Metabolism measurements of Aurelia aurita planulae larvae, and calculation of maximal survival period of the free swimming stage
Respiration, ammonia and phosphate excretion experiments were performed with planula larvae of Aurelia aurita (Scyphozoa) from Kiel Fjord, Baltic Sea, in summer 1983. The mean respiration measured was 3.22 nl O2 ind-1 h-1 (at ∼ 20 °C). Excretion experiments revealed average values of 11.41 pM NH4-N ind-1, and 0.92 pM PO4-P ind-1h-1, respectively. The atomic C:N:P ratio of excretion products was 133:10:1. The O:N ratio of 25:1 and O:P ratio of 313:1 point to a lipid-carbohydrate-oriented catabolism of the Aurelia larvae. On the basis of experimental results and of biomass determinations, the maximal survival period of the non-feeding free swimming planula stage was calculated. Typically, the value lies in the range of some days to one week.