Changes of the Mass, Length, and Metabolism of Simple and Composite Thalli of Marine Macrophytes in Their Ontogenetic Series

Abstract

Measurements in Fucus evanescens, Porphyra tenera, Enteromorpha linza, Sargassum miyabei and Cystoseira crassipes, of the mass and length of the thallus in the ontogenetic series (according to the increasing thallus mass), and also in the latter 2 spp. of the mass and length of the branches of different orders was presented. The relationship between the mass and the length is mostly well described by a power equation whose parameters were computed. The specific length (the length/mass ratio) of thalli and branches of different orders in S. miyabai and C. crassipes decreases with the increasing mass. However, the relationship between the specific length and the mass is not described by a power function. On the basis of radiocarbon data, the relationship between 2 components of the C exchange-photosynthesis and the total C output, on the 1 hand, and the increasing thallus mass in the ontogenesis of F. evanescens, C. flagelliformis and E. linza, on the other, was considered. The power approximation of the connection between either process and the thallus mass was inapplicable in the 3 cases. In E. linza, the 2 processes had a single-peak variation curve in ontogenetic mass series. The total C output rate is regarded as a function of the photosynthetic intensity. The difficulties involved in a causal interpretation of the ontogenetic phenomena in macrophytes due to a simultaneous ontogenetic change of the body mass and age were discussed.