Signs of Abundance Tour – The information on this page compliments that which appears on the sign that has recently been erected on the boardwalk at the bottom of Croteau Road in Macdonald Wood Park. To go to the map of all the signs in this series click here.

The Macdonald Wood Park Society  was formed in 1994 when this natural area was threatened by a potential development that would have seen 140 duplexes constructed on the site. The Society raised $1.6 million to purchase the property.  This included contributions from more than 500 members, The Town of Comox and the Province of British Columbia.  MWPS then transferred the property, with Provincial Protective Covenants, to Municipality of Comox while remaining stewards of the park. This valuable habitat contains one of the last intact midden on the coast and is a sensitive ecosystem encompassing a scarce salt marsh.

Salt Marsh

What are salt marshes?

Salt marshes lie at the edge of land and sea, on wave-protected coasts. They are dominated by low-lying, salt-tolerant vegetation and are laced with networks of tidal channels and pools. Salt marshes are communities of emergent herbs, grasses, or low shrubs, rooted in soils and alternately flooded and drained by tidal action.

Where are salt marshes found around the K’ómoks Estuary?

As in many places throughout the world, many salt marshes that previously existed in the K’ómoks Estuary have been destroyed, degraded or filled in and replaced with other land uses. For example, a salt marsh existed where there is now a 440 meter wall of sheet piling along the Courtenay River near the 17th street bridge.

Despite the loss of these historic salt marshes, some still remain and continue to provide valuable wildlife habitat; such as the one here along the shore in front of MacDonald Wood Park. The most productive salt marsh habitat, in terms of juvenile salmon rearing,  exists along Comox Road between the Rotary Viewing Platform and the cement area off the 17th street bridge. This is known as in Hollyhock Marsh.

Project Watershed has been working with volunteers to protect and restore salt marsh since 2014. We have created new salt marsh islands at the Royston Wrecks at the end of Hilton Road and just outside the south end of the Courtenay Airpark Lagoon off Mansfield Drive.

How do salt marshes form?

The extent and composition of salt marshes vary in different parts of the world. Whereas the Atlantic coast of North America is dominated by large deltas and salt marshes, the Pacific coast is much more rugged and has fewer and smaller salt marshes. Nevertheless, the structure and controlling factors of salt marshes in general are similar.

Salt marshes form along shallow-sloped coasts where there is a source of sediment that is transported to the ocean by streams or rivers, or deposited along the shore by wave action and currents. Marsh grasses initially colonize the sediment, by sending out underground stems called rhizomes. The roots, stems and leaves of the grass dissipate the energy of waves and cause more sediment to accumulate.

Eventually, dead plant mass and sediment build up, and the marsh grows vertically. It then becomes cut with channels and tidal creeks, from the flows of both fresh and salt water. As the structure of the marsh changes, different plants colonize the sediment, depending on their tolerance to salt and flooding, and their ability to compete with other species.

Mature salt marshes have high marsh and low marsh. High marsh is flooded only by the highest high tides, whereas the low marsh is flooded daily with the tides, and is dominated by salt-tolerant species.

What lives in salt marshes?

Salt marshes are highly productive environments. Abundant herbs, grasses and low shrubs dominate the view, while birds, crabs, snails and fish take shelter among the plants and in shallow water. Many species have evolved special traits to tolerate salt water, and the constantly changing conditions (wet/dry, freshwater/salt water, warm/cold).

In the low marsh, closest to the ocean, Lyngby’s sedge (Carex lyngbyi) is one of the most common colonizers of mud flats, and provides food for geese and trumpeter swans. Sea arrow-grass (Triglochin maritimum) and pickleweed (also called sea asparagus; Salicornia virginica) are also common. Slightly higher grows seashore saltgrass (Distichlis spicata). In the upper marsh, beyond the influence of salt water, cattails (Typha latifolia) and bulrush (Scirpus maritimus) are common.

Although few animals live exclusively in salt marshes, many feed or breed there. Some animals that can be seen in salt marshes include:

  • Invertebrates such as insects, worms, crustaceans (e.g. crabs, amphipods and shrimp) and molluscs (e.g. snails, mussels).
  • Birds such as Great Blue Herons, Brant Geese, Canada Geese, Mallards, Greater Yellowlegs, sandpipers, kingfishers, mergansers, Green-winged Teals, Gadwalls, plovers, snipe, Bald Eagles, Ospreys, hawks and owls.
  • Mammals such as shrews, mice, voles, raccoons and river otters.
  • Many types of fish shelter, rear and breed among the tidal channels of salt marshes, and in the deeper water of estuaries. Some of these include herring, salmon, cutthroat trout, stickleback, sole, flounder and surf perch.

Why are salt marshes important?

  • Salt marshes provide important feeding and breeding grounds for many bird species, and act as nurseries for fish such as Pacific salmon and Cutthroat trout. They therefore contribute significantly to the overall function of the marine environment, and host many commercially important species for at least part of their life cycle.
  • The plant material from salt marshes is broken down by microorganisms and exported offshore by tidal currents. This material is subsequently ingested by free-floating plankton, forming the basis of many marine food chains.
  • Salt marshes help to filter and store pollutants that flow through streams from urban sources.
  • Vegetation in salt marshes helps to anchor sediment and soil along the shoreline. This helps prevent stream flow, rainwater and waves from scouring away the land. This natural barrier also helps to dissipate the energy of large waves that can otherwise inflict serious damage on human life and property.
  • Salt marsh plants take in and store carbon from our atmosphere and help mitigate climate change. Carbon sequestered from ocean plants is referred to as blue carbon. To learn more about blue carbon click here.
  • The abundant wildlife in salt marshes provides valuable recreation, tourism, education and research opportunities for people.

What threatens salt marshes?

