286
1. Di Geronimo et aL
of dominant taxonomic groups (protobranchs,
scaphopods, etc.) (Di Geronimo and La Perna
1997; Di Geronimo et al. 1997). Among bryozoans, a single anascan species is present in the
examined material, while anascans are more
diversified in the Pleistocene (Barrier et al. 1996;
Di Geronimo et al. 1997). This rises the relative
abundance of cyclostomatous, which' parallel
ascophorans as species number (46%) and
exceed them (77%) at specimen level. The
anascan/ascophoran ratio (0.16 and 0.09 respectively) is very low while values of about 0.6 can
be valued from the Pleistocene assemblages
(Rosso 1990; Di Geronimo et al. 1997).
The reported differences should be viewed
within the model of changes in the deep
Mediterranean benthos during the Quaternary
(Di Geronimo et al. 1996; Di Geronimo and La
Perna 1996, 1997; Rosso and Di Geronimo 1998).
The deep-sea benthos underwent a progressive
impoverishment due to the set of warm-homothermic conditions, which replaced the PlioPleistocene psycrospheric ones. The Gibraltar sill
up-lift seems to have played a major role, turning
the Mediterranean into a threshold-controlled
basin, and cutting it of from the deep oceanic circulation. This led to the disappearance of most
cold-stenothermic species (extinct species of
Atlantic affinity, and extant Atlantic species), and
to a drop in diversity and richness in general.
The «pseudopulation:" model (Bouchet and
Taviani 1992) does not fit the present data. The
Recent deep Mediterranean benthos appear as
"residual", i.e. composed of species which survived the hydrological changes. Many molluscs,
usually encountered as empty shells, seem to
have little chance of crossing the Gibraltar sill, as
they lack long-living planktotrophic larvae and
their depth range begins well beyond the sill
depth (280 m). Further, several bryozoans are
found as fertile colonies. testifying in situ reproduction.
Acknowledgements. Thanks are due to the master and the
crew of "Ammiraglio Magnaghi" (Italy Navy), who greatly
helped the cruise during the sampling; and to Dr M. Triscari
(Messina University), for providing SEM facilities. This
research was financially supported by M.U.R.S.T. (40% Di
Geronimo and Rosso).
References
Allen rA, Sanders HL (1996) The zoogeography; diversity and origin of the deep-sea protobranch bivalves of the Atlantic: the
epilogue. Prog Oceanogr 38: 95-153
Allen JA. Sanders HL. Hannah P (1995) Studies on the deep-sea
Protobranchia (Bivalvia); the subfamily Yoldie1linae. Bull
Nat Hist Mus London ZooI61(1): 11-90
Amore C, Curzi VP, Geremia F, Lanti E. Principato MS (1996)
Risultati preliminari sulla dinamica sedimentaria attuale del
sistema de1le Isole Eolie e dei bacini limitrofi di Cefalu e di
Gioia. In: Faranda FM, Povero P (eds) Caratterizzazione
ambientale marina del sistema Bolle e dei bacini limitrofi di
Cefalu e Gioia (EOCUMM95). Data Rep CoNI SMa. Genova,
pp431-442
Barrier P, Di Geronimo I, La Perna R, Rosso A. Sanfilippo R,
Zibrowius H (1996) Taphonomy of deep-sea hard and soft
bottom communities: the Pleistocene of Lazzaro (Southern
Italy). In: Melendez G, Blasco F, P~rez I (eds) II Meet
Taphonomy Fossilization, Institution "Fernando el
Cat6lico", Zaragoza, pp 39-46
Ben Eliahu MN, Fiege D (1996) Serpulid tube-worms (Annelida
Polyc:haeta) of the Central and the Eastern Mediterranean
with particular attention to the levant basin.
Senkenbergiana Marit 28(1-3): 1-51
Bouchet P, Taviani M (1989) Atlantic deep-sea gastropods in the
Mediterranean: new findings. Boll Matac 25: 137-148
Bouchet P, Taviani M (1992) The Mediterranean deep-sea fauna:
pseudopopulations of Atlantic species? Deep-Sea Res 39(2):
169-184
Bouchet P, Waren A (1993) Revision of the Northeast Atlantic
bathyal and abyssal Mesogastropoda. Boll Matacol Suppl 3:
579-840
Calvet L (1907) Bryozoaires: expeditions scientifiques du
"'Travailleur" et du "Talisman" pendant les annees 18801883. Masson C Paris 8: 355-495
Carpine C (1970) Ecologie de l'etage bathyal dans la Mediterran~e
occidentale. MemInst Oceanogr 2: 1-146
Di Geronimo I (I973) Tiberia. octaviana n. sp. di Pyramidellidae
(Gastropoda,Opistobranchia) del Mediterraneo, Conchiglie
9(11-12): 217-222
Di Geronimo I (1974) Molluschi bentonici in sedimenti recenti
batiali ed abissali dello Jonio. Conchiglie 10(5-6): 133-172
Di Geronimo I, Bellagamba M (1985) Malacofaune del dragaggi
BS 77-1 e BS 77-2 (Sardegna nord-orientale). Boll Soc
PaleontolItal24(2-3): 111-129
Di Geronimo I, La Perna R (1996) Bathyspinula. excisa (Philippi.
