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Jelly-falls are marine Carbon cycle events whereby gelatinous zooplankton, primarily , sink to the seafloor and enhance carbon and nitrogen fluxes via rapidly sinking particulate organic matter. These events provide nutrition to Benthic zone megafauna and bacteria. Jelly-falls have been implicated as a major “gelatinous pathway” for the sequestration of labile biogenic carbon through the biological pump. These events are common in protected areas with high levels of primary production and water quality suitable to support cnidarian species. These areas include Estuary and several studies have been conducted in fjords of Norway.
With global climates shifting towards creating warmer and more acidic oceans, conditions not favored by non-resilient species, jellies are likely to grow in population sizes. Eutrophication areas and dead zones can become jelly hot spots with substantial blooms. As the climate changes and ocean waters warm, jelly blooms become more prolific and the transport of jelly-carbon to the lower ocean increases. 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.
Decomposition of jelly-falls is largely aided by these kinds of . In general, , such as Starfish, have emerged as the primary consumer of jelly-falls, followed by and fish. 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 , and finally decapod shrimp. Photographs taken off the coast of Norway on natural jelly-falls also revealed caridean shrimp feeding on jelly carcasses.
With increased populations and blooms becoming more common, with favorable conditions and a lack of other filter feeders in the area to consume plankton, environments with jellies present will have carbon pumps be more primarily supplied with jelly-falls. This could lead to issues of habitats with established biological pumps succumbing to nonequilibrium as the presence of jellies would change the food web as well as changes to the amount of carbon deposited into the sediment. 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. In a study conducted by Andrew Sweetman in 2016, it was discovered using core samples of the sediment in Norwegian fjords, the presence of jelly-falls significantly impacted the biochemical process of these benthic communities. Bacteria consume jelly carcasses rapidly, removing opportunities of acquiring sustenance for bottoming feeding macrofauna, which has impacts traveling up the trophic levels. 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. 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. By providing abundant nutrients and surfaces for bacterial colonization and interactions, jelly-falls can also be hotspots for the transmission of antimicrobial resistance genes among marine bacterial communities.
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