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 ex- isting 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 hy- potheses: (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.
Highlights
Jellyfish blooms are a known threat to coastal industries, yet our ability to predict or even quantify the threat remains an on-going challenge (Nickell et al 2010). Many studies of such aggregations have focused on areas dominated by those jellyfish (i.e. Phylum Cnidaria, Class Scyphozoa) with a metagenic life history comprising an alternation of free-swimming and sexually reproducing medusae with asexually bud
Aquacult Environ Interact 4: 263–272, 2013 lematic incursions of P. noctiluca are well documented in the Mediterranean Sea (Rottini-Sandrini et al 1980, Zavodnik 1987, CIESM 2001), yet the species had received little attention in the North East Atlantic (NEA) until recently (Doyle et al 2008, Licandro et al 2010)
Jellyfish stranding data were collected from the north of Ireland (Counties Down to Donegal) as part of a systematic beach survey programme from July 2009 to August 2011 (40 beaches, > 580 individual surveys covering ~1800 km of coastline; Fig. 1) following methods outlined by Houghton et al (2007) and Doyle et al (2007)
Summary
Jellyfish blooms are a known threat to coastal industries (e.g. aquaculture on-growing facilities, recreational beaches and power stations), yet our ability to predict or even quantify the threat remains an on-going challenge (Nickell et al 2010). Most notable were the extraordinary abundances recorded around the north of Ireland in November 2007 (spanning more than 4° of latitude along a 1500 km cruise track) that caused damage worth over £1 million to the Northern Irish aquaculture industry in a matter of days (Doyle et al 2008). This species was a suspected causative agent of over 1 million Atlantic salmon Salmo salar killed off northwest Ireland in 2003 (Cronin et al 2004), and aquaculture companies still express grave concern over this ongoing threat (Nickell et al 2010). As the drivers of oceanic jellyfish incursions in the NEA are poorly understood (Doyle et al 2008), insurance companies have, in the past, had no other option than to classify such events as ‘acts of God’, with subsequent marked negative economic impacts for the marine aquaculture sector
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
