While some limited observations exist of some scavengers consuming jelly falls, many studies report little to no scavenging.
Scavengers play a vital role in deep-sea ecosystems, deriving and distributing nutrients from energy-rich animal carcasses, such as dead mammals and fishes, as well as more refractory plant matter. Gelatinous zooplankton carcasses (jelly falls) from overlying blooms are known to accumulate at the seafloor as both small and large deposits, where they can enrich seafloor sediments in organic carbon, reduce sediment oxygen levels through smothering and alter benthic biogeochemical cycles. As gelatinous zooplankton carcasses have high sinking speeds (1500 m d −1, ), they are capable of rapidly transporting nutrients from the pelagic zone to the deep sea. Many species are able to form large blooms that can die off episodically.
Gelatinous zooplankton efficiently incorporate C and N from pelagic primary producers and secondary consumers into gelatinous biomass. This has caused researchers to project fundamental shifts in the biological structure and biogeochemical functioning of affected marine ecosystems, with significant environmental, societal and economic implications (such as negative effects on pelagic and benthic food webs, reductions in fisheries production and reduced tourism). 20 years), there are indications that ocean warming, over-fishing, aquaculture, eutrophication and coastal development are causing increased gelatinous zooplankton populations in many other regions. While recent meta-analyses show that numerous areas experience recurrent oscillations in jellyfish blooms (lasting approx. Gelatinous zooplankton are common worldwide, constituting a total biomass in the ocean of 38.3 Tg C. smothering of the seafloor) of enhanced jellyfish production on deep-sea ecosystems and pelagic–benthic coupling. Our results also demonstrate that the energy contained in gelatinous carrion can be efficiently incorporated into large numbers of deep-sea scavengers and food webs, lessening the expected impacts (e.g.
These rapid jellyfish carrion consumption rates suggest that the contribution of gelatinous material to organic fluxes may be seriously underestimated in some regions, because jelly falls may disappear much more rapidly than previously thought. We also show that scavenging rates on jellyfish are not significantly different from fish carrion of similar mass, and reveal that scavenging communities typical for the NE Atlantic bathyal zone, including the Atlantic hagfish, galatheid crabs, decapod shrimp and lyssianasid amphipods, consume both types of carcasses.
We show from baited camera deployments in the Norwegian deep sea that dense aggregations of deep-sea scavengers (more than 1000 animals at peak densities) can rapidly form at jellyfish baits and consume entire jellyfish carcasses in 2.5 h. This has led to a paradigm of limited energy transfer to higher trophic levels at jelly falls relative to vertebrate organic falls. Although mass falls of jellyfish carcasses have been observed recently at the deep seafloor, the dense necrophage aggregations and rapid consumption rates typical for vertebrate carrion have not been documented. Jellyfish blooms are common in many oceans, and anthropogenic changes appear to have increased their magnitude in some regions.
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