Bay of Fundy

views updated May 14 2018

Bay of Fundy

The Bay of Fundy is a marine ecosystem that lies on the northeastern coast of North America, bordering parts of the Canadian provinces of New Brunswick and Nova Scotia and the U.S. state of Maine. It encompasses about 62.5-thousand mi² (180-thousand km²) of marine coastal-shelf habitat , mostly less than about 660 ft (200 m) deep. The Bay is renowned for its exceptionally high tides, which can exceed 53 ft (16 m) in its upper reaches in the Minas Basin. These are higher tides than occur anywhere else in the world. During the peak tidal flooding of the Bay the flow of water is about 880-million ft³/s (25-million m³/s), equivalent to about 2000 times the average flow of the Saint Lawrence River.

The astonishing tides of the Bay of Fundy occur because its long shape, great size, and increasing up-bay shallowness result in its tidal waters "piling up" to great depths. This effect is amplified by the natural period of tidal oscillation of the Bay of about 13 hours, which further pushes against the natural tidal cycle of 12.4 hours. This rare physical phenomenon is known as a "near-resonant response." The tidal heights are particularly extreme in the upper reaches of the Bay, but even in its lower areas small boats are commonly left high and dry during the twice-daily low tides, and rivers may have a reversing tidal bore (or advancing wave) moving upstream with each tide. The "Reversing Falls" near the mouth of the Saint John River is another natural phenomenon associated with the great tides of the Bay of Fundy.

The huge tidal flows of the Bay of Fundy result in great upwellings of nutrient-rich bottom waters at some places, allowing high rates of ecological productivity to occur. The high productivity of marine phytoplankton supports a dense biomass of small crustaceans known as zoo-plankton , which are fed upon by great schools of small fishes such as herring. The zooplankton and fishes attract large numbers of such seabirds as gulls, phalaropes, and shearwaters to the Bay during the summer and autumn months, and also abundant fin whales , humpback whales, northern right whales (this is the most endangered species of large whale), harbor porpoises, and white-sided dolphins .

The high productivity of the Bay once also supported large stocks of commercial marine species , such as cod, haddock, scallop, and others. Unfortunately, most of these potentially renewable resources have been decimated by over-fishing. The Bay still, however, supports large commercial fisheries of lobster and herring. There has also been a huge development of aquaculture in the lower Bay, especially in the Passamaquoddy Bay area of New Brunswick. In the late 1990s the production of Atlantic salmon had a value exceeding $100-million (Canadian). The intense management systems associated with salmon aquaculture have caused environmental damages in the vicinity of the holding pens, including the build-up of organic waste , contamination with anti-fouling chemicals and antibiotics, and genetic "pollution" caused when escaped fish inter-breed with the endangered native salmon of the Bay.

In shallow areas, the extreme tidal ranges of the Bay expose extensive mudflats at low tide. In some parts of the upper Bay these mudflats are utilized by immense numbers of shorebirds during their autumn migration . The most abundant of these is the semi-palmated sandpiper, one of the most abundant shorebirds in the world. During its autumn migration, hundreds of thousands of these birds feed on mud shrimp in exposed mudflats at low tide, and then aggregate in dense numbers on shingle beaches at high tide. The sandpipers greatly increase their body weight during the several weeks they spend in the upper Bay of Fundy, and then leave for a non-stop flight to South America, fuelled by the fat laid down in the Bay.

During the early 1970s there was a proposal to develop a huge tidal-power facility at the upper Bay of Fundy, to harvest commercial energy from the immense, twice-daily flows of water. The tidal barrage would have extended across the mouth of Minas Basin, a relatively discrete embayment with a gigantic tidal flow. Partly because of controversy associated with the enormous environmental damages that likely would have been caused by this ambitious development, along with the extraordinary construction costs and untried technology, this tidal-power facility was never built. A much smaller, demonstration project of 20 MW was commissioned in 1984 at Annapolis Royal in the upper Bay, and even this facility has caused significant local damages.

[Bill Freedman Ph.D. ]