In 2014, harmful algal blooms (HAB) made national headlines for toxifying the western Lake Erie basin and temporarily poisoning the drinking water of 400,000 Ohio residents. Despite efforts by the state of Michigan to curb significant blooms, HABs world-wide continue to steadily increase, relative to yearly rainfall. Algae is not innately toxic; it typically acts as the foundation for freshwater and marine ecosystems. Within freshwater ecosystems, there are several types of algae, such as diatoms, thread algae, green spot algae, red algae, and cyanobacteria. Algae becomes toxic when cyanobacteria, commonly referred to as blue-green algae, releases cyanotoxins or “toxic algae” blooms.
Sunlight, slow-moving currents, and shallow waters all can create cyanotoxins, but anthropogenic soluble phosphorus (SP) loads are the largest contributors to the production of cyanotoxins. Soluble phosphorus loads account for the soluble phosphorus that enters bodies of water. Cyanobacteria algae, like other plant life, normally gains energy through photosynthesis. When exposed to areas subjected to eutrophication, defined as excessive nutrients within a body of water leading to a lack of oxygen for animal life, cyanobacteria releases cyanotoxins. In areas rich in SP nutrients, cyanotoxin organisms grow and reproduce exponentially. Lake Erie is plagued by these toxins that temporarily poisoned the water supply.
There are several reasons for the steady increase of SP entering Lake Erie; the first is agricultural operations. Monocropping, the repeated and widespread planting of one crop, has become extremely popular due to the profitability of corn for the production of ethanol and livestock feed. However, monocropping traditionally increases soil rotation and lessens crop diversity, both of which result in lower quality soil. This lower quality soil is not able to hold water as well, not as nutrient rich, and thus requires more water and SP-packed fertilizer.
Additionally, fertilizer is often applied broadly over crops, rather than directly to soil. Such application allows surface fertilizer to get swept into the runoff water. Furthermore, the fertilizer recommendations are not calibrated for individual location, but multiple states. Therefore, inaccurate and overestimated fertilizer recommendations for less productive soil on farms surrounding Lake Erie have created a potentially compounding effect on SP runoff. The runoff problem is exacerbated by increased rainfall from climate change. Since the agricultural facilities are located on or near surrounding rivers and water basins, all of this SP loaded water ends up in Lake Erie directly, or eventually reaches the lake through bodies of water such as the Maumee River, fueling the growth of cyanotoxins.
Harmful cyanotoxins, within cyanobacteria algae, devastate ecosystems, impact human health, and deplete surrounding economies. Within ecosystems, fish are the first impacted by either absorbing, ingesting, or encountering an infected organism. Contact with these toxins can cause a multitude of problems for these organisms, including liver damage or death. Below the surface, algae blooms block out vital sunlight and can get dangerously stuck in fish gills. Algae remaining on the surface also decreases the oxygen available under the surface for aquatic organisms. Moreover, cyanobacteria can create other freshwater toxins such as microcystin. For humans, microcystin can cause health effects like abdominal pain, headaches, sore throat, nausea, blistering, and pneumonia. HABs continually jeopardize the health of numerous surrounding ecosystems.
Economies will also face detrimental hardships due to HABs. HABs create thick and dense blooms atop bodies of water that make fishing hazardous and nearly impossible, directly harming the fishing industry dependent on Lake Erie. Similarly, HAB’s give the water a green hue and slimy surface texture that is equally dangerous for tourists to swim or boat in. In addition, roughly eleven million people receive drinking water from Lake Erie. With toxicity rising, water treatment will become costlier for surrounding homeowners and business owners who rely on this water. Each of these industries will suffer greatly if Lake Erie is not rehabilitated.
To date, there have been multiple efforts to combat HAB growth in Lake Erie. Through the Great Lakes Water Quality Agreement, the US and Canada have agreed to further regulate total phosphorus loading. The Western Basin of Lake Erie Collaborative Agreement, signed by Michigan’s governor, Ohio’s Lieutenant Governor, and the Premier of Ohio, has similar aims. These conservation efforts have reduced the amount of total phosphorus entering Lake Erie, but the amount of soluble phosphorus is still increasing. Soluble phosphorus, the filterable form directly taken up by plant cells, is more damaging than other types of phosphorus by heavily contributing to the creation of cyanotoxins. In an extra effort, the Michigan Department of Environmental Quality has labeled Michigan’s segment of the western Lake Erie basin as “impaired”, or damaged, due to excessive levels of phosphorus. Much to the dismay of local farmers, Michigan has plans to reduce annual sediment losses and phosphorus losses by allowing the Michigan Agriculture Environmental Assurance Program to provide farmers technical assessment, support, and verification of completed conservation practices. Contrarily, the Ohio Environmental Protection Agency (EPA) has resisted the classification of “impaired” and created their own minimalistic conservation plan. While the federal EPA has approved this decision, they also approved Michigan’s decision to list Lake Erie as “impaired”. Due to this inconsistency, the state of Ohio, which controls the largest portion of Lake Erie, is not held to a high enough standard to rehabilitate the western basin of Lake Erie. It is imperative that these institutions reconsider their stances in favor of ecosystems, human health, and surrounding economies.