Despite its inhospitable appearance and lack of any ... - Udine Cultura

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82 Although the ecology of this unsaturated habitat is similar to that of porous surface aquifers, it is very unstable and unpredictable. Organisms from adjacent and underlying aquifers may migrate to these habitats to feed. The same aquifer often hosts more than one of the above categories: for instance, there are streams in cavities between flysch and limestone (in Friuli Venezia Giulia), between limestone and conglomerate (Veneto Pre- Alps), travertine and tuff (Latium), limestone and chalk (Grotte di Frasassi), limestone and lava (Lessini mountains), and limestone and granite (Sardinia). In addition, the water of karstic aquifers often drains to alluvial beds in valleys with complex hydrogeological and ecological relationships. ■ Groundwater habitats The main ecological aspect deriving from the classification described above is that the various types of aquifers provide fauna with a complex availability of living space, with changes in structural complexity, food resources, stability of hydraulic conditions and water chemistry. Basically, different aquifers develop different habitats, and may host completely different animals. For instance, locally or extensively saturated karstic aquifers often have large hydric spaces (underground rivers or lakes), and therefore contain larger organisms which may reach a few centimetres in size, like large cirolanid isopods, mysids, decapods and the olm, the only Italian stygobiont vertebrate. Unsaturated karstic environments host smaller animals because the pools in caves - large pools or lakes of trickling water - are only transient habitats for fauna living in limestone micro-fissures above, adjacent to or underneath the pools. Medium-fine porous aquifers provide little living space, and only small animals - less than 1 cm long, often smaller than 1 mm, according to the size of particles - with particular adaptations have been able to colonise them. Fractured aquifers, in line with their nature, may offer different extension of living spaces, and therefore host relatively large animals (in flysch, amphipods of the genus Niphargus are up to 4 cm long) as well as microscopic organisms typical of porous systems. Unsaturated karstic habitat (micro-concretions) Porous habitat with (detail) a specimen of Niphargus in its environment 83
84 85 The discovery of a new submerged world: anchialine environments Diana Maria Paola Galassi Anchialine environments were first discovered in 1966, when the Austrian scientist Rupert Riedl described them as “marginal caves”. Since then, experts have debated the correct definition of anchialine systems. Today, they agree on defining them as caves or other underground aquatic habitats near the coastline of islands and continents, supplied by continental freshwater and with underground connections to the sea. Consequently, the water of anchialine pools is brackish, and light-weight freshwater generally floats on top of heavier seawater. The most typical feature of anchialine environments is the absence of a surface connection with the sea, which manages to reach far inland through deep infiltration passages in limestone and volcanic rocks. The most fascinating, extraordinary examples are the well-known Mexican cenotes, small bodies of crystalline brackish water, like blue eyes glittering in the tropical forests of Mexico and Belize, not far from the coast. In Italy, typical anchialine pools are found in the Grotta Zinzulusa, Abisso and Buco dei Diavoli (Salento), together with other water-tables in Apulia, groundwater in Porto Palo (Sicily), the Grotta Verde, Grotta di Nettuno and Grotta del Bue Marino (Sardinia) and the Grotta di Punta degli Stretti (Argentario, Tuscany). Anchialine pools are marked by few food resources, total darkness, and vertical gradients of salinity and oxygen concentrations. Although in the past anchialine ecosystems were believed to support themselves on allochthonous organic matter (deriving from the rock above and from seawater), today we know that part of the organic matter is locally synthesised by chemo-autotrophs. The most fascinating aspect that makes these environments true treasure troves of biodiversity is their exclusive fauna. Examples are remipedes, the most primitive class of living crustaceans, which have been found in anchialine caves on the Bahamas, in lava tubes on the island of Lanzarote and, more recently, in Australia. Remipedes, like many other animal groups found in these habitats, are true living fossils, whose distribution, enigmatically uneven in several areas of the world, dates back to the breakup of the ancient Tethys Sea. In addition to these unique organisms, there are also other extraordinary animals, some of which are Italian endemics with restricted distribution, like the sponge Higginsia ciccaresei, the thermosbaenacean Monodella stygicola, the mysid Stygiomysis hydruntina, and the decapod Typhlocaris salentina. It is worth noting that the copepod Muceddina multispinosa was recently discovered in the Grotta Verde (Capo Caccia, Alghero, Sardinia), a species with disjunct distribution also found in anchialine environments on the islands of Mallorca and Lanzarote (Spain). Generally speaking, anchialine habitats host heterogeneous assemblages which includes strictly marine animals and, to a lesser degree, freshwater organisms. Typically anchialine species are closely associated with the particular environment in which they live, and have never been found in other types of underground habitats. They are also stygobionts, and have marked specialised features. Their origin dates back to various geological times, from the Tertiary to the more recent Sea entrance to the Grotta Zinzulusa (Salento, Apulia) Pleistocene. Some researchers believe that their ancestors lived in the abysses of the sea; others trace their origin back to organisms living in shallow seawater on the continental shelf.
Page 1 and 2: Fauna FABIO STOCH Despite its inhos
Page 3 and 4: 44 45 Methods for sampling and anal
Page 5 and 6: 48 Shells of gastropods Iglica voba
Page 7 and 8: 52 collected in phreatic waters in
Page 9 and 10: 56 ● Cyclopoid copepods. So far,
Page 11 and 12: 60 those associated with percolatin
Page 13 and 14: 64 Species of genus Niphargus; top:
Page 15 and 16: 68 ■ Decapods Italian fauna has o
Page 17 and 18: 72 Stygofaunal provinces in Italy T
Page 19 and 20: 76 aquifers in the Sabini mountains
Page 21: 80 ■ The ecology of aquifers Acco
Page 25 and 26: 88 anastomoses, often adjacent to t
Page 27 and 28: 92 93 The saline springs of Poiano:
Page 29 and 30: 96 Modified sensory setae on the an
Page 31 and 32: 100 Theoretical evolutionary sequen
Page 33 and 34: 104 Sketch showing degrading phases
Page 35 and 36: 108 109 Stygodiversity in the Presc
Page 37: 112 animal groups still living on t

Despite its inhospitable appearance and lack of any ... - Udine Cultura

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