Consequences of lake hypoxia are devastating for wildlife in the lakes: fish and other aerobic organisms need oxygen to survive so hypoxic or anoxic (completely oxygen-depleted) conditions can lead to massive fish kills and the collapse of local aquatic populations. This would lead to the loss of the entire ecosystem as the food web of the lake would be disrupted and, in turn, this would lead to a general loss of biodiversity. 
In low-oxygen environments, harmful substances such as methane, ammonia, and hydrogen sulfide can be released from lake sediments and this is a further impact on an already weak ecosystem. Additionally, the lack of oxygen can cause the release of phosphorus from sediments, further fueling eutrophication. In general, water quality would be negatively impacted and many lakes serve as sources of drinking water. Low oxygen can affect taste, odor, and safety, complicating treatment processes and increasing costs for water purification.

Addressing the oxygen crisis in lakes requires a combination of short-term interventions and long-term systemic changes that would start with nutrient reduction. This, in turn, can only be achieved by implementing more sustainable agricultural practices (e.g., buffer strips, precision fertilization), upgrading wastewater treatment plants (through drip or precision irrigation) and controlling urban runoff are crucial to reduce nutrient inputs.

Restoring wetlands can also be helpful as they act as natural filters, capturing nutrients before they end up in the lake. The Ramsar Convention (issued in 1971) has been a successful treaty to ensure the conservation of such fundamental areas, as it is focused on the conservation of wetlands Mechanical aerators or oxygenation systems can also help restore oxygen levels, particularly in small or isolated lakes.

The lack of oxygen in lakes is more than a hidden ecological issue—it is a clear indicator of environmental stress with wide-reaching implications for biodiversity, human health, and water security. While the challenges are complex, a combination of science-driven policy, sustainable land management, and community engagement offers a path toward revitalizing and preserving these vital freshwater systems for future generations and since lakes are important biodiversity hubs, their preservation is prioritarian.

Cover image: Blanca Lake, Washington, USA. Image by Caleb Jack on Unsplash.

This article is part of the project “Quiz Ambientali per un Trentino Più Verde!” carried out by Econtrovertia APS and sponsored by Fondazione Cassa Rurale di Trento (Notice of Approval of December 20, 2024).