Paralia sulcata is one of 7 species out of 216 identified from 95 surface sediment samples which has a relative abundance of ≥2% of the total count. The relative abundance of P. sulcata in the surface sediments increases in the direction of increasing salinity in the surface waters, toward the mouth in high and medium runoff inlets, and toward the head in the low runoff inlets. The absolute abundance of P. sulcata in the surface sediments, and primary productivity, both increase toward the mouth in high and medium runoff inlets. Increasing valve diameter of P. sulcata is associated with both increasing salinity of the surface waters and increasing primary productivity.