The annual forecast for the severity of the Harmful Algal Bloom on Lake Erie was released on July 9th.The actual forecast was dramatically different than the early forecast which was in the C.O.R.N. 2015-14 (http://corn.osu.edu/newsletters/2015/2015-14/noaa-lake-erie-algal-bloom-projection ). Beyond limiting farmers from field activities such as planting, sidedressing corn, wheat and hay harvest, and weed control the excessive rainfall dramatically changed the amount of phosphorus moving down the Maumee River into the Western Basin of Lake Erie. The severity of the expected bloom has steadily increased with the June rainfall experienced to where the current predication is for the second highest level of bloom severity, only exceeded by 2011. A summary is below or the entire broadcast of the 7/9 webinar can be viewed athttps://ohioseagrant.osu.edu/research/issues/habs
The HAB forecast is coordinated by NOAA with other partners. The forecast and monitoring report of current HAB severity is updated about once a week through late summer at http://www.glerl.noaa.gov/res/waterQuality/ . The prediction severity of the western Lake Erie cyanobacterial harmful algal bloom (HAB) is dependent on phosphorus inputs from March 1st through July 31st, called the loading season and is used for prediction. The amount of Dissolved Reactive (or Soluble) Phosphorus (DRP) has the greatest correlation and is used for the modeling efforts.
The cumulative loading of DRP and Total P is shown with 2015 (Red) accumulation to date compared to year 2011-2015. Note the dramatic accumulation starting with June 1 rainfall events.
Figure 1. Spring Phosphorus loading numbers from the Maumee River (Near Waterville). Summarized is Cumulative loading of Dissolved Reactive Phosphorus (left) and Total Phosphorus (right). Source Heidelberg University.
These cumulative numbers are used to develop the likely forecast of the severity of HAB’s in Lake Erie. The scale is 1-10 with 10 being 2011. Figure 2 shows the prediction of 2015 with a range of severity that could place the current year between the 2013 and 2011 year blooms with a significant bloom.
Figure 2. 2015 Predicted HAB Bloom severity. Source: NOAA.
Figure 3 shows a MODIS true color image (Top) and Cyanobacterial Index from NASA’s MODIS-Aqua data (Bottom ) for 2011 and 2013 at peak bloom for each year. The MODIS-Aqua data gives a concentration index with the red color indicated a higher concentration and the blue a lower concentration of cyanobacteria which is the organism of concern with HAB Blooms.
Figure 3. Peak bloom images for the 2011 and 2013. Source: NOAA.
Ohio’s HAB incidence is not limited to the Lake Erie Watershed. OEPA provides a Map noting current HAB warnings on Lake in the state athttp://epa.ohio.gov/habalgae.aspx. Currently warnings are issued for Grand Lake Saint Mary’s (Mercer County), Buckeye Lake (Fairfield County)and Kiser Lake (Champaign County). No advisory for HAB is currently posted for Lake Erie