Distribució i ecologia dels macròfits submergits del delta de l'Ebre

Resum

Data on distribution and phenology of 16 species of submerged macrophytes in the Ebro Delta are given, together with a summarized table of some physical and chemical parameters of the waters where they were found. The distribution of the spermatophytes in relation to the salinity of the water is: freshwater (Nasturtium officinale and Myriophyllum verticillatum), β-oligohaline waters, up to 1 g Cl^- l^-1 (Ceratophyllum demersum, M. spicatum, Utricularia vulgaris, Potamogeton nodosus, P. pusillus, P. crispus, Zannichellia palustris and Najas minor). Oligo-β-mesohaline waters, up to 4 g Cl^- l^-1, (Najas marina). Mixohaline waters, 0,5-17 g Cl^- l^-1 (Potamogeton pectinatus, Ruppia maritima and Ruppia Cirrhosa). α-meso-polyhaline waters, 5-17 g ^- l^-1 (Zostera noltii and Z. Marina). The submerged spermatophytes that are dominant in the coastal lagoons in the freshwater period (April-December) are: P. pectinatus, R. Cirrhosa and N. Marina. It seems that in α-oligohaline waters these enter into competition with each other. Field observations suggest that Najas dominate in clay and organic mud areas, P. pectinatus in silty-clay sediments and Ruppia in those of sandy composition.