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Mediterranean Marine Science

Vol. 8, 2007

A critical review of records of alien marine species from the Maltese Islands and surrounding waters (Central Mediterranean)

SCIBERRAS M. Department of Biology, University of Malta, Msida MSD2080 SCHEMBRI P.J. Department of Biology, University of Malta, Msida MSD2080 https://doi.org/10.12681/mms.162

To cite this article:

SCIBERRAS, M., & SCHEMBRI, P.J. (2007). A critical review of records of alien marine species from the Maltese Islands and surrounding waters (Central Mediterranean). Mediterranean Marine Science, 8(1), 41-66. doi:https://doi.org/10.12681/mms.162

http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | Review Article

Mediterranean Marine Science Volume 8/1, 2007, 41-66

A critical review of records of alien marine species from the Maltese Islands and surrounding waters (Central Mediterranean)

M. SCIBERRAS and P. J. SCHEMBRI

Department of Biology, University of Malta, Msida MSD2080, Malta e- mail: [email protected]

Abstract

An updated list of alien marine species recorded from the Maltese Islands and surrounding waters, compiled from scientific and ‘grey’ literature and from authenticated unpublished reports to the authors, is presented. The listed species are classified in one of four categories as regards establishment status: established, casual, invasive and questionable. Doubtful records are listed as ‘?’. A total of 48 species, including nine dubious ones, are included in the list. Of the accepted records, 64% are established, of which 15.4% are invasive, 18% are casual and 18% are questionable. The most represented groups are molluscs (14 species), fish (13 species) and macrophytes (10 species). Six species are classified as invasive in Maltese waters: Lophocladia lallemandii, Womersleyella setacea, Caulerpa racemosa var. cylindracea, Percnon gibbesi, Fistularia commersonii and Sphoeroides pachygaster; impacts of some of these species on local ecosystems are discussed. Since the early 1900s, there has been an increasing trend in the number of alien marine species reported from the Maltese Islands. Transportation via shipping and in connection with aquaculture, as well as the range expansion of Lessepsian immigrants, appear to be the most common vectors for entry, accounting for 20%, 11% and 32% respectively of the alien species included in this review. The general warming trend of Mediterranean waters and increasing marine traffic may be facilitating the spread of warm-water Atlantic and Indo-Pacific species to the central Mediter- ranean, including the Maltese Islands.

Keywords: Alien species; Invasive species; Malta; Biodiversity; Aquaculture; Lessepsian immigrants.

Introduction 1996). The environmental impact of invasive marine species may be so severe that Invasion of native biotas by non- the introduction of aliens has been identi- indigenous species is a threat to the fied as one of the four greatest threats to integrity of biotic communities, the econ- the world’s oceans (IMO, 2000-2007). omy and even human health that is recog- Alien species may affect recipient ecosys- nized worldwide (VITOUSEK et al., tems through predation, direct and indi-

