Jellyfish in coastal ecosystems: Advances in our understanding of population drivers, role in biogeochemical cycling, and socio-economic impacts

Jellyfish (herein, cnidarians and ctenophores) are natural members of marine ecosystems, and are widely distributed in the coastal zone. Flexibility in their physiology, trophic ecology and life history enable several species to form population outbreaks or blooms. Because of the potential impacts blooms have on ecosystem structure and function and human activities, research focuses on understanding their causes and consequences. A brief introduction to jellyfish research from the last 20 years is followed by three areas of recent research: (1) In the complex metagenic life cycle of scyphozoans, which life-stages(s) are the key determinants of population fluctuation? (2) What is the role of jellyfish in nutrient cycling and ecosystem productivity? (3) How are jellyfish detrimental and beneficial to human activity?