ABSTRACT: Interactions between jellyfish and aquaculture operations are frequent around the world, with scyphozoan (in particular Pelagia noctiluca) and hydrozoan species documented as causative agents in major fish kills. Identifying areas of major aggregations or incursions of particular species around a coastline is a good starting point when assessing the threat of jellyfish blooms to existing or potential aquaculture facilities. Here we tested the viability of shoreline surveys to identify areas at risk from coastal and/or oceanic jellyfish species. Surveys were undertaken at over 40 sites around the north of Ireland (covering ~1800 km of coastline) from 2009 to 2011 to test 2 specific hypotheses: (1) strandings of coastal jellyfish species with life cycles involving production of medusae from benthic polyps or hydroids would display a marked spatial consistency over time, although the magnitude of events may vary inter-annually; and (2) incursions of oceanic jellyfish species (lacking polyps) would impact large areas of coastline and be more episodic in nature. Seven jellyfish species known to harm farmed finfish displayed spatially consistent stranding distributions, with major stranding events evident at several locations. More generally, coastal species stranded throughout the study area at the end of summer, whilst oceanic species were found along the exposed north shore of Ireland, washing ashore during the autumn/winter. The numbers of individuals within stranding events were greater for oceanic species (e.g. P. noctiluca, mean ± SE = 1801 ± 978 ind. km-1) than coastal species (e.g. Aurelia aurita = 112 ± 51 ind. km-1), supporting the idea that large offshore aggregations of P. noctiluca remain a threat to the aquaculture industry across the region.
KEY WORDS: Scyphozoan · Hydrozoan · Gelatinous zooplankton · Community composition · Pelagia noctiluca · Ireland
Full text in pdf format | Cite this article as: Fleming NEC, Harrod C, Houghton JDR
(2013) Identifying potentially harmful jellyfish blooms using shoreline surveys. Aquacult Environ Interact 4:263-272. https://doi.org/10.3354/aei00086
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