By Julia Roeder\u00a0<\/p>\n
Every spring, as the Great Lakes region warms, scientists watch for the return of harmful algal blooms.\u00a0\u00a0<\/p>\n
While the average passerby\u00a0doesn\u2019t\u00a0notice the blooms until the bright green layer covers the shoreline, scientists can begin predicting the blooms weeks or even months before they become visible.\u202f\u00a0<\/p>\n
Harmful algal blooms are the rapid\u00a0growths\u00a0of toxin-producing bacteria that\u00a0infiltrates\u00a0drinking water,\u00a0threatens\u00a0wildlife\u00a0and\u00a0poses\u00a0health risks to people and pets.\u00a0<\/p>\n
The forecasts for the blooms are important not only for beachgoers, but also for fishers and businesses that depend on the Great Lakes.\u00a0<\/p>\n
While harmful blooms occur throughout the Great Lakes, the National Oceanic and Atmospheric Administration (NOAA) currently issues seasonal forecasts only for western Lake Erie, which has the right combination of nutrients, weather and decades of scientific data to forecast, compared to the other lakes.\u00a0<\/p>\n
The reason for forecasting the lake is simple: Lake Erie\u2019s algal blooms can threaten drinking water,\u00a0recreation\u00a0and the local economy.\u00a0<\/p>\n
Predicting blooms\u00a0<\/p>\n
While NOAA\u2019s short-term forecasts help track blooms as they develop over the span of a few days, the seasonal outlook\u00a0looks\u00a0months ahead. These predict how severe the bloom is likely to be based primarily on phosphorus levels in the Maumee River.\u00a0<\/p>\n
The Maumee flows from Indiana east through Ohio, ending in Toledo, where it drops off into the western side of Lake Erie. Agriculture along the waterway dumps phosphorus from fertilizers into the river, which carries nutrients to the lake.\u202f\u00a0<\/p>\n
When too much phosphorus enters Lake Erie, it acts like fertilizer, feeding algae and driving the harmful blooms that spread across the lake.\u00a0<\/p>\n
\u201cThe main factor that impacts how bad a bloom is going to be is the amount of nutrients,\u201d said Gregory Dick,\u00a0the\u00a0director of the Cooperative Institute for Great Lakes Research at the University of Michigan.\u00a0<\/p>\n
Dick said NOAA\u2019s seasonal outlook intentionally focuses on bloom size rather than location in the basin because winds, lake currents and weather\u00a0determine\u00a0how algae\u00a0moves\u00a0and accumulates throughout the summer.\u00a0<\/p>\n
\u201cThe seasonal forecast is essentially predicting how bad the bloom is going to be that year,\u201d Dick said. \u201cIt\u2019s not making specific predictions about when or where the bloom is going to be.\u201d\u00a0<\/p>\n
Every year in late June, NOAA releases its seasonal forecast for harmful algal blooms in western Lake Erie. This year, the agency predicted a\u202fmoderate<\/a>\u202fbloom, and by mid-July, the first visible signs of cyanobacteria had begun appearing in parts of the lake\u2019s western side.\u202f\u00a0<\/p>\n Harmful effects, compounded by a changing climate\u00a0<\/p>\n Algae on its own is not an issue. It is a naturally occurring part of the Great Lakes ecosystem, and the base of the food chain \u201cthat feeds the small shrimp-like organisms that then feed the fish and everything else in the lake,\u201d said Thomas Bridgeman, an ecology professor and director of the Lake Erie Center at the University of Toledo.\u202f\u00a0<\/p>\n Problems begin when extra nutrients, like phosphorus or nitrogen, wade into the lake, prompting an overgrowth of algae and the rapid reproduction of certain bacteria. One of the more harmful kinds is\u00a0the cyanobacteria, which behave like algae but produce chemicals dangerous to people and animals.\u00a0<\/p>\n \u201cThey\u2019re particularly worrisome because they can produce really potent toxins,\u201d Bridgeman said. \u201cIf they get into drinking water supplies, or if they wash up on beaches and people or dogs are exposed, they can be made very sick or even die.\u201d\u00a0<\/p>\n These dangers became\u202fclear<\/a>\u202fin 2014 when toxins from a harmful bloom contaminated Toledo\u2019s drinking water.\u00a0It left about\u00a050,000\u00a0residents\u00a0without safe tap water.\u202f\u00a0<\/p>\n Although nutrients drive most of the\u00a0bloom\u2019s\u00a0growth, weather\u00a0determines\u00a0how much phosphorus\u00a0actually reaches\u00a0the lake from agricultural fields.\u00a0<\/p>\n \u201cIn years when we have much more rainfall, there\u2019s much more runoff, and that washes more phosphorus into the lakes and causes bigger blooms,\u201d Dick said.\u00a0<\/p>\n Rick Stumpf, an oceanographer who leads NOAA\u2019s harmful algal bloom forecasting efforts at the National Centers for Coastal Ocean Science.\u00a0noted that not all rainy springs look the same.\u00a0<\/p>\n \u201cA wet spring could be because it just keeps raining, or because there\u2019s a week of\u00a0intensive\u00a0rain,\u201d Stumpf said. \u201cThe worst blooms have occurred when there have been floods in the Maumee River Basin.\u201d\u00a0<\/p>\n Rising lake temperatures from global warming\u00a0add\u00a0more uncertainty to predicting blooms.\u00a0<\/p>\n According to October data\u202ffrom<\/a>\u202fthe Great Lakes Environmental Research Lab\u00a0operated\u00a0by the NOAA, all five of the lakes were around 4 to 5.5 degrees Fahrenheit warmer last fall than their long-term average for the last three decades.\u00a0<\/p>\n Warming temperatures also extend bloom seasons across the Great Lakes, Dick said.\u202f\u00a0<\/p>\n Calm weather on the lakes favors blooms because of how mobile the algae can become.\u202f\u00a0<\/p>\n \u201cWinds matter because these blooms do better in calm water,\u201d Stumpf said. \u201cIf it\u2019s calm, they float up to the surface and block the light, keeping the competition down.\u201d\u00a0<\/p>\n Stumpf also said the organisms dominating Lake Erie\u2019s blooms have preferences in their environment.\u00a0<\/p>\n \u201cLake Erie cyanobacteria like warm water, but they particularly like water with a lot of nutrients, especially phosphorus,\u201d he said.\u00a0<\/p>\n Using technology\u202f\u00a0<\/p>\n Once a bloom begins developing, forecasting shifts from seasonal to daily predictions.\u00a0<\/p>\n \u201cSatellite data is a key piece because we can determine how much bloom there is over the whole lake every clear day,\u201d Stumpf said. \u201cThat\u2019s way more data than you can possibly get from field sampling and way cheaper.\u201d\u00a0<\/p>\n Satellite imagery distinguishes harmful cyanobacteria from beneficial algae that forms the base of the food chain, something that is hard to notice for the everyday beachgoer.\u202f\u00a0<\/p>\n There are two types of algae forecasts the NOAA publishes \u2014 one that predicts long-term, months in advance, and another that is short-term, days in advance.\u202f\u00a0<\/p>\n