Glaciers, lakes, and rivers
Learn how water moves through the Rockies, and how the different ecosystems support each other.
Glaciers and Snowpack
Snow and ice act as a battery in the mountains, storing water late into the summer. At high elevations, where the temperatures are cooler, snow and ice can last late into the summer, melting at a steady rate. This constant influx of water into alpine lakes and streams creates a stable environment for ecosystems, as there is always freshwater flowing in, replenishing water flowing down stream to lower elevations.
Alpine Waters
As snow melts, it often collects in the bowls of mountains, forming ponds and lakes. These smaller bodies of water are often covered in ice for over 9 months of the year. With such a short ice-free period, organisms that live in these systems must be able to persist under the ice over winter and tolerate the extreme conditions in the summer. At high elevations, UV radiation is intense, so many organisms have bright coloured pigments that act as a kind of “sunscreen”. These water bodies are often shallow, and can warm up quite quickly during the hot days of summer. These large yearly temperature fluctuations are also challenging for organisms to handle, limiting the number of species that are able to persist in these systems.
Large Lakes and Rivers
Tumbling down the mountain slopes, smaller creeks feed into river and lakes in the valley bottoms. Fed by cold, clean water, these systems are often home to a wider array of organisms, with more complex food chains. Aquatic invertebrates are often in high enough abundance to support fish populations, making the river and lakes in the Rockies popular destinations for fishing. Their accessibility also makes them much easier to modify for human uses; Many of the notable lakes in the Kananaskis area were formed by damming rivers for electricity generation.
Riparian Areas
Though not truly aquatic, riparian areas are intimately linked to freshwater ecosystems. Where the land and water meet, a unique mix of species springs up, adapted to the changing conditions of the waterways in the Rockies. Riparian areas are important habitat for fish and land animals alike, and also host unique plant species. Healthy riparian areas help to prevent flooding and erosion, and are unique landscapes themselves. These ecosystems are great habitat for moose and deer, as the large amount of shrubs provide lots of food over winter.
What is driving change in these aquatic ecosystems?
Climate Change
As the climate of the Rockies warms, we are seeing changes in the amount and form of precipitation. Rain-on-snow events create large pulses of melt water, that can cause severe flooding and wash out river ecosystems, damaging habitat and scouring organisms out of the system. These events also deplete the snowpack, leading to lower amounts of meltwater later in the summer, potentially drying out smaller wetlands and leading to low water levels.
Climate change is also changing the ice-free period of alpine lakes, leading to a longer growing season. This will cause [something].
Fisheries Management
Many of the alpine lakes in the Rockies have been stocked with fish to support recreational fishing opportunities. Some lakes have naturally occurring populations of native trout, which then suffer due to competition with introduced fish species.
In lakes that historically had no fish, the introduction of fish can have profound impacts on the species already present in the lake. Invertebrates in high alpine lakes have adapted to the extreme environment with large body sizes and bright pigments. When trout arrive, these invertebrates are easy to spot and catch, and rapidly decline in abundance. This causing cascades down the whole food chain, changing the structure of the lake’s food web.
In recent years, Parks Canada has begun clearing stocked fish out of lakes that were historcially fishless. Even when the fish are removed, the lakes can take up to 20 years to recover back to a “healthy” state.
Land Use Change
Further downstream, in the valley bottoms and foothills, human impacts on the landscape drive change in aquatic ecosystems. Dams built to store water for drinking supply and provide electricity also flood valleys and limit the migrations of Bull Trout, Alberta’s provincial fish. The large floodplains carved out by rivers also provide prime land for townsites, roads, and other developments, and subsequent flood-control measures to prevent rivers from accessing their floodplains change fish habitat, water temperatures, and the ecology of the riparian area, the sensitive zone where water and land meet.
Research Highlight
Retreating Glaciers, Changing Meltwaters
In the alpine, glaciers act as batteries of water, storing it in the winter and releasing it throughout the summer. The meltwater coming off of these glaciers is ice-cold, fast flowing, and full of sediment; a tough environment for life to thrive in. Despite the extreme conditions, species of algae and midges have adapted to life in these streams, thriving where few other species can.
As glaciers continue to recede due to climate change, these glacial streams are slowing down and shrinking. As this happens, the water becomes slower, warmer, and clearer. This relatively gentler environment opens these streams up to invasion by new species, both introduced and native. Invasive algae may move up from the larger rivers further below in the valleys, along with fish, disrupting the sensitive and specialized species currently found in these streams. Researchers at the University of Alberta have been studying these alpine streams, trying to measure the changes in the stream environment and inhabitants as glaciers shrink and the streams slow and warm.
Pictures clockwise: Sampling a glacial stream for invertebrates. Hannaea arcus, a species of diatom specialized for mountain streams (credit: simomusa CC BY-NC 4.0). A winter midge, which spend their larval stages living in streams such as the one shown here (credit: Owen Strickland CC BY-NC 4.0)
A colony of Hydrurus foetidus, a common algal species in these mountain streams. Credit: iwbishop CC BY-NC 4.0
Conservation Highlight
Taking a Stand for Native Trout
Did you know that Alberta’s provincial fish is a trout? Bull trout (Salvelinus confluentus) are related to arctic char and brook trout, and can travel hundreds of kilometers up and down streams as they look for food and breeding habitat. Adult Bull Trout hunt other fish for food, including Cutthroat Trout, another native species that are found in the Rockies. These trout are perfectly adapted to exist in the cold mountain streams in the rockies, but are currently threatened by human activity.
A promotional video made by the Alberta Native Trout Collaborative, highlighting some of the challenges facing the trout living in the Rockies’ waters
Native trout depend on cold, clean, complex, and connected rivers. Unfortunately, human activities like recreation, resource extraction, and increased forest fires resulting from climate change are all threatening our trout populations. The Alberta Native Trout Collaborative is working with stakeholders and the public to help safeguard our trout. They take pride in the trout species that call the Rockies home, and hope that you can find a similar pride in these remarkable species. If you want to learn more about native trout, including how to identify the different native trout species in our rivers, head over to their website!
A young westslope cutthroat trout. Cutthroat trout have 14 different subspecies, but only the westslope subspecies is native to Alberta. Credit: USFWS - Mountain Prairie