Identification of jellyfish from Continuous Plankton Recorder samples
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Previous analysis of the Continuous Plankton Recorder (CPR) long-term data set for the presence of ‘coelenterate’ tissue revealed changes in the frequency of jellyfish occurrence in the North Atlantic Ocean and North Sea; however, the identities of the jellyfish were unknown, causing uncertainty in interpreting these findings. To improve the utility of the ‘coelenterate’ data from the CPR, 62 CPR samples were selected for re-analysis from an area where the widespread occurrence of the holoplanktonic scyphomedusan, Pelagia noctiluca (Forsskål, 1775), was previously documented from net tows to test if the CPR sampled P. noctiluca. Examination of the samples revealed smears (<1 mm) of golden gelatinous tissue on the sampling mesh. Subsequent microscopic examination and measurement of nematocysts identified most of the smears as P. noctiluca. Indeed, P. noctiluca was identified on 53% of the CPR samples from the area that best coincided with the documented bloom area. Although hydrozoans were also identified in the samples, the characteristic golden colour of P. noctiluca and its distinct suite of nematocysts allowed identification to species level. The identification of other jellyfish may be more complicated due to the labour-intensive examination of samples and unclear delineation of nematocyst types when multiple similar species are present. Nevertheless, re-analysis of CPR samples holds great promise for identifying the underlying reason for increases in jellyfish occurrence in the CPR records.
KeywordsPelagia noctiluca Nematocysts Medusae North Atlantic Ocean
This project [Grant-Aid Agreement No PBA/AF/08/002(01)] was carried out under the Sea Change strategy with the support of the Marine Institute and the Marine Research Sub-Programme of the National Development Plan 2007–2013, co-financed under the European Regional Development Fund. EJB was supported by the above grant aid. TKD was supported by an Irish Research Council for Science Engineering and Technology fellowship. The authors would like to acknowledge all past and present members and supporters of the CPR survey, especially the ships that voluntarily tow CPRs on regular routes and the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) for facilitating the use of the CPR samples and the SAHFOS laboratories. We thank G. Hays and two other anonymous reviewers for their comments on the article.
- Attrill, M. J. & M. Edwards, 2008. Reply to Haddock, S.H.D. Reconsidering evidence for potential climate-related increases in jellyfish. Limnology and Oceanography 53: 2763–2766.Google Scholar
- Avian, M., P. Negro & L. Sandrini, 1991. A comparative analysis of nematocysts in Pelagia noctiluca and Rhizostoma pulmo from the North Adriatic Sea. Hydrobiologia 52: 480–485.Google Scholar
- Fraser, J. H., 1955. The plankton of the waters approaching the British Isles in 1953. Marine Research 1: 1–12.Google Scholar
- Haddock, S. H. D., 2008. Reconsidering evidence for potential climate-related increases in jellyfish. Limnology and Oceanography 53: 2759–2762.Google Scholar
- Hardy, A., 1935. The continuous plankton recorder: a new method of survey. Rapports et Proces-Verbaux des Reunions. Conseil International pour l’Exploration de la Mer 95: 36–47.Google Scholar
- Östman, C. & J. Hydman, 1997. Nematocyst analysis of Cyanea capillata and Cyanea lamarckii (Scyphozoa, Cnidaria). Scientia Marina 61: 313–344.Google Scholar
- Russell, F. S., 1970. The Medusae of the British Isles: II. Cambridge University Press, Cambridge.Google Scholar
- Sabatés, A., F. Pagès, D. Atienza, V. L. Fuentes, J. E. Purcell & J.-M. Gili. Planktonic cnidarian distribution and feeding of Pelagia noctiluca from near shore to open sea in the NW Mediterranean Sea. Hydrobiologia. doi: 10.1007/s10750-010-0221-z.