The common jellyfishAurelia aurita: standing stock, excretion and nutrient regeneration in the Kiel Bight, Western Baltic

✍ Scribed by G. Schneider

• Publisher: Springer-Verlag
• Year: 1989
• Tongue: English
• Weight: 762 KB
• Volume: 100
• Category: Article
• ISSN: 0025-3162
• DOI: 10.1007/bf00394827

✦ Synopsis

The population dynamics, ammonia and inorganic phosphate excretion, and nutrient regeneration of the common jellyfish Aurelia aurita was investigated from 1982 to 1984 in the Kiel Bight, western Baltic Sea. During summer 1982, medusae abundance ranged between 14 and 23 individuals 100 m -a, biomass was estimated at about 5 g C 100 m -3 and the mean final diameter of individuals was 22 cm. Abundance, based on numbers, in 1983 and 1984 was an order of magnitude lower; biomass was less than 2 g C 100 m-3 and jellyfish grew to 30 cm. During the summers of 1983 and 1984, A. aurita biomass constituted roughly 40% of that of the total zooplankton>200/tm. In 1982, for which zooplankton data were lacking, it was assumed that medusae biomass was greater than that of all other zooplankton groups. Total nmrnonia excretion ranged between 6.5 and 36 amol h-1 individual-1, whereas inorganic phosphate release was 1.4 to 5.7 amol h-1 individual-1. Allometric equations were calculated and exponents of 0.93 for NHg-N release and 0.87 for PO4-P excretion were determined. Nitrogen and phosphorus turnover rates were 5.4 and 14.6% d-1, respectively. In 1982, the medusae population released 1 100/maol NH4-N m-z d-1, about 11% of the nitrogen requirements of the phytoplankton. The inorganic phosphate excretion (150/anol m -z d-1) sustained 23% of the nutrient demands of the primary producers. In the other two years the nutrient cycling of the medusae was much less important, and satisfied only 3 to 6% of the nutrient demands. It is suggested that in some years A. aurita is the second most important source of regenerated nutrients in Kiel Bight, next to sediment.