the pleistocene bathyal teleostean fauna of archi

12 Pages·2013·3.07 MB·English

, Rivista Italiana di Paleontologia e Stratigrafia March
THE PLEISTOCENE BATHYAL TELEOSTEAN FAUNA
OF ARCHI (SOUTHERN ITALY):
PALAEOECOLOGICAL AND PALAEOBIOGEOGRAPHIC IMPLICATIONS.
ANGELA GIRONE
Receioed Januaty 31,2002; accEted, Nooember 18,2A02
Key Words: Otoliths, palaeoecology, palacoceanography, plei- recenrly, Di Geronimo er al. (1997) carried out a new
stocene, southern ItalI study of the benthic faunas (foraminifers, molluscs,
Ab*ract. The carly-middle Pleistocene releosrean fauna of the bryozoans, and serpulids) in light of the modern know-
Archi section, cropping out along the Calabrian side of the Messìna ledge regarding the deep-sea Pleistocene Mediterranean
Straits was studied. The ìntegrated approach, based on the palaeobathy- invertebrate faunas, bringing to attention the strong
mone tdriece mp ectihrcoadl icttoourpalel da nwdi tehp tihbea tphaylaale oaessceomlobgliacgael sa, pwpraosa cahp, palilereda dfov ru sthced affinity of the benthic palaeocommuniries wirh the pre-
palaeoenvironmenral reconstruction. The otolith benthic and ben- sent-day North Atlantic.
thopelagic associations, strongly bathyal in their compositron, suggesr a In the presenr work, the otolith assemblages from
deep bathyal palaeoenvironmenr, 5OO to lOOO m deep, which is in agrce- the Archi section were analysed to improve the know-
manedn tt awxoitnho mthìeca iln vfeearttuerbersa toef btheen ttheilce ofsatuenaans .a sCsoemmbploagseitsio ninadl,i castteru cclteuararlyl, ledge of the Pleistocene deep-sea teleosrean fauna, focu-
Atlantic or more generally oceanic affinitìes. The Archi releostean fauna sing mainly on their palaeoecology and palaeobiogeogra-
indicates a palaeoceanographic pattern with deep-water and near-bot- phy. The integrated approach proposed by Girone
tom temperature lower than 8-10'C, quite different from the Recent (2000b), based on the palaeobathymetric method akeady
Mediterranean.
well known in the literature (Nolf & Brzobohary 1994)
Riassunto. E'stata studiata la fauna a teleostei della sezione pleis_ together with the palaeocological approach, was applied
tocenica di Archi che affiora lungo il versante calabro deilo Stretto di for the palaeoenvironmental reconsrruction. Indeed this
Messina. L'analìsi delle associazioni ad otolìti è stata condotta applican- integrated approach, already used on Pleistocene orolith
do I'approccio inregraro, già utilizzato per associazioni del circalitorale assemblages (Girone 2000b), has provided a great
profondo e dell'epibatiale, basato sul metodo paleobatimetrico e l,ap-
proccio paleoecologico. Le associazioni bcntoniche e bentonectoniche improvement in the palaeoenvironmental reconstrucrion
ad otoliti indicano un paleoambiente batiale presumìbilmelre compreso of deep circalittoral (sensu Pérès & Picard 1964; pérès
tra 500 e 1000 m. 1967) and epibathyal deposits. The deep-sea assemblages
Aspetti con-rposizionali, strutturali e tassonomici di queste asso- from the Archi site represent a good example to tesr rhe
mciaenzitoen oi cienadnicicaan. oT alale loarffoin fitoàr ttee satfimfinointàia cuonn rlae gfaimuen ap aaltelaoncteicaan oog rgaefinccor icdae-l sensitiveness of the integrated approach in deeper set-
tutto differente da quello dcl Mediterraneo attuale, con remperature al tings.
fondo inferiori agli S-tO'C. The relationship between the teleostean fauna of
the Archi section and the Atlantic fauna is discussed also
in the conrext of an evolutionary model of the deep
Introduction
Mediterranean benthos based on the invertebrate faunas
The Archi site is one the best known deep-sea (Benson 1972;Di Geronimo et aL. 1996; Di Geronimo &
deposits cropping our in the Messina Straits area. It has La Perna 1.997; Corselli 2001).
been studied several times with parricular arrenrion ro
cnidarian faunas (Placella i928; Guadagno et al. 1979) and
Geological setting
molluscan faunas (Crovato & Thviani 1985; Taviani et al.
1990; Micali & Villari 1986; Rindone 1990). placella The Archi secrion crops out on the Calabrian side
(1978) and Guadagno er a,I. (1979) also addressed the of the Messina Srrairs. The Messina Straits zone is cur-
deep-sea Atlantic characrer of the Archi corals. More rently interprered as a basin belonging to the Calabrian-
Dipartimento di Geologia e Geofisica, Università di Bari, via E. Orabona 4,70125 Bari, ltaly; e-mail: [email protected]
100 A. Girone
PIio-Pleistocene
sedimenlary units
I ) Catona-Messina
2) Calanna
3) Reggio
4) Motta
5) Capo dell'Armi
6) Melitto
7) Castanea
C
A
ftom Di Ce.onjmo el al., 1997r L
Fig. 1 - A: Location of the studY
LEGENDA B area; B: The tectono-sedi-
|E ,b Il Srho"uetrnher,on ,gAh dr)r'niancr'i: chlo' ^nJ,raenr /I| -l' /'/ l sournec"l rar 'rcl"''ne tf_-- :_- : II t;1" '1"' RI Mmeesnstainrya Sfrtarmaitesw aorreka o (ffr othme
l{1 .,,"0,,*o^ ffi fll .,', .' Di Geronimo et al., 1997,
^n-riunr,*,..o modified); C: The Archi
. Sanple s e ctron.
