Sep 26, 2024
Zostera marina: one of the world's most widespread marine plants
A heritage to study and safeguard
Nicolas Winkler
Zostera marina, commonly known as "eelgrass," is one of the world’s most widespread marine plant species. It is predominantly found along the temperate and cold coasts of the Northern Hemisphere (Atlantic Ocean, Pacific Ocean, and Baltic Sea), but it is also present in the Mediterranean Sea, where its distribution is more limited and in gradual decline.
More than just a plant that benefits coastal communities and supports the entire marine ecosystem, Zostera marina is an invaluable resource to support biodiversity, protect the shorelines, and in the fight against climate change.
We discuss this with Dr. Kristina Boerder, a researcher at Dalhousie University in Halifax (Canada) and Lead Scientist of the Community Eelgrass Restoration Initiative (CERI), who has been dedicated to research and raising awareness on these issues for years.
Related to the more well-known Posidonia oceanica, Zostera marina has a complex and fascinating evolutionary history. Originating from primitive marine algae, this species underwent an extraordinary evolutionary transition, first moving to land and then returning to marine waters.
This reverse evolution process required Zostera marina to readapt to the aquatic environment, dealing with new conditions of salinity, light, and essential nutrients for survival. The genome of Zostera marina is a valuable scientific resource as it retains traces of these evolutionary and environmental adaptations. By studying its genome, researchers are trying to understand how the plant evolved to cope with the unique conditions of the marine environment. This knowledge not only sheds light on plant evolutionary strategies but is also crucial for developing more effective conservation methods.
The meadows of Zostera marina play a crucial role in coastal ecology. Their extensive areas act as natural barriers against coastal erosion caused by storms, which are becoming increasingly frequent due to climate change.
Beyond their “protective” function, these plants are a significant hotspot of biodiversity, providing essential habitats for fish, crustaceans, mollusks, and other invertebrates that inhabit coastal marine environments.
Moreover, Zostera marina meadows are part of so-called “blue carbon ecosystems” – ecosystems capable of sequestering and storing carbon dioxide from the atmosphere, contributing to the fight against climate change.
"Research all over the world has shown that seagrasses, eelgrass among them, are very effective in trapping and sequestering carbon through different mechanisms. The meadows transfer carbon from the tissues to the sediment, where it can remain stored for long periods. This is why it is so important to protect seagrass meadows, to avoid releasing the carbon stored and support the natural benefits of their ability to sequester more." says Dr. Boerder.
Despite its ecological value and long evolutionary history, Zostera marina is currently threatened by the consequences of climate change and human impact. Pollution, declining water quality, introduction of invasive species, eutrophication, and physical damage from human activities such as hardening of shorelines, fishing and boating are putting its meadows at risk. The regression of these habitats has direct consequences not only on marine biodiversity but also on coastal stability and the economies of communities dependent on fishing and tourism.
"We reap a lot of benefits from eelgrass growing along our shores - for our economies, the places we live at, the beaches and clean water we like to swim in - but as with many things, we tend to only realize the benefits when we are losing them.," concludes Dr. Boerder.
Protecting Zostera marina is essential for safeguarding coastal ecosystems. Ecological restoration interventions, regulation of human activities, and improving water quality are among the most urgent measures.
One Ocean Foundation is strongly committed to raising awareness and promoting projects for the protection of marine plants, as demonstrated by the Blue Forest project, carried out in collaboration with leading institutions and universities. Thanks to the partnership with the Future of Marine Ecosystem research lab at Dalhousie University and CERI, the Foundation’s project gains international scope: preserving these meadows means protecting not only biodiversity but also the health of the ocean and the well-being of future generations.