Comparative study of periphyton colonisation on common reed (Phragmites australis) and artificial substrate in a shallow lake, Manyas, Turkey

Abstract

Colonisation of epiphytic algae on the common reed (Phragmites australis) and on glass slides were studied during a twenty-four week exposure period in a shallow, turbid lake, Manyas (Bird Paradise), western Turkey. Slides were used as substrate and positioned near the reed stands. To understand the effect of light on the colonisation of periphyton on P. australis and artificial substrates, three perspex frames (each frame consisted of 60 glass slides) were positioned at depths of ca. 25 cm, 50 cm and 75 cm, called 'upper', 'middle', and 'lower section', below the water surface. For the determination of periphyton and chlorophyll a content three new stems, which were cut above the rhizomes and subdivided into 25 cm, and three slides were taken from the each frame at four-weeks intervals. The rapid increase was recorded in algal species richness and biovolume on P. australis, whereas relatively slow colonisation was observed on glass slides. Filamentous centric diatoms, (mainly Aulacoseira italica and Melosira varians) was the dominant group, accounting for 29 to 82% of the total algal biovolume, and adnate diatoms (Surirella spp.), filamentous, and Chlorococcal chlorophytes (Pediastrum spp. and Oedogonium spp.) were the subdominant groups on the artificial substrate during the colonisation period. Pennate diatoms, mainly prostrate/motile and filamentous diatoms (Navicula tripunctata, Navicula radiosa, and Aulacoseira muzzanensis), and filamentous cyanobacterium (Planktolyngbya linmetica) were recorded as dominant groups on the reeds. Generally, epiphytic algal biomass was higher upon P. australis than upon glass slides. However, after the twelfth week colonisation biomass increased less than on earlier stages on the P australis. Total algal biovolume was positively correlated with chlorophyll a and with Soluble Reactive Phosphorus (SRP), and negatively correlated with the water level and Secchi disc depth.