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | rect competition, contamination of the ber of non-indigenous species in the native gene pool by exotic genes (for Mediterranean Sea has been attributed to example, through hybridization), habitat such human activities as seafaring, com- modification, and through the introduc- merce, and tourism; to the occurrence of tion of new parasites and pathogens. numerous habitats susceptible to inva- Human communities may also be impact- sion, in particular those subject to anthro- ed in several ways. For example, in the pogenic disturbance such as lagoons, Mediterranean, the massive swarms of estuaries, and marinas; to aquaculture the voracious Indo-Pacific jellyfish, ventures; and to the opening of the Suez Rhopilema nomadica Galil that have Canal which has led to the introduction of appeared along the Levantine coast since hundreds of Lessepsian immigrants the mid-1980s, have adversely affected (CHU et al., 1997; COUTTS et al., 2003; tourism, fisheries and coastal installations OCCHIPINTI-AMBROGI & SAVINI, when large groups of the jellyfish draw 2003; GALIL, 2006; MINCHIN, 2007). close to the coast (GALIL & ZENETOS, Although temperature change scenarios 2002). On the contrary, Erythrean fish in Europe vary regionally, there is a clear (Upeneus moluccensis (Bleeker), U. pori trend towards overall warming Ben-Tuvia & Golani, Dussumieria acuta (SCHROTER et al., 2005). Consequent- Valenciennes in Cuvier & Valenciennes) ly, present day sea warming favours the and penaeid prawns (Marsupenaeus occurrence and establishment of warm- japonicus (Bate), Metapenaeus monoceros water species, whether alien or native, in (Fabricius), M. stebbingi Nobili), consti- the Mediterranean Sea (BIANCHI, 2007; tute most of the catches along the Egypt- OCCHIPINTI-AMBROGI, 2007). The ian and Israeli coasts (GALIL & number of macroscopic marine species ZENETOS, 2002). inhabiting the Mediterranean is today estimated at about 12,000 Invasion by non-indigenous species (BOUDOURESQUE, 2004), of which may be a natural phenomenon whereby around 745 species are alien to the region an organism is dispersed into a region (ZENETOS et al., 2005). Immigration where it did not exist before by means of through the Suez Canal and transporta- natural mechanisms. Such invasions have tion by ships are the two vectors con- been termed ‘range expansions’ by MORI tributing largely to introductions into the & VACCHI (2002). The problem with Mediterranean (STREFTARIS et al., human-facilitated introductions is that, 2005). more often than not, these occur at rates The fate of immigrants is decidedly higher than the natural rate of range mixed. Those which survive the multitude expansion (MACK et al., 2000), often of physical stressors during the immigra- overcoming many natural barriers to dis- tion or transportation processes, and suc- persal, such as distance or currents ceed in reaching a suitable new environ- (SCHEMBRI & LAFRANCO, 1996; ment, may survive to reproduce and RUIZ et al., 1997). Consequently, existing become established, and some become equilibria between the native biota and invasive. The degree of success of the their physical and biological environ- introduced species depends on a multitude ments may be disrupted. The high num- of physical and biological factors, such as

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | the availability of vacant, under- or un-uti- assess the reliability of the available infor- lized niches, escape from biotic constraints mation as a prelude to future studies. (competitors, predators, parasites and dis- eases), low resident-community species Methods richness, disturbance before or upon immigration to the recipient environment, Records of alien species from the Mal- as well as the physico-chemical require- tese Islands and their surrounding waters, ments of the invader and its community taken to be the sea area within the 25 NM interactions (RUIZ et al., 1997; MACK et Fisheries Management Zone established al., 2000; TORCHIN et al., 2001). by the European Union (CAMILLERI, Because of their location on or close to 2003), were searched for in scientific, grey, the biogeographic boundary between the and popular literature. Unpublished western and eastern Mediterranean bio- reports to the authors by other workers, regions (BIANCHI, 2007), the Maltese fishers, sea users and others were also Islands are an important station for moni- included if these records were supported toring the entry and spread of alien marine by physical evidence such as specimens or species in this sea. With increasing marine photographs. The reliability of each record traffic, both commercial and tourist (cruise was assessed, and where possible, the liners, yachting), the Maltese Islands face establishment status of the species in the the ever increasing threat of alien species Maltese area was determined, using the arriving in ballast water or on ship hulls. terminology that follows. Due to their position, the Maltese Islands may act as a stepping stone for already Indigenous: A species which occurs established alien species to expand their naturally in a particular place – in the pres- range from west to east or vice versa. ent case, the Maltese Islands and sur- Moreover, the Maltese Islands are at the rounding waters as defined here; (synony- meeting point of Atlantic-derived aliens mous term: native, autochthonous). with those originating from the Red Sea and Indo-Pacific, providing an interesting Alien: Species or infraspecific taxon, opportunity to study the interactions of inclusive of parts, gametes or propagules, alien species of different biogeographic that may survive and subsequently repro- affinities. duce and spread outside of its historically However, records of alien marine known range (geographical area occupied species from the Maltese Islands are naturally) and beyond its natural dispersal sparse and scattered; the most recent potential (due to minor climatic oscilla- review, that by SCHEMBRI & tions) as a result of deliberate or acciden- LANFRANCO (1996), is now outdated. tal introduction by humans; (synonymous The aim of the present work is to present terms: non-native, non-indigenous, an updated list of alien marine species allochthonous, foreign, exotic, immigrant, reported from the Maltese Islands, based imported, transported, adventive, stages I on scientific and popular literature and on to V of the scheme proposed by unpublished observations, and to evaluate COLAUTTI & MacISAAC, 2004). these records in order to provide a base- line account of the situation to date and to Established: An alien organism that is

