Eelgrass Research
By Dante Torio

• Traditional Ecological Knowledge as our guide.

• Listening to what the elders are saying about eelgrass, its state, waterfowl feeding behavior, and meat quality.

• “Before (i.e., 1975), geese and other waterfowl were too fat to fly after eating eelgrass; now they are skinny and do not eat eelgrass anymore.”

• “Eelgrass was dark green, clean, and as long as boat paddles; now they are black, short, and slimy.”

• “Our faces were full of salt when we traveled out of the bay, not anymore.”

•Eelgrass is one of the 16 kinds of underwater flowering plants widely known as seagrass.

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•Eelgrass or Zostera marina in Latin or SHIKAAPAASHKWH in Cree, grows in the cold regions of the northern hemisphere.

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•Peak growing season in James Bay is in September.

Very resilient

• has genes for freshwater and saltwater tolerance 

• get nourishment through leaves and roots

• resistant to infections 

• adapted to low light (turbid) conditions

• adapted to drying and osmotic stress (water imbalance) during low tide mainly due to the high concentration of sugar and pectin (gelatin-like substance) in its tissues

• Resistant to toxic heavy metals

UV susceptible

Eelgrasses are sweet

• 90% of eelgrass plant matter is sucrose (ordinary table sugar)

• Eelgrass is considered as ‘marine sugarcane.’

• Sugar is used by eelgrass in osmosis to draw fresh water in and leaves the salts out

• The higher the salinity of water surrounding eelgrass, the sweeter the eelgrass plants

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Finding 2. Sugar concentration in eelgrass is reduced by a high concentration of nitrogen in the water

• The more nitrogen in the water, the less sweet the eelgrass

• Sources of excess nitrogen in the water includes:

• Fertilizer, animal, and plant matter from the atmosphere

• Excess nitrogen can cause growth of bacteria and algae

Finding 4. The severity of dead eelgrass leaves was related to the following:

• Excessive amount of impurities (Total Dissolve Solids), i.e., organic matter and minerals (e.g., calcium, silica, magnesium, iron, etc.) in the water column

• TDS increases as you go south of the sampling areas

• It seems like silica is related to the plume

• There are more cocconeis in marginal eelgrass than healthy ones

• Cocconeis and other diatom multiply because of excessive amounts of dissolved silica (from sand, rock, and silt)

• Silica is released from detrital materials (clay, sand, and rocks) when these materials interact with seawater and wave action (Mackenzie and Garrels 1965, Fabre et al., 2020)

• There's higher silica along the La Grande plume

• Marginal eelgrass areas are also infested by cyanobacteria (a noxious type of blue-green algae)

• Impacts: Cyanobacteria competes with eelgrass for light and space

• Decaying bacteria produce noxious gases and toxins

•TEK guides what, when, and where to gather data  (indicator species, locations, peak growing season).

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•TEK + Western science develop questions and hypotheses.

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•What is in the eelgrass that makes geese fat?

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•Why did geese stop eating eelgrass?

•What causes eelgrass to turn black, short, and slimy?

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•Can we bring eelgrass back to their previous (1975) state.

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•Western Science helps how to collect and analyze data.

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•WS and TEK co-develops insights.

•Eelgrass reproduce through seeds and young shoots.

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•Both annual and perennial types.

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•Freshwater lineage but fully adapted to marine conditions.

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•Grows best in soft sediments(70% silt: clay).

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•Shallow environments (0.33- 2.4 meters).

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•Wide tolerance to salinity (2-20 PSU).

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•tolerate temperatures between -1 to 25 °c.

USA, Puget Sound, 40 years of monitoring

• Wasting disease, recovered

• Resilient to Global

• More vulnerable to local factors  

Australia’s massive and long-term seagrass decline.

• Smothering of fine sand from eroded and deforested areas.

• Nutrient inputs to the bay (dead plant materials and fertilizer).

James Bay.

• Decline in the early 90s

• Slow to no recovery

Finding 1. We found a link between goose fat content and eelgrass sugar!

• The kind of sugar (e.g., sucrose) that is in eelgrass is the form that is easily digestible and provides energy

• Migratory waterfowl requires a tremendous amount of energy stored as fat for long flights during migration

• Among known geese plant foods in James Bay, eelgrass had the highest sugar content.

Finding 3. Reference sites have sweeter eelgrass than marginal sites.

• Eelgrass was sweeter in areas where Weewobwaow (Brant’s Goose)  were feeding

• Sites where Weewobwoaw were feeding, had fewer Cocconeis

Finding 5. Eelgrass leaves were infested by slimy, tiny, scale-like creatures called Cocconeis

• There are two kinds of them Cocconeis scutelum and C. placentula

• The shell of these Cocconeis are made up of pure silica

What does Cocconeis do to eelgrass

• Prevent light from reaching the leaves (less sugar produced, therefore less sweet eelgrass)

• discourage geese and other animals from eating eelgrass leaves (Sieburth and Thomas 1973)

• make the leaf surfaces hot during the day and choke the leaves with toxic gas during the night (Noisette et al. 2020)

• Transmit UV radiation to the leaf surface killing the plants (De Tommasi et al., 2018)

• Patterns of dissolved organic matter plume from La Grande  detected by satellite

• Eelgrass closer to the land and in sheltered bays is in a better state compared to more offshore eelgrass.

• Sugar provides the vital link between geese and eelgrass

• Excessive amounts of impurities in coastal waters resulted in more dead eelgrass leaves

• Infestation by Cocconeis resulted in reduced photosynthesis, thereby reduction of sugar in eelgrass

• Heavy Cocconeis presence in leaves could be preventing geese from feeding on eelgrass

• Silica is likely coming from effluents from major rivers such as La Grande, and they are being released as they interact with salt water.

• There is enough evidence showing that Cocconeis presence, competition with cyanobacteria, and impurities in coastal waters have resulted in eelgrass decline.