MYSIDACEA (CRUSTACEA) AS ECOLOGICAL AND BIOGEOGRAPHICAL MARKERS IN
MEDITERRANEAN BRACKISH ENVIRONMENTS
Antonio P. Ariani
1*
and Karl J. Wittmann
2
1
Dipartimento di Zoologia, Università di Napoli Federico II, Naples, Italy - * ariani@unina.it
2
Lab. Ökophysiologie und Ökotoxikologie, Institut für Medizinische Biologie der Universität Wien, Währinger Strasse 10,
A-1090 Vienna, Austria - karl.wittmann@univie.ac.at
Abstract
The brackish water mysid faunas (especially Diamysis) are well differentiated between the eastern and the western basins of the
Mediterranean. Unlike the more species-rich meta- to polyhaline waters, the meso- and oligohaline waters frequently show only a single
mysid species, that is D. mesohalobiain the eastern and the vicariant Mesopodopsis slabberiin the western Mediterranean.
Paleogeographical and paleoecological considerations suggest that certain mysids with low-salinity affinities may have colonized the
Mediterranean from the East (brackish Paratethys) while other “brackish” species may have immigrated from the West, i.e. from the
Atlantic, at the end of the Messinian salinity crisis.
Keywords: Mysidae, faunas, lagoons, salinity, paleoecology
Rapp. Comm. int. Mer Médit., 37,2004
479
Until recently, only relatively few species of the family Mysidae were
cited from the Mediterranean brackish ponds, lagoons, and estuaries.
However, recent extensive faunistic investigations led to a revision of
the genus DiamysisCzerniavsky, and to new ideas about the colo-
nization of the Mediterranean brackish environments by mysids (1).
Main information could be obtained from Diamysisspecies,
previously lumped together under the name D. bahirensis(G. O.
Sars). As a consequence of its emendation, this species now appears
to be restricted almost entirely to the SW Mediterranean basin.
D.bahirensis lives in poly- to metahaline waters, with salinity (S)
ranging from 25 (drain near Mazara del Vallo, Sicily, previously
unknown locality) to 40 (Stagnone di Marsala, Sicily).
A similar ecology, but a different geographical distribution, is
reported for D. lagunaris Ariani & Wittmann. It inhabits the NW
Mediterranean (where a new population has been discovered in 2003
on Menorca Island, Baleares) and also shows one Atlantic population
in Portugal, possibly due to passive transport (Cunha, cited in 1) from
the Mediterranean.
Two Diamysisspecies, this is D. hebraicaAlmeida Prado-Por and
D. sirbonicaAlmeida Prado-Por, and the species complex
D.mesohalobiaAriani & Wittmann inhabit the eastern
Mediterranean. The first two taxa, both from the Levantine basin, are
known only from one oligohaline stream or one metahaline lagoon,
respectively. The nominal form of D. mesohalobiais present with
very dense populations in mesohaline karstic springs of the Adriatic
basin, whereas the subspecies gracilipes and heterandramostly prefer
more saline waters in the Adriatic and Ionian basins. Lastly, a
stygophilic species closely allied to D. m. mesohalobia, i.e.
D.camassaiAriani & Wittmann (2), is endemic of mesohaline dolinas
near the Ionian coast of southern Italy.
Owing to the mineral composition (CaCO
3
instead of ?uorite) and
certain morphological features, the statoliths of all Mediterranean
species of Diamysisremind the statoliths of Mysidae from Miocene
deposits of the brackish Paratethys. This gives further evidence (1, 3)
to Bacescu’s hypothesis (4) of a brackish water, Paratethyan origin of
these forms. Therefore, the Diamysis ecology and distribution pattern
in the Mediterranean may be understood in relation to a colonization
of this basin starting from the East (Paratethyan drainage during the
salinity crisis), with adaptation to near-marine salinity upon
expansion towards the West. In line with this context, laboratory
experiments showed (1) that survival of brood pouch larvae in
D.lagunarisand D. m. gracilipesis higher at mesohaline compared
with euhaline conditions, though the test populations originated from
marine or mixoeuhaline natural waters. It is also most remarkable that
inspections of many meso- or hypohaline waters in the western
Mediterranean yielded no Diamysis population, but occasionally
Mesopodopsis slabberi(van Beneden) as the only mysid species
(Étang de Berre, S = 15, and Étang de Mauguio, S = 12; Golfe du
Lion). The Mediterranean forms (5) of the genus Mesopodopsis
Czerniavsky may be considered, therefore, as vicariants of Diamysis
in low salinity waters of the W Mediterranean, although co-occurring
with Diamysisin the E Mediterranean.
The oligo- to mesohaline waters of the Mediterranean are usually
inhabited by only one mysid species (belonging to Diamysis or
Mesopodopsis), as D. hebraicaat Nahal Taninim in Israel (S = 0.7-1.8),
D. m. gracilipes with its “anomalous” population in the Fiume Chidro
(southern Italy, S = 4), D. m. mesohalobiawith all populations in
southern Italy (S = 10-16), Mesopodopsis slabberiwith the above
cited populations.
On the contrary, the poly- to metahaline waters are usually
inhabited by more than one mysid species; if only one, this is again a
Diamysis (D. lagunarisin the Étang de La Palme, Golfe du Lion;
S=23) or a Mesopodopsis(mouth of Lao river, Tyrrhenian coast of
Calabria, S = 38). With the exception of Paramysis helleri (G. O.
Sars), showing calcareous statoliths and belonging to a typical Ponto-
Caspian genus (5), all remaining mysids(including Mesopodopsis)
associated with Diamysisand/or Mesopodopsis have ?uorite statoliths
and may be considered of Atlantic origin. They belong to the genera
Siriella Dana, and Leptomysis G. O. Sars.
The Siriellaspecies most frequently encountered are S. armata
(M.-Edwards) and S. jaltensisCzerniavsky, which share brackish
affinities with S. clausiiG. O. Sars. Leptomysis is a typically
Mediterranean marine genus (6), but one species, Leptomysis truncata
(Heller) is also found in brackish environments: in the Golfe du Lion
together with Diamysis, Paramysisand Siriella(Étang de Thau, Étang
de Leucate) or with Diamysisand Siriella, exclusively (mouth of the
Rhône in Port St. Louis). The atlantic genus Neomysishas been
reported as N. integer(Leach) from only one Mediterranean brackish
locality: the Arles canal near Fos (7) in the Golfe du Lion. However,
recent investigations (7)in this locality as well as in the near Étang de
l’Estomac did not confirm previous data.
In conclusion, mysids may be considered suitable study objects in
order to reconstruct the colonization of the Mediterranean brackish
environments (mainly the less saline ones) in relation to
paleogeographical and paleoecological situations.
References
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