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | capable of reproducing and maintaining Results self-perpetuating populations in the wild, without deliberate human intervention, Records of alien species from the outside its native range; (synonymous Maltese area are presented in Table 1. terms: naturalized, stages III to V of the In this table, the natural range (when this scheme proposed by COLAUTTI & could be ascertained), the first record from MacISAAC, 2004). the Maltese Islands, the mode of introduction and establishment success (status) Casual: Species which find their way of the alien species in the Maltese Islands outside their native range but which do not are given, if known. The natural range seem to become established; this term is for molluscs and fish species was obtained used for species which have been recorded from the CIESM Atlas of Exotic only once or twice from the study area (as Molluscs in the Mediterranean per ZENETOS, et al. 2005); (synonymous (http://www.ciesm.org/atlas/appendix3.ht terms: stage II of the scheme proposed by ml) and the CIESM Atlas of Exotic COLAUTTI & MacISAAC, 2004). Fishes in the Mediterranean (http://www.ciesm.org/atlas/appendix1.ht Questionable: Species for which insuffi- ml), respectively. Synonyms of the genus cient information exists; also newly report- or species names under which reports have ed ‘aliens’ not verified by experts (as per appeared in the literature are given in Zenetos et al., 2005), cryptogenic species parentheses after the genus or species (species whose native geographic distribu- names respectively, if such synonyms exist. tion is unknown), and supposedly alien Explanatory notes are provided after species which are very similar to native the table where appropriate and are cross- species and which are difficult to identify. referenced in the table by numbers in square brackets (e.g. [1], [2] etc.). In addi- Invasive: An alien species whose pop- tion, some notes on species imported for ulation has undergone an exponential aquaculture are also given. growth phase and may threaten the diversity or abundance of native species and the ecological stability of the impacted ecosystem (as per OCCHIPINTI-AMBROGI & GALIL, 2004) and which may also threaten economic activities dependent on these ecosystems, and/or human health.

When known, the exact date of the first record of the alien in the Maltese Islands is given, otherwise it is labelled as unknown. When the species has been found during a prolonged study but no exact date is known, then the period of the study is given. In the list that follows, ‘?’ signifies doubt.

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | 1997 1997 1997 1997 1997 (continued) et al., et al., et al., et al., et al., (pers. comm.) (pers. comm.) Established Established LANFRANCO, 1989 Questionable CORMACI CORMACI Questionable Invasive CORMACI Invasive CORMACI Casual CORMACI Questionable E. LANFRANCO E. LANFRANCO Mode of introduction Status Cited by Table 1 Unknown Unknown Lessepsian immigrant Lessepsian immigrant? Lessepsian immigrant? Unknown Lessepsian immigrant? Lessepsian immigrant 1969 1994 1994 1994 1994 1997 1994 Prior to 1994 First Maltese record Alien species reported from the Maltese Islands. Red Sea and Indian Ocean Cosmopolitan Indo-Atlantic tropical Indo-Pacific Indo-Pacific Circumtropical Pacific Ocean Pacific Ocean boergesenii & Kraft [2] cf. Allender SpeciesRHODOPHYCEAE Acanthophora nayadiformis (Delile) Papenfuss Asparagopsis armata Harvey [1] Botryocladia Natural range madagascariensis G. Feldmann [2] Chondria pygmaea Garbary & Vandermeulen [2] Lophocladia lallemandii (Montagne) F. Schmitz [3] Womersleyella setacea (Hollenberg) R.E. Norris [3] FUCOPHYCEAE Colpomenia peregrina Sauvageau Padina

