Bay of Fundy Tides,
Mudflats and Estuaries
one hundred billion tons of water from the Atlantic Ocean swirl
their way up the shores of the Bay of Fundy. This water volume
is estimated to nearly equal the 24-hour flow of all the rivers
in the world.
Petitcodiac River and the Shepody Bay estuary are important tidal
systems influenced by the phenomenal Bay of Fundy tides. The tides
reach upwards of 9 m in height on the Petitcodiac River and some
14 m in the Shepody Bay area (Hopewell Rocks), uncovering kilometers
of mudflats at low tide, and nourishing some of the world's greatest
On the Atlantic
coast, estuaries are among the most important coastal features,
both ecologically and with respect to human settlement and use.
Estuaries rank with tropical rainforests and coral reefs as the
world's most productive ecosystems, more productive than both
the rivers and the ocean that influence them from either side.
reaching speeds of 13 km/hour and carrying huge volumes of water
and suspended sediment flow up the Petitcodiac River twice a
day, depositing sediment particles on the banks as the tide rises
and only returning them into suspension as the tide recedes or
as rain events occur. The combination of these features makes
the natural concentration of suspended sediment in the river
among the highest in North America and gives the Petitcodiac
River its nickname, Chocolate River.
rock of the Petitcodiac River system, made up of sandstone, is
the possible source of high concentrations of suspended sediment.
The Petitcodiac River
River's claim to fame is its tidal bore, forming twice a day
as the tides from the Bay of Fundy push upriver towards Moncton.
A tidal bore occurs in areas of the world where tidal amplitudes
are strong, as is the case with the Bay of Fundy region. The
phenomenon is created and influenced by a number of factors including
river slope, downstream flow, river basin morphometry, moon phases,
seasons and winds.
accompanying wave or vertical front moves upriver on the incoming
tide, channeling itself into a narrower body of water such as
the Petitcodiac River. Depending on the amplitude of the phenomenon,
the wave in the Petitcodiac River varies today from a few cm
in height to as much as 75 cm (formerly as high as 2 m), and
at speeds ranging from a few to 13 km/hour.
Since the time
of the explorers and first settlers of this region, the Petitcodiac
River tidal bore has facinated visitors and local residents alike.
Through most of the 20th century, the Petitcodiac River tidal
bore (2 m) was considered to be among the top tidal bore phenomena
occuring in North America and worldwide, ranked with the Qiantang
(China), the Hoogly (India) and the Amazon (Brazil) as one of
the world's most impressive.
are a series of descriptions of the tidal bore phenomenon provided
oceanographic account of the Petitcodiac River tidal bore
les fleuves possédant une embouchure peu profonde ou obstruée
sur une mer à fortes marées présentent ce
phénomène; les plus intenses sont ceux de la rivière
Petitcodiac (baie de Fundy), du Tsien-Tang-Kiang (au sud de Chang-Haï),
de la bouche occidentale de l'Amazone (pouvant atteindre 6 m).
courants marins, Jacques Bouteloup, Que sais-je?, Presses Universitaire
de France, 1960.
Plessis' account of the Petitcodiac River tidal bore
sait que la baye de Fundy est fameuse par la rapidité
avec laquelle la marée y monte, et par l'énorme
différence qui s'y trouve dans la hauteur de l'eau de
la basse marée à la haute. Les rivières
qui s'y déchargent participent à ce reflux extraordinaire,
que les habitans du pays appelle le refoul (mascaret). Dans celle
de Memramcook, le reflux élève les eaux de vingt
pieds. A Peticoudiac on l'entend venir de très loin et
avec grand bruit. C'est un torrent furieux, élevé
de six à dix pieds (environ 2 m) au dessus du niveau de
la rivière, qui accourt en se déroulant avec un
fracas terrible. Malheur à la chaloupe, même à
la goélette qui se trouverait sur son chemin. Elle serait
immanquablement culbutée et engloutie sans ressource.
Lorsque le refoul est rendu à l'endroit où le créateur
a réglé qu'il s'arrêterait, alors tout le
niveau de la rivière gonfle en masse jusqu'à ce
que la marée soit parvenue à sa hauteur. »
des visites pastorales en Acadie de Mgr Joseph-Octave Plessis,
1812, Les Cahiers, Société historique acadienne,
vol. 11 no. 1-2-3, 1980.
