Synergistic effects of nutrients and light favor Nostocales over non-heterocystous cyanobacteria

A. AGUILERA; L. AUBRIOT; R.O. ECHINIQUE; G.L. SALERNO; B.M. BRENA; M. PIREZ; S. BONILLA

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2017 vol. 794 p. 241 - 255

0018-8158

Bloomsof Nostocales(Cyanobacteria) are thought to be invading subtropical and temperate waterbodies. According to nutrient stoichiometry and physiologicaldifferences between cyanobacterial groups, the replacement of non-heterocystous species byNostocales is favored when dissolved inorganic nitrogen decreases. However, somestudies have shown different trends. We used laboratory bioassays to evaluate theconcomitant effects of light and nutrient enrichment on phytoplanktonassemblages dominated by non-heterocystousfilamentous cyanobacteria. Three nutrient conditions (no addition, addition of phosphate, and additionof nitrate and phosphate) andtwo light intensities (40 and 80 µmol photon m-2 s-1)were assayed. Nostocales replaced or co-dominated with non-heterocystous species in alltreatments by the end of the study. The shift in community composition towardsNostocales dominance led to an increase in species richness, which suggests that species withdifferent eco-physiological traits may have differential impacts on diversity. Thehighest saxitoxin concentrations were measured in no addition treatments, whichcould link production to nutritional stress. Nostocales featured highphenotypic plasticity in terms of changes in average trichome volume andgrowth rates. These results help to have a better understanding of the conditionsunder which Nostocales predominance can occur.