Factores que controlan la variabilidad morfológica de Pediastrum tetras bajo diferentes condiciones experimentales

Abstract

Morphological variability and plasticity in phytoplankton populations are important for taxonomy, systematic, and evolutionary studies and are key characteristics for ecological plankton processes. The green algae Pediastrum tetras (Ehrenberg) Ralfs was studied to describe the variation in its population size structure and its response to changes in biotic (presence of Daphnia magna (Straus) and its info-chemicals) and abiotic factors (nutrient concentration). The results indicated that the nutrient supply could affect the coenobium population structure (diminishing the most common coenobium, the 8-celled one). D. magna significantly reduced P. tetras population density, because depredation affected it by significantly decreasing the biggest coenobium's density. In addition, info-chemicals induced a lower increase of the biggest coenobium when compared to the controls (rate of change was 45 % lower than in control cultures). Our study suggests that P. tetras coenobium size is subjected to a possible compromise (trade-off) in their natural environment: P. tetras population would tend to increase their size for a better use of nutrients and to decrease it when big herbivores are present. © Asociación Ibérica de Limnología.