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Sanibel Sea School provides update on sand dollar research

By Staff | May 6, 2020
PHOTO PROVIDED Graph depicts adult abundance each month from sampling. It shows a high number of individuals in the summer months, with a steady decline in the spring and a sudden drop in October.
PHOTO PROVIDED Graph depicts juvenile abundance in the same months during 2019. In an inverse relationship to adults, it shows an increase in juveniles in the spring and fall, but no juveniles found in the summer months.

On April 28, the Sanibel Sea School reported that it is conducting a 10-year study on sand dollars (Mellita quinquiesperforata) to analyze spawning and growth rate patterns.

Currently, it is headed into year four of the study and has started to notice some annual patterns.

Sampling has shown an abundance of adult individuals in the summer months, with a steady decline in the spring and a sudden drop in October. For juvenile individuals, it shows an inverse relationship to adults; there is an increase in the spring and fall, but no juveniles found in the summer months. Juvenile sand dollars are defined as those measured less than 40 centimeters, or about 16 inches.

The Sanibel Sea School is less than halfway into its study and it is too soon to draw conclusions, but it is starting to see a correlation between annual spawning and growth rates. There are many variables playing into the study, like temperature, weather and anthropogenic activity.

Meanwhile, the Sanibel Sea School recently discovered the largest sand dollar of the project to date. Found in February, it was 124 centimeters – nearly 29 inches – long.