Lake Erie algae bloom less severe than expected

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Harmful algae in a jar.
Harmful algae in a jar.

SALEM, Ohio — This year’s harmful algal bloom on Lake Erie was considerably less severe than scientists predicted in the summer, according to a release from the National Oceanic and Atmospheric Administration.

The 2018 bloom had a severity index of 3.6, compared to the 6 that forecasters predicted in July. The index ranges from zero to 10, with 10 being the most severe.

The severity index captures the amount of bloom biomass over the peak 30 days of the bloom.

Scientists predicted a range between 4.9 to 7.8 — all higher than the actual bloom. According to NOAA, scientists will take a closer look at the science that may have led to a smaller bloom.

Unusual bloom

This bloom was unusual in that it started early, the last week of June. The early start was probably a result of the rapid early warming of Lake Erie, starting at the end of May.

Another factor may have been the storm that occurred Sept. 9-10, which produced strong winds over Lake Erie, severely disrupting the bloom. The bloom did not recover, and ended by the first week of October, one of the earliest ends of the bloom on record.

While some scums did occur, scum was both more localized and less common in this bloom, especially in contrast to the much larger and more severe 2017 bloom.

In addition, the Cleveland Plain Dealer reported that there was an unusual occurrence of a second, non-harmful algae this year, which may have helped reduce the presence of harmful algae.

Top priority

Lake Erie water quality and the presence of harmful algal blooms have been a top priority for Ohio over the past several years. Seven of the last 10 years have seen blooms above 4.0, which NOAA classifies as significant.

The forecast models are based primarily on the load of bioavailable phosphorus from the Maumee River during the spring and early summer (March to July).

Weather patterns, especially rainfall, usually have strong correlations with the type of discharge into the lake.

River discharge and rainfall in 2018 were typical of long-term averages, higher in March and April, lower in May and June, and very low in July.

This is much different from 2017, which saw extremely wet months in May and July, leading to extremely high discharge and load in those months.

This information was announced by NOAA Oct. 26. On Thursday, a state panel that oversees soil and water conservation efforts in Ohio, is expected to vote on an executive order that asks eight western Lake Erie watersheds, to be declared “watersheds in distress.”

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