Dataset: Metagenomic Time Series of Winam Gulf, Lake Victoria from 2022-2023 (ASI Lake Victoria project)

Water samples were collected from Lake Victoria were depth discrete (1.0 meters) collections performed using a Van Dorn sampler. Samples were collected on 0.22 micron sterivex filters for subsequent DNA extraction and stored at room temperature in DNA/RNA Shield (Zymo). Concurrently, a multiparameter sonde was deployed to record temperature, pH, dissolved oxygen, conductivity, turbidity etc. In addition, sterivex filtrate was collected and stored at -20 degrees Celsius for subsequent dissolved nutrient analysis at the Ohio State Stone Laboratory.

In turn, samples were collected for chlorophyll a and processed using a 24 hour 90% acetone extraction performed at -20 degrees Celsius followed by quantification using a fluorometer. Samples for toxin analysis (microcystin) were collected and stored at -20C until processing using standard ELISA kits. 

In situ analysis was performed with a field Algae Torch (bbe Moldaenke) fluorometer, which was equipped with chlorophyll a and phycocyanin probes. We collected data in the form of cells per liter by lowering the fluorometer into the water column at the same depths where water samples were collected. We then converted the data to percentages to determine the relative abundance of cyanobacteria in the context of the full phytoplankton community (Brown, et al. 2024).

The toxin data was collected and processed as follows: whole water samples were collected at the designated sample depth (refer to the “Sampling_depth” column within the primary data file of this dataset) and lysed using three freeze / thaw cycles. The lysate was investigated for the presence of the cyanobacterial toxin / secondary metabolite “microcystin” using the Microcystins/Nodularins (ADDA) ELISA kit (Gold Standard Diagnostics, Warminster, PA) (Brown, et al. 2024). Absorbance was read at 450 nm on a Multiskan FC Microplate Photometer (Thermo Fisher Scientific Inc).