Meeting Abstract
Diurnal exposure to air during fluctuating tides, and forces imposed by crashing waves, make the intertidal zone, the habitat of Northern clingfish, unusually stressful. To cope with environmental pressures, clingfish utilize both behavioral and morphological adaptations. Modified pelvic and pectoral fins form a suction cup, which enables the fish to attach to challenging surfaces that can be extremely rough or fouled. In this study we are interested in (1) the characteristics of the intertidal rocks that make up the clingfish habitat, (2) the impact of the changing water level on distribution, and (3) the wave forces in their environment. Clingfish distribution along an intertidal transect was recorded between June 30-July30, 2014. Each collection day we overturned every rock in the transect, noted in which quadrat fish were found and determined characteristics such as rock size and roughness. Water height in relation to the mean lower low water (MLLW) was determined for the transect. Since the tides fluctuate each day, we calculated the daily time under water (DTUW) for each fish assuming it stayed in the area in which it was captured. We deployed dynamometers at 3 locations on San Juan Island to measure the maximum wave velocities. Clingfish prefer large rocks (15cm), with a huge range of surface roughness. Clingfish were found exclusively in areas that had at least 80% DTUW, this corresponds to a low intertidal region where wave forces are expected to be high. However, the maximal flow velocities measured did not exceed 4m/s in the summer. We expect higher velocities, and potentially different distribution of clingfishes in the stormier winter.
