Note
At the beginning of the Holocene 12 to 15 thousand years ago, sea level began to rise from a point approximately 250 to 300 feet below its present position. The Indian River lagoon was obviously a freshwater system at this time and undoubtedly contained a freshwater ichthyofauna somewhat similar to that found today in the St. Johns River and marshes west of the lagoon. As sealevels increased to the point that portions of the lagoon became tidal, a marina fauna invaded the lagoon basin.