Seasonal dynamics of epilithic periphyton in oligotrophic Lake Taupo, New Zealand

Abstract

Abstract The biomass and species composition of epilithic periphyton in oligotrophic Lake Taupo was measured over a full year. Measurements of photosynthetic carbon uptake were made during summer and early winter. The lake supported a high biomass of epilithic periphyton throughout the year, averaging 100–600 mg m‐ 2 over the 0–35 m water depth and peaking in early summer. Periphyton extended to at least 40 m depth. Depth‐integrated carbon fixation rates of 242–362 mg m‐2 h‐1 were measured. Periphyton constituted more than 90% of the algal biomass and carbon fixation within the littoral zone, but less than 2% of production on a whole‐lake basis. Based on taxonomic composition, periphyton could be divided into three zones, surface (0–2 m), mid water (2–20 m) and deep (> 20 m). The diatoms Aulacosira granulata, Rhopalodia novae zealandiae, Epithemia sorex, and Fragilaria spp. dominated the deep assemblage, Tolypothrix tenuis and Mastogloia elliptica the mid water, and Scytonema, Dichothrix, and filamentous ...