Jelly-falls historic and recent observations: a review to drive future research directions

Decomposition of jellyfish carrion in situ: Short-term impacts on infauna, benthic nutrient fluxes and sediment redox conditions

“…Although the sulfide profiles in the first two days were variable, the final day showed significant increases in porewater sulfide concentrations in jellyfish plots. The accumulation of these reduced analytes was likely also enhanced by the physical presence of the jellyfish, which formed a barrier and probably impeded the transfer of dissolved oxygen to the underlying sediment (Lebrato et al, 2012), limiting chemical and biological reoxidation of iron (II) and sulfide and allowing them to accumulate and diffuse towards the sediment surface (Middelburg and Levin, 2009). Furthermore, the physical barrier created by the jellyfish carrion may have limited the ability of burrowing fauna to ventilate their burrows, thus reducing the transport of oxygen into the deeper sediment strata and limiting the reoxidation of reduced respiratory electron acceptors (Welsh, 2003), favoring their accumulation beneath the jellyfish.…”

“…The nutrients assimilated within these blooms are often released back to the environment as one large pulse when the blooms collapse and decompose (Pitt et al, 2014). Decaying medusae often sink to the benthos in large quantities (Lebrato et al, 2012(Lebrato et al, , 2013 but virtually nothing is known about how collapsed blooms affect benthic redox conditions and infaunal communities .…”

“…Jellyfish carrion that reaches the benthos can be rapidly scavenged by a diverse range of taxa, including echinoderms, crustaceans and fish (see Lebrato et al, 2012;Sweetman et al, 2014). However, the biomass of carcasses that accumulates on the benthos after a bloom collapses can be so large that it exceeds the amount that can be scavenged.…”

“…Since carcasses often remain intact when they sink to the benthos and can cover patches of the sediment several meters in diameter (e.g. Billett et al, 2006;Lebrato and Jones, 2009), they may also create a diffusive barrier that inhibits reoxidation of sediments below their tissue (Lebrato et al, 2012). This could potentially exacerbate the adverse conditions for fauna below or in close proximity to the gelatinous carrion by favoring anaerobic microbial metabolism, sediment reduction and the accumulation of toxic sulfides in the sediment porewater.…”

Jellyfish biochemical composition: importance of standardised sample processing

“…After the decline of such populations, organic material released into the water column from the decomposing jellyfish tissue promote a microbially dominated food web (Con-don et al 2011, Tinta et al 2012, thus altering ecosystem diversity and function. Large accumulations of jellyfish carcasses at the sea bed are an important source of labile organic material for a wide spectrum of benthic macroorganisms (for a review see Lebrato et al 2012). Nevertheless, the unconsumed jellyfish material is decomposed by microbes, and oxygen consumption together with remineralization products that accompany the decomposition may further impact the benthic biota (Billett et al 2006, West et al 2009, Lebrato et al 2012.…”