Peloritan Arc. It consists of tectonic crystalline-meta- Reggio Calabria (southern ltaly) (Fig. 1) and is well
morphic units covered by the Capo d'Orlando Flysch exposed along an N-S abandoned quarry front. It consists
(Late Aquitanian - Langhian) (Bonardi et al. 1980). This mainly of well-stratified pelitic sediments with beds ge-
unit is tectonically overlain by the "argille varicolori", a nerally faintly sloping westward (Di Geronimo et al.
chaotic mélange of pelitic matrix containing macrofossils 1997). Two bed-sets were recognised along the quarry
as old as the Cenomanian and enclosing olistoliths of front: a lower one, whose beds are involved in a gentle
Palaeogene calciturbidites and Chattian-Early Miocene flexure, and an upper one, showing paraliel bedding.
qtr rtzareniric turbidites. The mélange is overlain by an Vithin the markedly homogeneous pelitic sequence' two
unnamed sequence of Serravallian-Tortonian turbiditic thicker and coarser (silty-sandy) beds stand out at the
deposits and rare Messinian evaporites. base of the upper bed-set (Di Geronimo et al. 1'997).
A subsequent discordant Plio-Pleistocene sequence According to the calcareous nannofossiÌ assem-
was recently recogn;sed (Barrier & Keraudren 1983; Bar- blages, the section ranges from the early Pleistocene
rier et al. 1985; Barrier 1987; Arfa et aI. 1987 Montenat et (smal| Gepbyrocapsd nannofossil biozone) in its basal part
al. tssz). It consists of diachronous facies whose age ge-
(about the first three m), to the middle Pleistocene (Psea-
neraily decreases from mainland to coastline and from
doemiliania lacwnosa nannofossil biozone) in the middle-
north to south. They were deposited within smali basins
upper part (Di Geronimo et al. 1992) (Fig. 1).
bounded by fauit escarpments, which sometimes crop out
Previous studies of the benthic invertebrate fauna
showing remains of sessile faunas (Barrier et al. 1989,
(foraminifers, mol1uscs, bryozoans and serpulids) indi-
1996).The Plio-Pleistocene fault systems split the Messi-
cate a bathyal palaeoenvironment, 5OO to 10OO m deep.
na Straits area into several blocks that evolved as distinct
According to the planktonic foraminifera assemblages,
basins corresponding ro the "tectono-sedimentary enti-
the deposition occurred during a cold phase (Di Geroni-
ties" of Barrier (1.984, 1,987).
The Archi section, 9 m thick, belongs to the Reggio mo et al. 1997). Moreover, the compositional, structural
tectono-sedimentary entity (Fig. 1), which developed and taxonomical features of the palaeocommunities indi-
during the upper part of the Early Pliocene up to the mid- cate a strong affinity with the present-day North Atlantic
dle-late Pleistocene. The sedimentary sequence begins or oceanic conditions involving a psychrosphaeric palaeo-
with transgressive shallow-water deposits, evolves to ceanographic model with bottom temperatures lower
bathyal units, and ends with the "Messina Gravel". than 8"-10' C, which is very different from the Recent
In particular, the section studied is located near Mediterranean model (Di Geronim o et aI. 1997).
P /e istct cette te leo stean s of Ar ch t
PLATL,1
All fossil otoliths_are.cleposited in the collcction of the Dip:irtimento di Geologia c Geofisic:, Unir,ersitr.of Bari
In thc captions, thc abbreviation L st;rnds îor left otolith and the abbreviation R for right otolìth.
Ftg. l-- Nans.enia groenlandica (Reìnhardt, 18a0) Lr samplc Archi 9. Iig. 2 - Micromesistius pailtdssou (Risso, 1826) I-; sample Archi 8. Fig. i -
Chauliodus.sloarzl (Schncider, 1801) L; sample_Archi_10. Fig. a - Bathttlagus e uryops (Goodc & Bean, 1896) L; sarlple Archi S. irig. S - Coeloriicbus
sreliarls Nolf & Girone, 2OO0 a: L; b: R; samplc Archi Z. Fig. 6 - Coryphaenoicle's cÍ. guentheri (Vaillant, 18S8) , r: L; b-c: R; sample Archi 8. Fig.
7_- Corypbrtenoides rupesrris (Gunners, 1265) R; a: sample Archi 8; b-c: Archi l. Fìg. S - Zoarcidae inci. L; :r: s:rrlplc Archi Zl b: Archi 4. Fìg. 9 -
Bathypterois sp. R; sarlple Archi Z.
142 A. Girone
T:h. | - Sv'remrric Ii'r of teleost raxa
SYSTEMATIC I,IST OF THE TAXA FRONÍ ARCHI Sf,CTION ; ;
from Archi section. Relative
l'a x=a cixn lnbcotl dsp:e cRreescenl Atlantic taxa disappcared fron Mediterranean abundance of each species
PELAGIC D% D% D% D% D% D% D% D% D% D% D.l, D% and total amount of speci-
Bathylagus eurlops Goode & Bean, I 896 5.1 mens per sample.
