Growth and ingestion rates of the freshwater jellyfish Craspedacusta sowerbii

The invasive freshwater hydromedusa Craspedacusta sowerbii Lankester, 1880 (phylum Cnidaria, class Hydrozoa, family Olindiidae) is native from East Asia but for more than 20 years, reports of this species have been increasing in Europe, North America, and Australia. Due to the sporadic presence of the medusa stage and difficulties in the sample polyp stage, there is a lack of data on the physiological parameters of C. sowerbii and its potential impact. We present data on growth and ingestion rates of the medusa stage measured at 29 degrees C, temperature at which polyps are maintained in the Cineaqua Aquarium (Paris). Medusa growth increased from 0.60 +/- 0.08 to 9.0 +/- 2.1 mm (mean: 0.28 +/- 0.26 mm d(-1)), and gonads appeared after 11.5 +/- 3.0 days. Ingestion rates increased significantly from 28 +/- 16 prey ind(-1) d(-1) (<1 mm) to 442 +/- 170 prey ind(-1) d(-1) (>7 mm).