Estructura poblacional en relación con factores físicos y modelado del crecimiento individual de Chaetopleura isabellei (D’ORBIGNY, 1839) en el intermareal de punta verde, Río Negro, Argentina

Abstract

El objetivo de esta tesina fue estudiar la estructura poblacional y el crecimiento individual del quitón C. isabellei en el mesolitoral inferior de Punta Verde, Bahía San Antonio, Río Negro. Para ello se realizaron distintos muestreos entre abril 2021 y mayo 2022 con el fin de estudiar la relación entre la granulometría y el tiempo de emersión con la densidad de la especie en el mesolitoral inferior, determinar el periodo de formación de los anillos de crecimiento, conocer la estructura demográfica respecto a las tallas, pesos y edades, y estudiar el crecimiento individual. Los resultados indican que la densidad de la especie está relacionada con la granulometría, presentando mayores densidades en sitios con mayor tamaño de grano promedio.

The chiton Chaetopleura isabellei is a common species in the intertidal zone of the Southwestern Atlantic Ocean, however available information is scarce. The objective of this thesis was to study the population structure and individual growth of the chiton C. isabellei in the low-intertidal zone of Punta Verde in San Antonio Bay, Río Negro, Argentina. To achieve this, several samplings were carried out between April 2021 and May 2022 in order to study the relationship between grain size and emersion time with the species' density in the low- intertidal zone, determine the period of growth rings formation, understand the demographic structure in terms of sizes, weights, and ages, and study individual growth. Results indicate that the species density is related to granulometry, with higher densities in areas with larger mean grain size. Emersion time does not appear to directly affect the species density, but it could have indirect effects on its distribution. Growth rings have an annual periodicity and are formed at the beginning of summer. There is a vertical segregation by sizes, weights and ages: youngest and oldest chitons are found on lower levels, while in the upper levels, chitons generally exhibit intermediate ages. The species maximum longevity is at least 11 years. The results of this study provide information about the population of C. isabellei in the low-intertidal zone of Punta Verde and are presented as a first approach to the use of growth rings for age determination in polyplacophoran mollusks in Argentina.