'RCÈ!1]NIDAF 'lansenia grcenlandica (Reinhafdt, 1840) 1.4
03 0l
IERNOFTHYCHIDAI vaurcli.us nuellerì (Cmelin, 1789) 3.2 0.6
Po\)ípilus àîf poilí Schultz, l96l ìl 2.6
]ONOSîOMATIDAE Gonostona |nd. 04 Results
,HOTICH'IHYIDAE fincinguerria auetuafo (Coc.o, 1838) Ì
yincingilerria po'|eriae (Cocco, I 838) t.l The twelve bulk samples
:HA!LIODONTIDAE Chauliodus stoani Schneider, I E0l 0.4
Benthoserna glaciale (Reinhardt. I 83?) 9.6 8.9 22 545 20.6 117 5l 45 2.1 20.ó 9.5 collected along the Archi section
Ceratoscopelus naderers6 (Lowe, 1939) 3ó 20.3 18,5 15.4 18.2 3 8.2 29.6 21 ì0.3 l6 40.5 l5 contain otoliths referable to
Diaphus hohi Taaning, l9l8 1.7 ó
Diaphus rafnesqui (Cocco, I 838) I 0l 0.5 t.l thirty eight teleost taxa (Tab. 1),
EDlìedcpthrounsa t aisdsiloinig (i CNococmo,a 1[8 2l9g)30 1.2 t88 9 50.66 t6.2 4.7 thirty four of which can be clas-
Htgaphun benaíti (Cocco. 1838) 23.2 183 l9 225 18.2 ll4 lÌó 5.2 ó.9 lóì 632 sified ar specific level. The
Hr yHgyogpohptmh uhny sgpo. nIi (Lurken, I 892) 3.2 6.9 07..53 3 5132 8ó.51 68 preservation of the otoliths is
" Lampadena bxicd Girone & Noll 2002 0.8 0l 1.1 generally good. In some cases,
LMofb.tioanpchhrina dpou|nle.tiailib t(nZ ugRmafainyeesrq,u le9, l Il )El0 l2 8I' 96 78 E 52 1.4 24.6l E.ú ll though. the specimens of myc-
Notascopel$ elangatus (CostÀ. I 844) 2.4 2 3.2 l.ó I0.5 ll t.1 2 21 tophids show soiution effects
S*Svmcobpoelol opp sltìos rupsl ioveceranni(yùi sl MAorneta u&. MI 8o8s8n)a, 197ó 0.8 84 ì.I1 0t..57 8.I7 (especially on the inner faces,
totaì oelaqlc sDeomenr 135 Ì42 i35 3l 306 188 29 230 131 l4J and in particuiar in the suicus
IFNTHOPFT À(:TI D% D% D% Dr/. D% D% D% D% D% D% D% D% area, whereas the outer faces are
ALEPdEPIIALIDAE 21.2 only slightly worn) or are
Lampanyctus cracodilur (Risso, l8L0) 9l.l 84.ó 8ó 45.4 100 82.1 ó5.1 87.5 50 857 encrusted by bryozoans or
Caaiculus orgentils Guichenot, I 850 E2
iíicromesistius poutasso! (Risso, 1826) l 18.2 il7 8.1 20 25 foraminifers indicaring long
Phycìs blennoid* (Brunnich, 1768) 2
MACROIJRIDAE CoeLoùnchus caelorhtnces (Risso. l8 l0) l 3 exposure on the sea-bottom and
* Cnelatínchus stellarìs Nolf& Gìrone 2000 ó.1 a slow sedimentation rate. The
Corlphaenoides rupestru\ Gunners. 1765 2 2A 75
Coryphaenoi<les cÍ. guentheri (Vaillant. I 888) difference in preservation of the
CAMNCIDAE ì2 5 inner and outer face of the
}ENTHIC
otoliths may be due to the struc-
CHLOROPHTHÀLMIDAF 2
ìelloria cî. apoda Ciglìoli, I 883 i.6 3l ture of the sulcus area. The sur-
]ythitidae sp. ind. 1.6 3 0.5 t4.l face of the sulcus of several fish
NCERTAE SEDIS
loaecidae sD.ind. 9 2 is built of somewhat irregularly
total benthìc and benthoDelaeìc specimenr 34 22 E 6 assembled carbonate particles
which are loosely connected and
Material and methods
show a meshwork structure, while areas outside the sul-
Twelve bulk-samples, each measuring about 1O dml, cus have a more compact structure (Martini 1974). Solu-
were collected along the section (Fig.t). They were rou- tion will affect the sulcus area much more than the other
tinely processed for macrofaunal studies, and the residues areas. The outer face of the sagittae will be more resistant
sieved through a 250pm mesh. The coarser residues to solution processes,
In sharp contrast to the other samples, samples
Qa25'pm) contained the greatest number of specimens
Archi 6 and Archi 7 are rich, both in species and speci-
while the finer portions (>250 pm) were sorted in order
mens. Sample Archi 5 contains the lowest number of
to detect small-sized pelagic species. The abundance and
specimens that are poorly significant palaeoecologically.
dominance of each taxon for each sample were calculated
The otolith assemblages include 22 species that still
following the criterion proposed for the bivalve group by
live in the Mediterranean Sea with two of them, Symbo-
Di Geronimo & Robba (1976). The calculations were car-
lophorws oeranyi and Chauliodus sloani (Pl. 1, fig. 3) iden-
ried out separately for the pelagic and benthic - ben-
tified as fossils for the first time. There are also five taxa,
thopelagic groups (Tab. 1). referable to Atlantic species, which have long disappeared
In the palaeoecological approach, only the ben- from the Recent Mediterranean. Among these, the bathy-
thopelagic and benthic fishes were taken into account pelagic species Bathylagus euDtops (Pl. 1, fig. 4),Nansenia
and, besides the taxonomic composition, other attributes groenlandica (P1. 1, fig. 1) and the benthopelagic
of the associations were analysed (Girone 2000b). On the Coryphaenoides rwpestris (Pl. 1, fig. 7) are, for the first
contrary, the entire assembiage (mesopelagic, ben- time, reported as fossil species whrle Polypnws cf. polli and
thopelagic, and benthic fishes) was analysed using the Diaphus taaningi were already known in the Mediter-
palaeobathymetric method proposed for this group by ranean area. P. cf. polli has been reported in the middle
Nolf sc Brzobohaty (1994). Pleistocene of the Montalbano Jonico section (Girone
Pleistocene teleosteans of Archi 103
pliocenicus and Coelorinchws stellaris (Pl. 1, fig. 5) are fos-
trpelagic lbmthio-benthopelagic sil species; the first and the second are reported only in
Pleistocene sediments of the Medirerranean (Girone Ec
Nolf ZOOZ; Girone & Varola 2001). S. pliocenus is known
as an endemic species of the Mediterraîean area from the
Miocene (Tortonian) to the Pleistocene, while C. stellaris
has been reported in the late Oligocene sediments of
Aquitaine and in the Late Pliocene (Gelasian) and early-
middle Pleistocene of the Medit err^nean (Nolf Sc Girone
2000).
