Differences in bacterial community composition between fish-stocked and fishless lakes from an arid Patagonian plateau

Abstract

Bacterial community composition (BCC) can be modulated by different indirect and direct fac- tors. The Strobel Lake Plateau (Patagonia, Argentina) holds natural fishless lakes. Fish introduction in some of these lakes has affected the structure of their zoo- plankton, phytoplankton and autotrophic picoplank- ton communities, whereas its effects on bacterio- plankton are unknown. Hence, we analyzed BCC to assess the potential effect of fish introduction on this community in lakes of this region. We sampled fish- less and fish-stocked lakes during three summer cam- paigns and analyzed the BCC. Our results revealed a contrasting arrangement in the main limnological var- iables and significant differences in the BCC between fishless and stocked lakes. In fish-stocked lakes, Alp- haproteobacteria class had a higher proportion and SAR11_cladeIII was the most abundant amplicon sequence variant (ASV); these lakes also showed a marginally higher mean richness but less exclusive ASVs. Environmental and biotic factors contributed to explain BCC variations. The lower percentage of exclusive ASVs and the closer BCC ordination in a non-metric multidimensional scaling suggest a homogenizing effect in fish-stocked lakes. This study contributes to understand the consequences of fish introduction on the plankton communities in lakes of this invaluable region for biodiversity conservation.