Διερεύνηση της εξέλιξης του λεσεψιανού μεταναστευτικού ρεύματος όσον αφορά στα μαλάκια (mollusca) και ψάρια (pisces)
Creators: name: Τζώμος, Θεόδωρος Αριστείδη
Publisher: name: Aristotle University of Thessaloniki
Year: 2007
Subjects: Λεσεψιανή μετανάστευση
Μαλάκια
Lessepsian migration
Mollasca
Pisces
Rate
Distribution expansion
Ψάρια
Επέκταση διανομής
Ρυθμός

description: Lessepsian immigration is the phenomenon of the unidirectional and successful immigration of Red Sea organisms in the Mediterranean Sea through Suez Canal. The first and unique description of the lessepsian immigratory current has been giv-en from Por (1978) who introduced for the first time the term “leesepsian immi-grants”Although during the last years there is an increase of the research interest con-cerning the lessepsian migration, which is reflected by the increase in number of relevant publications there are no recent information concerning the coasts of Cy-prus, while in respect of the Greek coasts, the information given in relevant publica-tions deal almost exclusively with coasts of Rhodos Island.The objectives of this research were:(a) to record the modern geographical distribution of lessepsian immigrants be-longing to the taxa Mollusca and Pisces.(b) to investigate the spatio-temporal progress of their geographical distribution.(c) to investigate the environmental factors that propel or inhibit the expansion of the geographical distribution of the lessepsian immigrants.(d) to estimate possible changes in the intensity of the lessepsian current rate, in relation to possible changes of the abiotic factors that exert effects on this rate.Based on the collected bibliographic data, a suitable network of sampling sta-tions was designed including 5 stations at the coasts of southern Cyprus, as well as 20 stations at the coasts of Kastelorizo I., Rhodos I., Karpathos I. and Kasos I., as well as Simi, Kos, Kalymnos, Pserimos, Samos, Lesvos islands and at the Turkish coasts of Aegean (Bodrum, Gόmόslόk, Turgutreis and Kusadasi).Samplings were curried out during 2004 - 2005, with all of available gears, de-pending on the habitat type.In order to analyse the progress of the lessepsian current 6 Mediterranean areas [west of Suez Canal, the Suez-Turkish coasts, the SE coasts of Turkey (at the bor-ders of Syria with Turkey till Anamur), the SW coasts of Turkey (from Anamur till cape Yeni) and the Aegean Sea] were determined. For each one of them and for each lessepsian immigrant the year of its first record in the area was registered..During this research, 115 species of Mollusca and 64 species of Pisces were fi-nally considered as lessepsian immigrants.Till today, 30 lessepsian molluscs have been known from Cyprus. According to the results of this study, the presence of 2 lessepsian species is confirmed and the distribution of other two is expanded at the coasts of Cyprus. The latter are the gas-tropod Cerithium scabridum Philippi, 1848 and the bivalve Brachidontes pharaonis (Fischer P., 1870). These two species had been reported only from the northern coasts of Cyprus and thus their distribution is expanded at the southern coasts, since they were found at Agia Napa - Larnaka - Pafos and Agia Napa - Pafos respec-tively.Concerning the lessepsian molluscs of Aegean Sea, 17 species have been known. The known distribution of the gastropod Strombus persicus Swainson, 1821 is expanded since it was also found at the islands of Simi and Karpathos, while the respective one of the bivalve Brachidontes pharaonis (Fischer P., 1870) also is ex-panded, since it was also found at the island of Kos.In Kastelorizo I., the gastropods Cerithium scabridum Philippi, 1848 and Strombus persicus Swainson, the 1821 as well as the bivalve Brachidontes pharaonis (Fischer P., 1870), were found. According to the results of this study these species are reported for first time from this island. The bivalve Barbatia pli-cata (Dillwyn, 1817) was also found in Kastelorizo I. for the first time and this re-port adds one species to those known from the region of the SW Turkish coasts. This report expands the known geographical distribution of this lessepsian species, since this has been known till now only from the coasts of Israel.Concerning Pisces, 11 lessepsian species are known today from the coasts of Cyprus. The species Fistularia commersonii Rόppell, 1838 and Upeneus pori Ben-Tuvia and Golani, 1989 are reported for the first time as elements of the fauna of Cyprus and their finding in this region constitute expansion of their known distribu-tion in the Mediterranean Sea. The presence of other 6 lessepsian fish species is confirmed since they were re-found in the framework of this study.In respect of the lessepsian fishes of the Aegean coasts, 27 species have been known till now. They now become 28 by one addition from this study. Pempheris vanicolensis Cuvier, 1831, is reported for first time from Aegean Sea. Moreover, the results of this study confirm the presence of 2 species [Siganus luridus (Rόppel, 1829); Siganus rivulatus Forsskεl 1775] known from the region and expand the known distribution of other 7 lessepsian fishes [Hemiramphus far (Forsskεl 1775); Sargocentron rubrum (Forsskεl 1775); Stephanolepis diaspros Fraser-Brunner, 1940; Upeneus moluccensis (Bleeker, 1855); Etrumeus teres (De Kay, 1842); Fistu-laria commersonii Rόppel, 1838; Sphyraena chrysotaenia Klunzinger, 1884].The species Fistularia commersonii Rόppell, 1838 is reported for the first time from Kastelorizo I., while in the Aegean its distribution is expanded at Simi and Kos Islands, as