Phytoplankton limitation in Patagonian and Pampean shallow lakes: effect of phosphorus and light

TORREMORELL A; DIÉGUEZ MC; QUEIMALIÑOS, C.; IZAGUIRRE, I.; ZAGARESE, H.

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2017

0018-8158

In order to evaluate patterns of phytoplanktoncommunity structure and primary productionlimitation, we analyzed the phytoplankton communities(chlorophyll a, biovolume, species richness, andprimary production) of a set of 20 shallow lakesencompassing a wide range of phosphorus and lightlevels. The degree of limitation or co-limitation byphosphorus and/or light was estimated using a combinedindex. We found a direct relationship betweenirradiance in the water column (Imean) and the lightsaturation parameter (Ik) and, a negative relationshipbetween Imean and total phosphorus (TP)concentration. Lakes at the lowest and highest endsof TP tended to display the simplest phytoplanktoncommunities (i.e., only one or two algal classesaccounted for the total phytoplankton biovolume). Incontrast, lakes with intermediate TP exhibited a morecomplex phytoplankton composition. Low values ofphytoplankton abundance proxies (chlorophyll a andbiovolume), species richness, and primary productioncould be observed at any combination of phosphorusand light availability. However, the highest values ofthe previous variables were observed only when therelative availability of both resources was similar. Thecombined index developed provides a single metricfor describing light versus nutrient limitation. Theimportance of its use is that can be applied to theanalysis of clear lakes lacking vegetation and inorganicturbid lakes, besides organic turbid and clearlakes with vegetation.