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | (continued) 2004 2004 1997 et al., et al., et al., LANFRANCO, 1989 LANFRANCO, 1996 Invasive BORG EstablishedCasual MIFSUD & SAMMUT, 2006 CACHIA, 1981 Established LANFRANCO, 1970 CasualQuestionable CACHIA Established CACHIA Established SCHEMBRI & PALLARY, 1912 oysters and mussels used for Mode of introduction Status Cited by Lessepsian immigrant Lessepsian immigrant Lessepsian immigrant Unknown Deliberate introduction for aquaculture Various [6] Transport in ballast tanks Accidental importation with aquaculture; accidental importation by shipping Table 1 (continued) 1997 1970 1977 1970 1912 2005 1973 mid-1970s First Maltese record Red Sea and Indian Ocean Indian Ocean Red Sea and Indian Ocean Indian Ocean and Red Sea Western Pacific Ocean Indo-Pacific and Red Sea Red Sea, Indian Ocean Atlantic coast of North America ) Philippi (Linnaeus) var. (Gmelin) (Leach) variabilis (Sonder) ) [4] glabrata Brachidontes pharaonis (P. Fischer) (= (= Crassostrea gigas (Thunberg) [5] Pinctada radiata SpeciesCHLOROPHYCEAE MAGNOLIOPHYTA Natural range BIVALVIA Atactodea striata GASTROPODA - PROSOBRANCHIA Cerithium scabridum Crepidula fornicata [7] Verlaque, Huisman & Boudouresque [3] Caulerpa racemosa cylindracea Halophila stipulacea (Forsskal) Ascherson

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | (continued) 1996 et al., 1997 1998 1998 EstablishedQuestionable BEBBINGTON, 1970 Established BEBBINGTON, 1970 Established PERRONE & SAMMUT, Established? MIFSUD, 2007 Established? SAMMUT & PERRONE, SAMMUT & PERRONE, CasualCasual SCHEMBRI, 1979 CACHIA G. is very common. Mode of introduction Status Cited by Accidental introduction probably with oyster spat imported from Anglesey, Wales, where Lessepsian immigrant Lessepsian immigrant Lessepsian immigrant Lessepsian immigrant or transport in ballast water Unknown Unknown cineraria Unknown Table 1 (continued) 1976 1996 1969 1967 1993 2006 1992-1998 1992-1998 First Maltese record Western Pacific Circumtropical Circumtropical Indo-Pacific Indo-Pacific, Sudanese Red Sea Circumtropical Tropical Atlantic East Atlantic from Norway to Gibraltar Indian Ocean, Red Sea, Tropical Heller (= Verrill Recluz [9] (Linnaeus) de Blainville [10] [12] Guilding in SpeciesGibbula cineraria [8] Natica gualteriana Natural range GASTROPODA - OPISTHOBRANCHIA Bursatella leachi Aplysia parvula Morch [11] Chelidonura fulvipunctata Baba Haminoea cyanomarginata & Thompson T. Aeolidiella indica Bergh takanosimensis) Polycerella emertoni [12]

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | (continued) 1977 1977 et al., et al., LANFRANCO, 1984 MONTALTO, 2002 2001 EstablishedInvasive SCHEMBRI & BORG & ATTARD- CasualQuestionable? MIFSUD, 2005 Questionable? RIZZO & SCHEMBRI, 1997 LAPERNAT & RAZOULS, CasualEstablished SCHEMBRI, 1978 TANTI & SCHEMBRI, 2006 QuestionableQuestionable AGIUS AGIUS Mode of introduction Status Cited by Unknown Natural range expansion by currents; ballast water; un/intentional introduction by aquarium trade Unknown Fouling species on ship hulls Unknown Ballast water Ballast water Ballast water; accidental importation with species used for aquaculture Ballast water; accidental importation with species used for aquaculture Table 1 (continued) 1972 2001 2004 1972 2001 1976 1998 1975-1976 1975-1976 First Maltese record East coast of America Tropical and subtropical regions of the west and east Atlantic Ocean and East Pacific Ocean Indian Ocean Atlantic Ocean Cosmopolitan? East Atlantic, south of Gibraltar Antarctic - Sub- Antarctic Indo-West Pacific Indo-Pacific (Canu & Ellis (Hincks) [18] Rathbun (Linnaeus) [14] CRUSTACEA - MALACOSTRACA Callinectes sapidus Percnon gibbesi (H. Milne-Edwards) CRUSTACEA - MAXILLOPODA ECHINODERMATA Prionocidaris baculosa (Lamarck) [16] Eucidaris tribuloides (Lamarck) [17] BRYOZOA Celleporaria pilaefera Bassler) [18] Celleporaria aperta & Solander [13] Megabalanus tintinnabulum tintinnabulum Species Natural range Dosima fascicularis Spinocalanus terranovae Damkaer [15]

