Episode 7 - River Mouth and Nearshore

River Mouths
The connection point where a river enters Lake Huron is referred to as the River’s mouth.

River mouths are a mixing place where river water meets lake water. As the warm river water enters the cooler lake water, a unique ecosystem forms fostering areas for fish movement and breeding.

Large rivers provide sediment, vegetation and water from inland sources to nearshore waters.

River mouths are unique habitats for aquatic and terrestrial species specially adapted to live here. Some Species at Risk including Queen Snake can only survive near river mouth’s, relying on a single species of crayfish for food.

Although areas of dynamic change, river mouths on Lake Huron have historically attracted settlers, most towns still present today because of their importance as marine harbors, sources of water, navigation, and food sources.

River mouths experience the highest rate of human-caused stress compared to other aquatic habitats.
Other threats include development, invasive species, sedimentation from soil erosion, farmland tilling upstream, overfishing, eutrophication, pollution and damming for flood control or water diversion.

Unfortunately, rivers also bring washes of plastic pollution and litter from inland sources, causing river mouths to be highly contaminated with garbage on the river banks and in the water.

Renaturalizing river mouths by creating vegetated, meandering banks free from concrete, steel, or armor stone revetments is the best way to restore these areas and improve water quality.

Installing vegetated buffers around river mouths will improve water quality and the aesthetics of the river mouth area improving appeal for visitors and residents alike.

Nearshore Waters

The nearshore zone of Lake Huron exists where the shoreline meets the Lake extending to a depth of 6-meters.

This area is constantly fluctuating, relying on lake water levels to define boundaries- changing seasonally and annually.

The Nearshore lake bottom ranges from hard, dolomite shoals and blocks, to sandy, highly erodible sediments.

The nearshore zone is directly influenced by ecosystems adjacent to the shoreline and cumulative impacts from further inland, as well as greater-lake, holistic influences.

Roughly 90% of Great Lakes fish and invertebrate species live in or rely upon nearshore habitats.

Nearshore water quality is important for the health of Lake Huron’s coastal communities, with ~2.4 million individuals relying on Lake Huron for drinking water, tourism and commercial fishing.

Commonly used for swimming, fishing, and boating; the socio-economic importance of the nearshore zone to coastal communities is strongly focused around tourism and visitation, which needs to be balanced with protection and sustainable use.

Reducing threats and stressors such as algae blooms, toxic chemicals, pollutants, and sedimentation is essential to guaranteeing nearshore water quality to swim in and drink for future generations.

Understanding that what happens on the landscape eventually trickles down into Lake Huron’s nearshore waters will help reduce the stressors that harm the lake’s water quality in the nearshore zone, which affects the health of all other shoreline ecosystems, and our ability to use the beautiful shoreline.

To find out more, go to lakehuron.ca