Recently, the Toledo Lucas County Health Department has issued a recreational public health advisory for a portion of the Maumee River due to the current algae bloom. The toxic algae, also known as microcystis, has spread to the Maumee River from Lake Erie. Harmful algal blooms in Lake Erie are caused by run-off from nearby farms and cities. The bloom of microcystins is so prominent now that the top of the affected water is coated with the thick, vibrant green algae. Two tests that were taken in the Maumee River resulted in 1.8 and 11.8 parts per billion of microcystins, which is under the 20ppb limit set by the World Health Organization for safe drinking water. While the water is still safe to drink for humans, the algae can still be toxic to local wildlife if they have been exposed for prolonged periods of time. Earlier this month, tests along Maumee Bay State Park recorded measurements of upwards of 250ppb in areas but had decreased down to just 30ppb by September 11th.
Areas of water with a strong presence of microcystins can result in low or depleted oxygen levels, also known as hypoxic zones. When algae die, they drop to the water floor and decompose. The bacteria that decompose the algae respire, which absorbs oxygen in the area. Larger blooms of algae being decomposed lead to greater amounts of oxygen being consumed by the bacteria. When the water is warmer, the oxygen at the bottom of the water is not replaced because the warm surface water will not blend with the cooler water on the bottom. The current warm front northwest Ohio has been experiencing this September has led the temperature levels in the Maumee River to increase by 23-25 degrees Fahrenheit. Along with the rising heat, the area has not received much rain lately, which is causing the river to become more stagnant. These conditions could pose a threat to local fish populations if the blooms become worse in the area. Some fishes will be unaffected because they can swim beneath the algae and avoid hypoxic zones, but other species such as the round goby (Neogobius melanostomus) or rainbow smelt (Osmerus mordax) may not be as fortunate. During this time of year, these fish are feeding on aquatic invertebrates near the bottom of the water column. In times when oxygen is depleted, their prey cannot escape to areas with more oxygen and die off. Less prey to feed on leads to decreased habitat quality in these species. With the current climate trends leading to warmer temperatures, it is likely that northwest Ohio will continue experiencing these algal blooms and hypoxic zones in their waters, despite the efforts of nearby cities and farmers to mitigate run-off. This may have an effect the future of fish populations in the region.
Cited Sources:
1.) US Department of Commerce, National Oceanic and Atmospheric Administration. “Hypoxia.” NOAA’s National Ocean Service, 6 Oct. 2014, oceanservice.noaa.gov/hazards/hypoxia/. Accessed 28 Sept. 2017.
2.) “Maumee River recreational advisory continues during algal bloom.” The Blade, The Toledo Blade, 23 Sept. 2017, www.toledoblade.com/local/2017/09/23/Maumee-River-recreational-advisory-continues-during-algal-bloom.html. Accessed 28 Sept. 2017.
3.) “Green algae leads to water advisory for Maumee River near Downtown Toledo.” The Blade, The Toledo Blade, 21 Sept. 2017, www.toledoblade.com/local/2017/09/21/Recreational-water-advisory-issued-for-Maumee-River-near-Downtown-Toledo.html. Accessed 28 Sept. 2017.
4.) “Old Woman Creek National Estuarine Research Reserve Technical Bulletin No. 3.” How is Fish Habitat Affected? Lake Erie’s Dead Zones, July 2015, wildlife.ohiodnr.gov/portals/wildlife/pdfs/public%20areas/OWC_TechBull3.pdf. Accessed 28 Sept. 2017.
5.) Staff, WTOL. “Algal bloom on Lake Erie thrives in September heat wave.” Wtol.com, 25 Sept. 2017, www.wtol.com/story/36449847/algal-bloom-on-lake-erie-thrives-in-september-heat-wave. Accessed 28 Sept. 2017.