Tracking When Boreal Lakes Freeze and Melt
Climate change impacts when lakes freeze over and melt
Evidence from temperate zone sites around the globe has indicated a decline in the duration of ice cover due to climate change. Few such sites, however, exist in the lake-rich boreal region of Canada.
For nearly 50 years, researchers at IISD Experimental Lakes Area have been collecting measurements on the duration of ice cover, ice thickness and snow thickness. This project uses the long-term record of ice cover to develop and modify existing models of the dates when lakes freeze over (“ice-on”) and melt (“ice-off”).
Current efforts focus on improving our understanding of the role of lake size (surface area, volume) in modifying the relationship between air temperature and ice-on/ice-off dates in the boreal zone.
This ongoing work benefit from a strategic collaboration with Natural Resources Canada and the Canadian Space Agency, who are developing algorithms to estimate ice cover from the satellite constellations. The estimates that the satellites provide, once validated, will allow a broader examination of the role of lake size in modifying shifts in ice-on and off-dates resulting from climate change.
Lee Hrenchuk explains more in her recent blog post.
This research is carried out in collaboration with Natural Resources Canada.
Aquaculture
Freshwater fish farms have the potential to help meet increasing demand for fish, but the effects of aquaculture are not well understood.
Fish farming (aquaculture) is increasingly supplying protein for humans, but its effect on freshwater environments is not well understood. At one IISD-ELA lake, researchers installed an aquaculture cage and stocked it with a high density of rainbow trout and monitored changes of the lake ecosystem. They found significant increases in nutrient delivery to the water and sediments of the lake, and consequently, detectable increases in algae growth in the water. These results suggest that freshwater fish farms can negatively impact lake water quality, and they highlight the need to develop aquaculture legislation focused on reducing the environmental effects of its operations.
Reservoir Development
Studies at ELA have looked at the impacts of hydro reservoir development on both greenhouse gas (GHG) emissions and mercury cycling.
Flooding of ecosystems for hydro electricity generation had been known to result in elevated concentrations of toxic methyl mercury in fish since the 1970s. In 1993, researchers suggested that reservoirs might be an important source of greenhouse gases to the atmosphere. Studies investigating both pre- and post-flooding conditions, and factors promoting elevated mercury and greenhouse gases, were lacking. Both the Experimental Lakes Area Reservoir Project (ELARP) and the FLooded Uplands Dynamics EXperiment (FLUDEX) were devised to understand the full effect of flooding wetlands and uplands, respectively. Results from these studies showed, for the first time, that flooding wetlands produced higher amounts of greenhouse gases and mercury than flooding upland areas. Another whole-lake study also examined the ecosystem effects of winter water drawdown, a common feature of many northern reservoirs.
Key findings included: 1) that reservoirs produce GHGs through the decomposition of flooded soils and vegetation; and 2) that flooded wetlands produced higher amounts of GHGs and mercury than upland areas. Power companies such as Manitoba Hydro and Hydro Quebec have used study findings to build reservoirs with lower environmental impacts.
The research and its findings are summarized in this blog post.
Hormones
Waste from sewage treatment plants often contains chemicals known as “endocrine disruptors” such as artificial estrogen found in birth control pills.
Wastes from sewage treatment plants contain synthetic estrogen and similar compounds that are known to affect the reproductive health of exposed fishes in laboratory studies. However, little is known if this pollution could affect populations of fish or other organisms in the wild. ELA researchers added artificial estrogen to a lake for three years and observed the “feminization” of male fish and altered egg production by female fish, leading to the collapse of resident populations. The decline in numbers of small fish, in particular, resulted in negative effects on organisms not directly affected by the added estrogen. These ecosystem changes persisted long after artificial estrogen was detectable in the lake. The study provides guidance to policy makers about the control of synthetic hormones in wastewaters.
Looking at the Impacts of Nanosilver on Fresh Water
In 2014, researchers began to add nanosilver, tiny particles that have anti-microbial properties, to an IISD-ELA lake.
Nanosilver particles that have anti-microbial properties are being added to many consumer items including clothing, washing machines, and baby products. The release of these compounds to freshwater ecosystems have unknown effects on lakes and rivers. In 2014, researchers began to add nanosilver to an IISD-ELA lake.
Following two years of experimental nanosilver additions, we start to recover and monitor Lake 222 in 2016. To date, large scale changes have not been observed. Several papers on this project have been published several more are on the way.
Researchers in this whole-ecosystem nanosilver study included graduate students and principal investigators from Trent University, Lakehead University, and Institut national de la recherche scientifique. Research internships were provided through support from an NSERC CREATE program (CREATE H2O), coordinated by the University of Manitoba. Funding for the whole-lake addition project was provided by the Natural Sciences and Engineering Research Council of Canada through the Strategic Grants Program, and matching grants from Environment and Climate Change Canada. IISD-ELA provided in-kind support for the project, Support for biomarker analyses was provided by the National Contaminants Advisory Group of Fisheries and Oceans Canada. Mercury, energy density analyses, and bioenergetics modelling was supported by infrastructure funded by the Canadian Foundation for Innovation, NSERC Discovery, and support from IISD-ELA and the Mitacs Accelerate Program.
Genetically Modified Fish
With a growing need for fish protein to feed the world’s human population, genetically modified (transgenic) fish are being proposed for use in fish farms.
A study began in 2008 to observe the growth rates of rainbow trout selectively bred for aquaculture compared to a wild trout, and has already found that the aquaculture fish have much higher growth rates. Future phases of the experiment will include adding a growth hormone to the experiment and examining transgenic fish in the wild.