Respiration in the scyphozoan jellyfish Aurelia aurita and two hydromedusae (Sarsia tubulosa and Aequorea vitrina): effect of size, temperature and growth

摘要

ABSTRACT: The effect of body size on respiration was examined in the common scyphozoan jellyfish Aurelia aurita (ephyrae and medusae) and in 2 hydromedusae, Sarsia tubulosa and Aequorea vitrina. The starvation respiration rate (R_M, µl O₂ d–1) as a function of dry body weight (W, mg) could be expressed by means of the equation R_M = aWb, and was determined to be 18.9W0.76 for A. aurita (ephyrae and medusae), 19.4W0.91 for S. tubulosa, and 2.39W1.02 for A. vitrina. Further, the effect of temperature, feeding and growth on respiration was studied in A. aurita. The weight-specific respiration rate (R_W, µl O₂ [mg dry wt]–1 d–1) increased exponentially with temperature (T,°C) within the 7 to 22°C interval at R_W = 0.93e0.11T (Q₁₀ = 3.1). A. aurita ephyrae responded rapidly to the presence of food, and maximum respiration rate was attained after 4 h; after the supply of food was stopped, the respiration rate decreased to the starvation level within 2.5 h. Respiration was measured in A. aurita that were fed different concentrations of an assortment of prey organisms (copepods, rotifers, cirriped larvae, Artemia sp.) to obtain a spectrum of specific growth rates. The weight-specific respiration rate as a function of the weight-specific growth rate was linear, and from the slopes of the regression lines the energetic cost of growth was found to be equivalent to 209% of the growth of A. aurita ephyrae feeding on a variety of prey organisms, and 69 and 42% of the growth of A. aurita medusae preying on Artemia sp. and Acartia tonsa respectively.