Jellyfish, jellypress and jellyperception: Final report - Belgian case study

During the last decades, the number of reports on invasions and blooms of jellyfish has increased, both in scientific literature as in the general media. There is however no clarity about a global rise of gelatinous zooplankton due to the lack of extended time series, and due to the fact that public perception is potentially driven by the media. However, public perception is a key driver in policy decisions, including coastal zone governance and research funding. Consequently, it is useful to investigate the variability within public perception and the relationship between media and public perception in the light of policy. This was investigated within a case study at the Belgian coast regarding the perception on jellyfish and the consequences of jellyfish blooms, based on the results of a questionnaire survey and a media search. The results indicate that perception is only partly driven by the press if it comes to jellyfish. Personal experience seems to be at least equally important as driver. Additionally, the results indicate that there is a large variation in perception on jellyfish, in this study illustrated by the differences in perception between beach tourists and divers. The lack of knowledge about differences between jellyfish species turns out to be a key issue determining perception. Both the variability in perception and the species issue are important for the incorporation of the jellification problem in integrated coastal zone management. In first instance, it is important to extend perception surveys to all groups directly and indirectly affected by jellyfish. By doing so, opportunities may emerge for cooperation between scientists, policymakers and public parties in the form of citizen science. Secondly, management actions concerning jellyfish increases should include the provision of species-specific information, for example by distributing leaflets and putting up warning boards on the beach. This would likely result in a higher acceptance of jellyfish, a better communication between scientists and the public, and in a better quality of data in citizen science programs

Modelling survival and connectivity of Mnemiopsis leidyi in the south-western North Sea and Scheldt estuaries

Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a high-resolution particle tracking model with passive particles, a low-resolution particle tracking model with a reproduction model coupled to a biogeochemical model, and a dynamic energy budget (DEB) model. The results of the models, each with its strengths and weaknesses, suggest the following conceptual situation: (i) the estuaries possess enough retention capability to keep an overwintering population, and enough exchange with coastal waters of the North Sea to seed offshore populations; (ii) M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii) under current climatic conditions, M. leidyi may not be able to reproduce in large numbers in coastal and offshore waters of the North Sea, but this may change with global warming; however, this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality at different life stages to improve models such as used here