Meeting Abstract
The gregarious settlement of dominant intertidal organisms, such as barnacles, is essential for recruitment and it’s a critical determinant in the structure of the adult population. However, the recruitment density of larvae is largely dependent on physical and temporal factors, which interact dynamically in the intertidal. The barnacle, Chthamalus panamensis, found on the Pacific coast of Panamá is a dominant organism that has a higher settlement during neap tides than spring tides. In this study, diel cycles, substrate composition, and other physical parameters (temperature, wind direction, wind speed, and tide amplitude) were studied during the summer 2016 to understand the settlement behaviour of this species, particularly during the quarter moons. Settlement of C. panamensis, was higher during diurnal than nocturnal neap tides, which correlated with the warmer temperatures that occur during the day. We expected that bigger tidal amplitude and stronger inshore winds would enhance settlement rate, since this would provide transport and onshore delivery of more planktonic larvae. However, wind speed and wind direction had no significant effect on settlement, while lower tidal amplitude positively correlated with higher settlement rates. As for substrate composition, color was not a strong driving factor for substrate selection since there was no significant difference in settlement rates between the different colored plates. For substrate texture however, settlement was higher on plates with more abrasive sandpaper-like texture that had a more even microstructure. This study provides a better understanding on the settlement patterns of C. panamensis and the insight that is gained when considering the interactions among temporal, physical and hydrodynamic conditions that exhibit the intertidal ecosystem.
