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AB prepress abstract   -  DOI: https://doi.org/10.3354/ab00742

Freshwater jellyfish in northern temperate lakes: Craspedacusta sowerbii in British Columbia, Canada

Florian Lüskow, Pablo J. López-González, Evgeny A. Pakhomov

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ABSTRACT: The freshwater jellyfish species of the genus Craspedacusta purportedly originated from the Yangtze River catchment area, China, and has now been observed on all continents, except Antarctica. Sightings of C. sowerbii in the Pacific regions of Canada were compiled to document some of the northernmost records of this species in the Americas. Species identification has been difficult in the past. Therefore, field collection of specimens was carried out on southern Vancouver Island. The morphology was described macro- and microscopically as well as molecularly using mitochondrial and nuclear markers. Collected hydromedusae from British Columbia (BC) did not deviate morphologically from C. sowerbii specimens from other continents, but molecular analyses supported the idea of two main widely distributed lineages hidden under similar morphological features (species complex). A community science approach allowed establishing the distribution extent of C. sowerbii in western and southern BC (present in 24 lakes from as early as 1990). Results showed that the number of sightings increased considerably in the period after 2010. Recent increases in sightings of C. sowerbii in BC and worldwide could be indicative of climate warming-related distribution range extension or be a result of growing public awareness and/or increased observational efforts. Even after more than 120 years of Craspedacusta research, much about their biology and ecology remains unknown, which motivated us to compile a list of knowledge gaps based on an extensive literature survey.