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Research on ground-water arthropod diversity at the Medcore sites

Authors: Giuseppe Messana*, Daniele Della Valle*, Adnène Ghlala° (*Partner 1; °Partner 7)

 

Stygobionts are present in almost any subterranean systems, are easy to collect, are characterised by low mobility, a long life span (ratio ca. 1/5), low metabolic rates, are resistant to environmental stress and to organic pollution but sensible to some toxic products. 

 

In May 2003 at the Maremma site (Italy), they studied the interstitial animal community and population of the ecotone surface/subterranean water of the river Ombrone, of it’s catchement and of subterranean waters of the Maremma park. A study on the behaviour of the isopod Stenasellus racovitzai was begun inside the Fontanile dei Cavalleggeri, utilising video recording techniques. Three piezometers were installed inside the Park nearby those utilised by M. Teobaldelli (pine tree study). All piezometers were visited twice and resulted dry. On the river Ombrone four stations were chosen to collect interstitial fauna and ten litres of water were filtered at each pumping sites (8 samples were made). Near the river mouth only surface fauna was found (Oniscidae and Dytiscidae); upstream larvae of insects (Tricoptera, Ephemeroptera, Plecoptera and Diptera), Oligochaeta and rare Idracara, Copepoda and Nyphargus Amphipoda were found. On the whole, it was found low hyporreic and high phreatic diversity, and interesting endemisms (Stenasellus).

 

In the North of Tunisia, before this investigation,  the only stygibitic species known was Proasellus bagradicus. During 2003 – 2005, 84 stations were investigated in two Tunisian sites : 41 samples in Bouterfess and Berkoukech catchment areas and 16 samples from Ichkeul park. Samplings used the Karam-Chapuis methods in the river, filtering of water in springs, Cytkov net and baited traps in the wells. In the Tabarka region underground fauna was present in 13 % of stations with 5 populations of Proasellus sp and 6 populations of anophtalmous amphipods. At Ichkeul different cathment areas were explored. The following groups: Isopoda (Typhlocirolana), Amphipoda, Cladocera, Copepoda and Mollusca. The new record of  Tyohlocirolana in Tunisia bring certainly new elements for the understanding of paleogeographic distribution of the Cirolanids family in Mediterranean basin. On the whole, in Tunisia a high phreatic and hyporrheic diversity exists with interesting endemisms (Proasellus, Typhlocirolana). Genetic analysis of DNA have been started to test the robustness of morphological hypotheses. 

 

At Oued Laou (Morocco) the following waters were explored: Caves (2), Hyporrheic (11), Springs (5), Wells (7). High phreatic and hyporrheic diversity was found, with a lack of Isopoda.