Journal Article
Epigean and hypogean palaemonetes sp. (Decapoda, Palaemonidae) from Edwards Aquifer: an examination of trophic structure and metabolism.
Bishop, R., Humphreys, W.F. and Longley, G.
Record Number:
5102
Year:
2014
Journal:
Subterranean Biology
Pages:
79-102
Volume:
14
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.
Times Cited:
4