Original paper
Seasonality of macroalgal distribution patterns within the reach of a gravel stream (Isar, Tyrol, Austria)
Pfister, Peter
Archiv für Hydrobiologie Volume 129 Number 1 (1993), p. 89 - 107
45 references
published: Nov 29, 1993
DOI: 10.1127/archiv-hydrobiol/129/1993/89
ArtNo. ESP141012901004, Price: 29.00 €
Abstract
Macroalgae of the surface sediments of a clean calcareous mountain stream were investigated by means of the quadrat charting method over a period of 16 months. The results of the mapping of a permanent transect showed that the recorded species form characteristic heterogenous spatial and temporal distribution patterns. The blue-green algae Chamaesiphon geitleri and Schizothrix fasciculata and the moss Drepanocladus lycopodioides show both highest abundance in the shallow reaches near the banks. These areas are characterized by low currents (< 40 cm/s) and shallow depths (< 20 cm). Chamaesiphon polonicus and Chamaesiphon geitleri also prefer shallow areas. The bluegreen Phormidium autumnale is mainly found in the permanent wetted areas of the river and avoids the drying parts of the bank (depths > 10 cm). The area with the strongest current (> 60 cm/s) and greatest depths (> 30 cm) is mainly colonized by the chrysophyte Hydrurus foetidus. Besides a characteristic spatial distribution pattern, some of the observed macroalgae also show a clear seasonality in frequency of occurrence. Hydrurus foetidus and Phormidium autumnale are especially marked by distinct standing crop maxima during late autumn and early winter. As expected, the standing crop of most species is lowest from June to August coinciding with the period of the summer flood. Spatial and temporal distribution of phytobenthos algae is strongly influenced by discharge and floods, leading to a significant reduction of algal standing crop.
Keywords
macroalgae • heterogenous • floods • phytobenthos