The assemblages recognised are composed of low
percentages of benthic and benthopelagic componenrs
that generally make up for less than 20% with respecr ro
the pelagic group (Fig. 2), which is mostly represented by
mesopelagic fishes (myctophids). Similar to the pelagic
assemblages, the benthic and benthopelagic associations
of Archi 6 and Archi 7 are the richest in specimens; the
association of Archi Z is also the richest in species (Tab.
1).
e È t È E i E E i Therefore, in the benthic-benthopelagic group ir is
== possible to distinguish bottom-related taxa thar swim just
above the sea bottom (benthopelagic) or that live in con-
tact with it lbenthic).
Fig.2 - Benthopelagic-benthic-mesopelagìc ratio in the otolith Benthic fishes (Tab. 1) are not common with only
assemblages from the Archi section. two species, Bellotia cf. apoda found in three samples
(Archi 2,7 and 11) and Bathypterois sp. (Pl. 1, fíg.9)
2000a; Girone & Varola 2001), and D. taaningi has been detected only in sample Archi 7. The Recent vertical dis-
found from the Miocene (only Tortonian) to the middle tribution of B. apoda is poorly documented because this
species is known only from a few specimens found off
PleistoLcaemnep a(Bderznoab oiohnaictya ,& H Nygoolfp h2OwOmO ; sGpir.o ln,e S2c0o0p0elbo)p.sis Madeira and Portugai and in the Mediterranean. It has
been caught in bottom trawls at depths from 3O to 5OO m
(Whitehead et al. 1986). On the conrrary the genus
E! III class (d>2mm) f II class (l mm<d<2mm) E I class (d<lmm) Bathypterois is circumglobal at tropical and temperate la-
titudes and is typical at bathyal to abyssal depths (Vhite-
loovo
head et al. 1989).In the Recent Mediterranean and in the
90% Atlantic, five species belonging to this genus are reported.
These, considered typical of deep bathyal environmenrs,
800/. are generally found exclusively at depths greater than ZOO
m (Maurin 1968; Stefanescu et al. 1994).
100/"
The abundance of benthic fishes in the Archi sec-
60% tion could increase if the specimens referred to Bythitidae
sp. ind. andZoarcrdae sp. ind. (Pl. 1, fig.8) were inclu-
50%
ded. These families are represented mostiy by benthic
40yo species living from a few merers to abyssal depths with
only a few species being bathypelagic. In particular, the
30%
specimens referred to the Bythitidae are very small in size
20% and are lacking diagnostic features for specific identifica-
tion. Nevertheless, it is nor to be excluded that they could
too/o belong to B. apoda.
The specific attribution of the specimens referred
o%
ós€FoÈd _É
';F===- to the Family Zoarcidae was not possible due to the scarce
vseeeg44+
Recent material available for comparison. The zoarcids
sample are reported in cold and temperare waters of both hemi-
spheres. Temperature and salinity are the main factors
Fio ì Size distribution of otoliths in Lampanyctus crocodilws that influence their distribution. Several boreal species are
populations from rhe Archi secrion. linked to water temperarures lower than O" C and a sali-
104 A. Girone
'c
a
ú9 I & E!
I Sample cE tE! g-g 9{ "Íeo"Í- ! F, YE pP Sample
€i!,69F éOO=ITeJllÈ .E 2ÈEea*ea: Archi 2 ;g €3 {;f<È;.: 9=0ó_t.:àÈ!?éo.Eè ;:* *.è9g -.E4É,!ì Èe Eb !?i ú!x Eî Archi 7
i00.. X8%,t* 100- lrl !l
?00 I I 200-
100 :: I 54.tq . 30ù l.
400 ti**|{l 859" 400
500 lr'ilìll]ilii:*lir.l:!irt;li-ll e2% 50ù
:
600.. " Il77La 60c
700 70(!
S-i$il
800 80ù I
900 ;i!ìillai:l 54% 90ù
!1138%
".9i s: ;i3: É arî _F'bi" a - Recenr h:thvmetrìc disrribu-
g Ei* îE +;e- ÉEÉ Eg ai 6 ÈÈ ;a E=ePÈ tsieonnte do fi nt eAlerocshti t2a,x Aa rcrehpìr e7-,
'E: ASracmhpi lle0 E ?i=é$î;zVzIut ASracmhip l1e1 Archi 10, and Archi 1 1
assemblages. For each 1OO m
E.