Although salt marshes are highly valuable and productive ecosystems, they are also vulnerable to damage. They are often located in areas that are highly desirable for agriculture, shipping, industry and urban development. By far the greatest threat to salt marshes is the practice of filling them in, for construction related to these activities. In many cases the process was begun by diking and draining the salt marsh for agriculture. Since 1800, 70% of Pacific salt marshes in Canada have been drained or lost to other functions. Other threats to salt marshes include:

  • The spread of invasive species such as reed canary grass, which can crowd out native species and reduce the habitat value of the marsh
  • Runoff of pollution such as heavy metals, oils and gas, particularly from impervious surfaces in urban areas
  • Agricultural contamination, such as pesticides and fertilizers
  • Pollution from boats
  • Trampling of vegetation by people and animals

Another concern is the threat of sea level rise due to global warming. If this occurs too quickly, the salt marsh may not be able to adapt by migrating inland. Furthermore, landward migration is often constrained by agricultural, residential or urban development, a situation known as “salt marsh squeeze”. On one hand salt marshes help to protect inland property from the damage of storm surges, which are predicted to become more frequent with climate change in our region. On the other hand, their ability to perform this service is seriously hampered by coastal development. Restoration of salt marshes may therefore become even more important in the near future.

Shell Middens

Archaeologists and natural historians have long been fascinated by shell middens because of their great potential to enhance information about human adaptations and cultures. Early studies focused on the Mesolithic køkkenmøddinger (“kitchen middens”) of northern Europe, but similar studies were conducted in Canada by the late 19th century. The English term midden is derived from a Scandinavian root referring to a trash heap composed of domestic refuse and located near a dwelling. The term shell midden refers to such a heap composed predominantly (50% or more) of the shells of MOLLUSCS and/or other shell-bearing animals such as ECHINODERMS and ARTHROPODS. The term shell midden was once commonly used to designate an archaeological site type but is now mostly employed to refer to a type of archaeological feature. Thus, shell middens are features that occur in some – but not all – shell-bearing archaeological sites, along with other types of deposits, such as natural soil layers, anthropogenically modified soils, dwelling floors (often the remains of houses constructed and occupied by the people who accumulated the shell middens), hearths, storage pits, mortuary features and so on. Archaeological sites containing shell middens present archaeologists with stratigraphic and ZOOARCHAEOLOGICAL puzzles that are intriguing, challenging and daunting.

Information shown here is from The Canadian Encyclopedia.

Shell Midden Development and Occurrences

Shell middens develop where human populations – whether hunter-gatherers, horticulturalists, agriculturalists or industrialists – harvest large quantities of shellfish, shuck out and process the meat for consumption and/or use the shells as raw materials, and leave large quantities of shell debris on their habitation and processing sites. Shell middens are a world-wide archaeological phenomenon, most frequently found on sites adjacent to marine shorelines and composed of marine shellfish remains (seeSEASHELL), although shell middens composed of the remains of freshwater molluscs also occur in interior riverine locations in many places.

Once thought of as a hallmark of the Mesolithic and Neolithic periods, following the end of the last glaciation (10 000-12 000 years ago), shell middens are now known to date from early in the Upper Palaeolithic (ca. 160 000 years ago) through to recent times. The earliest known shell middens have been found in South African near-shore caves and were accumulated contemporaneous to the emergence of anatomically and behaviourally modern humans (Homo sapiens sapiens) from archaic hominin populations.

Archaeological Significance of Shell Middens

Studies of shell middens contribute to the development of archaeological history in Canada in five main ways. First, when past people accumulated shell middens, they produced stratified archaeological sites, and enhanced cultural component separation, in contexts where these phenomena would otherwise be unlikely to develop. Second, shell middens allow and enhance the preservation of a variety of organic materials (shell, bone and charcoal) amenable to radiocarbon dating. Together, these two factors enable archaeologists to construct more fine-grained and firmly dated culture-historical sequences than would otherwise be possible.

Third, calcium carbonates from the shells cause shell middens to be depositional environments that preserve organic remains – for example, the bones of animals used as food, tools and artistic/ornamental objects made from bones, teeth, antlers and shells, and human skeletal remains – infrequently preserved in the generally acidic soils characteristic of much of Canada. These finds allow for more detailed understandings of past technologies, lifeways and symbolic/spiritual behaviours. Fourth, and closely related to the previous point, applications of quantitative zooarchaeological, growth increment and stable carbon and nitrogen isotopic analyses to organic remains from shell middens enable archaeologists to construct more complete understandings of the human ecology of past populations – palaeodiets, subsistence practices, seasonal rounds and settlement patterns. Finally, the bones of extinct species, and species whose geographical ranges have fluctuated through time, are frequently preserved in shell middens; these finds contribute to understandings of biogeographic change. In addition, techniques such as sclerochronology (the study of physical and chemical variations in accretionary hard tissues) and oxygen isotope analysis are being applied to shellfish remains from shell middens in studies of prehistoric human ecology and long-term climatic and environmental changes.

What can I do to help?

Volunteer

We are often looking for extra hands to help harvest and plant salt marsh.  To volunteer fill out our volunteer form we will contact you with dates and times our activities occur.

Donate

Salt Marsh Restoration

Costs per Square Meter (m2)

$200 = 1 m2 of salt marsh

Salt marsh planting requires much effort, time and money as gravel islands need to be built at specific elevations to create the conditions that the salt marsh plants require. In some cases invasive plant species such as Spartina also need to be removed. Click on the donate button and you can help restore important habitat. We appreciate any and all donations that are received.

Photographers

David Ingram

David Ingram

Eiko Jones

Eiko Jones

Terry Thormin

Terry Thormin

Kerry Dawson

Kerry Dawson

Owen Grant