A Look Inside How NOAA Tracks Harmful Algal Blooms

In the Great Lakes, summer means the arrival of sun, warmth and time spent enjoying the outdoors. Unfortunately, it also often means the arrival of harmful algal blooms (HABs), out-of-control algal growths that coat lakes in green slime.

HABs occur when algae grow rapidly, forming dense layers on top of the lakes and changing the lakes’ water color from blue to green. But they don’t just look gross — they also give off toxins that can contaminate drinking water, harm swimmers and pets, and cause problems for recreational and commercial boating and fishing. HABs are caused by excess nutrients from fertilizers, sewers, and water treatment plants that are washed into the Great Lakes by heavy rain and rivers.

Harmful algal blooms, like this one in the Western Basin of Lake Erie on July 2, 2018, can turn lake water green. (Photo Credit: Aerial Associates Photography, Inc. by Zachary Haslick)

On Thursday, NOAA and its partners released the 2019 Lake Erie Harmful Algal Bloom Seasonal Forecast, which predicts that western Lake Erie will experience a large bloom this summer. To create a forecast like this, NOAA needs data. That’s where NOAA’s Great Lakes Environmental Research Lab (GLERL) comes in. GLERL researchers use satellites, remote sensing, buoys and robots to gather information on the Great Lakes and inform bloom forecast models. 

Here are a few ways GLERL is working to understand algal blooms and help make HAB forecasts as accurate as possible.  

Using Robots to Keep Drinking Water Safe

GLERL’s Environmental Sample Processor (ESP) — also known as NOAA’s “lab in a can”— is a robot that collects water samples to check for microcystin, the algal toxin of greatest concern in western Lake Erie. The goal is to alert drinking water managers about toxic algal growth in the Lake, before the algae in the water reaches municipal water intakes. 

NOAA and CIGLR researchers are teaming up with a group of scientists and engineers from the Monterey Bay Research Institute (MBARI) to test how well a third-generation environmental sample processor (3GESP), mounted inside a long-range autonomous underwater vehicle (LRAUV), can track and analyze toxic algae in the Western Basin of Lake Erie.

“ESPs are powerful tools because we can’t always be out on the water, but the robots can,” says Reagan Errera, Ph.D., a research ecologist at NOAA GLERL. This year, researchers will be using three ESPs in western Lake Erie, near city water intake pipes, with two ESPs constantly in the water throughout the season. This placement provides drinking water managers earlier warning of blooms and toxicity. Ultimately, GLERL scientists want to use ESP data for an official microcystin forecast, which has not been included in the HAB operational forecast in the past.

Using Underwater Vehicles to Map Blooms

In August, NOAA GLERL and partners will conduct an experiment using two long-range autonomous underwater vehicles in western Lake Erie — one for mapping the bloom and the other equipped with a sensor that can measure toxin levels while moving through the water. The vehicle also collects and preserves samples for additional testing and experiments back in the lab. This experiment will provide scientists with near-real-time toxin data from potential bloom hot spots.

Monitoring Blooms from Above

In addition to providing data for NOAA’s forecast at the beginning of HAB season, GLERL monitors HABs from late spring through the end of the bloom season in October. NOAA GLERL scientists conduct weekly hyperspectral imaging flyovers of western Lake Erie, using a low-flying airplane to collect images of the lake with special hyperspectral cameras. These cameras provide much more detail than satellite images, allowing researchers to identify more algal species. The camera-equipped airplane is also able to fly below cloud cover and collect data on cloudy days, which satellites can’t do. The flyovers focus on water intake areas, and the information collected is included in a weekly update to the Michigan Department of Natural Resources, Ohio EPA, and drinking water managers in Monroe, Michigan.

Imagery of the Western Lake Erie harmful algal bloom from September 26, 2017. The scum shown here near downtown Toledo stretched all the way to Lake Ontario. This photo is from Landsat-8 (NASA/USGS satellite), which has a resolution of about 30 meters.

GLERL and its partners from the Cooperative Institute for Great Lakes Research (CIGLR) also maintain a weekly sampling program, from which scientists study and archive samples and conduct experiments. This lab work is important for understanding what causes toxic algae in the Great Lakes. The information from field monitoring, buoys, and sensors helps scientists create tools to predict how big the bloom is and where it’s moving. 

The Big Picture: A Better Understanding of the Blooms

GLERL’s HAB research doesn’t just help scientists forecast blooms — it helps them better understand why the blooms happen in the first place, and why they’ve been getting worse in Lake Erie. Scientists have found that typically, warmer water temperatures and heavy rainfall early in the season means more algae growth and larger blooms. GLERL’s research on specific algal species is also helping NOAA better understand how and why some blooms are more toxic than others, a topic that scientists are just beginning to understand.

GLERL’s HAB data is publicly available — explore it for yourself on GLERL’s website.