Event Title

Incorporating freshwater macrophytes into the silicate budget for Estabrook Park Pond

Presenter Information

Loretha Jack

Mentor 1

Erica Young, John Berges

Location

Union Wisconsin Room

Start Date

27-4-2018 1:00 PM

Description

The macronutrients nitrogen and phosphorus are known to limit primary productivity in freshwater ecosystems, but many important phytoplankton also use silicate. I examined the effect of Si on phytoplankton communities over the summer and determined that Si availability is important in shaping phytoplankton community composition. However, much of the pond is covered by rooted and suspended aquatic macrophytes, which account for much of the pond’s primary productivity, and their role in silicate cycling is unknown. The aim of our research was to characterize the silicate dynamics in Estabrook Pond, incorporating phytoplankton as well as macrophytes and their epiphytic algae, to create an Si budget for this small ecosystem. Fluxes between pools were examined in a degradation experiment using the macrophyte Myriophyllum during fall. We collected macrophyte and water samples from Estabrook pond which we divided among six different containers and stored in the growth chamber. We monitored silicate in three pools: Si dissolved in the water (dSi), particulate Si in the suspended community (pSi), and biogenic Si in the macrophytes (bSi). Over the course of the experiment, dSi was consistently low. BSi was initially high but decreased during the experiment. As bSi decreased, pSi increased suggesting breakdown of the macrophytes or detachment of epiphytes. Although the Si budget was not perfectly balanced, these findings suggest that aquatic macrophytes may have a strong influence over Si dynamics in Estabrook Pond along with diatoms and other Si-demanding cells within the phytoplankton.

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Apr 27th, 1:00 PM

Incorporating freshwater macrophytes into the silicate budget for Estabrook Park Pond

Union Wisconsin Room

The macronutrients nitrogen and phosphorus are known to limit primary productivity in freshwater ecosystems, but many important phytoplankton also use silicate. I examined the effect of Si on phytoplankton communities over the summer and determined that Si availability is important in shaping phytoplankton community composition. However, much of the pond is covered by rooted and suspended aquatic macrophytes, which account for much of the pond’s primary productivity, and their role in silicate cycling is unknown. The aim of our research was to characterize the silicate dynamics in Estabrook Pond, incorporating phytoplankton as well as macrophytes and their epiphytic algae, to create an Si budget for this small ecosystem. Fluxes between pools were examined in a degradation experiment using the macrophyte Myriophyllum during fall. We collected macrophyte and water samples from Estabrook pond which we divided among six different containers and stored in the growth chamber. We monitored silicate in three pools: Si dissolved in the water (dSi), particulate Si in the suspended community (pSi), and biogenic Si in the macrophytes (bSi). Over the course of the experiment, dSi was consistently low. BSi was initially high but decreased during the experiment. As bSi decreased, pSi increased suggesting breakdown of the macrophytes or detachment of epiphytes. Although the Si budget was not perfectly balanced, these findings suggest that aquatic macrophytes may have a strong influence over Si dynamics in Estabrook Pond along with diatoms and other Si-demanding cells within the phytoplankton.