What are seagrass and eelgrass?
Eelgrass, or Zostera marina, is one of 72 species of marine flowering plants known as seagrasses! These seagrasses are unique in that they are the only marine plant with both shoots and rhizomes that live completely under the water. Seagrasses form large underwater meadows in the shallow, soft sediment of coastal waters and depend on many factors to thrive. Eelgrass meadows provide essential resources to Kataq (American eel), a species of cultural significance to the Mi’kmaq.
Where is it found?
Eelgrass is a widely distributed plant with known locations in 6 different bioregions within the oceans of 191 countries! It can be found in Canada, where out of the 6 species of seagrass in the country, eelgrass (Zostera marina) is the most common and widespread. Eelgrass has spread along the shores and can be found in the Atlantic, Pacific, and Arctic ocean. On the Atlantic side, eelgrass can be found as far south as North Carolina and as far north as Greenland! Here in Nova Scotia, eelgrass beds are found along the entirety of the coast including the South Shore, Eastern Shore, and along Cape Breton island.
Decline
It is estimated that since 1980 we are losing an additional 110 km2 per year (about the same area as Disney World!)
Unfortunately, seagrasses (including our very own eelgrass) have been experiencing dramatic declines around the globe. It is estimated that since 1980 we lose an additional 110 km2 per year (about the same area as Disney World). Seagrasses, like many aquatic plants, are especially vulnerable to human induced stressors. In Nova Scotia, this is nutrient pollution and coastal development due to human land use along the coasts and rivers, invasive species, destructive fishing and aquaculture development, and warming waters as well as the spread of diseases due to climate change.
Benefits of eelgrass
Biodiversity
Eelgrass meadows are very productive and biologically diverse ecosystems. The leaves of the eelgrass themselves are home to many different algae which grow on the eelgrass leaves and in turn foster micro-fauna such as snails, small anemones, barnacles and others. Eelgrass is also home to many detritivores and herbivores who love to graze on the dead and living materials that make up these meadows. Many fish species and invertebrates use eelgrass meadows as nursery habitat, as well as for foraging and protection. Some creatures who call Nova Scotian eelgrass meadows home are shrimps, sculpins, snails, perch, cod, salmon, lobster, and Kataq (eel)! The Mi’kmaq are culturally connected to Kataq as this species has traditionally and continues to be a vital food source. For some Mi’kmaw communities, Kataq was the main source of food during the winter months. It has also been used for medicinal purposes and for traditional cultural practices. Eelgrass beds are also important habitat for some waterfowl, like the beloved (and sometimes feared) Canada Goose.
Fisheries
Because seagrass beds are a suitable habitat for a wide variety of species, they are strongly linked to global fish catches – 21.5% of the most commonly fished species in the world rely on eelgrass as a nursery ground, such as several flatfishes, cod, salmon and herring. In North America, studies have shown that when eelgrass beds experience significant decline so do commercially important species such as clams, lobster, crab, scallops, cod, and flounder.
Blue Carbon
Seagrasses sequester about 10% of all blue carbon buried in the ocean every year, while only covering 0.2% of the ocean floor
Blue carbon is a term that is used to describe carbon that is circulating and stored in the world’s oceanic and coastal waters and ecosystems. This carbon can be found in both living and non living things, as well as above and below ground. Seagrasses, due to their overall fast growth rates, can capture carbon in their leaf and root system about 35 times faster than tropical rain forests on land. Researchers estimate that seagrasses alone sequester about 10% of all blue carbon buried in the ocean every year, while only covering 0.2% of the global ocean floor. If undisturbed, the carbon buried in these sediments can remain there for millenia.
Shoreline Protection and Water Quality
Seagrasses are an important tool in protecting our coastlines and help to combat erosion by minimizing the energy of incoming waves before making landfall. This decrease in energy can also lead to an increase in sediment deposits from incoming waves, which in turn further contributes to the minimization of wave energy.
On top of everything previously mentioned, seagrasses also contribute to water quality! Seagrasses act like a filter, trapping sediment and absorbing nutrients suspended in the water column. These processes change season to season, but do result in increased water quality when compared to areas with no vegetation/seagrass.
Protection
Thankfully, some progress is being made on protecting eelgrass in Canada, but more work still needs to be done! Eelgrass has been designated as an Ecologically Significant Species (ESS) due to the variety of benefits it provides, and it is protected from harmful disruption, alteration, and destruction by the Fisheries Act. Due to the importance of eelgrass, and all other seagrasses, more research and restoration efforts (like CERI) are essential for it’s survival in the face of human development, interference, and climate change.
References
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