ÉEEÉgÉFEÉÉiÉiÈÉÉÈÉ itgÉÉÉÉttÉgÉti bathymetric interval, the
graph shows the potential
100 lzzv, 100 presences, expressed as a
200 S]]ro* 200_ percentage of the total num-
300 : 300 ber of taxa utilised in the
400 __J/r"/o 400 analysis. The dotted lines
500 iilii*lllir:lil sr% 500 indicate nìghtly presence of
600 t*!t:;t5!tìlàil 88% 600 mesopelagic species at the
700 " I''''" 700. surface; see Nolf & Brzobo-
9E0000 $i{e$l:l,l 055r7"" 980000 hdeattayil e(d1 9d9is4c)u sf osiro na o mf othree
I 000. 1000
methodology.
nity of 34 "/"". Melanostigma atlanticwm is the only species blennoides and Gadicwlus argenteus were found only occa-
reported in the western Mediterranean. It is bathypelagic sionally. The gadid species are represented mostly by
over the continental slope mostly at 400 - 1000 m depth. medium-large specimens, though very large specimens of
The benthopelagic group includes mostly gadids M. poutassou and P blennoides were found in samples
and macrourids that represent the most abundant species. Archi 6 and Archi Z. Among the macrourids, the North
On the conrrary, the myctophids, represented only by Atlantic Corypbaenoides rupestris is the most abundant. It
one species, are the most abundant in specimens and was recognised in the samples from the middle-upper part
occur widely throughout the section. However, the myc- of the section (samples Archi 7, Archi 8, and Archi 9;
tophids show the highest diversity in the pelagic group (Tab. 1) where it is represented by very large specimens.
(Tab. 1). Among the myctophids, L. crocodilus is a species In the sample Archi 8, it is associated with the congene-
that can change life habits during growth and conse- ric species C. cf. guentheri whjch represents 60o/" of the
quently may be considered a pelagic or benthopelagic associations. C. gwentheri, is the deepest species of this
fish. In particular, the adults of this species dwell close to genus and, in particular, it has been found exclusively at
the bottom changing their life habit from mesopelagic in depths greater than 800-1000 m (Stefanescu et al. 1994;
the juvenile stage to benthopelagic in later stages (Ste- Morales-Nin 1990).
fanescu Er Cartes 1992). The distribution of the three The macrourid group includes also the Recent
class sizes recognised in the population of L. crocodilws Coelorincbws coelorincus found in samoles Archi 1 and
from Archi (Fig. 3) suggests that the second and third Archi 6 and the fossil C. stellaris recognised in samples
classes are the most abundant. Observations performed Archi Z and Archi 11 (Tab. 1). The former species is re-
on the sizes of recent populations (Girone 2000b) indi- presented mostly by medium-iarge individuals whereas
cate that the second and third ciasses are made of adult the sizes of the specimens referable to C. stellaris range
specimens whereas the first is made of juveniles. Conse- from medium-large in Archi 11 to very large in Archi 7.
quently, the populations of Z. crocodilws were included in Other species that occur occasionally tnclude Ale-
the benthopelagic associarions. pocEhalus sp. and Trachwrus sp. whose taxonomic status
Among the gadids, Micromesistiws powtassow (PL 1,, is not well defined because of their poor preservation. The
fíg. 2) is the most common species whlle Phycis pelagic group includes mesopelagic and bathypelagic
Pleistocene teleosteans of Archt 105
7*
&aEE ÈÉóEdÈ(tr .Ò=63F:* I e ÌE:Igl Je2É.s0* àei*>É.Xed,o EEÉ,-: g EaAFE,."!o:'aÉz-'o:b5la s a._Es, có8gx>E-2è?9'_9úqz.:!É4.g >g "e:EÈ ASarcmhpil eI E óCg CÒEFp"Pú€AÈí ,':úÉTi -*àt-l-qÉe:g:E€È>fi!à;::9F:É,.. ASarcmhpi le3 oE €:<x2AFl2 î.ty!ccèli :Òó6:L f,é,Ò;úY1f gJ6>>. Fi!eE€;E3=;F-! >È;93L i,{EX2:8OàÌ! r>E9N SAarcmhpi le4
|il%
1 00- -lo:r" 100.- IIIilerv" I 00-
Xiilsogt
?00- 200 20u
'164-" -"..lttu" ;ilrìlilll 58%
100- T-ltto" 300 100-
400_ 400. "----l 100% 400- *ìJYl"/o
50ù -1i s6% 500 *'l*+-/ 50ù t:Jl#u;$-l ili-!,;ttl
ó0G ffiff' 600., :''lae"/" 60ù .*----l- -]a:z"
7800{ùr ---:-1.-I8f-o/" 780000. T'"T:'l 7800&0 ,".' . .t,, II
." .ll rva
90ù lro1*64% 900 :1*È 90ù
I 0ùù I 000 1 dtv" 100{r $lil{li$losx
3
i,l 2^a
ooa 'È=i,=eÈ9É EóEd2o .Èl;tcEÉto ' ,giGsí{: -:'Eó21,É8- - .RÉ 3*2E. *.àóàE2*,Bl*.-È25 ,Éé- .gF36="P6$l o$oeF "EXb.E9óp A:E€U ASarcmhpi le6 Ia >9IEa 6éGhoÉÒ- 9ÉtldE_t tt.aJ>à-à. ->za a€Eé9li6 s sz:ÉE9o ASracmhip l1e2
100, il,,* r 00- ffiillssz
200- 200- r ", "188%
300- +'"^ 300- :
*&.N
400_ fiaru" 400- ...
500 î--11 50{t =il:.T"::r;,*.:"i1l100%
ó0ù -Trl,,* 60&
É_+l
70& -::--::-1 700- 88%
;;+-J
80ù -=tj 800- :: ,.:"1zra
90& fr*rill ssx 900- '.
xlì,* ''loox
t000 I 000-
F;- q - R.^.-t k".1".'-.'"ic distribution of teleost taxa represented in Archi 1, Archi 3, Archi 4, Archi 6, and Archi 12 assemblages; see Fig. 4
for the explanatìon.
species. The mesopelagic species belong to the Family
F
eP,úE z2sf, Myctophidae, to the sternoptychids Mawrolicus mwelleri
gri;g**i, I :ilHEseci and Polyipnus cf. polli, to the photichthyids Vincinguenia
Sample I60 31si; Sarnple attenuata and V poweriae, and to the stomiatoid Chaulio-
Archi 8 sE
Archi 9 dus sloani. Bathylagus euTyops and Nansenia groenlandica,
ÉiàAsÉEei é7,
E'i8àÈ:È,:s iijiÉ occurring respectively in Archi 8 and Archi 9, are bathy-
pelagic fishes. The myctophids are notably dominant
100 ltiit 100 ii, from 95"/" to 1OO%. Benthosema glaciale and Cerato-
200 Xaax 200 tl !lzs"z scopelus rnaderensis occur in all samples whereas Hygo'
110000 Ittnloov" 140@0_ i{lt:lltuìiìuliitl.tl:6t 3%75% phum benoiti, Myctophum punctatum, and llofoscopelus
il*r*tlsgx elongatus are distributed widely throughout the section.
