Responses of Lake Erie phytoplankton communities to P, N, and Si loading from the Maumee River

Session: Poster session

Lyndsie Collis, The Ohio State University, [email protected]
Lienne Sethna, Indiana University, School of Public and Environmental Affairs, [email protected]
Todd Royer, Indiana University, School of Public and Environmental Affairs, [email protected]
James Hood, Aquatic Ecology Lab, The Ohio State University, [email protected]

Abstract

Lake Erie has been confronted with multiple physiochemical stressors that have led to recent increases in hypoxia and harmful algal blooms. Cyanobacterial blooms, which have been increasing for a decade, are strongly associated with spring total phosphorus loading from the Maumee River, OH. Yet, we have a more limited understanding of how nutrient loading shapes intra-annual phytoplankton dynamics, particularly for non-cyanobacteria taxa. Here, we present analyses of a 20-year phytoplankton biomass time series (1995-2015) from a site near the Maumee River mouth. We used multivariate statistics and generalized additive mixed models to examine how phosphorus, nitrogen and silica loading from the Maumee River shapes inter- and intra-annual phytoplankton community dynamics. Non-metric multidimensional scaling separated phytoplankton communities along two axes. The first axis was associated with the relative abundance of cyanobacteria, and the second with diatoms and Cryptophytes. Peak phytoplankton biomass increased between 1995 and 2015, driven by cyanobacterial blooms, and was positively related to both weekly and seasonal total P loading, particularly when bioreactive P was high. Our results suggest that the influence of nutrient loading on phytoplankton community dynamics is complex and dependent upon the loading of multiple chemical species at both weekly and annual scales.

1. Keyword
Lake Erie

2. Keyword
nutrients

3. Keyword
phytoplankton

4. Additional Keyword
Maumee River

5. Additional Keyword
cyanobacteria

6. Additional Keyword
phosphorus