 38, 96 (2015). [OpenUrl][18][CrossRef][19] 2. [↵][20]1. N. K. Dulvy et al ., eLife 3, e00590 (2014). [OpenUrl][21][CrossRef][22][PubMed][23] 3. [↵][24]1. C. Pimiento et al ., Nat. Ecol. Evol. 1, 1100 (2017). [OpenUrl][25] 4. [↵][26]1. A. Paillard, 2. K. Shimada, 3. C. Pimiento , J. Fish Biol. 98, 445 (2021). [OpenUrl][27] 5. [↵][28]1. E. C. Sibert, 2. L. D. Rubin , Science 372, 1105 (2021). [OpenUrl][29][Abstract/FREE Full Text][30] 6. [↵][31]1. E. C. Sibert, 2. K. L. Cramer, 3. P. A. Hastings, 4. R. D. Norris , Palaeontol. Electronica 20, 1 (2017). [OpenUrl][32][CrossRef][33] 7. [↵][34]1. G. J. Slater, 2. J. A. Goldbogen, 3. N. D. Pyenson , Proc. Biol. Sci. 284, 20170546 (2017). [OpenUrl][35][CrossRef][36][PubMed][37] 8. [↵][38]1. V. J. Perez, 2. R. M. Leder, 3. T. Badaut , Palaeontol. Electronica (2021). 9. [↵][39]1. C. Pimiento et al ., J. Biogeogr. 43, 1645 (2016). [OpenUrl][40] 10. [↵][41]1. C. Pimiento, 2. C. F. Clements , PLOS ONE 9, e111086 (2014). [OpenUrl][42][CrossRef][43][PubMed][44] 11. [↵][45]1. R. W. Boessenecker et al ., PeerJ 7, e6088 (2019). [OpenUrl][46] 12. [↵][47]1. R. W. Stein et al ., Nat. Ecol. Evol. 2, 288 (2018). [OpenUrl][48] 13. [↵][49]1. N. Pacoureau et al ., Nature 589, 567 (2021). [OpenUrl][50] 14. [↵][51]1. N. K. Dulvy et al ., Curr. Biol. 27, R565 (2017). [OpenUrl][52][CrossRef][53][PubMed][54] 15. [↵][55]1. R. A. Myers, 2. J. K. Baum, 3. T. D. Shepherd, 4. S. P. Powers, 5. C. H. Peterson , Science 315, 1846 (2007). [OpenUrl][56][Abstract/FREE Full Text][57] [1]: #ref-1 [2]: #ref-2 [3]: #ref-3 [4]: #ref-4 [5]: #ref-5 [6]: #ref-6 [7]: pending:yes [8]: #ref-7 [9]: #ref-8 [10]: #ref-9 [11]: #ref-10 [12]: #ref-11 [13]: #ref-12 [14]: #ref-13 [15]: #ref-14 [16]: #ref-15 [17]: #xref-ref-1-1 "View reference 1 in text" [18]: {openurl}?query=rft.jtitle%253DEcography%26rft.volume%253D38%26rft.spage%253D96%26rft_id%253Dinfo%253Adoi%252F10.1111%252Fecog.00793%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [19]: /lookup/external-ref?access_num=10.1111/ecog.00793&link_type=DOI [20]: #xref-ref-2-1 "View reference 2 in text" [21]: {openurl}?query=rft.jtitle%253DeLife%26rft_id%253Dinfo%253Adoi%252F10.7554%252FeLife.00590%26rft_id%253Dinfo%253Apmid%252F24448405%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [22]: /lookup/external-ref?access_num=10.7554/eLife.00590&link_type=DOI [23]: /lookup/external-ref?access_num=24448405&link_type=MED&atom=%2Fsci%2F372%2F6546%2F1036.atom [24]: #xref-ref-3-1 "View reference 3 in text" [25]: {openurl}?query=rft.jtitle%253DNat.%2BEcol.%2BEvol.%26rft.volume%253D1%26rft.spage%253D1100%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [26]: #xref-ref-4-1 "View reference 4 in text" [27]: {openurl}?query=rft.jtitle%253DJ.%2BFish%2BBiol.%26rft.volume%253D98%26rft.spage%253D445%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [28]: #xref-ref-5-1 "View reference 5 in text" [29]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DSibert%26rft.auinit1%253DE.%2BC.%26rft.volume%253D372%26rft.issue%253D6546%26rft.spage%253D1105%26rft.epage%253D1107%26rft.atitle%253DAn%2Bearly%2BMiocene%2Bextinction%2Bin%2Bpelagic%2Bsharks%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.aaz3549%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [30]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjEzOiIzNzIvNjU0Ni8xMTA1IjtzOjQ6ImF0b20iO3M6MjM6Ii9zY2kvMzcyLzY1NDYvMTAzNi5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30= [31]: #xref-ref-6-1 "View reference 6 in text" [32]: {openurl}?query=rft.jtitle%253DPalaeontol.