Ostracod assemblages in the Frasassi Caves and adjacent sulfidic spring and Sentino River in the northeastern Apennines of Italy
Peterson, D.E., Finger, K.L., Iepure, S., Mariani, S., Montanari, A. and Namiotko, T.
Journal of Cave and Karst Studies
Abstract: Rich, diverse assemblages comprising a total (live + dead) of twenty-one
ostracod species belonging to fifteen genera were recovered from phreatic waters of the
hypogenic Frasassi Cave system and the adjacent Frasassi sulfidic spring and Sentino
River in the Marche region of the northeastern Apennines of Italy. Specimens were
recovered from ten sites, eight of which were in the phreatic waters of the cave system
and sampled at different times of the year over a period of five years. Approximately
6900 specimens were recovered, the vast majority of which were disarticulated valves; live
ostracods were also collected. The most abundant species in the sulfidic spring and
Sentino River were Prionocypris zenkeri, Herpetocypris chevreuxi, and Cypridopsis vidua,
while the phreatic waters of the cave system were dominated by two putatively new
stygobitic species of Mixtacandona and Pseudolimnocythere and a species that was
also abundant in the sulfidic spring, Fabaeformiscandona ex gr. F. fabaeformis.
Pseudocandona ex gr. P. eremita, likely another new stygobitic species, is recorded for
the first time in Italy. The relatively high diversity of the ostracod assemblages at Frasassi
could be attributed to the heterogeneity of groundwater and associated habitats or to
niche partitioning promoted by the creation of a chemoautotrophic ecosystem based on
sulfur-oxidizing bacteria. Other possible factors are the geologic age and hydrologic
conditions of the cave and karst aquifer system that possibly originated in the early–
middle Pleistocene when topographic uplift and incision enabled deep sulfidic waters to
reach the local carbonate aquifer. Flooding or active migration would have introduced
the invertebrates that now inhabit the Frasassi Cave system.