Chlorophyll nitrogen isotope values track shifts between cyanobacteria and eukaryotic algae in a natural phytoplankton community in Lake Erie
Date of Original Version
Chlorophylls are produced by all photosynthetic organisms and are ideal targets for compound-specific isotopic studies of phytoplankton. In laboratory cultures, the difference between the nitrogen (N) isotope ratio (δ 15 N value) of chlorophyll and the δ 15 N value of biomass, known as ε por , varies taxonomically, yielding potential applications for studying productivity in modern and ancient environments. Here we take advantage of the annual cyanobacterial bloom in Lake Erie, USA, to demonstrate ε por patterns in a natural community. The resulting time series shows that environmental observations are similar to laboratory cultures: predicted ε por endmember values range from 4.6‰ to 7.4‰ for eukaryotic algae, and −18‰ to −21‰ for cyanobacteria. Because the range and sensitivity of ε por is similar between laboratory and natural settings, the data support the use of ε por as a reliable tracer of the relative contributions of cyanobacteria and eukaryotic algae to nutrient utilization and primary production in lacustrine environments.
Publication Title, e.g., Journal
Kharbush, Jenan J., Derek J. Smith, McKenzie Powers, Henry A. Vanderploeg, David Fanslow, Rebecca S. Robinson, Gregory J. Dick, and Ann Pearson. "Chlorophyll nitrogen isotope values track shifts between cyanobacteria and eukaryotic algae in a natural phytoplankton community in Lake Erie." Organic Geochemistry 128, (2019). doi: 10.1016/j.orggeochem.2018.12.006.