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | et al., 2007 (continued) et al., PANCUCCI- PAPADOPOULOU 1999 Questionable?Invasive SAMMUT, 2001 Established CINI, 1999 Established LANFRANCO, 1993 LANFRANCO, 1993 Established GALIL, 2006 Questionable? EstablishedInvasive LANFRANCO, 1993 Established? CINI, 2006 Established INSACCO & ZAVA, 1999 AZZURRO Mode of introduction Status Cited by Unknown Unknown Lessepsian immigrant Lessepsian immigrant Unknown Lessepsian immigrant Lessepsian immigrant Atlantic immigrant or Lessepsian immigrant? Lessepsian immigrant Lessepsian immigrant Table 1 (continued) 1929 1961 2005 1999 2006 2001 1994 1993 1993 Unknown First Maltese record West Atlantic Ocean Indo-Pacific Indo-Pacific, Eastern Central Pacific Tropical Atlantic Indo-Pacific Indo-Pacific Circumglobal in tropical and temperate seas Indo-Pacific Western Indian Ocean [23] [22] (Forsskal) Muller and Troschel) [24] POLYCHAETA FISH SpeciesBranchiomma boholense (Grube) SIPUNCULA Aspidosiphon mexicanus Murina [19] Natural range Alepes djedaba Fistularia commersonii (Ruppell) [20] Pisodonophis semicinctus (Richardson) [21] Siganus luridus Ruppell Siganus rivulatus Forsskal Sphoeroides pachygaster ( Sphyraena chrysotaenia Klunzinger [25] Stephanolepis diaspros Fraser-Brunner

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | Notes on table 1 2006

1999 [1] Although Asparagopsis armata is 2000

et al., an established alien species in the Mal- et al., et al., tese Islands, it is relatively rare. A possible reason for this may be that whereas the conspicuous macrophytic gameto- phyte stage of this species is rare, the tetrasporophyte stage, which is micro- scopic and therefore not visible in the field, is the most common form in which this alga occurs. [2] Botryocladia madagascariensis, ?? PIZZICORI SAMMUT, 2001 ? ANDALORO ?? CILIA, 1979 FALAUTANO Chondria pygmaea and Padina cf. boergesenii are assigned ‘questionable’ status since the first two have not been reported again since the original record by CORMACI et al. (1997), while information on the latter has still to be published, therefore the presently available records of the distribution and frequen- cy of occurrence of these species are insufficient to assess their status. All Mode of introduction Status Cited by ? [27] [28] [29] Atlantic immigrant three species are very similar to common native species and difficult to iden- Table 1 (continued) tify in the field. [27] [28] [29] [30]

1979 [3] Lophocladia lallemandii, Womer-

First Maltese record sleyella setacea and Caulerpa racemosa var. cylindracea are invasive in that they are known to modify the floristic compo-

) sition of their habitat (E. Lanfranco, personal communication 2007). All three species are known from Malta, Gozo, and Comino and are abundant from the to past confusion with [26] Indo-Pacific Western and Eastern Atlantic. (Distribution in the eastern Atlantic is uncertain due Seriola carpenteri Tropical Atlantic Atlantic upper infralittoral to the circalittoral (BORG et al., 1997; CORMACI et al., 1997; personal observations).

[29] [4] Atactodea striata is considered a ‘casual’ since to date there is only one Kay) [27]

[26] record of a single specimen, with dead (Bloch) [28] ?

sp. soft parts, from Marsaxlokk Bay in August 1977 (CACHIA et al., 2004). sp. [30] [5] Crassostrea gigas was introduced SpeciesParupeneus Natural range Etrumeus teres (De Seriola fasciata Seriola carpenteri Mather Seriola deliberately in the Maltese Islands for

