Distribution and structure of Conocarpus erectus L. (Combretaceae) in the northern limit of the Pacific Ocean (Gulf of California)

Abstract

The distribution of species can expand or retreat following environmental changes. Climate change is driving changes in the distribution of several species. Changes in mangrove distributions have been reported subsequent to an increase in temperature following a tropicalization process. This study documents the presence of Conocarpus erectus above the reported northern limit for the Gulf of California (GC), updating its distribution limit in the Neotropic. The current northern distribution limit of C. erectus in the Pacific Ocean was found at Huatabampo, Sonora (26.69° N, −109.58° W) and San Jose Island, Baja California Sur (25.04° N, −110.63° W), which is different from previous estimates (1970: 23.23° N, −106.32° W; 2011: 23.31° N, −110.17° W). According to the model of the Center for Scientific Research and Higher Education of Ensenada (CICESE), the C. erectus seeds could be potentially dispersed as far north as Tiburon Island, Sonora. The sea surface temperature (SST) tended to increase more than >0.02 °C, which means an important increment on a decadal scale in the GC's SST. The temperature databases (atmospheric and SST) corroborated a temperature increase in this region since the 1980s. The expansion of C. erectus from its northern distribution limit supports the tropicalization process occurring in the GC. The current distribution and dominance of mangrove species in the GC could be changing due to oceanographic (e.g., El Niño-Southern Oscillation) and coastal (e.g., temperature and precipitation) changes. These types of changes have been reported previously in this region and for other mangrove distributional limits. These changes in mangrove distribution are expected to be accompanied by changes in the biota as well as in the provision of ecosystem services. Further and more specific studies are necessary to corroborate the changes in the distribution and the dominance/coverage of other mangrove species. The potential expansion of C. erectus could provide unique ecosystem services in arid and semiarid regions.