Review of jellyfish trophic interactions in the Baltic Sea

Abstract

Despite the diversity and oftentimes large biomass of jellyfish in marine systems, their ecological role remains poorly understood. We here provide the first systematic review of studies on jellyfish trophic ecology in the Baltic Sea (a regional marine system under strong multiple global and regional anthropogenic pressures). In total, we identified 57 peerreviewed publications, with notable taxonomic bias towards two species (Aurelia aurita; non-indigenous Mnemiopsis leidyi) and spatial bias towards five areas (Bornholm Basin, Kiel Bight, Kertinge Nor, Lim-and Gullmarsfjord). The studies provide evidence for diverse trophic roles of jellyfish as predators and as competitors of other jellyfish, zooplankton and fish species. In combination, the studies also highlight potentially large impacts via topdown (grazing) and bottom-up (nutrient excretion) effects, but also, strong spatio-temporal variability in the magnitude of these effects, depending on the occurrence of jellyfish blooms. Studies on the role of jellyfish as prey for fish, seabirds or marine mammals, and for benthic systems via food-falls, were limited or lacking for the Baltic Sea, despite increasing focus on these topics globally. Improved understanding of the temporal (seasonal, interannual, long-term) and spatial variability of blooms and corresponding trophic effects, would provide more systematic understanding of the ecological role of jellyfish in the spatio-temporally variable Baltic Sea. A broader spatial coverage, inclusion of more jellyfish taxa and under-studied early life history stages, as well as the implementation and continuation of long-term data series would represent important steps towards this goal.

Genetic structure of invasive ctenophore Mnemiopsis leidyi populations in temperate northern European waters supports the southern North Sea overwintering refuge

“…However, after energy allocation to reproduction, senescence will eventually lead to death and cessation of the population. Top-down control is the fourth dimension of seasonal population vanishment, however, regionally less well-studied (Stoltenberg et al 2021). Despite some studies investigating the effects of parasites on M. leidyi in invaded temperate northern European waters (Selander et al 2009) and intraguild predation being likely considerable (Hosia and Titelman 2011), there is a lack of knowledge of other predator-prey interactions.…”

“…This species has been shown to have detrimental effects, when abundant, on lower trophic levels (ichthyo-and zooplankton; Marchessaux et al 2021), competing zooplanktivorous species (e.g., Granhag et al 2011;Hamer et al 2011), changing microbial abundance and community composition through excretion of mucus and dissolved compounds (Dinasquet et al 2012), and causing trophic cascades that can locally lead to phytoplankton blooms and restructuring of pelagic food webs (e.g., Riisgård et al 2012; Tiselius and Møller 2017; but see Stibor et al 2004). Today, trophic interactions of M. leidyi are among gelatinous zooplankton species in the Baltic Sea well studied and are only surpassed by knowledge of the common jelly sh Aurelia aurita (Stoltenberg et al 2021). Large-scale impacts of M. leidyi infestations were reported in other Eurasian seas (Shiganova et al 2001a;Bilio and Niermann 2004) that could, in part, only be managed after the introduction of another (gelativore) ctenophore, Beroe ovata (e.g., Shiganova et al 2001b).…”

Stable isotope analysis in food web research: Systematic review and a vision for the future for the Baltic Sea macro-region

“…Shortcoming 3: Understudied trophic groups Several groups considered important for Baltic Sea food web functioning presently remain understudied by SIA. Examples include (1) jellyfish, addressed by only five SIA studies to date despite of their putative importance in Baltic Sea food webs (Stoltenberg et al 2021 ) contrasting with a rapid increase in studies globally (Choy et al 2017 ; Purcell 2018 ; Chi et al 2021 ), (2) marine mammals and seabirds addressed proportionally less than fishes, despite their role as top-level consumers and species of high conservation concern (Sinisalo et al 2008 ; Morkūnė et al 2016 ), and (3) NIS, addressed by only 11 SIA studies to date, neglecting the trophic ecology of most NIS in the Baltic (Ojaveer et al 2021 ). The application of SIA holds particular strengths in studies of fragile, highly mobile, protected and/or non-commercial fauna (e.g., Crawford et al 2008 ; Pitt et al 2008 ), but this potential has not been fully realized to date.…”

Coupling hydrodynamic drifting simulations and seasonal demographics to forecast the occurrence of jellyfish blooms

“…Aurelia aurita is a cosmopolitan jellyfish species and comprises one of the most abundant bloom-forming species within the Baltic region (Stoltenberg et al, 2021). Throughout their life cycle, A. aurita individuals pass through a series of discrete stages, each with differing vital rate profiles (Goldstein & Steiner, 2020; Fig.…”