Presence, abundance and bacterivory of the mixotrophic algae Pseudopedinella (Dictyochophyceae) in freshwater environments
GEREA, MARINA; SAAD, JUAN F.; IZAGUIRRE, IRINA; QUEIMALIÑOS, CLAUDIA; GASOL, JOSEP M.; UNREIN, FERNANDO
AQUATIC MICROBIAL ECOLOGY
Lugar: Oldendorf/Luhe; Año: 2016 vol. 76 p. 219 - 219
The genus Pseudopedinella has been described as mixotroph, however ecological information about this algal stramenopile (Heterokonta) is unclear. We set to unveil the environmental conditions that determine the presence, abundance and bacterivory rates of this genus in freshwater systems and for this, we analyzed 54 water bodies with different limnological features distributed along a latitudinal and trophic gradient. In addition, 14 grazing experiments were carried out in order to estimate their ingestion rate and impact on the bacterioplankton. Our results indicate that this genus was exclusively found in oligotrophic environments, and that develops well in a wide range of temperature. Average cell-specific grazing rate was 2.83 bact. cell-1h-1, with a maximum value of 6.74 bact. ml-1h-1. Interestingly, it increased with prey abundance and decreased with increasing nutrient availability. These patterns are common in highly bacterivorous protists that use phagotrophy as a main source of nutrient acquisition. Despite their usually low abundance (avg. 182 cell ml-1), this single genus was responsible for up to 24% (avg. 10%) of the total grazing impact exerted by all phagotrophs in these lakes. Overall, our results support the idea that Pseudopedinella is a highly bacterivorous group of freshwater protists, with the ability to develop well in oligotrophic conditions and with a potential significant impact on bacterioplankton.