Robert Lennox is a PhD student at Carleton University. He is working on Atlantic salmon migration in Norway in Steve Cooke’s lab (more info). He is also an avid naturalist with a special interest in birds.
Every winter the first snowfall brings out an army of trucks, ploughing – and heavily salting – Ottawa’s streets and highways to keep them safe. But safety comes at a price. Not only does it coat our cars and boots, we apply so much road salt in Canada (5,000,000 tonnes a year) that it creates environmental risks.
Much of the salt eventually finds its way by meltwater into local water bodies. There, it poses a risk to fish, freshwater ecosystems, plants, and animals that normally regulate the amount of salt in their bodies but are not adapted to saline water and cannot function properly in it (Rosenberry et al. 1999, Kelly et al. 2007, Environment Canada 2015).
Salt is toxic to wood frog larvae, which live in ponds throughout North America. If these larvae are exposed to salt for long periods they take longer to metamorphose into adult frogs, have physical abnormalities and reduced activity, weight, and survivability (Karakker et al. 2008, Sanzo and Hecnar 2006).
Large species, such as moose, and small winter finches in the Fringillidae family are attracted to road edges where they can satisfy their salt requirements. However, the downside is they may be struck by passing vehicles (Mineau and Brownlee 2005).
To reduce the environmental impact of road salt, most municipalities have adopted the 2004 national code of practice for organizations that apply more than 500 tonnes of salt a year. The code includes measures for salt storage (under cover and on an impermeable pad), application equipment and techniques, and salt vulnerable areas (identifying, monitoring and protecting areas that may be particularly sensitive to road salts).
Recently, Environment Canada reviewed the effectiveness of the code and set national targets for improved road salt management, notably, an increase in the number of road organizations that identify salt vulnerable areas and prepare an action plan for them.
What can we do? Some cities are testing creative solutions, including using garlic salt, cheese brine, and molasses (see news story) as alternatives to road salt on city streets and highways. At home you can try sprinkling sand on your icy paths and walkways, or save and spread some ashes from the yule log (see Road salts and alternatives). Maybe these can be practical solutions for you.
Environment Canada. Road salts. January 8, 2015.
Karraker, N.E., Gibbs, J.P., Vonesh, J.R. 2008. Impacts of road deicing salt on the demography of vernal pool-breeding amphibians. Ecological Applications 18(3): 724-734.
Kelly, V.R., Lovett, G.M., Weathers, K.C., Findlay, S.E., Strayer, D.L., Burns, D.J., Likens, G.E. 2007. Long-term sodium chloride retention in a rural watershed: legacy effects of road salt on streamwater concentration. Environmental Science & Technology 42(2): 410-415.
Mineau, P., Brownlee, L.J. 2005. Road salts and birds: an assessment of the risk with particular emphasis on winter finch mortality. Wildlife Society Bulletin 33(3): 835-841. (Abstract)
Rosenberry, D. O., Bukaveckas, P.A., Buso, D.C., Likens, G.E., Shapiro, A.M., Winter, T.C. 1999. Movement of road salt to a small New Hampshire lake. Water, Air, and Soil Pollution 109(1-4): 179-206. (Abstract)
Sanzo, D., Hecnar, S.J. 2006. Effects of road de-icing salt (NaCl) on larval wood frogs (Rana sylvatica). Environmental Pollution 140(2): 247-256.
By Jakob Mueller
On Saturday July 19, eight OFNC members joined me for a hike in Marlborough Forest. Marlborough Forest is the name ascribed to a large natural area owned by the City of Ottawa, in the southwestern corner of the municipal boundary. The largest forested area in the City of Ottawa boundaries, it contains a diversity of habitats, including various wetlands and alvar openings.
We started the day hiking south into the entrance that connects to the Cedar Grove Hiking Trail, which overlaps with a portion of the Rideau Trail. It wasn’t long before we began to see the site’s botanical diversity. A late Wild Columbine (Aquilegia canadensis) was still booming in the first clearing along the road, while Black-eyed Susans (Rudbeckia hirta) were putting on a show. We quickly found three species of aster, without the aid of the flowers that start to bloom much later in the summer: Arrow-leaved (Aster urophyllus), Heart-leaved (A. cordifolius), and New England (A. novae-angliae). Northern Leopard Frogs (Rana pipiens) hopped off of the trail here and there. This species’ spot pattern is extremely variable.
We soon found Foxglove Beardtongue (Penstemon digitalis), a common plant in moist open areas at Marlborough, Boneset (Eupatorium perfoliatum), and a Square-stemmed Monkeyflower (see photo).
OFNC member and entomologist extraordinaire, Diane Lepage, showed off an Acadian Hairstreak (see photo) and her skills with a butterfly net, and a White Admiral flew by.
Our first destination was an alvar clearing that has been the site of some dumping in the past. Although that may sound unappealing, one result is an abundance of discarded pieces of flat plywood – the herpetological equivalent of bird houses. After flipping boards for only a short time, we found a Northern Red-bellied Snake and an Eastern Gartersnake. The garter chose intimidation as its defensive strategy, by flattening out, puffing up, and striking haphazardly at the air, and at any shoe it saw moving. The bite of this species is harmless. The Redbelly was more mild-mannered, electing to demonstrate its characteristic “grin”. The snake curls its upper lip and bears its teeth, about as mean as this snake’s defense gets. It then rubs its head against the “predator” – in this case my fingers – and tries to create a scrape with the rough edges of its teeth. The resulting prickle feels a little like a single spoke of Velcro.
The ex-dump clearing also produced some unusual plants of alvars and dry grasslands, notably False Pennyroyal (Trichostema brachiatum), Grey Goldenrod (Solidago nemoralis), and Upland White Aster (Solidago ptarmicoides). A Broad-Winged Hawk was heard calling, and then soared into view.
We then proceeded to a large pond with an adjacent clearing that is cut periodically. We heard both Green Frogs and Bullfrogs calling from the pond, where a single Midland Painted Turtle was out basking. Butterflies and dragonflies abounded in the clearing. Common dragonflies included Twelve-spot Skimmers, Common Whitetails, and Widow Skimmers. The Common Whitetails were especially concentrated below a small dam, where we could also see Green Frogs, Bullfrog tadpoles, schools of minnows, and a large leech.
Crescent butterflies were particularly common in the clearing, and Diane Lepage again put her net to good use, managing to capture both a Northern Crescent and a Pearl Crescent for viewing in the same jar. These two species are notorious for being difficult to separate, and this allowed students of Lepidoptera to familiarize themselves with some of the key differences.
After returning to our vehicles for lunch, we explored a different section of the forest along a fire road. We found several more butterflies, including Mourning Cloaks, Eastern Commas, and Green Commas with their characteristic the greenish markings and the comma-shaped blotch. We also found Rhamnus alternifolia, Alder-leaved Buckthorn, a.k.a. “the native buckthorn.” It confused us initially as it was growing beside an invasive Glossy Buckthorn.
All-in-all, it was a fairly productive outing. We did not cover a lot of ground in terms of distance, but by taking our time we were able to see a lot of biodiversity.
All photos taken by Jakob Mueller