Eelgrass eats CO2
Molly Clarkson —
When the tide goes out, we fetch our buckets and shovels and head for the t’aanuu eelgrass meadows, where we hunt for ḵ’ust’an crabs and dig for kyuu clams. In the spring, iinang herring coat the t’aanuu with their eggs, and there are always many creatures to see resting, feeding, and mating between the piles of long green leaves.
As well as providing an abundance of seafood, vegetated coastal ecosystems such as t’aanuu meadows help prevent shoreline erosion, improve water quality by trapping and settling sediments, and – as has been recently discovered – capture and store large amounts of carbon dioxide or CO2, the greenhouse gas that is contributing significantly to global climate change. This last characteristic is notable because by storing or “sequestering” CO2, ecosystems such as t’aanuu meadows, saltwater marshes, kelp forests, and mangroves play an underappreciated role in mitigating climate change.
Recent research has also concluded that “blue carbon” ecosystems may be even more valuable for long-term climate change mitigation than land-based carbon sequestering ecosystems such as boreal, temperate, or tropical forests. While lush Amazonian rainforests may be the first thing that comes to mind when thinking about the sequestration of CO2, it turns of that “blue carbon” ecosystems can be up to ten times more effective at sequestering CO2 than their land-based counterparts. They are also able to capture carbon for far longer – while a forest’s retention of carbon can be measured in centuries, “blue carbon” ecosystems frequently retain massive stores of carbon for millennia.
The ability of marine ecosystems to store large amounts of carbon in leaves, roots, and sediments over long time spans has a downside, however. When these ecosystems are degraded or destroyed, they not only stop capturing and storing carbon – they also release their massive stores of carbon into the atmosphere. And because humans overwhelmingly live by or near the coast, these ecosystems are at high risk of being degraded by coastal development, dredging, draining, road construction, deforestation, agricultural runoff and untreated sewage disposal. Currently, it is estimated that over one third of the area of blue carbon ecosystems has disappeared over the course of the twentieth century, and the current rate of destruction ranges between 0.7 and 7% annually.
Global studies have shown that when protected, these ecosystems are able to avoid the loss the blue carbon ecosystems. Today, t’aanuu meadows alone cover 983 km or twenty-one percent of Haida Gwaii’s coastline. The CHN-BC Haida Gwaii Marine Plan recommends the protection of the majority of the archipelago’s coastline.* In addition, the Marine Plan contains objectives and strategies related to the protection of “blue carbon” ecosystems, including a strategy that directs the partners to design a network of marine protected areas that will increase ecosystem resilience.
To support the implementation of this strategy, the Council of the Haida Nation recently engaged in the MPA network planning process for the Northern Shelf Bioregion, which includes Haida Gwaii and its surrounding waters. Earlier work done by the planning partners to identify marine areas for protection is expected to make important contributions to the development of the Northern Shelf Bioregion network.
For more information on the MPA Network planning process for the Northern Shelf Bioregion check out the website at http://mpanetwork.ca/bcnorthernshelf/.
*Gwaii Haanas makes up an additional 7.5% of the Haida Gwaii Marine Plan area but is not included as part of the Marine Plan zoning as the area is being addressed through a separate planning process.