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Humphreys W.,Collections and Research Center | Humphreys W.,University of Adelaide | Humphreys W.,University of Western Australia | Tetu S.,Macquarie University | And 5 more authors.
Natura Croatica | Year: 2012

The anchialine system at Bundera sinkhole, Australia, exhibits pronounced hydrogeochemical structure through depth that is reflected in the composition and distribution of the fauna. It is a strongly structured microbial ecosystem the components of which also change with depth and which is dominated by sulfur bacteria and chemolithotrophic microbial classes. Source

Kornicker L.S.,Smithsonian Institution | Humphreys W.F.,Collections and Research Center | Humphreys W.F.,University of Western Australia | Humphreys W.F.,University of Adelaide | And 2 more authors.
Crustaceana | Year: 2010

Juvenile instars II, IV, and V of the anchialine halocyprid ostracod Danielopolina kornickeri Danielopol, Baltanas & Humphreys, 2000 (Thaumatocyprididae) are described and illustrated. In addition, a supplementary description of the adult male is presented. Specimens had been collected in Bundera Sinkhole, the type locality of the species in Western Australia. Also, juvenile instars I and II of the deep-sea species Thaumatoconcha radiata Kornicker & Sohn, 1976, which is in the same family as members of the genus Danielopolina, are described and illustrated. It is tentatively concluded that during its ontogeny, D. kornickeri has 6 growth stages; morphological characters useful in identifying the stage and sex of juveniles of D. kornickeri are presented. Finally, the hypothesis is proposed for an anchialine cave ancestor to the present-day planktonic Halocyprididae, now widely spread in the oceans. © 2010 BRILL. Source

Bishop R.E.,Pennsylvania State University | Humphreys W.F.,Collections and Research Center | Humphreys W.F.,University of Adelaide | Humphreys W.F.,University of Western Australia | Longley G.,San Marcos University of Costa Rica
Subterranean Biology | Year: 2014

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. © Renée E. Bishop et al. Source

Humphreys W.F.,Collections and Research Center | Humphreys W.F.,University of Adelaide | Humphreys W.F.,University of Western Australia | Bishop R.E.,Pennsylvania State University | And 9 more authors.
Journal of Crustacean Biology | Year: 2015

An improved understanding of the anchialine ecosystem and geology warrants a redefinition of the term 'anchialine. Originating from subareal biological observations, the term anchialine now encompasses chemical, physical, geological and biological elements within the subterranean realm. We propose a more accurate definition of the term anchialine as a tidally-influenced subterranean estuary located within crevicular and cavernous karst and volcanic terrains that extends inland to the limit of seawater penetration. This subterranean estuary is characterized by sharp physical and chemical stratification and merges with a marine system at the coast and a groundwater system inland. The anchialine ecosystem supports a relatively diverse biotic assemblage of stygobiotic species of marine origin dominated by members of Crustacea, both numerically and by species richness. © 2015 by The Crustacean Society. Source

Bradford T.M.,CSIRO | Bradford T.M.,University of Adelaide | Humphreys W.F.,University of Adelaide | Humphreys W.F.,South Australian Museum | And 4 more authors.
Marine and Freshwater Research | Year: 2014

The Yilgarn calcrete aquifers in Western Australia are an interesting system for investigating the process of speciation within subterranean habitats, because of the limited opportunities for dispersal between isolated calcretes. The presence of different-sized diving beetles (Dytiscidae) in separate calcretes, including sympatric sister-species pairs, suggests that species may have evolved within calcretes by an adaptive shift as a result of ecological-niche differentiation. We have studied the potential for trophic niche partitioning in a sister triplet of diving beetles, of distinctly different sizes, from a single aquifer. Fragments of the mitochondrial COI gene, specific to known species of amphipods and copepods, were polymerase chain reaction-amplified from each of the three beetle species, indicating that there is an overlap in their prey items. Significant differences were found in the detected diets of the three species, and results showed a propensity for prey preferences of amphipods by the large beetles and one species of copepod for the small beetles. A terrestrial source of carbon to the calcrete was suggested by stable isotope analyses. The combined approach of molecular, stable isotope and behavioural studies have provided insight into the trophic ecology of this difficult-to-access environment, providing a framework for more fine-scale analyses of the diet of different-sized species to examine speciation underground. © 2014 CSIRO . Source

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