Bay of Fundy tides

Eastern Canadian seaboard tidal characteristics result from a combination o f diurnal (daily) and semi-diurnal (twice daily) tides, the latter mostly d ominant. Because of the proportions of the Bay of Fundy, differences in tid al range are governed by near resonance with Atlantic tides. Exceptionally high Fundy tides result from this phenomenon, with upper reach tidal ranges commonly >15 m. Although Fundy tide curves are sinusoidal, tide prediction requires consideration of marked diurnal inequalities. Overlapping of the cycles of spring and perigean tides every 206 days results in an annual pro gression of 1.5 months in the periods of extra high tides. Strong tides can occur at all seasons, depending on the year. Considerable variation result s throughout the year, with six distinct cycles recognized. Tides play a ma jor role in erosion and in complex interactions among Fundy physical, sedim entological, biological, and chemical processes. Recent observations on mud flat grain size alterations, over-deepening areas of the sea bed, and bent hic community changes, indicate changing environmental conditions in the Ba y, possibly caused by increased! hydrodynamic energy in the system.