When late spring and early summer weather gets hot and muggy and we get lots of rain, expect things to grow. Unfortunately, that is also a good recipe for increased harmful algal blooms (HABs) in Lake Erie. New research shows that merely reducing phosphorus (P) loadings in Lake Erie will not solve the HAB problem; but may in fact, make them worse! Algal biomasses (actually cyanobacteria) will be reduced, but microcystin or toxic algal production will increase. With reduced P, the algae will take up increased amounts of fixed nitrogen, and in the absence of P will actually produce increased, toxic amounts of algal toxins, the microcysts. The lake won't be so green and will let in more light, but will become much more toxic (Hellweger et al, Science, 2022) Phosphorus is usually blamed for most HAB in freshwater because it is the most limiting element needed for plant growth. However, just a little extra P, greatly increases plant growth, especially in lakes. However, as far as poll...

Our agricultural producers will soon be hearing more about agricultural practices that reduce phosphorus (P) runoff. Ohio State University Extension and government agencies have been developing solutions to harmful algae blooms (HAB) and water quality concerns in Lake Erie and Grand Lake St. Marys. We know that most of the soluble nitrogen (N) and soluble P moves with the water. In a drought year like 2012, P runoff and HABs were not a big issue. However, expect P runoff to become an issue in a normal year with average rainfall. A little history may help explain what has occurred with P runoff in Northwest Ohio. In 1969, Lake Erie was considered a dead lake because it had too much P, HAB, and declining fish (walleye and bass) populations. At that time, about two-thirds of the P was coming from known sources. With soil conservation, new sewage treatment upgrades, and changes to laundry soap; total P in the surface water had declined. By the mid 1990’s, Lake Erie was recovering and fishi...