Freshwater Ecology

Students sample invertebrate populations as an indicator of river health

RiverWatch students learn the principles of freshwater ecology while raft floating to study sites along their nearest local river.

RiverWatch provides an authentic and generative science experience that helps students answer the question:

"Is this river healthy?"

RiverWatch teaches students to combine observations of basic river geography and biodiversity to determine river health.

A day on the river with RiverWatch addresses the following curriculum topics…

Water use in Calgary doubles during the summer growing season

Water Use

Each one of us uses a tremendous amount of water every day and even more during the summer growing season. Whether we consciously realize it or not, we use rivers each time we drink, eat, brush our teeth or flush the toilet. Our very bodies are composed of up to 80% river water!

Water Cycle

A day spent with RiverWatch increases student's understanding of the water cycle. Paddling a boat suddenly gives the headwater glacial and meltwater sources of a river more importance - is there enough water or too much water for rafting?

Watershed Impact

Watersheds are areas of land that eventually drain into one main river. We're all "downstream" users of water, and it becomes relevant to know what town or ranch used our water before us and who will receive our wastewater after us. RiverWatch tours conducted through wastewater treatment plants and the observation of storm water outfalls both serve to bring home our impact on watersheds.

The water cycle is the largest physical process on Earth

Erosion and Deposition

Paddling a raft creates real interest in current velocity and current direction. Other rafts pass you by if your boat is not in the main current, and you may even run aground on shallow gravel deposits and have to walk. "Catching an eddy" - a spin into a calm area along the shoreline - will cause a raft to stop.

Sufficient water depth for rafting is indicated by choppy waves, downstream "vee" channels, dark water or stone riprap reinforcing river banks against erosion on the outside of a bend. Students observe and record substrate or river bottom conditions that range from silt to bedrock slabs. Measurements of increased turbidity (cloudy water) may also indicate higher rates of erosion.

Flow Volumes and Velocity

A raft navigates a narrow and shallow section of river

The flow volume of river has a marked effect on how fast any raft can travel. More volume equals more current and faster velocities. River currents travel to the outside of a bend and leave shallow water and gravel on the inside of the bend. It pays to stay focused on stream dynamics in the cutthroat world of raft racing! Miss the main current or run aground on a gravel bar and the quick and easy raft ride turns into walking or paddling! RiverWatch students record daily flow volumes and measure current velocity.

Ecosystems

Ecosystems are networks of interactions that link living (biotic) and non-living (abiotic) things. Sunlight energy flows through producers and consumers in complicated food webs. Food webs also employ decomposer organisms to cycle nutrients such as nitrogen and phosphorus. River ecosystems often have few aquatic plants and instead depend on falling leaves and flying insects as an energy source. RiverWatch students observe and record abiotic factors such as dissolved oxygen and biotic factors such invertebrate populations.

Biodiversity

Rivers and terrestrial ecosystems lie in close proximity to each other. Water quickly gives way to beaches, riparian areas, prairies or forest. The water's edge is an especially rich ecosystem in its own right called the riparian green zone. The great biodiversity of riparian areas makes for many wildlife-viewing opportunities during a RiverWatch trip. Many species - like cottonwood trees or mayfly insects - exhibit amazing adaptations to their environments.

Invertebrate Indicators

Students sort through the contents of an invertebrate sample

RiverWatch provides all the expertise and equipment to collect and identify aquatic invertebrates at study sites above and below a sewage treatment outfall. Students can infer the water quality at a given sample site based on the diversity of the invertebrate life forms captured with a kick net. Fewer species and larger populations can be an indication of nutrient loading by a pollution source.

Nutrient Loading

Excessive weed growth hinders fishing

Wastewater treatment and cattle waste have a profound effect on the health of a river. Without good wastewater treatment or cattle watering strategies, excessive amounts of phosphorus and ammonia can enter a river and result in increased plant and algal growth. Algae and aquatic plants growing in thick mats can be an indication of nutrient loading. RiverWatch students measure phosphorus and ammonia levels in addition to qualitative observations of plant and algal growth.

Coliform Bacteria

The presence of Coliform bacteria is an indication that sewage or animal waste is entering the river. RiverWatch provides all the equipment and instruction necessary to collect a river sample and then culture bacteria back at school.