SCCF – Sanibel Tides

“Limitless and immortal, the waters are the beginning and end of all things on earth.” – Heinrich Zimmer, Historian.

Kristie Anders, SCCF Education Director, Kristie Anderswas our guest speaker last Friday morning.  Kristie’s talked about the influences the Moon and the Sun have on our Tides.

As the Earth rotates, the Moon orbits our planet. The distance between the Earth and Moon changes slightly during rotation and the strength of the gravitational pull on Earth also changes. The gravitational pull causes our oceans to bulge out in the direction of the moon and on the opposite side of Earth another bulge occurs because the Earth is being pulled toward the moon. The ocean bulges create our tides. High tide when the pull is greatest. Now add to this land mass and breaks in large landmasses, inlets, bays, rivers, estuaries, etc. Add positioning of the earth in its rotation, distance from the equator, and topography of the landmasses, weather, and currents. Now we’re talking. Here on Sanibel the water masses originate in the transition region of the Loop Current and the Florida Current.

“The Loop Current is an ocean current that transports warm Caribbean water through the Yucatan Channel between Cuba and Mexico. The current flows northward into the Gulf of Mexico, then loops southeastward just south of the Florida Keys (where it is called the Florida Current), and then just west of the westernmost Bahamas. Here, the waters of the Loop Current flow northward along the U.S. coast and becomes the Gulf Stream”. http://www.wunderground.com

The ebb and flow of the tides in and out play an important role in our ecosystem. High tides bring nourishing sediment and sea life into the estuaries. “Estuaries are coastal areas where freshwater mixes with ocean water that is delivered by the tides. Estuaries are home to biologically diverse and unique plant and animal communities.”Encyclopedia.com.  High tides bring in nutrients that create food for our fish, birds, and other wildlife. Shallow water pools provide nursery areas for fish and shellfish. Mangrove areas thrive along our island estuaries where many birds breed and nest.

Birds plan their feeding patterns on the tides. Long legged and taller birds have a longer feeding timeframe when the water is deeper and as the tide goes out; shorter legged birds feed in shallower water. Tides provide transport for organisms that begin life protected in the shallow areas of our estuaries and when mature use the tide to transport them out to the sea. Seagrasses are pollinated by water flow. Tides affect coastal shorelines in many ways…loss of beach sand and changing shorelines. Seashells are distributed along our shorelines, so much so, that Sanibel & Captiva are called the Shell Islands, known for the best shelling in the world.

When the sea level is rising or falling, water is flowing to and from the ocean. This flow causes currents called tidal currents. Tides enter San Carlos Bay threw three narrow water passageways under the Causeway Bridge and one in Red Fish Pass. Depending on water flow restrictions and wind tide times can reach different locations within our area and with as much as three hours difference. High tides drive ocean waters to our shores and along with wind drives currents through our water passageways and when the tide recedes causing low tide, leaving sediment behind with nutrients that our environment and wildlife thrive on.