Abstract

Limpet species have been considered as indicators of climatic variability. Climatic fluctuations over the North-east Atlantic from 1900 onwards showed an alternation of colder (1910s to 1920s; 1960s to mid-1980s) and warmer periods (1930s to 1950s; 1990s to recent days). To further our understanding of species responses to climate change, it is essential to incorporate historical records of distribution with present-day observations. However, it is still not clear which factors are setting species range-edges on distinct populations within same poleward limit. We used as a model system the double range-edge of the warm-water limpet Patella depressa. We compared the abundance and distribution between both poleward borders of P. depressa over last 70-years. Our results showed opposite changes in abundance and distribution between the two leading edges of its distribution: whilst the leading range edge of P. depressa in North Wales has contracted from previous record during the warm 1950s, its other range limit has extended in distribution in South-east England in last decades. The combination of ultimate and proximate factors in controlling intertidal species boundaries has not been formally tested yet, but we hypothesize that changes in sea and air temperatures are key determinants on poleward edges of P. depressa.