Influence of fish introduction and water level decrease on lakes of the arid Patagonian plateaus with importance for biodiversity conservation

IZAGUIRRE, IRINA; LANCELOTTI, JULIO; SAAD, JUAN F.; PORCEL, SOL; O´FARRELL, INÉS; MARINONE, M. CRISTINA; ROESLER, IGNACIO; DIEGUEZ, MARÍA DEL CARMEN

Global Ecology and Conservation

Elsevier

Año: 2018 vol. 14

2351-9894

Biodiversity loss in shallow lakes is associated to several factors among which water leveldecrease and fish introduction are indicated as potential stressors. The Patagonian basalticplateaus, located in one of the most arid regions of South America, hold thousands ofshallow lakes and ponds and some large lakes, where vegetated lakes are the prime habitatfor waterbirds, including endemic threatened species. We studied 31different lakes at thetwo main Patagonian plateaus (Strobel and Buenos Aires) during successive spring-summer field trips from 2007 to 2016. We focused on the differences between fishlessand stocked lakes under contrasting hydrologic regimes (relatively stable waters anddecreasing water level. Our survey evidenced the effect of fish introduction and water leveldecrease on the limnological features of the lakes and their phyto and zooplanktoncommunities. Arheic shallow lakes showed a decreased water level accompanied by anincreased conductivity, and several shifted from a clear-vegetated state to a more turbidcondition, with increased algal biomass and demise in submerged macrophytes. Fishlesslakes presented higher total zooplankton and macrozooplankton biomass and lowerphytoplankton biomass than fish stocked lakes. Our findings provide evidence that underscenario of climate change, the effect of the decrease in water level may enhance theadverse effects of fish introduction.a