Experimental investigation of seasonal development in six Antarctic red macroalgae

Abstract

The phenology of six Antarctic red macroalgae, Delesseria salicifolia Reinsch, Gymnogongrus antarcticus Skottsberg, Gymnogongrus turquetii Hariot, Hymenocladiopsis crustigena Moe, Kallymenia antarctica Hariot and Phyllophora ahnfeltioides Skottsberg, was investigated in a two-year culture study under fluctuating daylengths imitating the conditions of King George Island, South Shetland Islands. The algae were cultured at 0°C in filtered, nutrient enriched seawater under photon fluence rates of 3, 10, 25, 50 μmol photons m⁻² s⁻¹. All species are classified as season anticipators, starting growth in late winter–spring and stopping growth before the summer solstice. Formation of new blades was observed from January/February onwards in most of the species. Carpospore formation was observed in K. antarctica in early summer. Growth was light saturated at photon fluence rates of 3 μmol photons m⁻² s⁻¹ in D. salicifolia and at 10 μmol photons m⁻² s⁻¹ in the other species, corresponding to an annual light dose of 31.4 and 157 mol photons m⁻². The results show that this type of life strategy is typical for species from the Antarctic and give further evidence on the high degree of shade adaptation of Antarctic algae and predict a lower distribution limit for these species at 37 ± 15 m and 23 ± 10 m, respectively.