1844) (Bivalvia, Protobranch.ia): a witness of the PlioQuaternary history of the deep Mediterranean benthos. Riv
Ital Paleontol Stratigr, Milano, 102(1): 105-118
Di Geronimo I, La Perna R (1997) Pleistocene bathyal molluscan
assemblages from Southern Italy. Riv Ital Paleontol Stratigr
103(3): 389-426
Di Geronimo I, La Perna R (2000) Some Quaternary bathyal eulimids from the Mediterranean, with description of two new
species (Gastropoda, Eulimidae). J Concho136(6) (in press)
Di Geronimo I, Li Gioi R (1981) La malacofauna wurmiana della
staz. BS 77/4 allargo di Capo Coda Cavallo (Sardegna nordorientale). Ann Univ Ferrara Sez IX, (Suppl) 6: 123-151
Di Geronimo I, La Perna R, Rosso A (1996) The Plio-Quaternary
evolution of the Mediterranean deep-sea benthos: an outline. In: La Med.iterranee: variabilites climatiques, environnement et biodiversit~. Colloq Sci Int 6-7 Avril 1995,
o.keanos 95, Montpe1liel', pp 286-291
Di Geronimo I, D' Atri A, La Perna R, Rosso A, Sanfilippo R.
Violanti D (1997) The Pleistocene bathyal section of Archi
(Southern Italy). Boll Soc Paleontol ltal36(1-2): 189-212
Fredj G, Laubier L (1985) The deep Mediterranean benthos. In:
Moraitou-Apostoloupou M, Kiortis V (eds) Mediterranean
marine ecosystems. Plenwn Press, New York, pp 109-145
1. Di Geronimo et aL
of dominant taxonomic groups (protobranchs,
scaphopods, etc.) (Di Geronimo and La Perna
1997; Di Geronimo et al. 1997). Among bryozoans, a single anascan species is present in the
examined material, while anascans are more
diversified in the Pleistocene (Barrier et al. 1996;
Di Geronimo et al. 1997). This rises the relative
abundance of cyclostomatous, which' parallel
ascophorans as species number (46%) and
exceed them (77%) at specimen level. The
anascan/ascophoran ratio (0.16 and 0.09 respectively) is very low while values of about 0.6 can
be valued from the Pleistocene assemblages
(Rosso 1990; Di Geronimo et al. 1997).
The reported differences should be viewed
within the model of changes in the deep
Mediterranean benthos during the Quaternary
(Di Geronimo et al. 1996; Di Geronimo and La
Perna 1996, 1997; Rosso and Di Geronimo 1998).
The deep-sea benthos underwent a progressive
impoverishment due to the set of warm-homothermic conditions, which replaced the PlioPleistocene psycrospheric ones. The Gibraltar sill
up-lift seems to have played a major role, turning
the Mediterranean into a threshold-controlled
basin, and cutting it of from the deep oceanic circulation. This led to the disappearance of most
cold-stenothermic species (extinct species of
Atlantic affinity, and extant Atlantic species), and
to a drop in diversity and richness in general.
The «pseudopulation:" model (Bouchet and
Taviani 1992) does not fit the present data. The
Recent deep Mediterranean benthos appear as
"residual", i.e. composed of species which survived the hydrological changes. Many molluscs,
usually encountered as empty shells, seem to
have little chance of crossing the Gibraltar sill, as
they lack long-living planktotrophic larvae and
their depth range begins well beyond the sill
depth (280 m). Further, several bryozoans are
found as fertile colonies. testifying in situ reproduction.
Acknowledgements. Thanks are due to the master and the
crew of "Ammiraglio Magnaghi" (Italy Navy), who greatly
helped the cruise during the sampling; and to Dr M. Triscari
(Messina University), for providing SEM facilities. This
research was financially supported by M.U.R.S.T. (40% Di
Geronimo and Rosso).
