A crucial part of our underwater ecosystems, eelgrass beds face threats from human activity such as docks, boat moorings, log booms and coastal erosion. Efforts need to be stepped up to map, track, and re-colonize these underwater meadows.
Author: Nikki Wright, Executive Director SeaChange Marine Conservation Society
Reviewer: Cynthia Durance, Registered Professional Biologist, Principal, Precision Identification
Banner Photo Credit: Jamie Smith
Native eelgrass (Zostera marina) in Howe Sound serves as critical habitat for marine wildlife, including waterfowl, shellfish, fish and invertebrates.
These important and richly diverse habitats are most vulnerable to loss and degradation because they grow in shallow marine waters close to human activity. Eelgrass subtidal habitats in Howe Sound are presently at risk. Specific shoreline development practices, log storage locations (past and present), and boat moorage in eelgrass beds are the major impediments to the plants flourishing in the Sound.
Why is it important?
Eelgrass beds provide highly valued ecosystem services to wildlife and humans alike.
– Sound Investment: Measuring the Return on Howe Sound’s Ecosystem Assets (Michelle Molnar, 2015, David Suzuki Foundation)
Factoring these economic benefits into decision-making would reinforce the economic, cultural and ecological values of nearshore habitats within the Sound.
The meadows assist with coastal protection by providing a physical baffle (leaves) and reducing erosion (roots & rhizomes). Eelgrass also has important influences on ecological processes such as the cycle in which chemical elements and simple substances are transferred between living systems and the environment (biogeochemical cycling), sediment stability and the food web.
What is the current status?
A recent survey by the Islands Trust of all the islands of Howe Sound identified eelgrass beds along eight to 16 percent of shorelines (Table 1). Eelgrass is most likely present where the bottom is sandy or mixed with small pebbles, and most beds surveyed are described as patchy and sparse. Eelgrass does not flourish where there are large boulders or shallow sand. The survey did note areas with suitable sediment but a lack of eelgrass. This may suggest damage to native eelgrass beds and opportunities for re-colonization.
|Island||% of Shoreline||Survey Year||Potential Restoration Sites||Observed Threats to Eelgrass Habitats|
|Bowen||11.6||2013||Yes||Docks, moored boats, boat anchoring, boat wakes|
|Boyer||11.4||2013||No||Docks, chain debris|
|Gambier||8.3||2012||Yes||Historical log storage practices, docks, wharves|
|Passage||15.7||2013||No||Ropes, floating docks, moorings|
|Islands west of Bowen including Keats and *||13||2013||Yes||Docks, log booming, moored boats, water park play structures|
|* Shelter, Home, Preston, Ragged Islets, Pasley, Mickey, Worlcombe, Hermit, Little Popham, Popham, Grace, Woolridge, Anvil|
Several sites within the bays of southeast Gambier Island were identified during the surveys as potential restoration areas (Figure 1). These bays have been severely impacted by historical log boom activities. Potential restoration sites around other islands were also identified. For all maps and reports on native eelgrass in Howe Sound and related subjects, please visit the Seagrass Conservation Group.
Fish species and other marine wildlife observed in eelgrass during mapping in Howe Sound indicate that these habitats are functioning, but few eelgrass beds were classified as dense and robust. Most are continuous fringing, or patchy and sparse. Specific shoreline development practices, log storage locations both past and present, and boat moorage that block light needed for growth, create excess sediment, or physically disturb the plants are the major impediments to eelgrass flourishing in the Sound. For example, boat anchor chains that sweep across the bottom with changing tides and winds can destroy plants. Eelgrass is dependent on good water quality and thus healthy eelgrass beds serve as an indicator of good water quality near coastal communities.
What can you do?
Some Actions Contributed by CORI
Individual and Organization Actions:
- Protect eelgrass by learning where eelgrass beds are in Howe Sound.
- Familiarize yourself with Howe Sound islands’ eelgrass mapping initiatives.
- Familiarize yourself on Bowen, Passage, and Bowyer Islands’ eelgrass mapping report.
- Familiarize yourself with Sechelt’s eelgrass mapping report.
- Shoreline landowners can minimize the impact of docks by using light-penetrating materials, and using shared community docks rather than private docks.
- Shoreline owners can maintain trees, shrubs and ground cover plants close to the shore to reduce erosion and detrimental sedimentation.
- Join or contribute to funding eelgrass restoration efforts. Eelgrass habitat needs to be monitored and mapped every three to five years to evaluate changes over time.
- Avoid boating or anchoring in eelgrass beds.
- Participate in eelgrass restoration activities, and encourage your organization to participate.
Government Actions and Policy:
- Continue to financially support community eelgrass restoration and monitoring practices within Howe Sound. Ensure monitoring and mapping is occurring every three to five years, and updated data is made widely available.
- Support and facilitate community education and stewardship involving the importance of eelgrass, the threats eelgrass faces, and how coastal citizens can help.
- Consider relocating log boom tenures, or reducing size and restoring eelgrass beds.
- Prohibit shoreline armouring near eelgrass.
- Create protected zones for eelgrass areas identified as important. Within these areas; restrict removal of backshore native plants, encourage a “no anchor zone,” restrict the installation of non-light-penetrating docks, and restrict the implementation of new logging operations.
- Allow no new tenures in eelgrass habitat or habitat suitable for eelgrass restoration.
- Ban harmful chemical fertilizers and pesticides.