Bacterial communities forming yellow biofilms in different cave types share a common core.

The walls of different types of caves under diverse geological settings (limestone, gypsum and volcanic) are colonized by biofilms of different colors: white, yellow, pink, grey, green to dark brown, but only a few colored biofilms such as the white, yellow and grey ones have been extensively studied. However, an assessment among the microbial communities originating these biofilms in different lithologies is lacking. Here we compare the yellow biofilms from two caves, Covadura and C3, in the Gypsum Karst of Sorbas in Spain, with those from two Spanish limestone caves (Pindal and Santian), and four volcanic caves in Spain and Italy (Viento, Honda del Bejenado, Grotta del Santo, Grotta di Monte Corruccio).

Gypsum Cave Biofilm Communities are Strongly Influenced by Bat- And Arthropod-Related Fungi.

The Gypsum Karst of Sorbas, Almeria, southeast Spain, includes a few caves whose entrances are open and allow the entry and roosting of numerous bats. Caves are characterized by their diversity of gypsum speleothems, such as stalactites, coralloids, gypsum crusts, etc. Colored biofilms can be observed on the walls of most caves, among which the Covadura and C3 caves were studied.

Organic geochemistry and mineralogy suggest anthropogenic impact in speleothem chemistry from volcanic show caves of the Galapagos.

The network of lava tubes is one of the most unexploited natural wonders of the Galapagos Islands. Here, we provide the first morphological, mineralogical, and biogeochemical assessment of speleothems from volcanic caves of the Galapagos to understand their structure, composition, and origin, as well as to identify organic molecules preserved in speleothems. Mineralogical analyses revealed that moonmilk and coralloid speleothems from Bellavista and Royal Palm Caves were composed of calcite, opal-A, and minor amounts of clay minerals.

Author Correction: The potential of gypsum speleothems for paleoclimatology: application to the Iberian Roman Humid Period.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.