Abstract

The gastropod Nodilittorina peruviana inhabit rocky intertidal of the north and center Chile. Populations of this species exhibits aggregated distributions. Through field and lab records we studied the effect of spatial distribution of snails on their thermoregulatory and water conservation efficiencies. We studied individuals from two localities of the Chilean coast with different climatic conditions (Taltal 25 degrees 25 ' S; 70 degrees 29 ' W and Las Cruces 33 degrees 35 ' S; 71 degrees 38 ' W). Results indicate that the influence of spatial distribution thermoregulatory efficiency is dependent of the local conditions. Although individuals from both localities presented similar thermal tolerances, snails from Taltal showed lower rates of water loss. Aggregations size were negatively related with the rate of water loss in individuals from both localities. Only, individuals from Taltal decreased their limit of thermal tolerance, and exhibited a positive relationship between aggregation size and the temperature of the group. Results demonstrated that the local environmental conditions are determinate thermoregulatory strategies.