Shorter but thicker: analysis of internal growth bands in shells of intertidal vs. subtidal Antarctic limpets, Nacella concinna, reflects their environmental adaptation

LOMOVASKY, BETINA J.; DE ARANZAMENDI, M. CARLA; ABELE, DORIS

POLAR BIOLOGY

SPRINGER

Año: 2020 vol. 43 p. 131 - 141

0722-4060

The limpet Nacella concinna is a dominant macroinvertebrate along the coastal Antarctic Peninsula with two ecotypesinhabiting intertidal and subtidal areas, respectively. The ecological aim of the study was to understand whether higherstress competence and migratory energy expenses in intertidal Antarctic limpets shorten their lifetime and limit the shellgrowth rate compared to their sublittoral conspecific. We evaluated shell morphometry, age and internal shell growth bandsin a large number of intertidal and subtidal N. concinna shells in Potter Cove, South Shetland Islands. Comparisons of theirmorphometrics showed that intertidal limpets are relatively shorter and less wide, and have higher shell mass, i.e. at commonshell height, intertidal shells are relatively thicker and heavier than those of subtidal specimens. Internal shell growthbands showed alternating wide opaque (faster growth in summer) and thin translucent bands (slow growth in winter). Themaximum age read was close to 20 years for both groups. Comparisons of von Bertalanffy growth curves showed for shelllength and shell width lower growth rate k in intertidal animals than in subtidal ones associated to a great variability, withno differences in other growth parameters. However, when shell height vs. age is considered, no differences were observedfor any growth parameter. Curtailed variability of growth rates in the intertidal population reflects either a limitation of thefood reserves or feeding time, or an energy gap for shell growth due to the costs for migratory movements and stress defense.