Hermit crabs are known to use empty gastropod shells, which allows them to grow and avoid predation and desiccation stress. However, shell benefits lessen with crab growth and natural damages so that hermit crabs are always in search for new and better-quality shells. This makes these organisms dependent on the input of newer shells, presenting adaptations to locate new released shells, as perception of chemical cues liberated by predated gastropods. The allocation from older to newer shells suggests that the patterns of shell utilization by hermit crabs may reflect populational changes of gastropod species. In this scenario, we aimed to investigate whether a recognized population decline of the intertidal gastropod Olivella minuta in summer can be explained by mortality or intertidal migration. To do so, we analysed patterns of shell availability and use (number and quality) by hermit crabs before and after the population decline. Contrary to our mortality hypothesis, there was no increase in availability and occupancy of newer shells in the area, as well as no increase in shell quality after the period of population decline of gastropods. There were also no general changes in the size distribution of available and occupied shells. Thus, it is likely that O. minuta migrates towards lower areas of the intertidal to avoid thermal stress and mortality due to summer higher temperatures.

众所周知，寄居蟹使用空腹腹足动物的贝壳，这使它们得以生长并避免捕食和干燥胁迫。但是，随着蟹的生长和自然破坏，贝壳的好处会减少，因此寄居蟹一直在寻找新的，更好质量的贝壳。这使得这些生物依赖于更新的壳的输入，呈现出适应性以定位新释放的壳，如感知到由掠食性腹足动物释放的化学线索。从旧壳到新壳的分配表明，寄居蟹对壳的利用方式可能反映了腹足动物的种群变化。在这种情况下，我们旨在调查是否已确认潮间腹足纲Olivella minuta的种群下降夏季可以用死亡率或潮间带迁移来解释。为此，我们分析了种群减少之前和之后寄居蟹的壳供应和使用方式（数量和质量）。与我们的死亡率假设相反，在腹足动物种群减少之后，该地区较新的炮弹的可利用性和占有率没有增加，并且炮弹质量也没有增加。可用壳和占用壳的大小分布也没有任何一般性变化。因此，很可能O. minuta迁移到潮间带的较低区域，以避免夏季夏季高温造成的热应力和死亡。