*Due to internet issues, some parts of the recording are not available.
Schedule:
Date: Feb 2, 2021
Time: 10:00 - 12:30pm
10:05 - 10:20: Hysh’ke, Chief Harley Chappell, Semiahmoo First Nation - Opening remarks and acknowledgment
10:20: Wetland Portion - Introduction to Speakers and Topics
10:30: Lisa Dreves - Langley wetlands; their current state, biodiversity and their future
10:45: Pamela Zevit - Surrey wetlands; their current state, biodiversity and their future
11:00: Dr. Sarah Howie - Delta wetlands and Burns Bog update
11:15: Questions for speakers
11:20: Tidal Wetland Portion - Introduction to Speakers and Topics
11:25: Dave Scott - Importance of estuaries to salmonids
11:40: Chloe Hartley - Estuary plants: the good, the bad and the ugly
11:55: Marina Wright - Impact of invasive European Green Crab on marine/salt marsh habitats
12:10: Questions for speakers
12:20 - 12:30: Wrap up!
Questions & Answers From Our Speakers:
Dr. Sarah Howie:
1. Why fight natural process by using herbicides to eliminate Birch. Trees.
Invasion of birch trees is a concern in Burns Bog (see answer to question #4). Birch are able to withstand high and fluctuating water levels, so the hydrological restoration work we have carried out in Burns Bog hasn’t naturally eliminated birch trees from restoration sites. Herbicides were used on birch as an experiment to test different control measures. Since the herbicides were not particularly effective in this experiment, Metro Vancouver is looking at other options for birch control.
2. You mentioned that flux tower from which you recorded methane emissions was in a post-harvested section of bog. Have you taken any such measurements in an unharvested section?
The University of British Columbia has two flux towers currently operating in Burns Bog. Both of these towers are located in harvested fields of different ages. Flux towers require a large area of one type of plant community surrounding the tower in order to ensure that the measurements are specific to that plant community. The harvested fields are ideal for flux towers because they generally contain one main plant community that covers a large area. In contrast, the remaining undisturbed areas of the bog contain a patchwork of different plant communities at a fairly small scale, so it may not be possible to locate an undisturbed area containing a single plant community that is large enough for flux tower measurements. However, the university has other methods for measuring greenhouse gas emissions on a smaller scale.
3. Are you using traditional indigenous knowledge/methods in your work? How are you decolonizing your practice?
Most of the City of Delta’s past restoration work has been focused on retaining water in the bog and has therefore been treated as an engineering issue. As the Burns Bog management team begins to explore other restoration opportunities in the bog, many stakeholders, including those with traditional indigenous knowledge, will be included in the consultation process. Two examples of this are the wildland fuel management project (minimizing fire risk of natural areas that interface with buildings and critical infrastructure) and the management planning process for the Delta Nature Reserve and the Delta-South Surrey Regional Greenway.
4. Birch trees are a natural stage in restoration of damaged landscape. If its purpose is considered, can it not work towards bog restoration? I realize it might take decades to transition.
It is true that birch is sometimes a natural stage in the regeneration of disturbed sites. In some areas of Burns Bog where the water table is high and the birch coverage is sparse, we are letting the natural bog processes run their course. However, once a forest gets established in an area affected by drainage, the tree canopy intercepts rain water, the trees use a lot of water that the bog needs to maintain itself, and Sphagnum mosses generally cannot survive under the dense shade and leaf litter of deciduous trees. Older, established birch forests in Burns Bog have a low water table and very dry peat. The damage to the peat from these dry conditions is generally irreversible and it is unlikely that historic bog conditions would reestablish in these highly disturbed areas, even with intervention. In addition, many of the birch trees in Burns Bog are an introduced European species that is not desirable in a natural area. Our goal is to block the establishment of new birch forests so that bog species can become established instead.
5. Why is Ramsar not included in Robert’s Bank?
At the time of the designation of the Fraser River Delta Ramsar site, the province was still in the process of designating the Roberts Bank Wildlife Management Area. Provincial staff did not want to delay the submission of the Ramsar application. The decision was made to wait for the Roberts Bank Wildlife Management Area to be formally designated and then apply to amend the boundaries of the Ramsar site once the designation was complete. The City of Delta has since written to the provincial government requesting that Roberts Bank be added to the Ramsar site.
Maria Wright:
Note: Answers were provided in February 2021; conditions and knowledge may change.
1. Has Vancouver Island noticed any issues with their ecosystem because of their established EGC population?
Observational evidence (vs scientific studies) indicate that the abundance of native Hemigrapsus shore crabs may have declined where EGC have been present for several years. An experimental field based study in Barkley Sound indicated that a higher abundance of EGC (5 crabs/ m2) may be leading to degradation of eelgrass habitat.
2. What defines an EGC population as 'established'? And how do you prevent the areas that the crabs have been observed from becoming established?
EGC are considered established in an area if they persist as a self-sustaining population. This requires survival within the new environmental conditions where they are invasive as well as successful reproduction in the new area.
The best way to prevent establishment of EGC is to detect them early and respond before they are able to reproduce at the sites of new detection. A Response is a high intensity trapping effort to remove individuals, assess their abundance and distribution in the new area, and keep them from reproducing. This is intended to reduce the chance of EGC establishment. If EGC become established, then long term control and management is required.
3. Why introduce these Green Crabs? What is the commercial value of these crabs? Was there a purpose?
EGC were not introduced to the Pacific Region on purpose. They likely arrived in San Francisco Harbour in 1989 as stowaways within packaging material for transporting shellfish. EGC have a long larval lifestage which is planktonic and floats in ocean currents. EGC moved north naturally into British Columbia through larval dispersion after their accidental introduction to California.
4. Have you found any EGC in Robert’s Bank?
No EGC have been detected in Robert’s Bank to our knowledge as of today (February 2021).