%2BElectronica%26rft.volume%253D20%26rft.spage%253D1%26rft_id%253Dinfo%253Adoi%252F10.26879%252F677%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [33]: /lookup/external-ref?access_num=10.26879/677&link_type=DOI [34]: #xref-ref-7-1 "View reference 7 in text" [35]: {openurl}?query=rft.jtitle%253DProc.%2BBiol.%2BSci.%26rft_id%253Dinfo%253Adoi%252F10.1098%252Frspb.2017.0546%26rft_id%253Dinfo%253Apmid%252F28539520%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [36]: /lookup/external-ref?access_num=10.1098/rspb.2017.0546&link_type=DOI [37]: /lookup/external-ref?access_num=28539520&link_type=MED&atom=%2Fsci%2F372%2F6546%2F1036.atom [38]: #xref-ref-8-1 "View reference 8 in text" [39]: #xref-ref-9-1 "View reference 9 in text" [40]: {openurl}?query=rft.jtitle%253DJ.%2BBiogeogr.%26rft.volume%253D43%26rft.spage%253D1645%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [41]: #xref-ref-10-1 "View reference 10 in text" [42]: {openurl}?query=rft.jtitle%253DPLOS%2BONE%26rft.volume%253D9%26rft.spage%253De111086%26rft_id%253Dinfo%253Adoi%252F10.1371%252Fjournal.pone.0111086%26rft_id%253Dinfo%253Apmid%252F25338197%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [43]: /lookup/external-ref?access_num=10.1371/journal.pone.0111086&link_type=DOI [44]: /lookup/external-ref?access_num=25338197&link_type=MED&atom=%2Fsci%2F372%2F6546%2F1036.atom [45]: #xref-ref-11-1 "View reference 11 in text" [46]: {openurl}?query=rft.jtitle%253DPeerJ%26rft.volume%253D7%26rft.spage%253De6088%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [47]: #xref-ref-12-1 "View reference 12 in text" [48]: {openurl}?query=rft.jtitle%253DNat.%2BEcol.%2BEvol.%26rft.volume%253D2%26rft.spage%253D288%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [49]: #xref-ref-13-1 "View reference 13 in text" [50]: {openurl}?query=rft.jtitle%253DNature%26rft.volume%253D589%26rft.spage%253D567%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [51]: #xref-ref-14-1 "View reference 14 in text" [52]: {openurl}?query=rft.jtitle%253DCurr.%2BBiol.%26rft.volume%253D27%26rft.spage%253DR565%26rft_id%253Dinfo%253Adoi%252F10.1016%252Fj.cub.2017.04.038%26rft_id%253Dinfo%253Apmid%252F28586694%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [53]: /lookup/external-ref?access_num=10.1016/j.cub.2017.04.038&link_type=DOI [54]: /lookup/external-ref?access_num=28586694&link_type=MED&atom=%2Fsci%2F372%2F6546%2F1036.atom [55]: #xref-ref-15-1 "View reference 15 in text" [56]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DMyers%26rft.auinit1%253DR.%2BA.%26rft.volume%253D315%26rft.issue%253D5820%26rft.spage%253D1846%26rft.epage%253D1850%26rft.atitle%253DCascading%2BEffects%2Bof%2Bthe%2BLoss%2Bof%2BApex%2BPredatory%2BSharks%2Bfrom%2Ba%2BCoastal%2BOcean%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.1138657%26rft_id%253Dinfo%253Apmid%252F17395829%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [57]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjEzOiIzMTUvNTgyMC8xODQ2IjtzOjQ6ImF0b20iO3M6MjM6Ii9zY2kvMzcyLzY1NDYvMTAzNi5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=
领域	气候变化 ; 资源环境
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文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/329860
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	Catalina Pimiento,Nicholas D. Pyenson. When sharks nearly disappeared[J]. Science,2021.
APA	Catalina Pimiento,&Nicholas D. Pyenson.(2021).When sharks nearly disappeared.Science.
MLA	Catalina Pimiento,et al."When sharks nearly disappeared".Science (2021).