well at Karpathos and Kasos Islands.Summary - 239 -The time discontinuity, until today, in the publication of relative with the lessepsian immigration information, was the main cause of difficulty for an estima-tion of temporal progress of lessepsian immigratory current.The region of Port Said - Borders Syria with Turkey coasts, is the most accessi-ble for the establishment of lessepsian immigrants.The region of SE Turkey coasts is the next region in which lessepsian immi-grants have expanded their distribution, after passing from the coasts of Israel, ac-cording to the model “the longer the distance - the more time is required”.At the coasts of Cyprus, which are closer to the dispersal centre of the lessep-sian species (Port Said) than the coasts of Turkey, the numbers of species of lessep-sian immigrants are decreased, possibly due to their isolation from the neighbouring continental coasts. This view is supported by the fact that in the framework of this study, the presence of two new lessepsian fish pecies at Cyprus was recorded while the known distribution of two other mollusc species was expanded.At the coasts of SW Turkey the numbers of the known lessepsian immigrants are smaller than them at the SE coasts of Turkey and the Aegean Sea. This should be attributed to: (a) the longer distance of this region from the dispersal centre of lessepsian immigrants, (b) the more unfavourable ecological conditions for them and (c) the limited research effort in this region. This latter is supported by the fact that during this research in Kastelorizo, the presence of one more lessepsian mol-lusc was recorded, new for the SW coasts of Turkey.The longer distance from Port Said (dispersal centre) and the more adverse change of environmental conditions in the region of the Aegean coasts, appear to be the main reasons for the decreased numbers of lessepsian immigrants in this region. The fact that a new lessepsian immigrant was reported for the region (Pempheris vanicolensis), while the distribution of 9other known lessepsian immigrants was expanded, should be attributed to the expansion of the geographical distribution of these species and not to the limited sampling effort.In the area of north African coasts (westwards Port Said) the continuous high intensity of hydrodynamism, in combination with big spaces of fine sediments, should be considered as the most important factors for the inhibition on expansion of lessepsian immigrants distribution westwards.It was ascertained that for the time interval 1955-2006, the number of lessepsian molluscs in the Mediterranean increases progressively, with constant and statisti-cally significant rate of 1.9 species per year. For the time interval since the opening of Suez Canal (1869) up to 2003, it was ascertained also a statistically significantprogressive increase in the number of new lessepsian molluscs reported in the Mediterranean per 15 years.For the time interval 1927-2006, it was ascertained that the number of lessep-sian fishes in Mediterranean increases progressively, with constant and statistically significant rate 0.7 species per year. For the time interval 1869-2003, it was ascer-tained also a statistically significant progressive increase of new lessepsian fishes reported in the Mediterranean per 15 years.The observed increase of mean annual temperature of Mediterranean waters during the last decades, could possibly explain the increasing trend at the invasion rate of new lessepsian immigrants, as well as the progressive expansion of the dis-tribution of previously reported ones.
description: Αν και τα τελευταία έτη παρατηρείται γενικά αύξηση του ερευνητικού ενδιαφέροντος σχετικά με τη λεσεψιανή μετανάστευση, δεν υπάρχουν πρόσφατες πληροφορίες για τις ακτές της Κύπρου, ενώ για τις ελληνικές ακτές οι πληροφορίες που δίνονται σε σχετικές δημοσιεύσεις αφορούν σχεδόν αποκλειστικά τις ακτές της Ρόδου. Στόχοι της έρευνας αυτής ήταν : η καταγραφή της σύγχρονης γεωγραφικής διανομής των λεσεψιανών μεταναστών που ανήκουν στα μαλάκια (mollusca) και τα ψάρια (pisces), η εκτίμηση των τυχόν μεταβολών της έντασης του ρυθμού του λεσεψιανού ρεύματος. Κατά την έρευνα αυτή 115 είδη μαλάκιων και 64 είδη ψαριών θεωρήθηκαν τελικά ως λεσεψιανοί μετανάστες. Μέχρι σήμερα είναι γνωστά από την Κύπρο 30 λεσεψιανά μαλάκια. Οσον αφορά στα λεσεψιανά μαλάκια της ευρύτερης περιοχής του Αιγαίου είναι γνωστά 17 είδη. Επίσης στο Καστελόριζο βρέθηκε για πρώτη φορά και το δίθυρο μαλάκιο Barbatia plicata (Dillwyn 1817). Οσον αφορά στα ψάρια, από τις ακτές της Κύπρου σήμερα είναι γνωστά 11 λεσεψιανά ψάρια. Τα είδη Fistularia commersonii Ruppell 1838 και Upeneus pori Ben-tuvia &amp; Golani, 1989 αναφέρονται για πρώτη φορά ως στοιχεία της πανίδας της Κύπρου. Οσον αφορά τα λεσεψιανά ψάρια των ακτών του Αιγαίου, μέχρι σήμερα ήταν 27 είδη, που έγιναν 28 με μια προσθήκη από την έρευνα αυτή. Το Pempheris vanicolensis Cuvier 1831, αναφέρεται για πρώτη φορά από το Αιγαίο. Το είδος Fistularia commersonnii Ruppell 1838 αναφέρεται για πρώτη φορά από το Καστελόριζο, ενώ στο Αιγαίο επεκτείνεται η διανομή του στη Σύμη και Κώ καθώς και στην Κάρπαθο και Κάσο.Για το χρονικό διάστημα από τη διάνοιξη της διώρυγας του Σουέζ (1869) μέχρι το 2003, διαπιστώθηκε μια στατιστικά σημαντική προοδευτική αύξηση των νέων λεσεψιανών μαλάκιων ανά δεκαπενταετία. Η παρατηρούμενη κατά τις τελευταίες δεκαετίες αύξηση της μέσης ετήσιας θερμοκρασίας των υδάτων της Μεσογείου, θα μπορούσε να ερμηνεύσει τόσο την αυξητική τάση του ρυθμού εισβολής νέων λεσεψιανών μεταναστών, όσο και την προοδευτική επέκταση της εξάπλωσης των παλαιότερων