Jelly-falls
Jelly-falls are marine carbon cycling events whereby gelatinous zooplankton sink to the seafloor and enhance carbon and nitrogen fluxes via rapidly sinking particulate organic matter.[1] These events provide nutrition to benthic megafauna and bacteria.[2][3] Jelly-falls have been implicated as a major “gelatinous pathway” for the sequestration of labile biogenic carbon through the biological pump.[4]
Initiation
Jelly-falls are primarily made up of the decaying corpses of Cnidaria and Thaliacea (Pyrosomida, Doliolida, and Salpida).[1] Several circumstances can trigger the death of gelatinous organisms which would cause them to sink. These include high levels of primary production that can clog the feeding apparatuses of the organisms, a sudden temperature change, when an old bloom runs out of food, when predators damage the bodies of the jellies, and parasitism.[5] In general, however, jelly-falls are linked to jelly-blooms and primary production, with over 75% of the jelly falls in subpolar and temperate regions occurring after spring blooms, and over 25% of the jelly-falls in the tropics occurring after upwelling events.[1]
As the climate changes and ocean waters warm, jelly blooms become more prolific and the transport of jelly-carbon to the lower ocean increases.[6] With a possible slowing of the classic biological pump, the transport of carbon and nutrients to the deep sea through jelly-falls may become more and more important to deep ocean.[1]
Decomposition
The decomposition process starts after death and can proceed in the water column as the gelatinous organisms are sinking.[5] Decay happens faster in the tropics than in temperate and subpolar waters as a result of warmer temperatures.[5] In the tropics, a jelly-fall may take less than 2 days to decay in warmer, surface water, but as many as 25 days when it is lower than 1000m deep.[5] However, lone gelatinous organisms may spend less time on the sea floor as one study found that jellies could be decomposed by scavengers in the Norwegian deep sea in under two and a half hours.[7]
Decomposition of jelly-falls is largely aided by these kinds of scavengers. In general, echinoderms, such as sea stars, have emerged as the primary consumer of jelly-falls, followed by crustaceans and fish.[1] However, which scavengers find their way to jelly-falls is highly reliant on each ecosystem. For example, in an experiment in the Norwegian deep sea, hagfish were the first scavengers to find the traps of decaying jellies, followed by squat lobsters, and finally decapod shrimp.[7] Photographs taken off the coast of Norway on natural jelly-falls also revealed caridean shrimp feeding on jelly carcasses.[3]
Finally, decomposition is aided by the microbial community. In a case study on the Black Sea, the number of bacteria increased in the presence of jelly-falls, and the bacteria were shown to preferentially use nitrogen released from decaying jelly carcasses while mostly leaving carbon.[8] In addition, with the exclusion of scavengers, jelly-falls develop a white layer of bacteria over the decaying carcasses and emit a black residue over the surrounding area, which is from sulfide.[9] This high level of microbial activity requires a lot of oxygen, which can lead zones around jelly-falls to become hypoxic and inhospitable to larger scavengers.[9]
Research challenges
Researching jelly-falls relies on direct observational data such as video, photography, or benthic trawls.[1] This means that jelly-falls are not always observed in the time period in which they exist. Because jelly-falls can be fully processed and degraded within a number of hours by scavengers[7] and the fact that some jelly-falls will not sink below 500m in tropical and subtropical waters,[5] the importance and prevalence of jelly-falls may be underestimated.
See also
References
- ^ a b c d e f Lebrato, Mario; Pitt, Kylie A.; Sweetman, Andrew K.; Jones, Daniel O. B.; Cartes, Joan E.; Oschlies, Andreas; Condon, Robert H.; Molinero, Juan Carlos; Adler, Laetitia (2012). "Jelly-falls historic and recent observations: a review to drive future research directions". Hydrobiologia. 690 (1): 227–245. doi:10.1007/s10750-012-1046-8.
{{cite journal}}: Unknown parameter|last-author-amp=ignored (|name-list-style=suggested) (help) - ^ Lebrato, M.; Jones, D. O. B. (2009). "Mass deposition event of Pyrosoma atlanticum carcasses off Ivory Coast (West Africa)". Limnology and Oceanography. 54 (4): 1197–1209. doi:10.4319/lo.2009.54.4.1197.
{{cite journal}}: Unknown parameter|last-author-amp=ignored (|name-list-style=suggested) (help) - ^ a b Sweetman, Andrew K.; Chapman, Annelise (2011). "First observations of jelly-falls at the seafloor in a deep-sea fjord". Deep Sea Research Part I: Oceanographic Research Papers. 58 (12): 1206–1211. doi:10.1016/j.dsr.2011.08.006.
{{cite journal}}: Unknown parameter|last-author-amp=ignored (|name-list-style=suggested) (help) - ^ Burd, Adrian. "Towards a transformative understanding of the ocean's biological pump: Priorities for future research-Report on the NSF Biology of the Biological Pump Workshop" (PDF). OCB: Ocean Carbon & Biogeochemistry. Retrieved 30 October 2016.
- ^ a b c d e Lebrato, Mario; Pahlow, Markus; Oschlies, Andreas; Pitt, Kylie A.; Jones, Daniel O. B.; Molinero, Juan Carlos; Condon, Robert H. (2011). "Depth attenuation of organic matter export associated with jelly falls". Limnology and Oceanography. 56 (5): 1917–1928. doi:10.4319/lo.2011.56.5.1917.
{{cite journal}}: Unknown parameter|last-author-amp=ignored (|name-list-style=suggested) (help) - ^ Lebrato, Mario; Molinero, Juan-Carlos; Cartes, Joan E.; Lloris, Domingo; Mélin, Frédéric; Beni-Casadella, Laia (2013). "Sinking jelly-carbon unveils potential environmental variability along a continental margin". PLOS ONE. 8 (12): e82070. doi:10.1371/journal.pone.0082070.
{{cite journal}}: Unknown parameter|last-author-amp=ignored (|name-list-style=suggested) (help)CS1 maint: unflagged free DOI (link) - ^ a b c Sweetman, Andrew K.; Smith, Craig R.; Dale, Trine; Jones, Daniel O. B. (2014). "Rapid scavenging of jellyfish carcasses reveals the importance of gelatinous material to deep-sea food webs". Proceedings of the Royal Society B: Biological Sciences. 281 (1796): 20142210. doi:10.1098/rspb.2014.2210. PMC 4213659. PMID 25320167.
{{cite journal}}: Unknown parameter|last-author-amp=ignored (|name-list-style=suggested) (help) - ^ Tinta, Tinkara; Kogovšek, Tjaša; Turk, Valentina; Shiganova, Tamara A.; Mikaelyan, Alexander S.; Malej, Alenka (2016). "Microbial transformation of jellyfish organic matter affects the nitrogen cycle in the marine water column — A Black Sea case study". Journal of Experimental Marine Biology and Ecology. 475: 19–30. doi:10.1016/j.jembe.2015.10.018.
{{cite journal}}: Unknown parameter|last-author-amp=ignored (|name-list-style=suggested) (help) - ^ a b West, Elizabeth Jane; Welsh, David Thomas; Pitt, Kylie Anne (2009). "Influence of decomposing jellyfish on the sediment oxygen demand and nutrient dynamics". Hydrobiologia. 616 (1): 151–160. doi:10.1007/s10750-008-9586-7.
{{cite journal}}: Unknown parameter|last-author-amp=ignored (|name-list-style=suggested) (help)