HR: 0800h
AN: H51F-04    [Abstracts]
TI: Relevance of the Halocline in the Diet of the Troglobic Shrimp T.mitchelli in the Yucatan Peninsula
AU: * Cruz de la Garza, Y
EM: yvette_cruz@yahoo.com
AF: Facultad de Ciencias, UNAM, Circuito Exterior, Mexico, DF 04510, Mexico
AU: Escobar Briones, E
EM: escobri@mar.icmyl.unam.mx
AF: Instituto de Ciencias del Mar y Limnologia, UNAM, Circuito Exterior, Mexico, D.F 04510, Mexico
AB: The anchihaline cave systems are characterized by subsurface connections with the sea and the sinkholes, have polyhaline underground water masses and are locally influenced by the rainforest organic input during the rainy season. The specific physical characteristics of the two water masses (fresh and marine) define the presence of karst fauna and their diet, the halocline represents a physicochemical barrier for many organisms and retains suspended particles creating food source storage along a cline of geochemical reactions. We studied the occurrence of the shrimp Typhatya mitchelli, an endemic Decapod Crustacean from the Yucatan Peninsula anchihaline ecosystems. We analyzed its presence in the two water masses and related its muscle d13C and d15N stable isotopic composition to its diet and specific habitat preference. The presence of specialized setae in P1 and P2 and depleted C and N values (d13C -43.11 min. -21.05 max.; d15N -0.54 min. 9.34 max.) confirm a diet sustained on bacteria with similar signatures as those from chemoautotrophic environments where the dominant morphological structures show that scraping on the cave walls, cave floor and the halocline are the prevailing feeding strategy. The density differences of water masses (rainwater rho 0.996 to 0.997 kg m-3, halocline rho 0.997 to 1.009 kg m-3; marine water rho 1.09 to 1.024 kg m-3) at the halocline allow the species (rho 1.12 to 1.13) to find the interface as a suitable substrate where organic matter can concentrate and sustain a dense population of shrimps.
DE: 1829 Groundwater hydrology
SC: Hydrology [H]
MN: 2007 Joint Assembly