Shoreline hardening involves the installation of structures that replace the natural shoreline with hard surfaces of rock, concrete and paved surfaces. The natural shoreline is reshaped, altered and removed permanently. The shoreline is restructured with seawalls, revetments, armour rocks, pavement, headlands, nodes and riprap.
Despite the prevelance of shoreline hardening, the impact on natural ecosystems (both terrestrial and aquatic) is often ignored. Benefits of shoreline hardening are presented to the general public in support of the practice and the negative effects are denied.
There is a growing trend of global awareness and extensive research available revealing the importance of keeping shorelines natural and there are some coastal communities that are even reversing the practice.
'The Society for Freshwater Science' reveals the benefits of a natural shoreline in this recently publishing document by Stacey Wensink and Scott Tiegs:
Freshwater shorelines play critical roles in the maintenance of freshwater and riparian ecosystems that far exceed their spatial extent. As ecotones, shorelines mediate resource exchanges between aquatic and terrestrial ecosystems and, thereby, influence the ecological condition of both systems.
Despite occupying a small area of the landscape, shorelines often possess high levels of biodiversity, provide habitat for rare and endemic species, are feeding areas for shore birds and function as spawning grounds and nurseries for fish.
In addition, shorelines are sites of organic-matter retention, accumulation, and processing, and play unique roles in the biogeochemical cycling of nutrients.
Despite their ecological value and the ecosystem services that shorelines provide, these sites are frequently altered by human development, but with poorly understood ecological consequences.
The practice of shoreline hardening on the Great Lakes is one of the many stressors created by urban development:
Here are some the facts on shoreline hardening from the Great Lakes Environmental Assessments and Mapping Project (GLEAM). For more in-depth info, please visit their website. Shoreline structures constructed to protect and maintain human investments along the coast have a number of adverse impacts on nearshore ecosystems. In particular, artificial shoreline protective structures can:
destroy local vegetation, often replacing it with impervious surface and impacting storm water flow
cause local increases in water turbidity
alter nearshore sediment dynamics
accelerate lake bed erosion
facilitate the establishment of nuisance species like zebra and quagga mussels
From the Great Lakes Tributary Modelling Program, here are the facts on the environmental damage and biological processes linked to shoreline hardening, from their website:
burial or removal of habitat for bottom dwelling species due to shifts in beach material
alterations in or complete loss of vegetative cover resulting in temperature fluctuations in shallow water
loss of spawning, foraging and nursery habitat for fish due to alteration in the substrate
loss of migratory corridor for fish caused by shifts in water elevation from existence of armoring
decreased organic inputs due to loss of vegetation adjacent to the shoreline
interruption of beach access to foraging wildlife
Shoreline hardening is often used as a reason for enhancing aquatic habitat so it's important to point out that fish communities rely on many biological components.
The following information about the dynamics of shoreline habitat is from the Toronto Aquatic Habitat website. Please visit them for more about the importance of the following:
phytoplankton and zooplankton
aquatic and riparian vegetation
reptiles and amphibians
Shaping the future of Toronto's shoreline in Scarborough
The image below on the left is shoreline hardening along Lake Ontario at the Guildwood in Scarborough. It demonstrates the complete destruction of the natural shoreline. Hardened with armour rocks, it creates a solid barrier that prevents all access to the water from the shore.
This shoreline at one time was most likely a sandy beach with a diverse habitat of plant and wildlife though unfortunately all of that has now been lost forever. This shoreline hardening was done by the Toronto and Region Conservation Authority, an organization that is operated by the city, and for the public.
The image on the right is a section of the natural shoreline of Greyabbey Park and is an area that The Toronto and Region Conservation Authority is currently proposing to harden.
email the TRCA today - let them know you want this area protected!
We need to let the TRCA know that hardening the shore of this last stretch of beach is not acceptable. It is nothing short of environmentally irresponsible and it's also a public embarrassment for this to be done by a conservation authority.
You may also join the Facebook Page East Point Shoreline - Keep it Natural to be kept up to date on efforts to protect this area. This initiative extend beyond the shoreline and includes protecting the diverse habitat in the various forests and wetlands that line the shore from East Point to the Guildwood, it's about preserving the geological and environmental wonder of the Scarborough Bluffs and allowing access to the abundant fresh water of Lake Ontario to remain intact.
A petition has been started - please sign and circulate.
Let's protect the last remaining natural shoreline in the Toronto area!