Phytobenthos colonization in a lowland stream in Argentina

摘要

The effects of water current on phytobenthos colonization in different seasons of the year were studied in a high-nutrient pampean stream of Buenos Aires province (Argentinal). The accumulation rates of the community in places with different flows were estimated with artificial substrata which were removed in three-five day intervals during aproximately one month in each of the four seasons of the year. Biomass was measured as chlorophyll-a. Community development was most rapid when the water flow rate was low, and the accumulation rate was greatest in winter reaching 1000 mg Chl-a centre dot m~-2 in quiet water. The algae showed highest diversity in slow water zones. Most taxa observed were cosmopolitan. The results show that colonization rate of phytobenthos is influenced principally by water velocity, but these actions have different intensities during each season of the year.