Anchialine Fauna of the Yucatan Peninsula: Diversity and Conservation Challenges

Abstract

The anchialine caves of the Yucatan Peninsula (YP) are singular ecosystems that develop close to the shoreline, composed of underground passageways that can extend for tens of kilometers inland. These flooded caves contain a dense marine water layer always in the deeper parts and a freshwater layer on top that collects from meteoric water. The interface between the two water masses, the halocline, is deeper as distance from the coast increases. The water masses inside these conduits are under the influence of tides but do not have a superficial connection to the sea. A unique fauna has evolved in anchialine systems worldwide, in the YP in particular. This fauna is composed mainly of crustaceans, but also of sponges, annelids, mollusks, echinoderms, and fishes. A total of 67 anchialine species have been described, 58 of which are endemic to the region. A large potential for the discovery of new species still exists, since only a small fraction of these cave systems has been biologically explored. Distribution patterns can be analyzed to determine what areas hold a larger diversity and should then be preserved. With the available data, the conservation status of all these species should be assessed to face the future challenges that urban development, agricultural expansion, and the tourist industry will impose on the region.