Assessing the effect of salinity on barnacle adhesion and biomineralization

Abstract

Barnacles are dominant members of marine biofouling communities throughout much of the world’s oceans. The base of the barnacle attaches to surfaces with secreted proteinaceous adhesives that bond with surfaces and cure. Although the biochemical mechanisms involved in barnacle adhesion are starting to be understood, relatively little is known about how the environment affects barnacle adhesion and base plate mineralization. Here, the impact of variations in salinity on adhesion strength and biomi- neralization in the barnacle Amphibalanus amphitrite was assessed. Barnacle larvae were cultured from adults collected from the Beaufort Inlet, NC, where salinity is typically within the range of 30 – 36. Larval cultures were maintained at a salinity of approx- imately 35. Barnacles were settled on T2 silicone coated glass panels. Starting at 11 days post-settlement, juveniles were gradu- ally acclimated to eight target levels of salinity, ranging from 10 –45 in steps of five. After six weeks growth at target salinities mortality was low on all panels and not significantly affected by salinity. Growth, measured as area of the barnacle base plate, was also not affected by salinity. We will report on ongoing assessments of adhesion strength, the composition and abundance of adhesive proteins, and micromechanical properties of the shell plates (microhardness, fracture toughness, and density). Initial results suggest that A. amphitrite is well-adapted to a broad range of environmental salinities.