Increased Bioavailability of Anthropogenic Phosphorus in Lake Erie

Session: 41b. - Great Lakes Harmful Algal Blooms Research from Watershed Influence to Ecosystem Effects

Fasong Yuan, Cleveland State University, [email protected]
Christopher Kasden, Cleveland State University, [email protected]

Abstract

Lake Erie has received approximately one million metric tons of phosphorus (P) from agricultural runoff, urban, and other sources over the past century. Much of the anthropogenic flux of P is retained in lake sediments and potentially recycled and returned to the water column through diffusion and resuspension, acting as a persistent nutrient source that stimulates algal growth. While the diffusive flux from sediments has been recently estimated, considerably less is known about the P contributions by resuspension. Our sequential chemical extractions of P from sediments reveal that Lake Erie experienced two stages of enrichments in loosely-bound P, coinciding with the historical and contemporary episodes of massive algal blooms in the 1960s and 2000s. Although the exact causes remain elusive, these enrichments are linked to increased bioavailability of P in the resuspension loading and enhanced susceptibility of the lake to algal blooms. We suggest that the increased bioavailability of P has offset some effects from rigorous reductions in the tributary loading and contributed greatly to the recent unprecedented episode of harmful algal blooms.

1. Keyword
phosphorus

2. Keyword
biogeochemistry

3. Keyword
sediment resuspension

4. Additional Keyword
Lake Erie

5. Additional Keyword
Sequential extraction

6. Additional Keyword
algal blooms