The role of gelatinous zooplankton in coastal and oceanic food webs: life history strategy and trophic ecology
Gelatinous zooplankton (GZ) are comprised of diverse taxonomic groups. The population outbreaks of some GZ species occurring in marine ecosystems have drawn increasing attention because of their eco-economic consequences in recent decades. In this context, many ecological questions about GZ have not been well documented. This dissertation aims to investigate essential biomolecules transfer and consequences on life history traits of Aurelia aurita under the combined effects of food quality, food quantity, and temperature. Besides, large-scale stable isotope data were assembled in order to discover the general community structure of GZ in the oceanic food web. The dissertation structures in the form of five chapters. The first chapter gives a general introduction to GZ in food webs and basic theory of bio-tracers. Chapter 2 displays and discusses the role of food quality combined with food quantity and temperature affecting essential biomolecules transfer in a three-trophic-level food chain encompassing A. aurita polyps. Chapter 3 is a follow-up study, which stresses these environmental factors influencing on life history traits of the moon jelly, A. aurita, polyps. In Chapter 4, the trophic ecology of oceanic GZ is presented. By applying stable isotope analysis in the eastern tropical Atlantic, the general jelly web structure and isotopic niche differentiation of different GZ taxonomic groups in the overall pelagic food web was assessed. Finally, Chapter 5 summarized the findings from the experimental and field studies on GZ and put forwarded outlooks for further GZ ecology research in both coastal and oceanic food webs. In summary, this dissertation stresses food quality as an important factor playing critical roles on essential biomolecules transfer in food webs and explaining polyps’ life history strategies under multiple stressors. Furthermore, as GZ play diverse and critical roles in aquatic food webs, the trophic “dead-end” concept of GZ should be reassessed.