Jun. 12, 2012

The Bay of Fundy Tides

by Coastal Studies for Girls

Click to enlarge images
by Amy, 10th Grade, Coastal Studies for Girls
 
In Marine Science class, we have been talking about how the tides affect the ocean. Tides are an example of a force that greatly affects the organisms living in the rocky intertidal zone, mud flats, and salt marshes. Intertidal organisms have adapted to live in areas that are only under water for parts of the day.  One place where the tides have an extreme effect on the ecosystem is in the Bay of Fundy.
 
I remember going to the Bay of Fundy and walking through Alma when I was little.  I would see boats that had been floating in the bay only hours before, that were left beached on the sand.  I would then wonder what forces could create such tides.
 
In the Bay of Fundy, the tide can fluctuate by up to 15 meters -- the greatest tidal fluctuation in the world.  The primary cause of these enormous tides is the shape of the Bay of Fundy; the bay is shallower, narrower, and longer than the rest of the Gulf of Maine, of which it is a part.  As water enters the bay, it gets compressed into a smaller area and piles up along the coastline. As the water level continues to rise, the water spreads out along the shore. The Fundy tides are also abnormally large because the oscillations arising from flow over the Bay floor closely synchronize with the tides driven by the moon.  This causes most of the tidal water to surge in and out of the bay at once.
 
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These gigantic tides have a substantial effect on the ecosystem.  The strength of these tides causes the bottom of the bay to be constantly disturbed.   Every time the tide comes in, more sediments get disturbed.  The presence of  disturbed sediments in the water makes it really turbid, so light doesn’t penetrate deeply, making it more difficult for phytoplankton to photosynthesize.  This reduces the primary productivity and phytoplankton growth in the Bay of Fundy relative to other parts of the Gulf of Maine.
 
The enormous tides also have a large impact on the rocks of the coastline.  The red sandstone coastline is constantly being eroded by the tide.  As this erosion continues, more fossils that have been layered in the sedimentary rock become exposed.   However, these newly exposed fossils come at a price.  Some of the coastline -- including sea arches and sandstone towers -- are collapsing and disappearing. 
 
The Bay of Fundy is an integral part of the Gulf of Maine.  The bay is sometimes referred to as a nutrient pump because it helps disperse nutrient runoff from estuaries and mudflats.  When nutrients enter the bay from the land, they are taken with the tides, and are dispersed into the Gulf of Maine.  These nutrients continue to travel into the eastern Maine coastal current and provide nutrients to other ecosystems. 
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