The genus Sargassum in the Adriatic Sea: Morphology, systematics and ecology

Abstract

          In this paper we present long-term results (1947-1971) of morphological, systematic, and ecological studies of the genus Sargassum collected in many coastal and island areas on the eastern side of the Adriatic. Morphologically, we describe in detail the three parts of the algae tallus: the holdfast or root (basal plate, rhizoid), the tree or stipe (cauloid, central axis), and the phylloid parts consisting of branches, blades (leaves, phylloclades), cryptostomata, aerocista, bladders (aerocysts, air bladders, gas-filled bladders, swim bladders), and fructifications. Further, we describe Sargassum tissue, which is divided into an epidermis, cortex (primary and secondary), and central (axial) tissue. Systematically, we provide data on the composition, shape, and dimension of reproductive recesses (conceptacles) of reproductive organs (oogonia and antheridia). Ecologically, we discuss the vertical and horizontal distribution, variations, and adaptations to ecological factors (temperature, light, sea movements, salinity) of the eastern Adriatic Sargassum species. Three species of Sargassum are found in the eastern Adriatic. The species S. vulgare C. Ag. is represented by the typical form S. vulgare C. Ag. var. vulgare, the variation S. vulgare C. Ag. var. megalophyllum (Mont.) Grunow, a newly identified variation S. vulgare C. Ag. var. jabukae Špan, and a newly identified form S. vulgare C. Ag. var. vulgare f. ercegovicii Špan. The species S. salicifolium J. Ag. is represented by the typical form S. salicifolium J. Ag. var. salicifolium and the newly identified variation S. salicifolium J. Ag. var. linifolium Špan. The third species is S. hornschuchii C. Ag.