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | aquaculture purposes. In the mid-1970s [7] Other than a 1973 record of a attempts were made to start an aquacul- beached, freshly dead specimen from ture industry in the Maltese Islands and Marsaxlokk Bay and another in 1975 of the (then) Fort St. Lucian Marine Station live specimens from 10m at Marsamxett set up experimental oyster cultures at Harbour (CACHIA, 1981), there are no Marsaxlokk Bay, Mistra Bay and Rinella other published or unpublished reports of (AGIUS et al., 1977, 1978). Spat of C. gigas Crepidula fornicata from Malta. Further- was imported from Anglesey, Wales. more, the last aquaculture ventures involv- Although the aquaculture venture came to ing bivalves closed down in the mid-1970s, an end in the late 1970s (SCHEMBRI & so no fresh individuals could have been LANFRANCO, 1996), specimens of C. accidentally imported with bivalve spat. gigas are still occasionally met with in the This species is thus assumed to be a ‘casu- wild along the Maltese coast (MALLIA, al’ alien. 1991; personal observations), suggesting [8] No further specimens of Gibbula that this species has managed to establish cineraria have been found in the wild sub- small breeding populations. sequent to those recorded in 1976 [6] Pinctada radiata, has been reported (SCHEMBRI, 1979), hence this species is as abundant in the Levantine Sea by considered a ‘casual’ alien. GALIL & ZENETOS (2002), as well as [9] Natica gualteriana has not been from the Tyrrhenian Sea, off Sicily, Malta, recorded again since the original record in Pantelleria Island and France. In Malta it 1996, when CACHIA et al. (1996) found a has been found as single specimens few freshly dead specimens at Mellieha attached to stones in shallow (upper Bay. infralittoral) water (Bahar ic-Caghaq, [10] The sea hare Bursatella leachi is a Munxar Point, Ras il-Qawra and Gnejna Lessepsian immigrant that first appeared Bay), and attached to old fishing ropes and along the Israeli coasts around 1940 but is moorings, usually in clusters of many indi- now known from as far west as Sardinia viduals at various stages of growth, in (ZENETOS et al., 2004). It was first deeper (infralittoral to circalittoral) water recorded from Malta in 1969 by (CACHIA et al., 2004; personal observa- BEBBINGTON (1970). Another speci- tions). This species is also sometimes men collected by J.A. Borg from near fish offered at the local fish market in farm cages (no date) was reported by Marsaxlokk (CACHIA et al., 2004). SAMMUT & PERRONE (1998). Recent Although there is no information on the records of B. leachi in the Maltese Islands mode of introduction of P. radiata in the are from June and October 2007, when Maltese Islands, translocation of this several individuals were observed and pho- species in the Mediterranean has been tographed on a sandy bottom at 2m depth reported to include intentional introduc- at St. George’s Bay (St. Julians) (Joseph A. tion for mariculture purposes in Greece Borg, personal communication, 2007). (GALIL & ZENETOS, 2002), transport This species is thus regarded as established by ships (ZIBROWIUS, 1992), and as an in the Maltese Islands. epibiont on marine turtles (OLIVERIO et [11] Aplysia parvula was first recorded al., 1992); the latter two mechanisms may from the Mediterranean from the south- also have operated in the Maltese Islands. ern coast of Turkey in 1961, having been

