Drivers of phytoplankton diversity in Patagonian and Antarctic lakes across a latitudinal gradient (2150 km): the importance of spatial and environmental factors

IZAGUIRRE I.; SAAD J.F.; SCHIAFFINO M.R.; VINOCUR A.; TELL G.; SÁNCHEZ M.L.; ALLENDE L.; SINISTRO R.

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2015 p. 1 - 14

0018-8158

We investigated the phytoplankton structurein 60 lakes across a latitudinal gradient (2150 km),from Austral Patagonia to Antarctica, including environmentsranging from oligotrophic to eutrophic. Weanalysed the latitudinal variation of species richness(local and regional) and evenness, as well as thesimilarity decay in phytoplankton composition inPatagonia and Antarctica. The following hypotheseswere tested: (1) there is a decline of phytoplanktonspecies richness with increasing latitude; (2) phytoplanktonstructure is influenced by both geographicaland environmental factors. (3) The predominant algaltrophic strategy (autotrophic vs mixotrophic) is influencedby lake trophic status. Phytoplankton wasanalysed using a polyphasic approach (morphologicallybased species diversity, functional diversity,dominant molecular diversity). We found a significantdecline in phytoplankton richness with increasinglatitude. Multivariate analyses showed that phytoplanktonis structured by the lake geographic position(mainly latitude) and variables related with trophicstate (nutrients, conductivity and pH). The autotrophs/mixotrophs ratio increased towards higher trophicstates. The initial similarity was higher in Antarcticathan in Patagonia, whereas the halving distance waslower for Antarctic lakes. The three biodiversityapproaches of this meta-analysis evidenced that bothgeographic and environmental factors influence phytoplanktondiversity at large spatial scale, although thelocal effect was stronger.