DISTRIBUTION, GROWTH AND REPRODUCTION OF THE LIMPET NACELLA-(PATINIGERA)-CONCINNA (STREBEL 1908) IN RELATION TO POTENTIAL FOOD AVAILABILITY, IN ESPERANZA BAY (ANTARCTIC PENINSULA)

The present work addresses the effect of environmental factors (icing, water temperature, food availability) on the ecology of the patellid limpet Nacella (Patinigera) concinna, in a bay on the Antarctic Penins ula. Sampling was conducted at three depths (intertidal, 5 m, 10 m) fr om February 1987 to January 1988. Temperature was recorded and concent rations of Chlorophyll a were measured on the bottom, in the water and in the ice-water layer. The limpets were measured, weighed and a cond ition coefficient for somatic and gonadal mass was calculated. Their a ges were estimated through size frequency distribution analysis and a seasonalized von Bertalanffy growth model was applied. The intertidal subpopulation migrated to deeper levels at the beginning of the icing season and recolonized the intertidal zone after ice retreat. The grow th rate was very low (von Bertalanffy K almost-equal-to 0.08). Growth rates showed important seasonal variations, with maxima during Decembe r and January. Nacella (P.) concinna spawns once a year and spawning c oincided with raising water temperature (from -1.33-degrees-C to -0.84 -degrees-C), and probably was also related to increasing spring food a vailability. Body mass increased during periods of high standing stock of microphytobenthos, revealing that ice-algae and phytoplankton were of minor importance as food sources for limpets in Esperanza Bay.