Epigean and hypogean Palaemonetes sp. (Decapoda, Palaemonidae) from Edwards Aquifer: An examination of trophic structure and metabolism

By

Bishop, Renee.
Humphreys, William Frank
Longley, Glenn

Type

Article

Date of Publication

2014

Original Publication

Subterranean Biology

Volume

14

Pages

79-102

Subjects

citrate synthase , Edwards Aquifer , Lactate dehydrogenase , Metabolism , Palaemonetes antrorum , Palaemontetes kadiakensis , stable isotopes , δ13C , δ15N

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/subtbiol.14.8202

 

Abstract

This study addresses the causes of the metabolic depression observed when examining the metabolism of hypogean versus epigean organisms. We examined the two current hypotheses regarding the cause of metabolic cave adaptation, a paucity of food and low oxygen availability, both necessary for ATP production, by first determining if the hypogean environment examined, Edwards Aquifer, was resource limited. Stable isotope analyses indicate that there is extensive microbial chemolithoautotrophic production providing resources for the hypogean organisms. δ13C values (≤30‰ )were well below that of terrestrial biome indicating that C in the aquifer originates from chemolithoautotrophic inorganic carbon fixation, not photosynthetically derived material resulting from terrigenous sources. Data suggest the artesian system is a complex geochemical ecosystem providing inorganic energy sources from both methane and sulfates. Metabolism, examined via key aerobic and anaerobic proxies, and organismal proximate composition indicated there was no difference between metabolic rates and energy storage of Palaemonetes antrorum (stygobitic) and Palaemonetes kadiakensis (epigean). This indicates that resources within the oxic aquifer are not limited. We demonstrate that it is necessary for one, or both, of these selective pressures to be present for metabolic cave adaptation to occur.