1.2 What’s that floating in the water?
Find out more about what you might find on the surface of the water, like foam and excessive plant growth.
Ottawa Rowing Club. Photo: Paul Mudroch
Foam
The majority of foam that we see is natural. When organic matter like leaves and twigs begin to break down, they release compounds into the water called surfactants, which create foam when water is turbulent.
How do we know if the foam is natural?
Natural foam smells like fish or earth and has tan colour. Foam from pollution (detergents/soaps) can smell like perfume and is bright white.
Photo: Barry Stemshorn
Insect Skins
In early summer the skins of insects can be seen covering the water surface along the shore and may be mistaken for dead minnows. The skins come from the aquatic larvae of insects (e.g. mayflies, shadflies) that shed their skins to become flying adults.
Hudson, QC. Photo: Sue McLennan
Oily Sheen
An oil sheen on a water surface can be petroleum but it can also be the result of natural bacterial processes. Try using something to pierce the center of the oil sheen and if it rejoins then it is likely petroleum where as if it does not rejoin than it is likely natural.
Photo: John Stetson
Pollen
In spring and early summer, pollen often collects on the surface of the water forming a yellow film.
Norway Bay, QC. Photo: Meaghan Murphy
Excessive Plant Growth
Aquatic plant growth can vary from year to year due to nutrient pollution, the current or previous summer’s temperatures, and/or changes in water levels. In some cases, strong winds, wave action and/or boats can uproot aquatic plants, causing them to collect near shore. The introduction of invasive plants can also be a cause.
Victoria Island. Photo: Meredith Brown
Fish Kills
A few dead fish floating on the surface is not always a sign that something is wrong with the environment as fish may die of many natural causes (e.g. old age, predation). However, when larger numbers of fish (5+) of all sizes are found dead in a specific area it may be the result of pollution or disease and should be reported.
This is a page from the online Riverwatch handbook.