Journal of the Marine Biological Association of the United Kingdom

Cnidaria in UK coastal waters: description of spatio-temporal patterns and inter-annual variability

Stephen K. Pikesleya1a2, Brendan J. Godleya1, Sue Rangera1a3, Peter B. Richardsona3 and Matthew J. Witta2 c1

a1 Centre for Ecology and Conservation, University of Exeter, Cornwall, TR10 9EZ, UK

a2 Environment and Sustainability Institute, University of Exeter, Cornwall, TR10 9EZ, UK

a3 Marine Conservation Society, Ross on Wye, HR9 7QQ, UK


Concern has been expressed over future biogeographical expansion and habitat capitalization by species of the phylum Cnidaria, as this may have negative implications on human activities and ecosystems. There is, however, a paucity of knowledge and understanding of jellyfish ecology, in particular species distribution and seasonality. Recent studies in the UK have principally focused on the Celtic, Irish and North Seas, but all in isolation. In this study we analyse data from a publicly- driven sightings scheme across UK coastal waters (2003–2011; 9 years), with the aim of increasing knowledge on spatial and temporal patterns and trends. We describe inter-annual variability, seasonality and patterns of spatial distribution, and compare these with existing historic literature. Although incidentally-collected data lack quantification of effort, we suggest that with appropriate data management and interpretation, publicly-driven, citizen-science-based, recording schemes can provide for large-scale (spatial and temporal) coverage that would otherwise be logistically and financially unattainable. These schemes may also contribute to baseline data from which future changes in patterns or trends might be identified. We further suggest that findings from such schemes may be strengthened by the inclusion of some element of effort-corrected data collection.

(Received September 18 2013)

(Accepted January 20 2014)


  • citizen science;
  • jellyfish;
  • life cycle;
  • public sightings;
  • Scyphozoa;
  • Hydrozoa


c1 Correspondence should be addressed to: M.J. Witt, Environment and Sustainability Institute, University of Exeter, Penryn Campus, Treliever Road Penryn, Cornwall. TR10 9EZ, UK email: