Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
  • Problem Description
• Data Files
• Related Publications
• Parameters
• Project Information
• Funding

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).

In the data file, "NA" values are not applicable because that type of data was not collected for that site. The same equipment was not readily available at each site or each year.

If the analysis was run for a sample but no "data" could be detected (meaning it read "too low to detect" or some on-numerical output indicating a negative result), this is indicated by "ND" values in the primary data file (meaning not detected).

- Changed date format from %M/%D/%Y to %Y-%M-%D
- Removed units from parameter names
- Replaced special characters in parameter names with underscores ("_") (e.g. "TN:TP" renamed "TN_TP_ratio"; "Algal_Torch_%_cells_cyano" renamed "Algal_Torch_percentage_cells_cyano"

NSF Award Abstract:
The North American and African Great Lakes are vital global freshwater resources. These lakes contain nearly half of the world’s available surface fresh water and therefore the security and health of these lakes is critically important especially as freshwater supplies continue to dwindle globally. One of the most prevalent concerns is human-influenced nutrient (nitrogen and phosphorus) pollution that causes a phenomenon known as a harmful algal bloom. Harmful algal blooms are overgrowths of algae that can have negative impacts to the environment and/or the health of humans, pets or cattle due to the toxic compounds that can be produced. Freshwater harmful algal blooms have become more prevalent worldwide over the past few decades. They occur in lakes, ponds, rivers and reservoirs across all 50 states and in many of the world’s most socioeconomically-important waterbodies. Lakes Victoria (African Great Lake) and Erie (North American Great Lake) are the 3rd and 11th largest lakes by surface area and both have regions that are plagued by toxic harmful algal blooms. Western Lake Erie and Kisumu Bay, Nyanza Gulf, Lake Victoria are similar in that they are both shallow systems that experience heavy nutrient pollution, which results in annual Microcystis-dominated toxic harmful algal blooms. However, they are different in that Lake Erie is a temperate system dominated by agricultural nutrient pollution, whereas Kisumu Bay is a tropical system that receives a mixture urban and agricultural nutrient pollution. While much is known about the ecology of the Microcystis-dominated blooms in western Lake Erie, little is known about the ecology, spatial distribution and toxicity patterns of the Microcystis-dominated harmful algal blooms in Kisumu Bay. The Advanced Studies Institutes will provide US graduate students the opportunity to expand their research on water quality and harmful algal blooms in Lake Erie to Lake Victoria. Their research will help fill critical knowledge gaps on the similarities and differences between the blooms that occur in each lake to help us better understand the ecological strategies that Microcystis uses to be able to form blooms in fresh waters across the globe. Furthermore, the graduate students will have the opportunity to learn about Kenyan culture and begin to develop their international collaborations by conducting joint research projects with their Kenyan peers and mentors.

Earth’s surface fresh waters, including the Laurentian and African Great Lakes, are under assault from multiple stressors. One of the most prevalent concerns is increased anthropogenic nutrient pollution into these waters leading to many negative effects including harmful algal blooms. Under these conditions, cyanobacteria, commonly referred to as blue-green algae, can grow to dense concentrations in fresh waters across the globe forming what are known as cyanobacterial harmful algal blooms (cyanoHABs). Many cyanoHABs can produce toxins that can sicken or kill humans, cattle and other domestic animals. Indeed, in the last decade major cities in China, the United States, Africa and other parts of the globe have suffered from impaired drinking water due to cyanoHABs. Notably, many of these events are dominated by a single cyanoHAB-forming genus, Microcystis spp. This is important since Microcystis–dominated cyanoHABs form in lakes in temperate to tropical latitudes. Therefore, Microcystis must be able to adjust its ecological strategies to maintain dominance in lakes transcending major latitudinal boundaries. Lake Victoria (Africian Great Lake) and Lake Erie (Laurentian Great Lake) are two socioeconomically-important systems that have regions (Nyanza Gulf, Kenya and western Lake Erie, respectively) that experience annual toxic cyanoHABs dominated by Microcystis. As such, they are ideal comparative sites to study the differences in ecological strategies employed by Microcystis in a tropical and temperate system. The proposed Advanced Study Institutes (ASIs) will provide the opportunity for 10 US graduate students per year (30 US graduate students total) to participate; each ASI will have the duration of three weeks. Each ASI will include lectures by US and Kenyan scientists, two 5-day research cruises, followed by laboratory analysis of samples. Every US student will be teamed with a Kenyan graduate student who has a mutual research interest. The student teams will collaborate with their US and Kenyan mentors to develop experimental plans and the teams will give joint presentations during the ASI. Each team will co-author a scientific presentation that will be given by the US student at an international conference post-ASI. The impact of the ASIs will be broadened by developing innovative contributions to STEM education including training STEM educators. Students participating in the ASIs will help develop a case study that explores the top-down and bottom-up controls of cyanoHABs in Nyanza Gulf. This will include discussing culturally-relevant topics such as the influence of point- and non-point nutrient sources, while incorporating all results from the ASI projects.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.