Grace C. NeumillerFollow

Date of Award

2021

Document Type

Honors Thesis (Open Access)

Department

Colby College. Environmental Studies Program

Advisor(s)

Denise Bruesewitz

Second Advisor

Caitlin McDonough MacKenzie

Third Advisor

Karena McKinney

Abstract

Intense nutrient loading of nitrogen (N) and phosphorus (P) causes sudden regime shifts in freshwater ecosystems from clearwater to turbid conditions with frequent cyanobacterial blooms. Characterization of nutrient limitation patterns of primary productivity in these ecosystems is necessary for effective management of algal blooms. However, much of this research has focused on pelagic habitats. The influence of lake habitat (i.e. benthic littoral versus pelagic zones) on nutrient limitation of primary production in mesotrophic lakes is largely unknown, particularly in contrast to research on pelagic nutrient limitation in eutrophic systems. Using paired nutrient diffusing substrata and mesocosm experiments, we measured chlorophyll-a (chl-a) concentrations in response to 4 nutrient treatments (N, P, N + P, Control) to assess nutrient limitation patterns in littoral and pelagic zones of two temperate, mesotrophic lakes in late summer, prior to the fall mixing period (October 2020). While both lakes are mesotrophic, China Lake has approximately 2.18 times higher overall average [chl-a] in the water column than Great Pond in this late stratification period. In the pelagic zone, China Lake phytoplankton are colimited by N and P, while Great Pond phytoplankton are P limited. In the benthic zone, China Lake periphyton are serially limited by N then P, and Great Pond periphyton are N limited. These data will improve our understanding of nutrient limitation patterns in mesotrophic systems in danger of eutrophication and allow us to incorporate littoral zone production into our understanding of whole lake ecosystem productivity.

Keywords

phytoplankton, periphyton, nutrient limitation, algal blooms, cyanobacteria, chlorophyll-a

Download

Share

COinS