References
Allen rA, Sanders HL (1996) The zoogeography; diversity and origin of the deep-sea protobranch bivalves of the Atlantic: the
epilogue. Prog Oceanogr 38: 95-153
Allen JA. Sanders HL. Hannah P (1995) Studies on the deep-sea
Protobranchia (Bivalvia); the subfamily Yoldie1linae. Bull
Nat Hist Mus London ZooI61(1): 11-90
Amore C, Curzi VP, Geremia F, Lanti E. Principato MS (1996)
Risultati preliminari sulla dinamica sedimentaria attuale del
sistema de1le Isole Eolie e dei bacini limitrofi di Cefalu e di
Gioia. In: Faranda FM, Povero P (eds) Caratterizzazione
ambientale marina del sistema Bolle e dei bacini limitrofi di
Cefalu e Gioia (EOCUMM95). Data Rep CoNI SMa. Genova,
pp431-442
Barrier P, Di Geronimo I, La Perna R, Rosso A. Sanfilippo R,
Zibrowius H (1996) Taphonomy of deep-sea hard and soft
bottom communities: the Pleistocene of Lazzaro (Southern
Italy). In: Melendez G, Blasco F, P~rez I (eds) II Meet
Taphonomy Fossilization, Institution "Fernando el
Cat6lico", Zaragoza, pp 39-46
Ben Eliahu MN, Fiege D (1996) Serpulid tube-worms (Annelida
Polyc:haeta) of the Central and the Eastern Mediterranean
with particular attention to the levant basin.
Senkenbergiana Marit 28(1-3): 1-51
Bouchet P, Taviani M (1989) Atlantic deep-sea gastropods in the
Mediterranean: new findings. Boll Matac 25: 137-148
Bouchet P, Taviani M (1992) The Mediterranean deep-sea fauna:
pseudopopulations of Atlantic species? Deep-Sea Res 39(2):
169-184
Bouchet P, Waren A (1993) Revision of the Northeast Atlantic
bathyal and abyssal Mesogastropoda. Boll Matacol Suppl 3:
579-840
Calvet L (1907) Bryozoaires: expeditions scientifiques du
"'Travailleur" et du "Talisman" pendant les annees 18801883. Masson C Paris 8: 355-495
Carpine C (1970) Ecologie de l'etage bathyal dans la Mediterran~e
occidentale. MemInst Oceanogr 2: 1-146
Di Geronimo I (I973) Tiberia. octaviana n. sp. di Pyramidellidae
(Gastropoda,Opistobranchia) del Mediterraneo, Conchiglie
9(11-12): 217-222
Di Geronimo I (1974) Molluschi bentonici in sedimenti recenti
batiali ed abissali dello Jonio. Conchiglie 10(5-6): 133-172
Di Geronimo I, Bellagamba M (1985) Malacofaune del dragaggi
BS 77-1 e BS 77-2 (Sardegna nord-orientale). Boll Soc
PaleontolItal24(2-3): 111-129
Di Geronimo I, La Perna R (1996) Bathyspinula. excisa (Philippi.
1844) (Bivalvia, Protobranch.ia): a witness of the PlioQuaternary history of the deep Mediterranean benthos. Riv
Ital Paleontol Stratigr, Milano, 102(1): 105-118
Di Geronimo I, La Perna R (1997) Pleistocene bathyal molluscan
assemblages from Southern Italy. Riv Ital Paleontol Stratigr
103(3): 389-426
Di Geronimo I, La Perna R (2000) Some Quaternary bathyal eulimids from the Mediterranean, with description of two new
species (Gastropoda, Eulimidae). J Concho136(6) (in press)
Di Geronimo I, Li Gioi R (1981) La malacofauna wurmiana della
staz. BS 77/4 allargo di Capo Coda Cavallo (Sardegna nordorientale). Ann Univ Ferrara Sez IX, (Suppl) 6: 123-151
Di Geronimo I, La Perna R, Rosso A (1996) The Plio-Quaternary
evolution of the Mediterranean deep-sea benthos: an outline. In: La Med.iterranee: variabilites climatiques, environnement et biodiversit~. Colloq Sci Int 6-7 Avril 1995,
o.keanos 95, Montpe1liel', pp 286-291
Di Geronimo I, D' Atri A, La Perna R, Rosso A, Sanfilippo R.
Violanti D (1997) The Pleistocene bathyal section of Archi
(Southern Italy). Boll Soc Paleontol ltal36(1-2): 189-212
Fredj G, Laubier L (1985) The deep Mediterranean benthos. In:
Moraitou-Apostoloupou M, Kiortis V (eds) Mediterranean
marine ecosystems. Plenwn Press, New York, pp 109-145