https://doi.org/10.1088/1748-9326/ac0564

Molot, L.A., S.N. Higgins, S.L. Schiff, J.J. Venkiteswaran, Michael J. Paterson and H.M. Baulch, 2021. Phosphorus-only fertilization rapidly initiates large nitrogen-fixing cyanobacteria blooms in two oligotrophic lakes. Environmental Research Letters, 16: 12 pgs, https://doi.org/10.1088/1748-9326/ac0564.

Two small, oligotrophic lakes at the IISD-Experimental Lakes Area in northwestern Ontario, Canada were fertilized weekly with only phosphorus (P) in the summer and early fall of 2019. The P fertilization rates were high enough (13.3 µg l−1 added weekly) to produce dense, month-long blooms of N2-fixing Dolichospermum species in both lakes within 9–12 weeks after fertilization began, turning them visibly green without the addition of nitrogen. P-only fertilization increased average seasonal chlorophyll a concentrations and cyanobacteria biomass well above the pre-fertilization levels of 2017 and 2018. Nitrogen (N) content in the epilimnion of thermally stratified Lake 304 and the water column of shallow Lake 303 doubled and P storage in the water column temporarily increased during the blooms. These whole-lake fertilization experiments demonstrate that large cyanobacteria blooms can develop rapidly under high P loading without anthropogenic N inputs, suggesting that aggressive N control programs are unlikely to prevent bloom formation and that P controls should remain the cornerstone for cyanobacteria management.

FORMBLOOM, Refereed Publications

https://doi.org/10.1088/1748-9326/ac0564