An interdisciplinary assessment of the impact of invasive gelatinous zooplankton in a French Mediterranean lagoon

International audienc

Refugia area for the ctenophore Mnemiopsis leidyi A. Agassiz 1865 in the Berre Lagoon (southeast France) : the key to its persistence

The invasive ctenophore, Mnemiopsis leidyi has been proliferating in lagoons and coastal areas around Europe for almost 20 years but the role and the impact of its presence in sink ecosystems is still not completely understood. In France, Mnemiopsis leidyi is present in Mediterranean lagoons and estuaries along La Manche Sea. Mnemiopsis was first recorded in the Berre Lagoon in early 2000. This lagoon has been highly perturbated for years, with a large volume of freshwater inflow through natural rivers and a succession of large hydroelectric power plants, inducing important eutrophication. Legislation has been implemented to improve the health status of the lagoon since 1994. A long-term study was undertaken in 2010 to measure Mnemiopsis population dynamics, and to identify the main drivers of its persistence in this highly anthropogenic lagoon. In 2011 and 2012, during extreme winter conditions, populations of this ctenophore were not observed for months. Its re-appearance later in year could be linked to either a new introduction from the Mediterranean Sea or the existence of retention areas where individuals sought refugia. Following measurement of biochemical conditions (i.e. chlorophyll a), plankton biomass and Mnemiopsis populations structure (eggs, cydippid larvae/transitional phase and adult) in different areas of the lagoon, as well as the lagrangian modelling of "particles' distribution (i.e. Ichthyop), we highlighted the seasonal patterns in the population structure, the level of available carbon always above the minimal for the survival of Mnemiopsis (24 mu gC L-1) and the potential refugia area role the Vaine sub-basin could play. Populations from the Vaine sub-basin probably serve as source populations for the rest of the lagoon by advective transport in spring

Global literature database for freshwater jellyfish research between 1880 and 2023

Freshwater jellyfish (FWJ) research has historically been hampered by several factors, including but not limited to: focus on one life cycle stage, diversity of publication languages (numerous national languages), and regional bias, with results scattered across many sources. In this database, we attempted to compile all globally available literature pieces, i.e., peer-reviewed papers, reviews, notes, book chapters, and some grey literature published between 1880 and September 2023, but excluding newspaper articles, symposium and conference contributions, theses, and dissertations. The database contains information on three FWJ genera (Astrohydra, Craspedacusta, Limnocnida) totalling 697 entries. Other, less studied, taxonomically doubtful, and/or regionally restricted FWJ, salt lake, and low-saline tolerant genera (Australomedusa, Halmomises, Keralica, Mansariella, Moerisia) were not included. This database will enable investigators to systematically and comprehensively search for published research advancing the field of FWJ