ships had difficulty with the tidal bore. As he reported,
Tide is the most rapid of any of the rivers in the Bay of Fundy,
the Bore (or first of the Tide) running five or six feet high
(approximately 2 m) and sometimes seven at Spring Tides, which
makes it extremely dangerous for Vessells grounding in the River,
we were obliged to do when we went up, and when the Bore came
in it drove two of our Vessells foul of each other, did them
much damage and I was greatly afraid would have wrecked them
The History of Moncton, Volume I, C. Alexander Pincombe and Edward
W. Larracey, The City of Moncton, 1991.
Located on Shepody
Bay, the Hopewell Rocks are New Brunswick's best known and one
of Atlantic Canada's most impressive natural attraction. At low
tide, visitors walk the ocean floor surrounded by four-story-high
flowerpot sea stacks, gouged out of the cliffs by the force of
the Fundy tides. As the 14 meter tides return, these magnificient
sandstone columns turn into tiny islands, observed from the nearby
cliffs of the park or up close from a sea kayak
The Sandpipers of Fundy
summer the upper Bay of Fundy plays host to massive flocks of
migrating shorebirds. From late July to early August, the peak
of the fall migration, up to 2 million shorebirds converge on
Fundy's nutient-rich mudflats. Two of the most important sites
are located at Johnson's Mills and at Mary's Point, on Shepody
The shorebird flocks
are comprised of many species including the Semipalmated Sandpiper,
95% of whose world population depends on the Bay of Fundy mudflats
for their survival. From their breeding grounds in Canada's Low
Arctic, the shorebirds fly non-stop to the Bay of Fundy. Individual
sandpipers remain in the Bay of Fundy staging area for 10 to 20
days, doubling their weight to about 40 grams.
When the arrival
of a cold front brings strong tail-winds, the sandpipers orient
themselves south-southeast in huge flocks, finally taking wing
when high tide coincides with the end of the day. Their flight
pattern takes them well out to sea over the North Atlantic where
they catch the trade winds that carry them to landfall on the
northern coast of South America : 4,000 km in two to four days.
The majority winter in Suriname, foraging on expansive mudflats,
and roosting on beaches, in rice fields, and in mangrove swamps.
Fundy's Mud Shrimp
The tidal flats left
by the receding waters in Shepody Bay and on the Petitcodiac River
are the habitat of Corophium volutator, the mud shrimp. About
5 mm long, the shrimp feed on diatoms and detritus churned up
by the tides. As the tide goes out, the shrimp scurry along the
surface of the mud, seeking mating opportunities and leaving themselves
vulnerable to foraging birds.
In North America,
these mud shrimp occur only in the Bay of Fundy and the Gulf of
Maine. The mud contains exactly the right combination of coarse
sand and fine silt and clay particles to allow the shrimp to excavate
burrows. Under the right conditions, a square metre of mud may
contain as many as 60,000 shrimp; the average is 10,000
20,000. Because these shrimp are rich in energy and abundant,
they are the prey most sought by sandpipers. Within a short amount
of time, the birds can build up the fat reserves necessary to
fuel the exhausting flight to their wintering grounds in South
In 1971, the
international community adopted the Ramsar Convention (Convention
on the Conservation of Wetlands of International Importance),
enabling wetlands of international importance to wildlife to
be recognized on a global level. Canada signed this Convention
in 1981. Mary's Point in Shepody Bay was designated as a Ramsar
Site in 1982, whilst Shepody Bay and the Minas Basin area were
added to this designation in 1987. The designated site in Shepody
Bay includes 13,400 ha of intertidal area.
The Western Hemispheric
Shorebird Reserve Network is similar in nature to the Ramsar
Convention but applies to the recognition of shorebird areas
specifically. In 1987, Mary's Point and Shepody Bay were designated
as the first Western Hemisphere Shorebird Reserve Network in
Canada. The next year, the southern portion of Minas Basin, in
Nova Scotia, was added to this reserve.
The Fundy reserve
(Shepody Bay and Minas Bassin) is the most important shorebird
sanctuary in Atlantic Canada. To gain status as a hemispheric
reserve, the site has to host at least 500,000 shorebirds or
30% of the flyway population annually. Mary's Point is part of
the Shepody National Wildlife Area, which is owned and administered
by the Canadian Wildlife Service.
The American Shad
In the l970's and
1980's, research emerged about the phenomenal richness in nutrients
of the inner Bay of Fundy, especially Shepody Bay, and its direct
effect on the migrating patterns of the entire American shad fish
population. Dr. Mike Dadswell, a scientist from Acadia University,
tagged American shad along the Atlantic coast. He discovered that
their summer migrating patterns brought the shad from the tip
of the Florida peninsula to the Gulf of St-Laurence to Shepody
Bay, in order to live off some of the world's richest feeding
grounds. The Petitcodiac River and its tributaries significantly
contribute to the estuarine nutrient supply of this waterway.
River valley was formed during the Mississippi era over 250 million
years ago. A number of eruptions occurring during the last glacial
period are believed to have had spectacular consequences on the
topography of the region. This is attested by the extreme variety
of mineral deposits found in the southeastern region of New Brunswick
known as Albert County, on the western shore of the Petitcodiac
In 1849, the
famous scientist Abraham Gesner, inventor of kerosene, discovered
a bituminous mineral named Albertite in Albert County. During
the course of a 30-year period, over 200,000 tonnes of Albertite
were shipped to Boston. Some 8 km from these Albert mines also
lay a deposit rich in gypsum. From the old factory, once situated
on the banks of the Petitcodiac River in Hillsborough, ships
exported cargoes filled with gypsum extracted from these mines
to the four corners of the world.
The Petitcodiac River
In 1937, workers
discovered the skeleton of an almost perfectly preserved mastodon
(prehistoric elephant) incrusted in gypsum near Hillsborough
on the Petitcodiac River. The skeleton, believed to be over 37,000
years old, was transported to and has since been displayed at
the New Brunswick Museum situated in Saint John.