Marine Prairies

Have you ever heard of marine prairies? Do you know how important they are?

Sea grass beds or sea grass meadows, as the name implies, are formed by one or more species of sea grasses (Figure 1), which can form a complex habitat in estuaries, rivers or lagoons.

Figure 1 - Zostera marina

Their ancestors were terrestrial plants, which managed to adapt to the aquatic environment, living submerged in salt or brackish water. As such, sea grasses also have roots, stems, leaves and produce flowers, fruit and seeds.

They are found in quiet places, far from currents and in places where they can receive sunlight to carry out photosynthesis, as such, they are located in shallow areas, although there is a record of having been found at a depth of 70 meters, but in places where the water was crystal clear.  

There are about 70 species around the world and Portugal (mainland) has 3: Zostera marina, Zostera noltii and Cymodocea nodosa

Figure 2 – Distribution of seagrass around the world

 

But why are they so important? Well, sea grasses play two important roles that affect us directly or indirectly:

– They are important agents in the fight against climate change, fixing/removing a large part of carbon dioxide from the atmosphere, through the process of photosynthesis. And this fixation can be 30 times greater than terrestrial forests and 35 times greater than tropical forests.

– Function as a protection zone and nursery for marine life. They create a favorable habitat for countless species of fish, molluscs and crustaceans to feed there, have their young and seek protection.

On an economic/commercial level, grasslands are also of great importance, as one fifth of the 25 most important species for fishing use these areas.

Unlike the mainland, where there are (at least) two important seagrass beds (Rio Sado and Ria Formosa), the Azores, due to its geological characteristics, do not have seagrass beds, but have other extremely important habitats (coral gardens and sponge gardens, for example) that function like sea grass meadows and it is imperative that they be conserved.







References

Figure 1 - https://upload.wikimedia.org/wikipedia/commons/1/1a/Zostera_marina_nf.jpg

Figure 2 – Short F. et al, 2007. Global seagrass distribution and diversity: A bioregional model.

Journal of Experimental Marine Biology and Ecology 350, 3-20.

https://doi.org/10.1016/j.jembe.2007.06.012

 

Short F. et al, 2007. Global seagrass distribution and diversity: A bioregional model.

Journal of Experimental Marine Biology and Ecology 350, 3-20.

https://doi.org/10.1016/j.jembe.2007.06.012

 

Cunha A. et al, 2011. Seagrasses in Portugal: a most endangered marine habitat.

https://doi.org/10.1016/j.aquabot.2011.08.007

 

Unsworth RKF et al., 2018. Seagrass meadows support global fisheries production.

Conservation Letters. 2018; e12566.

 

Nordlund LM et al., 2018. Global significance of seagrass fishery activity. Fish and

Fisheries 19, 399–412.

 

Fourqurean JW et al., 2012. Seagrass ecosystems as a globally significant carbon

stock. Nature Geoscience 5, 505–509. https://www.nature.com/articles/ngeo1477

 

Mcleod E. et al., 2011. A blueprint for blue carbon: toward an improved understanding

of the role of vegetated coastal habitats in sequestering CO2.

https://doi.org/10.1890/110004

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