Atlantification alters the reproduction of jellyfish Aglantha digitale in the European Arctic

Abstract

Increasing heat content, salinity, and velocity of the Atlantic water masses passing northward through the Fram Strait accelerate the transition of the European Arctic toward more Atlantic state, a process referred to as Atlantification. A pronounced environmental shift leads to a poleward expansion of boreal species ranges and alters seasonal rhythms of local taxa, potentially affecting the whole food web structure. Here, we monitored a pelagic cnidarian, Aglantha digitale, commonly associated with boreal waters, throughout 12 consecutive summers (2003–2014) and along 2 branches of the West Spitsbergen Current, the main conveyor of Atlantic water to the Arctic. We documented a steady decrease in A. digitale abundance in the epipelagic waters of the European Arctic and a disproportionately larger northward advection of this jellyfish with the eastern branch of the West Spitsbergen Current compared to the western branch. Supported with modeling techniques, we found that year after year, A. digitale reproduced earlier in the southern region, thus leading to an earlier descent of the larger, more mature specimens, toward deeper waters, where they avoided our epipelagic sampling. Moreover, the prevalence of smaller jellyfish during years with record‐level water temperature and salinity (2005–2007) in the southern region of the Fram Strait indicated that a 2nd reproductive cycle may have occurred. We also showed that the northern population of A. digitale, or at least part of it, originates in the south and is advected northward with the West Spitsbergen Current. In addition, our work highlights the need to include jellyfish in zooplankton monitoring.

The Impact of Jellyfish Population on Human Economy and Countermeasures

“…This information (Fig. 1) [6]. suggest that the temperature and depth as well as salinity all of these were factors to affect the number of jellyfish grow and decline.…”

“…It is obvious that in group V the reproduction of small jellyfish is decreasing, but the reproduction of large jellyfish is increasing. And between group I and group II to group V there was a clear contrast, the population of jellyfish from size of A1 to A5 of was increase [6].…”

“…However, for the same species of jellyfish of different sizes, these factors had different effect on them (Fig. 1) [6]. Also, according to the provide, different jellyfish sizes will grow in diverse living conditions.…”

“…Interannual variability data analysis of the level of salinity, seawater temperature, depth of the sea and the latitude of the effects on the abundance and reproduction of jellyfish (Fig. 1) [6]. In the Fig.…”

Drivers behind the diversity and distribution of a widespread midwater narcomedusa

“…As depth was correlated with temperature, we cannot distinguish if reproduction was influenced by depth and/or temperature. The association between temperature and reproduction has long been demonstrated for a variety of zooplankton taxa, including jellyfish (Rossi et al 2019; Mańko et al 2022). Higher temperatures within the thermal optima of species often result in earlier reproduction and faster development (Beaugrand and Kirby 2018; Rossi et al 2019).…”