Abstract

Patagonian lakes are one of the most unexplored aquatic environments on Earth, and little is known about their thermo-hydrodynamics and trophic state. Meanwhile, increasing urbanization and industri-alization in their catchments compromise their health. Here, we investigate Lake Llanquihue, one of the Earths great freshwater bodies in Northern Patagonia. Still considered pristine, Llanquihue has experi-enced recent contamination events along its littoral, whose impacts remain unknown. In response, public and private agencies have started to develop tailor-made monitoring plans to survey Lake Llanquihue waters. However, without comprehensive knowledge of the lake's functioning, it is impossible to deter-mine the fate and effects of contaminants in the waterbody. Here, we characterize via numerical simu-lations the basin-scale hydrodynamics of Lake Llanquihue, crucial information for diagnosing the transport of matter within its basin. Aiming at delimiting the zones impacted by harmful effluents, we pose a fundamental question significant to any lake: What is the physical connectivity between two zones of interest within a lake? We address this question by introducing a framework that characterizes the pref-erential pathways and quantifies the timescale tracers take to stream from one zone to another within a waterbody. This framework is applied to investigate the physical connectivity among urban and rural set-tlements along Lake Llanquihue shore, finding that a time-persistent, large-scale gyre largely controls the physical connectivity between long-distance littoral regions. Lake managers can utilize the introduced framework to monitor lakes' health, identify and notify potential risk zones impacted by polluted dis-charge, and advance toward a sustainable relationship with aquatic systems.& COPY; 2022 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.