Bryozoan and barnacle settlement in relation to initial surface wettability: a comparison of laboratory and field studies

The hypothesis that surface chemistry, specifically initial wettability, can be a determinant in settlement of estuarine macroinvertebrate larvae was tested. Of additional interest was how well laboratory settlement tests would predict results obtained in the field. Initial surface wettability has an effect on settlement of barnacle and bryozoan larvae in the laboratory and in the field. The relationship between wettability and settlement in the laboratory and in the field is opposite for the two species. Barnacles settle in higher percentage on surfaces with higher initial wettability. Bryozoans settle in higher percentage on surfaces with lower initial wettability. At intermediate levels of wettability, both species of larvae settle. Surfaces exposed to sea water did not change wettability measurably in 6 days. Settlement of barnacles and bryozoans was inversely correlated (R = -0.94). These studies demonstrate that surface chemistry can play a significant role in determining the distribution and abundance of barnacles and bryozoans.