Age, growth and mortality in four populations of the boring bivalve Lithophaga patagonica from Argentina

The boring bivalve Lithophaga patagonica (d´Orbigny, 1842) is a locally abundant inhabitant of hard substrata in the coastal waters of the Southwestern Atlantic. In this paper, we describe the growth, age andmortality of three intertidal rock-boring populations of L. patagonica and one subtidal oyster shell (Ostrea puelchana) boring population. An analysis of acetate peel replicas of shell sections showed that L. patagonica slows down its growth during autumn-winter, which leads to changes in the direction and rate of shell deposition and the formation of conspicuous annual (low temperature induced) clefts in the shell margin. Cleft counts and Von Bertalanffy growth analyses indicated that maximum age varies from 4 years in the oyster-boring population to 13 years in a rock-boring one (longevity estimates varied between 6.5 and 15 years, respectively). Maximum asymptotic length (L∞) and Von Bertalanffy growth constant (K) were also variable between populations (L∞ between 14.76 and 36.95 mm and K from 0.20 to 0.90 yr−1 respectively). Mortality rates were higher at the two southernmost populations. Type (rock vs. oyster), composition and hardness of the substrata are likely the main factors controlling the observed differences between populations.Fil: Bagur Creta, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; ArgentinaFil: Richardson, Christopher A.. College of Natural Sciences- School of Ocean Sciences; Reino UnidoFil: Gutierrez, Jorge Luis Ceferino. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arribas, Lorena Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; ArgentinaFil: Doldan, María del Socorro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Grupo de Investigación y Educación en Temas Ambientales (GRIETA); ArgentinaFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; Argentin