OXYGEN, TEMPERATURE, AND NUTRIENT DYNAMICS IN A MESOTROPHIC LAKE DURING THE UNPRECEDENTED WARM WINTER OF 2023-2024

Evidence is mounting that lakes are more productive in the winter than originally thought. However, our knowledge of winter abiotic and biotic dynamics in lakes remains rudimentary. With the climate changing rapidly and northern lakes warming faster than others, it is critical to understand winter lake dynamics. Here, we examined the drivers of oxygen dynamics in Tree Top Pond, a mesotrophic lake in Southeast Michigan, USA, during the unprecedented warm winter of 2023-2024. From December 2023 until February 2024, the air temperature was on average 2 to 4 °C warmer than the long-term average. We measured vertical dissolved oxygen and temperature dynamics at 15-minute intervals from November 17, 2023, until mid-April 2024. Additionally, we collected sub-monthly to monthly water samples for dissolved and total nitrogen (N), phosphorus (P), particulate C, N, P, and chlorophyll a. We did not collect nutrient and chlorophyll samples during periods of ice cover due to unsafe conditions. So far, our data indicate that the lake had periods of inverse stratification before ice-on, which affected oxygen dynamics. During inverse stratification, the lower strata dissolved oxygen concentrations decreased rapidly, likely due to high respiration rates. We identified variable spatial, vertical, and temporal dynamics of dissolved and total N and P, particulate C, N, and P, and chlorophyll a indicating variability in the productivity and nutrient recycling within the lake. Overall, our preliminary results will help fill existing knowledge gaps on the drivers of winter productivity.      

Primary Presenter: Olivia Sowa, Oakland University (oliviasowa@oakland.edu)

Authors:

Olivia Sowa, Oakland University  (oliviasowa@oakland.edu)

Ryan Andrews, Oakland University  (ryanandrews@oakland.edu)

Hailee Mersino, Oakland University  (hmersino@oakland.edu)

Tessa Wallace, Oakland University  (tvwallace@oakland.edu)

Scott Tiegs, Oakland University  (tiegs@oakland.edu)

Nicole Wagner, Oakland University  (nicolewagner@oakland.edu)