Meeting Abstract
Many animals that make their living in the rocky intertidal cope with the forces of crashing waves by securing themselves to the surface of hard substrates such as rocks in which surface roughness has a crucial impact on the animal’s ability to attach. Northern clingfish inhabits the rocky intertidal and have been shown in lab studies to have the remarkable ability to stick to surfaces with a large range of surface roughness by means of their ventral suction disc. To compare this ability to the range of roughness encountered in its natural habitat we had to overcome several methodological problems. Clingfish can be found in the lower and lower middle intertidal zone causing short term access to rocks during low tide. To overcome this problem we molded the surface of the rocks where we found clingfish with a precise and fast hardening dental wax, allowing the molds to be analyzed later in the lab without time pressure and without removing rocks from the habitat. Technical devices for roughness measurements such as optical or contact profilometers, often designed to measure roughness of technical surfaces at a very fine scale, were not appropriate for this study, so we developed a simple method to measure roughness with inexpensive equipment in the range of coarser roughness orders. The roughness parameters used in this study were the maximum distance between the highest and lowest points in a segment per mold (RmaxDIN) and the total average distance between the highest and lowest points in all segments per mold (RzDIN). The results generated from this method show that the natural substrates in the rocky intertidal cover, and in few cases exceed, the range of roughness Northern clingfish can attach to.
