Meeting Abstract

4.4  Saturday, Jan. 4 08:45  Sticking to slippery surfaces – the impact of fouling on suction adhesion in Northern Clingfish DITSCHE-KURU, P.*; WAINWRIGHT, D./K.; SUMMERS, A./P.; University of Washington, Friday Harbor Labs, US; Havard, Cambridge, US; University of Washington, Friday Harbor Labs, US pditsche@UW.edu

In aquatic environments solid substrates are fouled by bacteria, algae and invertebrates. A biofilm starts to form just a few hours after a surface is immersed, and the surface becomes more complex and diverse with time. This growth changes the elasticity and surface roughness of the primary substrate, and therefore the attachment conditions for benthic organisms. In this study, we investigate the influence of fouling on the adhesive strength of a small, suctorial intertidal fish, the Northern clingfish. We incubated surfaces of various roughness for six weeks in the Salish Sea, leading to a substantial biofilm and periphyton. We compared the adhesive force of the fish on unfouled and fouled substrates with four selected roughnesses. We tested additional unfouled substrates of increasing surface roughness to identify the upper threshold of surface roughness. Northern clingfish less than 10 cm in TL could not adhere to surfaces rougher than a 2-4 mm grain size. Clingfish were able to attach to both fouled and unfouled smooth substrates with equivalent tenacity. However, the tenacity on fouled, rough substrates was less than unfouled, rough substrates. This decrease may be because the biofilm acts like a lubricant, and lowers friction between the disk margin and the substrate. Nevertheless, even on smooth, fouled surfaces the fish generate impressive adhesive forces about 150 times higher than the body weight of the fish.