PLENARY

 

Large-scale and long-term perspectives on jellyfish research

 

Jennifer E. Purcell

Western Washington University, USA

 

Many things have changed over my nearly 40-year study of “jelly” ecology, but many have not. Although jellies finally have achieved recognition as important, there remains a shortage of quantitative data on jellies around the world. This is a major impediment to understanding and predicting their abundances, biomasses, and ecosystem effects. Although jellyfish are known mostly for the problems they cause humans, and blooms occur where the environment is deteriorated by human activities, environmental deterioration is accelerating and jellies may benefit. Introductions of non-indigenous species (NIS) also have increased and probably will accelerate from increased shipping and widening of canals. Although blooms may have increased, causes of blooms are unknown for almost all species. Many basic life-history characteristics are inadequately studied, including reproduction, growth, and mortality rates that contribute to the dynamics of jelly populations. Those data are essential to understand their importance. Although of great potential significance for fisheries and aquaculture, the trophic interactions between jellyfish and fish are inadequately studied. New indirect trophic techniques have become popular to provide insight into food web relationships, but past methods should not be abandoned. Instead of laborious feeding rates, ingestion calculated from metabolic data can be combined with biomass data for use in ecosystem models. Jellyfish should be included in fishery studies, ecosystem studies, and fishery management plans. Improved and miniaturized technology has provided new techniques for studies on jellyfish. New uses for jellyfish are being developed, with many potential benefits in medicine and as food.