Whale fall

For the novel by Daniel Kraus, see Whalefall (novel).
A chemoautotrophic whale fall community in the Santa Cruz basin off southern California at a depth of 1,674 m (5,492 ft), including bacteria mats, vesicomyid clams in the sediments, galatheid crabs, polynoids, and a variety of other invertebrates.

A whale fall occurs when the carcass of a whale has fallen onto the ocean floor, typically at a depth greater than 1,000 m (3,300 ft), putting them in the bathyal or abyssal zones.[1] On the sea floor, these carcasses can create complex localized ecosystems that supply sustenance to deep-sea organisms for decades.[1] In some circumstances, particularly in cases with lower water temperatures, they can be found at much shallower depths, with at least one natural instance recorded at 150 m (500 ft) and multiple experimental instances in the range of 30–382 m (100–1,300 ft).[1] Whale falls were first observed in the late 1970s with the development of deep-sea robotic exploration.[2] Since then, several natural and experimental whale falls have been monitored[1][3] through the use of observations from submersibles and remotely operated underwater vehicles (ROVs) in order to understand patterns of ecological succession on the deep seafloor.[4]

Deep sea whale falls are thought to be hotspots of adaptive radiation for specialized fauna.[1] Organisms that have been observed at deep-sea whale fall sites include chordates, arthropods, cnidarians, echinoderms, mollusks, nematodes, and annelids.[1][5] New species have been discovered, including some potentially specializing in whale falls.[1] It has been postulated that whale falls generate biodiversity by providing evolutionary stepping stones for multiple lineages to move and adapt to new environmentally-challenging habitats.[1] Researchers estimate that 690,000 carcasses/skeletons of the nine largest whale species are in one of the four stages of succession at any one time.[6] This estimate implies an average spacing of 12 km (7.5 mi) and as little as 5 km (3.1 mi) along migration routes. They hypothesize that this distance is short enough to allow larvae to disperse/migrate from one to another.[6]

Whale falls are able to occur in the deep open ocean due to cold temperatures and high hydrostatic pressures. In the coastal ocean, a higher incidence of predators as well as warmer waters hasten the decomposition of whale carcasses.[1] Carcasses may also float due to decompositional gases, keeping the carcass at the surface.[7] The bodies of most great whales (which includes sperm whales and many species of baleen whale[8]) are slightly denser than the surrounding seawater, and only become positively buoyant when the lungs are filled with air.[9] When the lungs deflate, the whale carcasses can reach the seafloor quickly and relatively intact due to a lack of significant whale fall scavengers in the water column.[1] Once in the deep-sea, cold temperatures slow decomposition rates, and high hydrostatic pressures increase gas solubility, allowing whale falls to remain intact and sink to even greater depths.[7]

  1. ^ a b c d e f g h i j Smith, Craig R.; Glover, Adrian G.; Treude, Tina; Higgs, Nicholas D.; Amon, Diva J. (2015). "Whale-Fall Ecosystems: Recent Insights into Ecology, Paleoecology, and Evolution". Annual Review of Marine Science. 7 (1): 571–596. Bibcode:2015ARMS....7..571S. doi:10.1146/annurev-marine-010213-135144. PMID 25251277. S2CID 43201905.
  2. ^ Vetter, Tom (2015). 30,000 Leagues Undersea: True Tales of a Submariner and Deep Submergence Pilot. Tom Vetter Books, LLC. ISBN 978-1-941160-10-7.
  3. ^ Lundsten, Lonny; Schlining, Kyra L.; Frasier, Kaitlin; Johnson, Shannon B.; Kuhnz, Linda A.; Harvey, Julio B. J.; Clague, Gillian; Vrijenhoek, Robert C. (1 December 2010). "Time-series analysis of six whale-fall communities in Monterey Canyon, California, USA". Deep Sea Research Part I: Oceanographic Research Papers. 57 (12): 1573–1584. Bibcode:2010DSRI...57.1573L. doi:10.1016/j.dsr.2010.09.003.
  4. ^ Aguzzi, J.; Fanelli, E.; Ciuffardi, T.; Schirone, A.; De Leo, F. C.; Doya, C.; Kawato, M.; Miyazaki, M.; Furushima, Y.; Costa, C.; Fujiwara, Y. (24 July 2018). "Faunal activity rhythms influencing early community succession of an implanted whale carcass offshore Sagami Bay, Japan". Scientific Reports. 8 (1): 11163. Bibcode:2018NatSR...811163A. doi:10.1038/s41598-018-29431-5. PMC 6057991. PMID 30042515.
  5. ^ Sumida, Paulo Y. G.; Alfaro-Lucas, Joan M.; Shimabukuro, Mauricio; Kitazato, Hiroshi; Perez, Jose A. A.; Soares-Gomes, Abilio; Toyofuku, Takashi; Lima, Andre O. S.; Ara, Koichi; Fujiwara, Yoshihiro (24 February 2016). "Deep-sea whale fall fauna from the Atlantic resembles that of the Pacific Ocean". Scientific Reports. 6 (1): 22139. Bibcode:2016NatSR...622139S. doi:10.1038/srep22139. PMC 4764926. PMID 26907101.
  6. ^ a b Little, C. T. (2010). "Life at the Bottom: The Prolific Afterlife of Whales". Scientific American. 302 (2): 78–82, 84. doi:10.1038/scientificamerican0210-78. PMID 20128227.
  7. ^ a b Allison, Peter A.; Smith, Craig R.; Kukert, Helmut; Deming, Jody W.; Bennett, Bruce A. (1991). "Deep-water taphonomy of vertebrate carcasses: a whale skeleton in the bathyal Santa Catalina Basin". Paleobiology. 17 (1): 78–89. Bibcode:1991Pbio...17...78A. doi:10.1017/S0094837300010368. JSTOR 2400991. S2CID 129439319.
  8. ^ Baldanza, Angela; Bizzarri, Roberto; Famiani, Federico; Garassino, Alessandro; Pasini, Giovanni; Cherin, Marco; Rosatini, Francesco (2018). "The early Pleistocene whale-fall community of Bargiano (Umbria, Central Italy): Paleoecological insights from benthic foraminifera and brachyuran crabs". Palaeontologia Electronica. 21 (16): 1–27. doi:10.26879/779.
  9. ^ Reisdorf, Achim G.; Bux, Roman; Wyler, Daniel; Benecke, Mark; Klug, Christian; Maisch, Michael W.; Fornaro, Peter; Wetzel, Andreas (1 March 2012). "Float, explode or sink: postmortem fate of lung-breathing marine vertebrates" (PDF). Palaeobiodiversity and Palaeoenvironments. 92 (1): 67–81. Bibcode:2012PdPe...92...67R. doi:10.1007/s12549-011-0067-z. S2CID 129712910.