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | previously misidentified as Aplysia punc- Gibraltar to the Cape of Good Hope tata (BEBBINGTON, 1970). After its (RELINI, 1980), is common on ships first record from Malta in 1967 by entering the Malta dockyards for repairs, BEBBINGTON (1970), A. parvula was but it has never been found in the wild in cited by SAMMUT & PERRONE (1998) Maltese waters (SCHEMBRI & from Birzebbuga. This species is present- LANFRANCO, 1996; RIZZO & ly regarded as circumtropical. In the NE SCHEMBRI, 1997). Although this species Atlantic, its presence has been confirmed is a transitional alien with the possibility of for the Canary Islands, the Azores, becoming established locally, no other Madeira, Cape Verde Island, and also for records from the Maltese Islands exist to the Iberian peninsula including the our knowledge. Therefore, the status of Mediterranean coast of Spain; however, it this species remains ‘questionable’ for the is likely that Aplysia parvula is a complex present. of cryptic species and therefore the [15] LAPERNAT & RAZOULS Mediterranean populations may not actu- (2001) and RAZOULS et al. (2005-2007) ally be alien (José Templado, personal record Spinocalanus terranovae, a meso- communication 2007). This species is bathypelagic copepod, from a depth of therefore included as 'questionable' for 2000m off the southeast coast of Malta and the present. this appears to be the only Mediterranean [12] In their study, SAMMUT & record of this Antarctic to Sub-Antarctic PERRONE (1998) reported Aeolidiella species; RAZOULS et al. (2005-2007) indica spawning in January, and Polycerel- comment that ‘The presence of this species la emertoni spawning in July and August. in the Mediterranean is surprising, but On the basis of this information it is conforms to that of the descriptor’. Noth- assumed that these two species have ing else is known about this species in Mal- probably established populations in the tese waters therefore its status remains Maltese Islands. ‘questionable’. [13] A living specimen of Dosima fas- [16] The record by SCHEMBRI cicularis was found washed ashore at Gne- (1978) refers to an individual of Prionoci- jna Bay in 2004 (MIFSUD, 2005). This daris baculosa collected in 1976 from the record is the first for the Maltese Islands, ballast tank of a ship that had entered the and probably also for the Mediterranean Malta dockyards; no other specimens of (MIFSUD, 2005). Although we include D. this species have been recorded from Mal- fascicularis in the list of alien species, we tese waters (TANTI & SCHEMBRI, do so with some reserve; this species 2006), therefore this species is considered occurs attached to floating material and is as casual. common in the Atlantic, therefore we can- [17] The record of Eucidaris tribuloides not exclude the possibility that it entered from the Maltese Islands is also the first of the Mediterranean through the Straits of this species for the Mediterranean Gibraltar incidentally, in what may be a (TANTI & SCHEMBRI, 2006). Two pop- natural expansion of its range. ulations of E. tribuloides are known, one in [14] Megabalanus tintinnabulum tintin- the inner part of a sheltered creek (Kalka- nabulum, whose natural area of distribu- ra Creek, Grand Harbour) on mud at tion is the Atlantic coast of Africa from depths of 3-10m, and the other in Sliema

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | Creek (Marsamxett Harbour) on a bottom reported in a newspaper article by CINI of muddy sand at a depth of 3-7m; individ- (2006). Since then, this species has been uals occurred on debris or some other hard sighted more than once around the Mal- substratum rather than on the muddy or tese Islands, on two particular occasions in sandy bottom. In both localities, one or shoals of about 20 individuals (Mark two aggregates of 5-10 adult individuals Dimech, personal communication 2007; each were noted (TANTI & SCHEMBRI, Sarah Gauci Carlton, personal communi- 2006). cation 2007). [18] AGIUS et al. (1977) reported [21] According to INSACCO & Celleporaria pilaefera and C. aperta on bas- ZAVA (1999) and ELI (2006), kets and the cages holding these baskets Pisodonophis semicinctus occurs in the from an oyster farm at Rinella (in Grand ‘Malta Channel’, where the latter author Harbour); C. pilaefera was rare but C. aper- states it has become established. The geo- ta was common. To our knowledge, there graphical limits of the ‘Malta Channel’ can are no other records of these species from be interpreted in different ways, leading to Malta in the literature. All bivalve aqua- doubt as to whether this species has been culture ventures had shut down by the late- actually sighted in Maltese waters or not. 1970s and it is not known if populations of However, if the ‘Malta Channel’ is taken to these two species still persist, so their sta- include the sea area between Sicily and tus remains ‘questionable’. Tunisia, including also the Pelagian [19] PANCUCCI-PAPADOPOULOU Islands and Pantelleria, then the chances et al. (1999) make reference to unpublished of P. semicinctus also occurring in Maltese records by Galena-Vantsetti Murina of this waters as defined here are high. For this species from Malta and Lampedusa. We reason we include this species in the list of are not aware of any other record of Aspi- aliens occurring in Maltese waters and dosiphon mexicanus for Malta. Since regard its status as ‘established’ with some PANCUCCI-PAPADOPOULOU et al. reserve. (1999) give no indication of the number of [22] Six individuals of Siganus luridus individuals recorded from Malta or were collected from Malta in October whether the occurrence of this species was 2006; three of these were mature females transient or not, we are regarding its status (23.8 – 24.6 cm TL) carrying eggs and two in the Maltese Islands as ‘questionable’ for were mature males (23.0 – 24.0cm TL) the present. (AZZURRO et al., 2007). [20] Fistularia commersonii was first [23] LANFRANCO (1993) includes recorded in the Mediterranean along the Siganus rivulatus in his catalogue of Mal- coast of Israel in 2000; subsequently it tese fish and while hinting that this species spread westward along the coast of might occur in Malta, he does not provide Antalya (Turkey), Rhodes and Crete, and a definite record. SAMMUT (2001) has recently also reached the central includes this species in his work on fish of Mediterranean (GOLANI et al., 2004). the central Mediterranean with the follow- The first record of F. commersonii from ing comment ‘This new species lives at the the Maltese Islands was in 2005, when a edges of reefs with broken seabeds and specimen caught from Xwejni Bay, Gozo feeds mainly on algae. It is rare but may was identified by one of us (PJS) and become more common…’ and ‘…amateur

