LINKING RADIOCARBON AND TROPHIC WEBS IN KARSTIC GROUNDWATER ECOSYSTEMS IN THE YUCATAN PENINSULA, MeXICO

Stable isotopes have been used historically to track food webs. Our approach used a combination of delta C-13 and radiocarbon (C-14) 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 C-14 and delta C-13 values of whole tissues from the organisms were determined at the AMS laboratory (LEMA) of the Institute of Physics of the Universidad Nacional Autonoma de Mexico. 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.