Do stranded sand dollars indicate hydrodynamic conditions of sandy beaches?

Abstract

This article aimed to evaluate sand dollars' distribution (Mellitaquinquiesperforata) by relating it to hydrodynamic variations on Santos Beach (Brazil). Twenty-nine samplings were carried out between March 2015 and July 2018, through 6 transects in the seawater limit, along 5.5km of the beach. The survey of data consisted of two processes: counting and biometrics of the whole individuals present. We noted the wind's direction, the height of the tide, the lunar phase, and the seasons. Canonical Correspondence Analysis and 2way ANOVAs showed that the season, the direction of the prevailing winds, and the moon phase significantly influenced the cookies' spatial distribution, results that coincide with the existing models for erosion and sedimentation. We only registered adult individuals (>4cm). The largest and heaviest individuals occurred in late summer and early autumn (March-April), which suggests that this is the species' breeding season.