500 500
é00 600 ìtìiq:i:iì;ttìit The occurrence and abundance of Diaphus hohi and Elec-
---'1
700 **i#,t;{,{ roo% 700 t***!!llo0/o trona rissoi are occasional. The species recognised have a
980000 lllll -*---.l 980000. 1:t!:-11ì ìt11ìitiììi-i-:a lI w2OidOe m b taoth 1yOm0Oe tmric. Odtihsterrib supteiocnie sr aonf gai nmgo rfero dmef ianbedo ubta 1th0y0--
rli*llilrm '
I 000 1000. l88eo metric range, from 400 to 200 m, include Hygopbum bygo-
mi, Diaphus rafinesqwi, and Symbolopborus oeranyl. Most
of the myctophid species occurring in the assemblages
Fig. 6 Recent bathymetric distribution ofteleost taxa represented
in Archi 8 and Archi 9 assemblages; "c_"c'_ F -ìob 4 f'.^-'' t"h-"' "'""r.'ì_,- undergo size strati{ication with generally juveniles at shal-
nation. lower depths of the bathymetric ranges and adults at
106 A. Girone
greater depths. The populations of the myctophid species lmmobathyal Etbathyal 6eu
from Archi are generally composed of individuals of he-
r:mr
terogeneous size except for NotoscopeLws elongatus and Archi 12 re
Symbolopborus r;eranyi, which are represented entirely by
ffi*
very large individuals.
Archi I I @
According to the palaeobathymetric method, the
graphs reconsrructed for each assemblage indicate the Archi l0 f@fil
highest peaks relative to bathymetric intervals at depths
%
greater than 300-4OO m and a rapid decline of percenrages Archi 9
corresponding to the shallower depths.
The graphs of Archi 2, Archi 7, Archi 1O and Archi Archi 8
11 clearly position the lOOm-interval of maximum pre- k^
sence betrileen 400 and 5OO m for the assemblages Archi g ArchiT
2, Archi Z and Archi 11 and between 500 and 600 m for
Archi 10 (Fig. a). In the other cases, the graphs shovr the Archi 6
200 m and 300 m-intervals of maximum presence ar
depths between 4OO m and 600 m (Archi l),300 m and Archi 4
500 m (Archi 3, Archi 4, Archi 6) or 3OO and 600 m k
(Archi 12) (Fig. 5). The graphs of the assemblages Archi Archi 3
8 and Archi 9 show wide but clear maximum peak IT
between 500 and 9OO m with a rapid decline in the per- Archi 2 @-
centages above 500 m (Fig. 6).
VI
Archi I
l0 20 30 40 50 60 70 80 90 l00D%
Discussion
The otolith assemblages from the Archi section are Fig.7 - Distribution of benthic and benthopelagic fishes based on
characterised by the dominance of meso-bathypelagic life environment in the Archi secrion.
species over the benthic-benthopelagic species. The do-
minance of meso-bathypelagic individuals may be related
and are really indicative of the bottom depth.
to their biologicai features and the heterogeneous nature Similarly to benthic invertebrate associations (Di
&of tBheo sgeennecsei s1 o9f9 1fo)s. sCil oontosildithe riansgse bmiobllaoggeics a(sl ecnasuus eKsi,d wire ilsl Geronimo et al. 1,997), the increased richness of the
teleostean benthic and benthopelagic associations in the
s/orth noting that the pelagic species, in particular the
middle part of the section (samples Archi 6 and Archi z)
myctophids, form large shoals. On the contrary in the can be related to a positive ecological response of the
deep-sea environments, the benthic and benthopelagic deep-sea communities ro rhe hydrodynamically active
fishes are rarely represented by dense populations. More- phase. Field observarions and sedimentological and
over the mesopelagic fishes are the main preys of larger
palaeontological data suggest that the deposition of this
predators, which may introduce the mesopelagic otoliths
stratigraphic interval was affected by hydrodynamic
into the sediment through their excrements (Nolf 1985).
episodes, probably influenced by tectonics (Di Geronimo
However, this hypothesis does not exclude all the et aI.1997).
other factors that may have contributed to the origin of
This kind of ecological response of the deep-sea
the fossil otolith assemblages. The pelagic assemblages communities and of demersal fish associarions was
contain otoliths from all fishes, distributed in the entire
already highlighted by Gooday & Tirrley (1990 and refe-
water column, that fall to the bottom. However, the rences) and Stefanescu et al. (1994) who showed the
otoliths of benthic and benthopelagic species belong only
to fishes that lived on the sea-bottom. Consequently, prominent role of near-bottom currents in increasing the
organic inputs on the deep-sea bottom.
