Interaction between temperature and nutrients: How does the phytoplankton community cope with climate change?

Area of Science:

• Ecology
• Limnology
• Climate Science

Background:

• Lake ecosystems face dual threats from climate change and increased nutrient concentrations.
• Warming exacerbates eutrophication, necessitating urgent action to protect water quality and biodiversity.

Purpose of the Study:

• Investigate phytoplankton response to interacting temperature and nutrient variations in a deep subalpine lake.
• Analyze long-term observational data (1993-2021) to understand ecosystem changes.

Main Methods:

• Utilized long-term observational data from Lake Iseo, Italy.
• Analyzed phytoplankton community structure in relation to temperature and nutrient dynamics.
• Examined physicochemical parameters, including temperature, total nitrogen (TN), and dissolved silica to total phosphorus (DSi:TP) ratio.

Main Results:

• Observed a deterioration in the lake's physicochemical status, with accelerated warming (0.08 °C/year in the last decade).
• Warming increased nutrient concentrations and phytoplankton biovolume, while decreasing diversity and promoting Cyanobacteria.
• Nutrient variations and post-mixing events significantly restructured phytoplankton communities.

Conclusions:

• Deep subalpine lakes face severe phytoplankton changes due to climate change and nutrient loading.
• Complete mixing events can act as critical thresholds for community transformation.
• Integrated models using long-term data are crucial for understanding and mitigating climate change impacts on lake ecosystems.