Diversity and ecology of intertidal soil mites on the coast of Sonora, Mexico

Intertidal regions often support assemblages of organisms that are adapted to harsh conditions by fluctuation on water level leading to frequent environmental changes on moisture, salinity, temperature, and oxygen. In Mexico, most studies of intertidal soil arthropods have been conducted in the tropical regions of Quintana Roo. In contrast, little is known about soil mites in intertidal zones along the Pacific Ocean. For this reason, we surveyed for first time soil arthropods over a 16-month period in salt marsh and mangrove-associated habitats in the Estero Santa Cruz of Bahía de Kino on the Gulf Coast, Sonora, Mexico. Here the intertidal zone is bordered by desert. Mites accounted for approximately 59% of the invertebrates collected in our samples, with Endeostigmatid mites being most abundant (51% of all mites), followed by Oribatids (38%), Prostigmata (9%) and Mesostigmata (4%). Two Endeostigmatid species and 14 Oribatid species, with the three most abundant species belonging to the genera Nanorchestes, Speleorchestes and Scheloribates. Additionally, we report the first records of the families Selenoribatidae and Fortuyniidae for Mexico, as well as two new species in the family Lohmaniidae. Although, we found significant spatial variation in the density and composition of soil mite communities across the estuary. This variation was strongly associated with soil characteristics such as pH, organic matter content and soil moisture than with local plant community composition. Finally, the threats faced by saltmarsh and mangroves due to human encroachment and global warming highlight the need for additional studies of intertidal mites throughout ecologically diverse region.