Articles

Stable isotopes have been used historically to track food webs. Our approach used a combination of δ13C and radiocarbon (14C) dating to identify carbon sources in cave shrimp within caves of the Karstic Yucatan Peninsula, Mexico. Three sister species of stygobitic Typhlatya shrimps were collected from the cenote pool (cenote hereafter), cavern and cave hydro regions. New and previously reported 14C and δ13C values of whole tissues from the organisms were determined at the AMS laboratory (LEMA) of the Institute of Physics of the Universidad Nacional Autónoma de México. This new set of isotopic values of biomass and potential sources were incorporated into the Bayesian Mixing Modeling Software SIAR. In two hypothetical scenarios, the contribution from each feeding source among three species of the Typhlatya genus was determined. Slight differences were also observed between isotopic values of two groups of the same species collected in two distant cenote pools, suggesting this species may feed on a wider array of sources than previously found, and that the oligotrophic environment may have a strong influence on cave shrimp diet.

Using micrographs obtained from SEM, the arrangement of the bristles on the dactyle and propodium of pereiopods 1 and 2, defined here as the feeding apparatus, of 3 species of cave shrimp of the genus Typhlatya (T. mitchelli, T. .pearsei, T.dzilamensis) from the Yucatán Peninsula. The mushrooms were classified according to their morphology and position on the propodium and dactyl, resulting in 6 main types. The 3 Typhlatya species differed slightly in the number of each type of mushroom and showed some morphological variations, especially in the central setae. A comparison of the setal arrangement of Typhlatya spp. with that of the epigean species Potimirim mexicana and P. glabra, showed important differences probably generated by specialization to a certain habitat.

Cenotes are spectacular karst formations in Yucatan, Mexico, often used for recreation. However, their impact on water quality has yet to be explored in detail. Therefore, during Easter, water samples were collected from four cenotes to identify variations in water quality associated with the presence of tourists. PCO of water quality, before (PH) and during Holy Week (HW) in 2019, explained 49.02% of the total variation. The indicators contributing to the first principal coordinate’s variation were Sr, K, sulfate, and chloride (0.89). Whereas, alkalinity, temperature, conductivity, nitrate, and ORP contributed to the second PC. PERMANOVA indicated a significant interaction between “cenote” and “condition” factors, and post hoc paired comparisons indicated significant differences between PH and HW conditions. Significant correlations varied among the four cenotes as the result of hydrogeological differences. Whereas, numbers of visitors were correlated with at least one fecal-matter indicator, demonstrating anthropogenic influence on the cenotes’ water quality.

The presence of a long-wavelength sensitive (LWS) opsin gene was demonstrated in the stygobitic crustacean Creaseria morleyi (Creaser, 1936) by PCR readings from genomic DNA. In order to find the expression of this gene in extraocular tissue, shrimps were collected and placed in a tank to expose them to light/dark conditions for a period of 72 hours, and immediately after, sacrificed and sampled for RNA in the eyes, cephalothorax, abdomen, and sixth abdominal segment plus uropods. The transcripts of the LWS opsin gene were found in the eyes and abdomen of individuals exposed to light. The expression of these opsins could be involved in extravisual functions such as synchronization of their biological processes with environmental cycles related to diurnal vertical migration.

This study demonstrates the need for integrative/interdisciplinary approaches when conducting biodiversity assessments in complex and poorly studied aquifers. This first integrative evaluation (i.e., molecular, morphological, broad geographic and type locality sampling, and environmental data) of Yucatán Typhlatya reveals considerable species identity conflict in prior phylogenetic assessments, broad species ranges, syntopy within cave systems, and five genetic lineages.

This study demonstrates the need for integrative/interdisciplinary approaches when conducting biodiversity assessments in complex and poorly studied aquifers. This first integrative evaluation (i.e., molecular, morphological, broad geographic and type locality sampling, and environmental data) of Yucatán Typhlatya reveals considerable species identity conflict in prior phylogenetic assessments, broad species ranges, syntopy within cave systems, and five genetic lineages.

Here we describe physiological aspects of three of the most abundant and widespread Typhlatya species that thrive in the fresh and marine groundwater habitats of the anchialine ecosystem of the Yucatan Peninsula.

We studied benthic assemblages through X-Batún, a continental freshwater cenote and its associated submerged cave located in San Antonio Mulix (Yucatán, Mexico). Using cave diving techniques, we collected sediment samples at four zones of the system. We extracted and counted individuals of benthic species in three replicates of 5 grams of wet sediment at each site. The biological composition was integrated by 15 species from eight higher taxonomic groups. Non-metric multidimensional scaling distinguished four assemblages that coincided with surface, open water, cavern and cave zones. ANOSIM test revealed significant differences between the assemblages. In the deeper zones of the cenote characterized by twilight and total darkness, Ostracoda and Gastropoda show the highest diversity and abundance, with practical absence in surface sediments. This pattern may suggest ecological interactions with chemosynthetic bacterial activity. Surface shows an assemblage typical of epigean environments. Environmental variables along the cenote varied little from the upper layers to bottom. Linear correlation and detrended canonical analysis revealed that light is the main driver of benthic species assemblages. Temperature, pH, and dissolved oxygen exert higher influence at individual biological benthic assemblage in X-Batún.

This Research Topic was established with the aim to bring together the most recent outcomes and advances from a variety of scientific disciplines that link spatial and temporal changes in the environment to biogeochemical, ecological, and physiological changes at different biological scales in anchialine ecosystems, from microbes and macrofauna to habitat level. We have received contributions from disciplines spanning paleoecology, microbiology, biogeochemistry, and ecophysiology from four geographical regions around the world (Australia, Bermuda, The Bahamas, and the Yucatan Peninsula). Specifically, these studies aimed at characterizing the limits of physiological adaptations of cave-adapted crustaceans, the drivers of organic matter inputs over time, and how organic matter availability regulates microbial community structure and meiofauna assemblages. These contributions expand our understanding of anchialine ecosystem functioning and enable better predictions of future ecological changes within these coastal aquifer habitats.

In order to gain insights into the biological evolution of the subterranean environments of the Yucatan Peninsula, we evaluated the ostracode species composition of caves and cenotes in five independent sampling campaigns (2008, 2013, 2017–2019).

We present 52 new geographic location records for the peracarid crustacean Antromysis cenotensis Creaser, 1936, endemic in cenotes of the Yucatan Peninsula, Mexico. This species is currently considered threatened and, therefore, is protected by Mexican law.

Typhlatya is a genus of small, stygobitic shrimp in the family Atyidae. Species in this genus are found in subterranean anchialine habitats, and they span salt, brackish and fresh waters. None have been reported in the open sea (Botello et al. 2013).

Cave shrimps of the Typhlatya genus are common and widespread in fresh, brackish and marine groundwater throughout the Yucatan Peninsula (Mexico). These species are ideal models to test niche partitioning within sympatric species in oligotrophic systems.

This study provides an updated checklist and an illustrated guide to the 17 currently known stygobiont Malacostraca species of the state of Yucatan (Yucatan Peninsula, Mexico)

The biospeleological investigations of several cenotes in the eastern region of Yucatán state, Mexico, during January 2018 yielded, among other invertebrates, two new truncatelloid gastropod species described here in as Mexicenotica xochii gen. n. et sp. n. and Pyrgophorus thompsoni sp. n. Both species represent the first record of stygobiont gastropod species from the cenotes of Yucatán indicating the high biodiversity potential of the studied area.