River Works - Threats to Fraser

There are many threats to the biodiversity and productivity of the Fraser River, however before discussing the threats, it is essential that you understand the importance of the river and its estuary

Significance of wetland habitats

Estuarine wetlands are important because they act as:

Habitat: Many animals use the estuary either as a home, hotel, nursery or restaurant.

Home - Some animals live in the estuary year-round such as herons, beaver, crabs and shrimp.
Hotel - Many animals, such as salmon and birds, just pass through estuaries as they are migrating to other areas
Nursery - Some animals use the estuary to lay their eggs, or rear their young; for example, frogs, salmon and nesting birds.
Restaurants - All animals that are found in the estuary use it as a source of food. This results in a very complex food web.

A sponge: Estuarine wetlands are comprised of soils, mosses and grasses that can absorb large amounts of water, and then release it slowly back into the environment. This can reduce the occurrence of floods and drought, and can protect the homes of many animals, even humans, from drastic water level changes.
A filter: Estuary water has many sources, and is often contaminated by pollutants. Estuary plants will take up pollutants when taking up water and these plants can break down chemicals or absorb the chemicals from the water.

Impacts on the Fraser River Estuary

Human activity Unfortunately, in many cases damage to the fragile Fraser River estuary can be traced back to human activity.

Early settlers recognized the potential of the fertile soils along the Fraser for growing food. Busy harbours and towns grew nearby because of easy access to inland and marine transportation routes.
This intensely used river is home to five deep-sea port facilities, a ferry terminal, several fishing boat basins and numerous marinas and floating homes.
Over 200 companies, including several large wood and fish processing facilities operate on or near the Fraser. It also accommodates the largest log booming grounds in the world.

Other human activities that may affect the estuary include:

Agriculture
Fishing
Logging
Boat traffic
Roads
Residential, commercial, industrial developments
Wood processing
Liquid waste disposal
Recreation
Dyking

We must acknowledge the economic importance of these industrial activities as well as the significance of using the Fraser River estuary as human habitat. However, it is also important to recognize that approximately 75% of wetland habitat has been lost to human activity and development, which is why it is essential that we take care of what remains of the Fraser River estuary.

The industrial wood debris problem

Excess industrial wood debris has significant environmental impacts on wetland habitats along the Fraser River estuary. The following are some of the problems that River Works is trying to address:

Physical injury to vegetation: The movement of large pieces of industrial wood debris flattens, grinds and scours wetland vegetation, which makes it near impossible for vegetation to grow and habitat and food for other native organisms.
Competitive exclusion: Invasive plant species are often opportunistic and will quickly invade wetlands that have been degraded by industrial wood debris. This prevents native plant species from growing and may contribute to a loss of biodiversity.
Reduced primary production: industrial wood debris can compact and scour sediments, which may result in poor soil fertility, and thus affect plants and habitat values. If the top layer of the sediments is removed underlying anaerobic layer will be exposed and release hydrogen sulphide, which can greatly reduce habitat quality. Hydrogen sulphide is also responsible for the rotten egg smell you may have experienced in a marsh!
Displacement: Where industrial wood debris accumulations are heaviest, marsh vegetation can be completely displaced, resulting in loss of habitat for salmon, other fish and invertebrates.
Toxic chemicals Industrial wood debris can result in the loss of tannins—a chemical defense mechanism in plants that makes vegetation unpalatable or toxic when consumed—into the habitat. Additionally, the decomposition of debris can have toxic effects as oxygen concentrations are reduced while accumulation of toxic hydrogen sulphide increases.

It is estimated that there is approximately 80,000 cubic metres of wood lying in red-coded habitat (highly productive areas) along the Fraser River estuary. River Works volunteers remove industrial wood debris by hand from wetland areas and put it into dumpsters, which are then taken to a fibre recycling plant.

