Les estuaires logent une grande quantité de
zostères (eelgrass). Quoique souvent confondue avec les algues, la zostère est
bel et bien une plante.
Plusieurs espèces de poissons sabritent sous ces plantes, dont languille,
le flet, lépinoche et la morue. Les zostères peuvent mesurer plus de trois pieds.
En observant la plante avec une loupe, on peut apercevoir de nombreuses algues, brunes,
rouges et vertes, et dautres formes de vie étranges. Sa biomasse est à peine plus
grande que la biomasse des espèces qui sy greffent.
En dépit du fait que ces plantes nont pas beaucoup été étudiées, les
zostères jouent un rôle clé dans les cycles biologiques des estuaires.
Eelgrass Beds of Our Estuaries:
A forest under water
be encountered wherever a river meets the sea. They are places where the freshwater of the
river mingles with the saltwater of the ocean, creating unique conditions, and a very
special place for a great number of living creatures. On the eastern coastline of New
Brunswick estuaries are sheltered areas, particularly where barrier beaches protect them
from the ravages of storms. This is where eelgrass is particularly abundant.
A little bit more peaceful?
The eastern coastline of New Brunswick is more peaceful in terms of obvious ocean
activity than the Bay of Fundy. Scientists call it a low energy environment. In contrast,
the Bay of Fundy is a high energy environment. Beaches on the Eastern shore are mainly
gentle, sandy, and extensive. They are still very dynamic and this is clear to anybody who
has visited a beach before and after a storm. Sometimes the beach is unrecognizable after
Hidden from view
When you spend some time along the coast, and start exploring some of its estuaries,
you'll discover that these places are teeming with life. So much so that walking on a
muddy, smelly, oozing estuary bed with the eelgrass snaking around your legs, you might
wonder what sort of living beings are hidden from your view and what hidden creatures
might grab you.
The amazing mud plant!
There is more than just eelgrass to tickle your toes. This plant makes life possible
for many creatures that spend some time, or their whole lives, in our estuaries. It grows
like an underwater forest, and is, in many places, so dense that the sandy or muddy bottom
cannot be seen from a boat or canoe. It provides shelter for fish such as the American
Eel, Tomcod, flounder, Atlantic Silverside, different species of Stickleback, Mummichogs,
and many others. Among its blades, that can grow more than 3 feet long, salmon and trout
might hide during their time spent in the estuary before going either upriver to spawn or
moving out to the open ocean.
(photo: Mary Ann Coleman)
Eelgrass is not a seaweed, even though the dried black strands of this plant can be
found washed ashore on our ocean beaches and are often confused with seaweed. The Eelgrass
(Zostera marina) is a true submerged, aquatic, flowering plant that lives in our
estuaries, especially in the large expanses of shallow water behind barrier beaches,
The Eelgrass itself is worth looking at more closely with a magnifying glass. Its shiny
green blades are often covered with brown, red, or green seaweed, stalked jellyfish,
bryozoans, and other very strange living beings. True, you will need a magnifying glass to
really explore the surface of its leafs. Scientists actually consider the biomass that
grows on the blades of Eelgrass almost as significant as the biomass of the plant itself.
Eelgrass cannot grow everywhere. The plant prefers a certain level of salinity, and it
needs the relatively calm waters of the estuary to grow in. It also needs a sandy or muddy
bottom, as it has roots that need to pick up the nutrients. It is unlike most seaweed
which attaches itself to some hard object, such as a rock, with a structure called a
A critical link
Eelgrass is a very important plant. Although not studied very well, the importance of
other seagrass beds further south in the United States has been shown in a number of
studies. This plant is a keystone species in the estuaries.
Some unanswered questions.
Some fishermen have indicated that the number of eels caught is diminishing. Another
fisherman has indicated that he has observed a dieback of Eelgrass in the estuary. In the
1930's, an epidemic reduced the extensive Eelgrass beds to little patches here and there.
The resulting reduction of species in the estuaries that depended directly on Eelgrass was
noted at that time.
(photo: Mary Ann Coleman)
It's surprising that not more research has been done into this subject and we might
want to consider stepping more lightly in our estuaries and our Eelgrass beds, as they
play a major role in our coastal ecosystems.