Cyanobacteria, Nitrogen Cycling, and Export Production in the Laurentian Great Lakes
In collaboration with Drs. Joe Werne, Emily Elliott, Trinity Hamilton, we are investigating nitrogen cycling and export production using a combination of sediment microcosms and the molecular isotopic composition of porphyrins from both suspended particulate matter and sinking particulate material in modern lake systems (Lakes Superior and Erie). We will compare nutrient removal and processing in a system characterized by eutrophication and seasonal cyanobacterial blooms (Lake Erie) with one characterized by significant picocyanobacteria productivity but the near-absence of cyanobacterial blooms (Lake Superior).
In collaboration with Drs. Joe Werne, Emily Elliott, Trinity Hamilton, we are investigating nitrogen cycling and export production using a combination of sediment microcosms and the molecular isotopic composition of porphyrins from both suspended particulate matter and sinking particulate material in modern lake systems (Lakes Superior and Erie). We will compare nutrient removal and processing in a system characterized by eutrophication and seasonal cyanobacterial blooms (Lake Erie) with one characterized by significant picocyanobacteria productivity but the near-absence of cyanobacterial blooms (Lake Superior).
Lake Võrtsjärv and Lake Peipsi, Estonia
Winter, under-ice sampling is one of the biggest knowledge gaps in limnology. We are working with Dr. Margot Sepp (a postdoc in our lab) and other collaborators at the Estonian University of Life Sciences to measure nitrogen cycling under ice to understand the impact of climate change (shorter winters) and under-ice processes on summer algal blooms. This research is funded by fellowships and a grant to EMU through the Estonian government.
Winter, under-ice sampling is one of the biggest knowledge gaps in limnology. We are working with Dr. Margot Sepp (a postdoc in our lab) and other collaborators at the Estonian University of Life Sciences to measure nitrogen cycling under ice to understand the impact of climate change (shorter winters) and under-ice processes on summer algal blooms. This research is funded by fellowships and a grant to EMU through the Estonian government.
Assessing nitrogen dynamics in a closed, integrated aquaponics systems
We are collaborating with Dr. Kevin Neves at Bowling Green State University to investigate the fate of nitrogenous wastes in a freshwater, land-based, integrated multi-trophic aquaculture (IMTA) system of yellow perch, freshwater prawns, and tomatoes/herbs. We will optimize water quality and nitrogen cycling dynamics across the system to ensure that nitrogen levels are low enough for fish and prawn growth, but adequate for plant growth.This research will develop a dynamic model of the rates of nitrogen processes and the fate of nitrogen forms to scale the system for new projects.
This work is funded by Ohio Sea Grant.
We are collaborating with Dr. Kevin Neves at Bowling Green State University to investigate the fate of nitrogenous wastes in a freshwater, land-based, integrated multi-trophic aquaculture (IMTA) system of yellow perch, freshwater prawns, and tomatoes/herbs. We will optimize water quality and nitrogen cycling dynamics across the system to ensure that nitrogen levels are low enough for fish and prawn growth, but adequate for plant growth.This research will develop a dynamic model of the rates of nitrogen processes and the fate of nitrogen forms to scale the system for new projects.
This work is funded by Ohio Sea Grant.
Ammonium Dynamics in Lake Erie
The Western Basin of Lake Erie is hypereutrophic and subject to annual Microcystis blooms as a result of the phosphorus and nitrogen entering through the Maumee River. Although Microcystis is stimulated by and very competitive for ammonium, very little is known about its cycling in Lake Erie. We are measuring rates of ammonium uptake and regeneration, ammonia oxidation, and sediment ammonium efflux and burial, along with characterizing the nitrogen cycling bacterial communities, in order to construct a preliminary budget for the Western Basin. This work was funded by Ohio Sea Grant.
The Western Basin of Lake Erie is hypereutrophic and subject to annual Microcystis blooms as a result of the phosphorus and nitrogen entering through the Maumee River. Although Microcystis is stimulated by and very competitive for ammonium, very little is known about its cycling in Lake Erie. We are measuring rates of ammonium uptake and regeneration, ammonia oxidation, and sediment ammonium efflux and burial, along with characterizing the nitrogen cycling bacterial communities, in order to construct a preliminary budget for the Western Basin. This work was funded by Ohio Sea Grant.
Lake Taihu, China
Lake Taihu, third largest freshwater lake in China, is a hypereutrophic lake that experiences seasonal, cyanobacterial harmful algal blooms (cyanoHABs). These Microcystis blooms produce the toxin microcystin and have been linked to the increased input of the anthropogenic nitrogen. Studying the nitrogen cycle in this ecosystem and examining the genetic structure of the microbial community can provide critical information for managing excess nitrogen in the lake and its removal. The first step of nitrification, ammonia oxidation, links ammonium to N removal via denitrification. Does competition with Microcystis impact the ammonia oxidizers and, therefore, the nitrification and denitrification rates?
Lake Taihu, third largest freshwater lake in China, is a hypereutrophic lake that experiences seasonal, cyanobacterial harmful algal blooms (cyanoHABs). These Microcystis blooms produce the toxin microcystin and have been linked to the increased input of the anthropogenic nitrogen. Studying the nitrogen cycle in this ecosystem and examining the genetic structure of the microbial community can provide critical information for managing excess nitrogen in the lake and its removal. The first step of nitrification, ammonia oxidation, links ammonium to N removal via denitrification. Does competition with Microcystis impact the ammonia oxidizers and, therefore, the nitrification and denitrification rates?
Lower Great Miami River, Dayton
The Great Miami River has experienced severe algal blooms in recent years, due to nitrogen and phosphorus inputs. We are quantifying fluxes of removal and recycling of both nitrate and ammonium within sediments of the Lower Great Miami River. Comparing nitrogen loads to removal and recycling rates will allow us to answer the following critical questions: Are sediments a source or sink of nitrogen and phosphorus in the river system? Does this change seasonally (high flow/low flow)? Upstream or downstream of a dam?
The Great Miami River has experienced severe algal blooms in recent years, due to nitrogen and phosphorus inputs. We are quantifying fluxes of removal and recycling of both nitrate and ammonium within sediments of the Lower Great Miami River. Comparing nitrogen loads to removal and recycling rates will allow us to answer the following critical questions: Are sediments a source or sink of nitrogen and phosphorus in the river system? Does this change seasonally (high flow/low flow)? Upstream or downstream of a dam?
Lake Okeechobee and St. Lucie Estuary
Lake Okeechobee is a large, freshwater lake in central FL connected via a canal with Saint Lucie Estuary & then the Atlantic Ocean. Increasingly, Lake Okeechobee & Saint Lucie estuary experience summer cyanobacterial blooms of toxin-producing Microcystis. The bloom impacts fisheries, tourism & local residential areas. We investigated rates of ammonium uptake & regeneration and nitrification to determine N dynamics during the bloom. Additionally, we are looking at gene expression of N-cycling genes and Microcystis-associated genes, to compare geochemical rates with functional genes. Our research was funded by the Florida Sea Grant.
Lake Okeechobee is a large, freshwater lake in central FL connected via a canal with Saint Lucie Estuary & then the Atlantic Ocean. Increasingly, Lake Okeechobee & Saint Lucie estuary experience summer cyanobacterial blooms of toxin-producing Microcystis. The bloom impacts fisheries, tourism & local residential areas. We investigated rates of ammonium uptake & regeneration and nitrification to determine N dynamics during the bloom. Additionally, we are looking at gene expression of N-cycling genes and Microcystis-associated genes, to compare geochemical rates with functional genes. Our research was funded by the Florida Sea Grant.