populations of pelagic fishes recognised in the fossil
assemblages are mixed populations, with specimens rhar
lived in different strata of the water column and are not
Palaeobathymetry
necessarily indicative of the bottom depth. The wide size
range observed in the fossil pelagic populations reflects The otolith assemblages from the Archi section are
the size stratificarion that affects pelagic fishes during clearly bathyal in their composition. In fact assemblages
their life. The populations of benthic and benthopelagic with macrourid otoliths, usually accompanied by great
fishes occurring in the fossil assemblages and showing quantities of myctophid otoliths, are considered typical
generally a single or similar dominant size range, are rhe of continental slope sediments deposited at depths of at
genuine populations that inhabited the investigated area least 250 m (Nolf 1985; Nolf 8r Brozoboh aty 1994).They
Pleistocene teleosteans of Archi 147
appear uncontaminated by reworked elements, except for In this framework, it is worth noting that the
the specimen of a gobiid which records an environment gadids found along the Archi section are mostly referable
quite different from the deep-sea. to large individuals. In particular the larger individuals of
The benthic and benthopelagic associations include M. poutassou and G. argenteus were found in samples
species typical of bathyal environments deeper than 4OO- Archi 6 and Archi Z. Similarly, the iiving macrourid C.
5OO m, such as the chloropthaimid Bathypterois, the ale- coelorinchws, characteristic in about 200 to 500 m (Cohen
pocephaiid Alepocepbalws and the deeper bathyal et al. 1990), undergoes the larger-deeper phenomenon
macrourids C, rupestris and C. cf. guentheri. The genera (Massutí et aI. 1995; D'Onghia et al. ZOOo) and conse-
Bathypterois and C. cf. guentberi are generally reported as quently the occurrence of large individuals in deeper set-
taxa closely associated with depths greater than 700-800 ting is frequent. According to palaeontological evidence,
m (Stefanescu et al. 1994;Morales-Nin 1990). A similar the life habit of the fossil C. stellaris seems to be quite
ecologic setting is indicated by the genus Alepocephalus, similar to the Recent congeneric and it also seems to have
even though the living Mediterranean A. rostratus has been subjected to the larger-deeper phenomenon. Obser-
been found occasionally at shaliower bathyal depths, vations carried out on the size of otoliths from different
showing a wider bathymetric distribution from 300 to
sites showed that the specimens of C. stellaris recognised
3600 m (Whitehead et al. t989). Flowever, according to in epibathyal associations are often smaller than the
Maurin (1968), A. rostratus is related to a sea bottom
otoliths occurring in middle bathyal associations (Girone
deeper than 500 m often associated with Z. crocodilws.
2000b) in which the larger individuals are generally more
C. rupestris shows a larger bathymetric distribution common. The specimens of C. stellaris from the Archi
ranging from 400 m to over 1500 m even if it is more
section, in particular those found in the sample Archi 7,
abundant at depths deeper than 600-700 m (Hareide &
are comparable in size to the otoliths from middle bathyal
Garnes 2001; Lorance et al.2OO1) where it is the domi-
associations. It is worth stressing again that in this sample
nant species in the fish communities. It has been found in
the fossil species is associated with deep-sea taxa such as
Atlantic waters with temperatures of 8-10" C (Vhitehead
C. rupestris, Batbypterois, and L. crocodilus.
et al. 1986). This species undergoes seasonal vertical
The benthic and benthopelagic associations,
migrations, moving to deeper waters during the summer
bathyal in their composition and structure, clearly indi-
months and returning to shallowerwaters in the winter.
cate a deep bathyal environment located in the mesoba-
The common occurrence throughout the section of
adult individuals of L. crocodilus should be also stressed. thyal interval. A palaeodepth between 4OO-5OO m and
Maurin (1968) and Arena & Li Greci (1973) pointed out 1OO0 m can be tentatìve1y inferred in agreement with the
the frequent occurrence of the adult individuals of this data from the analysis of the benthic invertebrate associ-
myctophid at depths greater than 500 m on the sea floor ations (Di Geronimo et al. tSSlT . No notable evidence of
of the central Mediterranean in association with the deep bathymetric changes can be identified even though the
benthopelagic fishes. Therefore L. crocodilus, in its adult presence of deeper taxa such as C. cf. guentheri and
stage, takes on a notable meaning in the deep ben- Batlrypterois in the middle part of the section could sug-
thopelagic associations, in particular, in the Mediter- gest a somewhat deeper setting.
ranean Sea and is reported as a characteristic species on The data obtained with the palaeobathymetric
the middle slope 400-800 m deep (D'Onghia et a1. 1998; method are generaliy comparable with the data inferred
Stefanescu et al. tvv+). by the palaeoecological approach based on benthic and
In all benthic and benthopelagic associations from benthopelagic associations. According to the palaeoba-
the Archi section, the dominance value of deep bathyal thymetric method, the assemblages recognised clearly
species is over 7a"/" with the exception of the association indicate a bathyal environment but the palaeodepths
from Archi 11 which represents only 50% (Fig. Z). inferred are generally shallower than those calculated with
The group of epibathyal species, which are frequent the palaeoecological approach. The detailed analysis car-
along the section but with dominance value varying from ried out on the benthic and benthopelagic associations
l0o/o to 25% (Frg. Z), include the gadids G. argentews, M. suggests clearly that these are indicative of the mesoba-
poutttssou and Plrycis blennoides and the shallorver bathyal thyal environment and consequently the deeper parts of
macrourids C. coelorincbus and C. stellaris. the bathymetric range, indicated by the graphs, may be
The gadids recognised, in subadult - adult stage, are more probable. In several cases, the shallower bathyme-
considered as characteristic species of the upper conti- tric ranges are influenced by the presence of mesopelagic
nental slope in the bathymetric range between 2OO and fishes whose bathymetric distribution does not exceed
4OO m (Maurin 1968; Arena & Li Greci 1,973;Cohenetal. 400 m in depth. It is obvious that their presence is not
1990) where they show their maximum abundance. How- excluded in bottom assemblages deeper than 400 m but
ever, even if their abundance decreases sharply in the they are not representative of the real depth of the envi-
deeper setting, the presence of larger individuals is rather ronment in which the assemblages were formed. On the
other hand, the distribution of fish sizes and the larger-
108 A. Girone
deeper phenomenon must be taken into account for a Because of these faunistic, ecoiogical, and biogeo-
more precise reconstruction of the deep-sea environment. graphical features, a marked oceanic scene arises from the
fish associations which differ from those of the Recent
Mediterranean as already highlighted for other vertebrare
Palaeobiogeography and palaeoceanography Pleistocene assemblages (Girone 2OOOb; Girone Er Varola
2001). This is in agreement with results from the inverte-
The Archi benthopelagic and pelagic releostean
fauna is characterised by a marked Atlantic affinity, brate communities in the examined site (Di Geronimo et
already shown for the invertebrate benthic communities aI. 1997) and elsewhere (Benson 1972;Di Geronimo et al.
