Meeting Abstract

62.11  Wednesday, Jan. 6  The effects of substratum on patellogastropod size, abundance, and recruitment in a geologically complex temperate region PEROTTI, Elizabeth A.; University of Hawai’i, Manoa eperotti@hawaii.edu

Understanding the abiotic and biotic factors that influence spatial and temporal variation in the rocky intertidal is important for conservation of communities that face increasing alteration and degradation on a global scale. Variation in patellogastropod communities, which directly affects other trophic levels, is easily observed in body size and abundance. Limpet abundance, size, and number of limpet recruits were recorded along vertical transects on basalt, chert, sandstone, granite, and rip rap in the San Francisco Bay Area for all sympatric species observed at these sites. Vermeij (1972) proposed that upper intertidal species will exhibit a positive relationship with size and tidal elevation, whereas lower intertidal species should have the opposite trend. These predictions of shore-level size gradients for upper and lower intertidal species were generally supported; however, the relationship between size and tidal elevation differed by rock type. Most limpets recruited to middle or lower tidal elevations, suggesting that larvae of at least upper intertidal species recruit to lower elevations and migrate to adult habitats as they grow. Genetic variability made species identification difficult, but preliminary results highlight the promise of a molecular approach for recruit identification. There was also large annual variation in recruitment, including a year of extremely low recruitment driven by atmospheric anomalies during the upwelling season, which may account for the genetic variability of newly settled limpets.