Ecology of algal communities of different soil types from Cierva Point, Antarctic Peninsula.

GONZÁLEZ GARRAZA, G.; MATALONI, G.; FERMANI, P.; VINOCUR, A.

POLAR BIOLOGY

SPRINGER

Lugar: Stuttgart; Año: 2011 vol. 34 p. 339 - 351

0722-4060

During summer 2005/2006, we characterizedthree sampling sites on mineral soils and four on ornithogenicsoils from Cierva Point, Antarctic Peninsula, in termsof topographic and abiotic features (altitude, slope, magneticdirection, temperature, texture, pH, conductivity,organic matter, moisture and nutrient concentrations), andcompared their microalgal communities through taxonomiccomposition, species richness, diversity, chlorophyll a contentand their variation in time. Average values of pH, moisture,organic matter and nutrient concentrations were always significantlylower in mineral than in ornithogenic soils. LowN/P mass ratio showed potential N-limitation of biomasscapacity in the former. On the other hand, the results suggestedthat physical stability is not as a key stress factorfor mineral soil microalgae. Chlorophyll a concentrationwas not only higher in ornithogenic soils, but it alsoshowed a wider range of values. As this parameter was positivelycorrelated with temperature, pH, nutrients, organicmatter and moisture, we cannot come to conclusionsregarding the influence of each factor on algal growth.Communities of mineral soils were significantly morediverse than those of enriched ornithogenic soils due tohigher species richness as well as higher equitability. Also,their structure was steadier over time, as shown by a clusteranalysis based on relative frequency of algal taxa. AlthoughCyanobacteria and Bacillariophyceae dominated almost allsamples, Chlorophyceae represented 34% of the 140 taxarecorded, and most of them observed only in cultures. Thedetection under controlled conditions of a high latent speciesrichness in harsh mineral soil sites shows that the compositionand equitability of these microalgal communitieswould be more prone to modification due to the manifoldlocal consequences of climatic change than those of ornithogenicsoils.