Age, Individual Growth, and Mortality of the Chiton Chaetopleura isabellei (d'Orbigny, 1839) (Mollusca: Polyplacophora) in an Intertidal Boulder Shore of Patagonia, Argentina.

Abstract

AbstractThe chiton Chaetopleura isabellei is a common species in the intertidal shores of the southwestern Atlantic Ocean. This study investigates the age, individual growth, and mortality of C. isabellei on an intertidal boulder shore in San Antonio Bay (40°45' S, 064°56' W), Patagonia, Argentina. Growth rings on the valves were validated as annual, forming during the warm season, a pattern unusual among chitons. The age structure showed a stable population, with most individuals between 2 and 7 years and a maximum observed longevity of 11 years. The growth pattern, analyzed through both polynomial models and the von Bertalanffy growth model, indicated rapid growth during early years, followed by slower growth in later stages. Mortality was best described by the Siler mortality model, indicating variable mortality rates across the lifespan, with higher risks during early and late life stages. These findings provide insights into the life history of C. isabellei, emphasizing the influence of environmental factors on growth and mortality in this species.