Spatial and temporal abundance and size trends in scyphozoan jellyfish in coastal Icelandic waters in 2008

Scyphozoan jellyfish in Icelandic waters have received limited attention, despite apparent recent increases in jellyfish blooms and considerable regional oceanographic and climatic changes. We studied the species composition, abundance, phenology, and growth of scyphomedusae around the island and explored changes in distribution, species composition, and seasonality by comparing our findings with reports from the 1930s. Scyphomedusae were collected with a Bongo net (60 cm ring diameter, 250 cm net length, and 500 µm mesh size) in the top 10 m of the water column in five regions (fjords between 64 and 66°N) around Iceland in the spring, summer, and autumn of 2008. Between 4 and 36 tows were performed per sampling region. This dataset includes umbrella diameter, dry and wet mass, as well as abundance data of two species: Aurelia aurita and Cyanea capillata.