The first look at the salt marsh at the Delkatla Wildlife Sanctuary in Haida Gwaii is misleading. The salt marsh is characterized by shallow topography with limited drainage, the absence of freshwater incursion, regular tidal flush and organic matter input, penetration of sunlight to marsh floor, and protection from wind. Salt marshes exceed tropical and temperate rainforests in productivity and carbon sequestration, however they appear entirely unassuming. They also act as storm and erosion buffers, filters for terrestrial runoff, and crucial coastal habitat. This coastal intertidal wetland sequesters carbon at a rate ten times greater than the adjacent ecosystems. In British Columbia, salt marshes and eelgrass meadows sequester carbon equivalent to that of 200.000 cars! The extreme sequestration capacity of the salt marsh is due to a mucky, slimy, and wondrous conglomeration of substances that create biofilm. Biofilm is a matrix of sand, clay, and microphytoplankton. Filamentous algae form a net-like cotton ball structure that traps nutrients for enhanced uptake. Biofilm can be found in this salt marsh in a 2mm thick mat, somewhat slick to walk upon. A stroll through this salt marsh was encountered with small blooms of natural oil expulsion, colouring our footprints an iridescent black.
The Delkatla Wildlife Sanctuary is located on the Pacific Flyway, a major migratory stopover for over 150 bird species amidst harsh Pacific storms. The biofilm acts as a nutritious source of proteins and fats, crucial for birds like sandpipers who need to eat twice their bodyweight every day. Digging up a handful of sediment under the small, bumpy hill extrusions can land you a Peanut Worm (Sipuncula sp.). Bottom- feeding sculpins and other shiners were spotted here and there, but the main splendor was in the water. The plumes of biofilm and mud and oil that emerged with every footstep were mesmerizing. A diorama at the nearby interpretive nature center shows the tidal flush seeping into the crevices of the mud flats, and it is easy to understand why existing salt marshes are few and far between. They make perfect candidates for development for agriculture, with rich fertile soil and flat expansive topography.
Bio Film
Peanut Worm
The Delkatla salt marsh was restored after $1 million was raised in 1994 to build culverts in the causeway that blocked tidal flushes into the system, effectively drying it out. Salt marshes are often heavily vulnerable to erosion from land use change, which can impede sediment delivery to marsh banks. Another threat to salt marshes are the prospective impacts of sea level rise, which may expose foundational peat to overgrazing by predators like burrowing crabs, as seen in New England. A recognition of the invaluable ecosystem services provided by salt marshes is necessary to provide the appropriate protections and management for these hyper-productive ecosystems.
In a similar vein, estuaries also have inherent high primary productivity. This is owed to high levels of nutrient input from freshwater rivers, tides, and estuarine circulation. Estuaries occur at the interface between marine and freshwater systems. The seaward flow of freshwater over dense saltwater creates a pynocline, a mixing zone between the two types of water. The turbulence and mixing in the pynocline causes an upwelling from the seafloor into the water column, creating a perfect nutrient-rich broth for phytoplankton growth. The productivity of estuaries is locked in by a literally hidden player: clams.
Clams ingest phytoplankton and entrain these nutrients within the system. Clams excrete clay-phytoplankton fecal pellets called pseudofeces. In total, we estimated that there were 9 792 000 clams in Tarundl flats estuary, capable of filtering enough water to fill 98 Olympic swimming pools every day! Estuary species like nereid polychaetes and ghost shrimp act as bioturbators to stir up buried nutrients. Mya arenaria, the principle clam species observed in the estuary, is capable of coping with turbid conditions by reducing ventilation for short-term periods. Similar to the sand dunes, estuaries and salt marshes don’t appear to be highly active systems. Nonetheless, they are crucial in the storage of “blue carbon,” which is stored in sediments for millennia.
View atop Sleeping Beauty Mountain
Haida Gwaii’s intertidal zones are expansive, diverse, and seemingly endless. Each zone is characterized by an impossibly complex accumulation of factors – everything from ocean currents to Aeolian forces to substrate to topography, and more. These constantly shifting intertidal spaces can be extremely responsive to anthropogenic and natural disturbance. This year, our rocky intertidal bioblitz did not encounter a single sunflower sea star (Pycnopodia helianthoides), which is among the more common intertidal and deepwater sea star species. This is speculated to be due to the widespread Sea Star Wasting Disease, shown to have inflicted up to 81% in mortality in studied sites. In British Columbia, 43% of estuaries are threatened by land use changes and pollution, and only 13.5% are protected. The intricacies of species interactions in these unique ecotones are difficult to extrapolate in the context of extreme disturbance. Ongoing climate change, ocean acidification, invasion of non-native species, and sea level rise are all pertinent issues that face the MTI.
It was a privilege and stroke of luck to be able to study the MTI in a setting that, as mentioned initially, appears to abundant. However, anecdotal evidence from Haida and local residents demonstrate that the static image of the MTI we experienced is only a shadow of what once was. Haida Gwaii is a location wherein the society is uniquely intertwined with the natural environment, and this is equipped with the drive to protect it. A similar adoption of this integrated approach to MTI conservation is mandatory worldwide.
Article written by Hashveenah Manoharan
“I would like to acknowledge and extend my deepest gratitude to the Haida and all other residents of Haida Gwaii, the Haida Gwaii Institute and Dr. Scott Wallace for welcoming me and enabling this experience”