Daily changes of reed periphyton composition in a shallow Hungarian lake (Lake Velence)

Reed periphyton stucture was investigated int he middle of summer in 1992. Five replicate samples were collected at mid-day over 25 days from living and sterilised reeds. Two weeks before sampling, a 20 cm portion of 150 below water level reed stems were cleaned with brush. After cleaning they were covered with black nylon and aluminium foil. A day before starting the investigation, some substrata were collected as controls and examined under light microscope after preparation. Just before the experimental period the reed stems were placed in a frame. This frame was fixed under the water level to living reeds, at the same sampling point and depth. The number of living and dead cells was counted and chlorophyll-a content of the periphyton was measured. The ratio of dead: live cells was higher in almost all the samples taken from sterilised reed, and was lowest at the beginning of the experiment. The abundance increased continuously over 11 days on both substrata, then there was a slow-increase period („steady state”). The same tendency was observed int he chlorophyll-a content of cleaned green reeds. Changes in relative abundance of some diatoms was also examined during the investigation