Non-native vegetation

River Works has focused its efforts on reducing and controlling the impacts of English Cordgrass, purple loosestrife and scotch broom at its sites. These non-native species are very hardy and can out-compete many native plants. In areas where invasive species have become established, there is often a lack of biodiversity, as native plants are crowded out and potentially lost from the site.

These plants are cut at the base—as close to the ground as possible—and then disposed of off-site. As these plants are often able to reproduce with amazing speed and under less than ideal conditions it is essential that the vegetation is removed from the site and disposed of properly (generally via incineration).

English Cordgrass (Spartina anglica) is a hybrid, perennial, salt tolerant grass with a distinct 45-90° angle between the leaf blade and the stem. Spartina is extremely aggressive and will displace existing habitat as it spread’s over mudflats via seeds and/or rhizomes and moves upwards into natural salt marshes. Spartina was intentionally introduced into Washington in 1967 in order to stabilize sediments along the shorelines, and was first discovered locally at Roberts Bank in 2003. Unfortunately, Spartina’s aggressive nature often results in a loss of biodiversity and habitat for water birds, invertebrates and fish when the productive mudflats are transformed into monotypic stands of Spartina.

In Washington State, intertidal areas dominated by Spartina have shown a significant decline in the abundance of shorebirds and waterfowl despite significant resources being allocated to controlling Spartina. This exemplifies the importance of eradicating Spartina from our local wetlands now, before it dominates our productive mudflats. With over 25,000 hectares of tidal mudflats in the Fraser River Delta, we have a lot at stake, but with the continued efforts of River works and our dedicated partners, we have a real chance to rid our mudflats of this invasive species before things get out of hand.

Himilayan Blackberry (Rubus discolor) is an invasive species best known for its dark purple berries that can be picked and eaten in late summer. Himilayan Blackberry is an Asian species that was introduced from India via England and is often found in streamside and disturbed areas. Himilayan Blackberry is very persistant and will grow up and over native vegetation, essentially shading other plants out of the area.

English Ivy (Hedera helix) is an invasive plant that plaques all types of

plant communities. This aggressive evergreen vine often makes its way into natural areas after escaping a residential yard. English Ivy is of particular concern, because not only can it grow along the ground, shading and out-competing native ground cover, it is also able to climb trees and shrubs, which eventually leads to the strangulation and death of the plant. Additionally, English Ivy is able to reproduce both via seeds (often dispersed by birds) and vegetatively (i.e. a new plant can grow from a very small piece of the vine).

photo by: Sue Stanfield Purple loosestrife (Lythrum salicaria) is a tall plant with bright purple spiked flowers. It is likely this plant was introduced from Europe about 200 years ago through ballast water, livestock feed or intentional plantings for horticultural uses. It has spread quickly and become a noxious weed in many wetland areas. Purple loosestrife’s purple flowers are often considered aesthetically pleasing, which can be a barrier to removal as members of the public—who do not know that it is invasive—may express concern that we are removing a bright and beautiful flower from the wetland. (photo by:Sue Stanfield)

Scotch broom (Cytisus scoparius) is a spindly shrub with bright yellow flowers and explosive seedpods that grow in disturbed areas such as on the side of highways. Scotch Broom was introduced in 1850, when three plants were intentionally planted on Vancouver Island, and since then, has spread rapidly all over B.C. Of particular concern is the long term viability of the seeds, which can remain dormant in the soil for up to 30 years as they wait for “favourable conditions” to return.

Yellow archangel (Lamiastrum) is an ornamental vine with silver-white leaves and green edges that is commonly sold in nurseries and garden stores in planters and hanging baskets. Unfortunately Lamiastrum has invasive properties and has been found encroaching the native habitat of at least one River Works site. The relative availability of Lamiastrum combined with its trailing properties, extensive root system and ability to grow an entirely new plant from a very small piece of vegetation makes Lamiastrum a serious threat to our fragile wetland ecosystems and exemplifies the need to research plant choices before introducing them into our yards and gardens.