Download P05 - Galassi

Microcrustacean community structure in a chemoautotrophic cave ecosystem: the copepods
of Frasassi cave system.
Galassi D.M.P.1*, Fiasca B.1, Di Lorenzo T.2, Montanari A.3, Porfirio S.1, Fattorini S.4
1
Department of Life, Health and Environmental Sciences, University of L’Aquila, via Vetoio,
Coppito, 67100 L’Aquila, Italy; 2Istituto per lo Studio degli Ecosistemi, ISE-CNR, Sesto
Fiorentino-Florence, Italy; 3Osservatorio Geologico di Coldigioco, Apiro, Italy; 4CE3C – Centre for
Ecology, Evolution and Environmental Changes / Azorean Biodiversity Group and Universidade
dos Açores - Departamento de Ciências e Engenharia do Ambiente, Angra do Heroísmo, Portugal
* [email protected]
The Frasassi cave system (central Italy) hosts one of the few worldwide examples of groundwater
metazoan communities supported by sulfur-based lithoautotrophic microbes. Despite the
challenging conditions represented by high levels of hydrogen sulfide and low concentration of
oxygen, this cave system is home to many species of amphipods, ostracods and copepods. We
analysed here the copepods inhabiting sulfidic lakes (in both higher and low sulfidic states) and
non-sulfidic dripping pools, to investigate how the extreme environmental conditions of sulfidic
waters may influence community structure over time. To this end, we have sampled copepod
assemblages in various cave habitats and under different physico-chemical conditions. We used
cluster analyses based on species composition and abundance to identify similarities between
sampling sites and a canonical correspondence analysis to investigate relationships between species
assemblage composition and environmental parameters. Community structure was also analyzed by
using diversity, dominance and equitability indices. Cluster analysis and canonical correspondence
analysis separated the copepod assemblages inhabiting dripping pools from those of sulfidic lakes
and highlighted the importance of ionic concentration, pH and O2 values in determining species
composition. These results indicate that the distribution of groundwater copepods within the cave
system is ecologically and spatially structured. Sulfidic lakes showed lower dominance, higher
diversity and higher equitability in the higher sulfidic state. The complex community structure of
the copepods of the Frasassi cave system indicates that a chemosynthetically produced food source
favoured stygobiotic colonizers to settle in sulfidic groundwater, probably due to their adaptation to
tolerate extreme environmental conditions. In conclusion, the high diversity observed among
Frasassi microcrustaceans supports the high conservation value of this unique ecosystem, where
many species are hosted in an only apparent challenging environment.