WC132 SeptOct 2023 - Magazine - Page 6
FRONT
Water related news,
events, and trends
from Canada and
around the world
Low oxygen
levels trigger a
chemical reaction
that releases
sediment-stored
phosphorus,
counteracting
control e昀昀orts
and further fueling
6
YORK UNIVERSITY RESEARCHERS have
conducted a novel study on Lake Erie’s
declining oxygen levels using chironomid
larvae found in the lake’s sediment. This
research indicates that the lake’s bottom
oxygen has decreased significantly over time,
even before major Euro-American settlements.
“The situation today is worse,” says senior
author, associate professor Roberto Quinlan,
warning of increased future algal blooms if the
trend continues.
The team studied these larvae, which
morph into midges as adults, in sediment
samples spanning the past 150 years. They
discovered that oxygen depletion surged post1950s industrialization, exacerbated by population growth, intensified agriculture, and
the increased use of phosphorus-rich fertilizers
and detergents. This led to a particularly
severe period in the 1960s and 70s. Although
phosphorus abatement programs in the early
WATER C AN ADA • SEP TEMBER/OCTOBER 2023
1970s improved water clarity, oxygen levels
haven’t rebounded.
This scarcity of deep-water oxygen significantly impacts water quality, fostering algal
blooms in summer and causing mass fish dieoffs due to temperature inversions. Lake Erie,
the Great Lake most affected by human activity, is of high interest to U.S. and Canadian
governments. In particular, controlling phosphorus, a primary algae nutrient, is a central
concern. Low oxygen levels trigger a chemical reaction that releases sediment-stored
phosphorus, counteracting control efforts and
further fueling algal blooms.
These conditions promote harmful cyanobacterial blooms, posing risks to humans,
pets, and livestock, and making tap water
unsafe. “Lake Erie, already vulnerable to low
oxygen, faces increased risk due to urbanization, industrialization, and agricultural
fertilizers,” concludes Quinlan.
WAT E R C A N A D A . N E T
Getty Images
MORE ALGAL BLOOMS IN LAKE ERIE
