Tidal Mud Flat

April 11, 2010

Lowtide in sanibel 
Photographer: Richard W. Gross
Summary Author: Richard W. Gross; Jim Foster

The photo above showing tidal mud flats at Bunch Beach near San Carlos Bay, Florida was taken just before sunset on April 26, 2009 during an unusually low tide. I was probably 150 ft (46 m) or more from shore when I snapped this picture. It was quite interesting exploring these flats -- all sorts of marine life was exposed. On this day, the lower of the two low tides (by 1.87 ft or 0.57 m) occurred at 9:18 p.m. local time (Eastern Daylight Time). Particularly high and low tides can be counted on when the Sun, Earth and Moon are in alignment when the Moon is in the new or full phase. The Moon was a thin crescent on the afternoon/evening of the 26th (not visible on the photo). Though not aligned for a perfect “spring tide” the configuration was, nonetheless, close enough to exaggerate the tides. Additionally, the tidal force of the Moon depends upon its distance to the Earth during its period of revolution. When the Moon is nearest the Earth (perigee) the tidal force is stronger. In April of 2009 perigee occurred on the 28th. Thus a combination of the Moon being close to perigee and the near alignment of the Earth, Moon and Sun resulted in the abnormally low tide. The low tidal level may have been further amplified by winds blowing in the direction that the tide was ebbing.

Additional details: On April 26, 2009 at San Carlos Bay the Moon set at 10:00 p.m. Sunset was at 7:57 p.m. – 21 minutes after the photo was taken.