Freshwater is vital to human survival. York University researchers have now created a public water quality database for some 12,000 freshwater lakes globally – almost half of the world’s freshwater supply – that will help scientists monitor and manage the health of these lakes.
The study collected data for lakes in 72 countries, from Antarctica to the United States and Canada. Hundreds of the lakes are in Ontario, where York University is based.
“The database can be used by scientists to answer questions about what lakes or regions may be faring worse than others, how water quality has changed over the years and which environmental stressors are most important in driving changes in water quality,” says study lead Alessandro Filazzola in a statement.
The researchers reviewed 3,322 studies from as far back as the 1950s along with online data repositories to collect data on chlorophyll levels, a commonly used marker to determine lake and ecosystem health. Chlorophyll is a predictor of the amount of vegetation and algae in lakes, known as primary production, including invasive species such as milfoil.
“Human activity, climate warming, agricultural, urban runoff and phosphorus from land use can all increase the level of chlorophyll in lakes. The primary production is most represented by the amount of chlorophyll in the lake, which has a cascading impact on the phytoplankton that eat the algae and the fish that eat the phytoplankton and the fish that eat those fish,” says Filazzola.
“If the chlorophyll is too low, it can have cascading negative effects on the entire ecosystem, while too much can cause an abundance of algae growth, which is not always good.”
Warming summer temperatures and increased solar radiation from decreased cloud cover in the northern hemisphere also contributes to an increase in chlorophyll, while more storm events caused by climate change contribute to degraded water quality, says Sharma.
“Agricultural areas and urban watersheds are more associated with degraded water quality conditions because of the amount of nutrients input into these lakes.”
The researchers also gathered data on phosphorous and nitrogen levels – often a predictor of chlorophyll – as well as lake characteristics, land use variables, and climate data for each lake. Freshwater lakes are particularly vulnerable to changes in nutrient levels, climate, land use and pollution.
Photo credit: Benjamin, flickr/Creative Commons