Precipitation patterns dissolved organic matter and changes in the plankton assemblage in Lake Escondido (Patagonia, Argentina).

BASTIDAS NAVARRO, M.,; B. MODENUTTI,

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2012 vol. 691 p. 189 - 202

0018-8158

Abstract Global warming affects the hydrologicalcycle by increasing the frequency and intensity ofextreme rainfall events and dry spells. These changespotentially affect the quantity and quality of dissolvedorganic matter (DOM) input into lakes. In this study,we investigated if changes in precipitation over a3-year period correspond to changes in DOM andwhether these changes affect light attenuation andplankton community composition. We sampled LakeEscondido, a shallow, oligotrophic Andean lake, ninetimes, analyzing coloured DOM and plankton communitycomposition. During the study period, weobserved that variations in the precipitation regimecorrelated with DOM parameters (water colour andmolecular weight), and this, in turn, affected theplankton composition. Chlorophyll a concentrationsof both phytoplanktonic fractions (less than andgreater than 2 lm) were related to water colour andTDP. We observed in the small fraction ( lm) anincrease in phycocyanin-rich cells during periodsof high water colour. Larger phytoplanktonic cells([2 lm) presented two biomass peaks correspondingto increases of the cyanophyte Chroococcusplanctonicus and of the haptophyte Chrysochromulinaparva. As precipitation decreased, the lake becamemore transparent, favouring C. planctonicus andmixotrophic oligotrich ciliates with endosymbioticChlorella. In the context of global climate change, ourresults highlight the potential impact of changes inprecipitation patterns and, consequently, in DOMquality on the plankton community.