Influence of the 2011 Tohoku Earthquake on population dynamics of a rocky intertidal barnacle: cause and consequence of alteration in larval recruitment

Abstract

By analyzing data obtained from 23 plots on five shores along the Pacific coast of Japan over 7 years, we explored theinfluence of the 2011 Tohoku Earthquake on the population dynamics of a rocky intertidal barnacle, Chthamalus challengeri. Weaddressed the following three questions. (1) At local and intermediate scales, how did the spatial patterns of larval recruitmentchange after the earthquake? (2) At broader spatial scales encompassing the entire meta-population, did larval recruitmentchange with the alteration of stock size after the earthquake? (3) How did the relative importance of larval recruitment as a determinantof local population growth rate change after the earthquake? The results demonstrated that while the spatial patternof C. challengeri larval recruitment was only slightly modified by the 2011 earthquake, the population dynamics were significantlychanged immediately (1–2 years) after the earthquake at two contrasting spatial scales. At a broad spatial scale encompassingseveral bays, the population size increased, consequently enhancing recruitment intensity, whereas at the local scale,the dependence of local population growth rate on larval recruitment increased. The former finding contradicts a widelyaccepted assumption that severe physical disturbances occurring at a broad spatial scale heavily impact natural populations.Special Issue（東日本大震災特集