SHORT COMMUNICATION Carbon content of Mnemiopsis leidyi eggs and specific egg production rates in northern Europe

The comb jelly Mnemiopsis leidyi is considered to be a successful invasive species, partly due to its high reproduction potential. However, due to the absence of direct carbon measurements of eggs, specific reproduction rates remain uncertain. We show that egg carbon is 0.22+ 0.02 mg C and up to 21 times higher than previously extrapolated. With maximum rates of 11 232 eggs ind day, largest animals in northern Europe invest 10% day of their body carbon into reproduction. The comb jelly M. leidyi has received wide public and scientific attention during the last decades due to its commonly observed formation of bloom abundances in native and invaded areas (e.g. Costello et al., 2012; Riisgård et al., 2012). One of the traits suggested to be responsible for M. leidyi’s invasion success is its high fecundity. At the northern end of its distribution range in native areas, M. leidyi has been shown to produce up to 9380 and 14 233 eggs ind day (Kremer, 1976a; Graham et al., 2009), with similar rates of 9910 eggs ind day for the native southern population in Biscayne Bay, FL, USA (Baker and Reeve, 1974). Within invaded European waters, rates of up to 3000 and 12 000 eggs ind day have been recorded for northern and southern populations, respectively (Zaika and Revkov, 1994; Javidpour et al., 2009). Since M. leidyi is a simultaneous hermaphrodite and fertilized eggs are produced on a daily basis