(Di Geronimo er al. 1997). Several deep-sea Atlantic 1996; Di Geronimo & La Perna 1996, 1,997; Corselli
2001). A strongly different hydrological patrern is envi-
species, no longer present in today's Mediterranean, were
recognised and include the pelagic Bathylagus eulVops, saged with near-bottom temperatures lower than 8-10"C
Nansenia groenlandica, Polyipnws cf. polli, and Diaphus as suggested by the North Atlantic living populations of
aaningt. and the benthopelagic C. rupestris. benthopelagic fish C. rwpestris and of serpulids Neoaer-
B. euryops and N. groenlandica occur only in the milia falcigera andVitreotubus digeronimol (Di Geronimo
North Atlantic from off sourhern Iceland to about 35" N et al. 1997). A different palaeoceanographic setting is
and 45" N respectively (Vhitehead et al. 1989). They are suggested also by the presence of the northern Atlantic
meso-bathypelagic fishes caught at depths ranging from bathypelagic cold water dwellers Bathylagus euryops and
300 m to 1500 m in the northern areas and from 5OO m to Nansenia groenlandica and the presence of the eutrophic
1800 m in the southern areas. They are generally associa- mesopelagic fishes Diaphws taaningi and Polyipnus polli
ted with water temperarures lower than 8-10"C; in diffe- (Girone & Varola 2001).
rent localities they were caught in water between 3"C and
4-5'C (Bigelow et al. 1964).
A similar meaning is shared also by the ben- Conclusion
thopelagic C. rupestris. This species, associated with bot-
tom temperatures lower than 10"C, has been reported The analysis of the twelve bulk samples collected
only in the North Atlantic from about 37'N to Baffin along the Archi section resulted in the recognition of
Island and Greenland, in the western Atlantic, and from thirty eight teleostean taxa, thirty four to the specific
45'N to off Iceland and Norway in the eastern Atlantic. level. Among these, twenty two species still live in the
In the southern latitudes, C. rwpestris has been captured Mediterranean Sea and include Symbolopborus veranyi
off Africa in the Mauritania upwelling area. and Cbauliodus sloani, identified as a fossil for the first
Another faunal feature is represented by the occur- time, as well as Vincinguerria af[. attenuata and
rence of extinct species, closely related to deep-sea Coryphaenoides aff. guentberi, whose raxonomic status is
Atlantic or generally oceanic raxa, such as rhe pelagic not weli defined. The Archi assemblages include the
Lampadena ionica and Scopelopsis pliocenicws and the ben- Atlantic bathypelagic species B atlty lagus eury op s, N ans e-
nia groenlandica, and the benthop elagic Corypbaenoides
thopelagic Coelorinchws stellaris. Based on presenr know-
rupestris, ali reported for the first time as fossils and di-
ledge, Lampadena ionica and S. pliocenicus can be consi-
sappeared from the Recent Mediterranean. The Atlantic
dered as palaeoendemic Mediterranean species. The gene-
mesopelagic fishes D. taaningi and P. cf. polli, already
ra Scopelopsis and Lampadena have disappeared from the
reported in the Pliocene and Pleistocene sediments of the
Recent Mediterranean; the living Atlantic species of
Mediterranean (Nolf et al. 1998 Girone 2000b; Girone &
Scopelopsis has been reported in the southern Atlantic
Varola 2001), also occur.
while Lampadena is presenr in both North and South In this work, the palaeobathymetric method was
Atlantic (Nafpaktitis et aL. 1977; Nafpaktitis 8c Paxton integrated with the palaeoecological approach based on
1968; Nafpaktitis & Nafpaktitis 1969; HulIey 1981). A
benthic and benthopelagrc taxa providing more precise
significant geographic distribution is shown by S. multi- palaeoenvironment reconstructions. In particular, the
punctatus, the unique Recent species belonging to this analysis of the structure of fish populations, besides ta-
genus that is found in the Atlantic ocean. This species has xonomic composition, provided a good tool for the inter-
often been included in the sourh subrropical region pretation of Pleistocene deep-sea benthic and ben-
according to the zoogeographic distribution proposed by thopelagic associations as already demonstrared for the
Backus et al. (1970) (fide Nafpaktitis et al. tlZZl in rela- deep-circalittoral and epibathyal associations (Girone
tion to physical boundaries. Recently, Hulley (1981) 2000b).
obser-ved that in the south subtropicai region S. mwlti- The benthic and benthopelagic associarions, srrong-
punctatus is distributed only in the areas affected by the ly bathyal in their structure, are clearly indicative of a deep
cold Benguela Current. Consequently, this geographic bathyal environment located in the middle bathyal interval.
distribution suggests that this species cannot be consi- A palaeodepth comprising between 4OO-5OO m and lOOO m
dered only as a warm species. can be inferred in asreement with the data from the ben-