Algae bloom and churn in Lake Erie, shown in this image from the NASA Terra satellite’s MODIS sensor taken on February 20, 2012. Many of the greenish colors in the Lake are associated with algal blooms, whereas the murky yellow/brown colors are probably associated more with sediment input from the river mouth to the west. NOAA is engaged in monitoring phytoplankton levels in the Lake along with assessing whether these blooms are harmful to human and fish species, especially since these winter blooms in Lake Erie may trigger impacts much later in the year.
Nutrient input into Lake Erie is magnified due to its relatively shallow depth, making ideal conditions for phytoplankton blooms. However, as winter turns into spring and summer, the waters warm and the phytoplankton die, the bacteria involved in decaying the phytoplankton shells consume large amounts of oxygen in the Lake, creating hypoxic “dead zones.”
Surface algae are especially apparent this year, as most of Lake Erie never froze over – a stark contrast to the ice conditions of last year. Algae-rich waters can also be seen flowing along the Niagara River into Lake Ontario, which is otherwise mostly devoid of large algal blooms. Blooms in Lake Ontario are mostly constrained to the shallow coastal areas near the Niagara input, as opposed to the deep offshore zones.