Which environmental factors trigger the dominance 3 of phytoplankton species across a moisture gradient 4 of shallow lakes?

IZAGUIRRE I.; SÁNCHEZ, M. L.; SCHIAFFINO M.R.; O'FARRELL I.; HUBER P.; FERRER N.; ZUNINO J.; LAGOMARSINO, L.; MANCINI M.

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2015 vol. 752 p. 47 - 64

0018-8158

We investigated nine Pampean shallow 11 lakes (Argentina) across a moisture gradient (mean 12 annual precipitation 1000?500 mm), under the frame- 13 work of a network project of lakemonitoring whosemain 14 objective was to analyse the responses of ecosystems to 15 different stressors associated with human activities. We 16 postulate that species bloom in different shallow lakes 17 will be determined mainly by local optical features, 18 nutrients and salinity. We analysed the phytoplankton 19 structure during the warm season 2012?2013, identifying 20 those species and functional groups that proliferate in the 21 lakes. Most lakes showed high phytoplankton biomass, 22 except a saline lake located in the driest part of the 23 gradient and an inorganic turbid lake. In some lakes, 24 cyanobacteria blooms occurred in summer, persisting 25 until autumn. Small colonial cyanobacteria and small fast-growing chlorophytes were abundant in most turbid 26 enriched and anthropogenically impacted systems. Low- 27 est species and functional diversity occurred in the saline 28 lake.Multivariate analysis indicated that the phytoplank- 29 ton structure was mainly defined by conductivity, 30 transparency and variables associated with the trophic 31 state, also reflecting the importance of the geographical 32 location. Our results evidenced the vulnerability of most 33 shallow lakes in the region to water level fluctuations, 34 eutrophication and canalization.