The effect of river-borne phosphorus loading on the phytoplankton community of Nottawasaga Bay

Session: 37. - Harmful Algal Blooms (HABs) and their Toxicity: Remote Sensing and Modeling Approaches

Chris Farrow, University of Guelph, [email protected]
Josef Ackerman, University of Guelph, [email protected]

Abstract

Coastal embayments are susceptible to eutrophication because of anthropogenic factors in their watersheds. Nottawasaga Bay provides a model system to study the effect of nutrient loading because Georgian Bay is oligotrophic. We investigated the effect of nutrients provided by the Nottawasaga River on the nearshore phytoplankton composition of Nottawasaga Bay over two field seasons in 2015 and 2016. We used imaging flow cytometry to enumerate algal taxa and multivariate statistics (RDA, perMANOVA, hierarchical clustering) to examine how nutrients and the transport of algal taxa affect community composition. Sampling stations with different proportions of river water had significantly different phytoplankton communities. Eutrophy indicator taxa were positively associated with phosphorus concentrations in the bay, whereas oligotrophy indicators were opposite. Diversity and evenness were not different among stations, but exhibited patterns consistent with seasonal succession of the phytoplankton community. The Nottawasaga River has pronounced effects on the nearshore phytoplankton community by transporting its algal taxa and by providing nutrients, but these effects were nearly indistinguishable. 

1. Keyword
algae

2. Keyword
eutrophication

3. Keyword
Georgian Bay