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | fishermen occasionally find it entangled in eries of the Government of Malta their trammel nets…’ The date of intro- (BARBARA, 1961). However, it is clear duction of this species in Malta therefore from his introductory comments that Bar- appears to be between 1993 and 2001. On bara was giving vernacular Maltese names the other hand, neither author includes to species known to occur in the Mediter- Siganus luridus so there is the possibility ranean without any regard as to whether that the records of Siganus rivulatus may these species actually formed part of the refer to Siganus luridus and for this reason, Maltese fauna or not; this work cannot for the present we regard this record as therefore be taken as a reliable source of doubtfully ‘questionable’. information on the occurrence of Sphyrae- [24] In the Mediterranean, Sphoeroides na chrysotaenia (or any other alien fish) in pachygaster was first reported from the Maltese waters. The first reliable record of Balearic Islands in the western basin in this species from Malta is due to 1979, and subsequently from the eastern LANFRANCO (1993). basin from Ashdod, Israel, in 1991 [26] CILIA (1979) records (PSOMADAKIS et al., 2006). Sphoeroides Pseudupeneus barberinus (Lacepède) (= pachygaster is now widespread and com- Parupeneus barberinus) from Gozo and mon throughout the Mediterranean, LANFRANCO (1993) repeats Cilia’s including the Straits of Sicily (BIANCHINI record. According to GOLANI et al. (2004) & RAGONESE, 2007). Although general Parupeneus barberinus is to be excluded opinion considers S. pachygaster a recent from the Mediterranean list of exotic fish immigrant of Atlantic origin, there is also since records of this species in the litera- the possibility that this circum-globally dis- ture have been shown to be erroneous. tributed puffer fish is a Lessepsian immi- Parupeneus barberinus does not occur in grant of ancient origin (RELINI & ORSI the Red Sea but the closely related Paru- RELINI, 1995). Neither LANFRANCO peneus forsskali (Fourmanoir & Guézé) (1993) nor SAMMUT (2001) record this does (GOLANI et al., 2004), and this species in their catalogues of Maltese fish- species has recently been recorded from es; however, in an illustrated newspaper the Levantine coast of Turkey (CINAR et article on this species (given as Sphoeroides al., 2006). We include a species of Paru- cutaneus, which is a junior synonym), CINI peneus in our list since CILIA (1979) pro- (1999) states that fishermen he interviewed vides a good description of the fish he said that they first noted the species in Mal- records as ‘Pseudupeneus barberinus’ (‘… tese waters around 1994. S. pachygaster is unmistakable longitudinal black line from now relatively common in the Maltese the nostril, through the eye, to the second Islands and is caught regularly in trawls dorsal fin was clearly seen’ and a crude (Mark Dimech, personal communication drawing; however, the fish depicted shows 2007). some resemblance to P. forsskali. Although [25] GALIL (2006) gives 1961 as the no further information or records exist, date when Sphyraena chrysotaenia was first there is a possibility that Cilia might have reported from Maltese waters, apparently actually encountered a species of Paru- basing this on a list of the Maltese vernac- peneus (P. forsskali ?) in Gozo. ular names of Mediterranean fish pub- [27] FALAUTANO et al. (2006) lished by the (then) Department of Fish- reported the occurrence of this Lessepsian

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | immigrant at Lampedusa in 2005. This description of the fish and states that he species has yet to be recorded from the has personally captured fry, young and Maltese Islands. However, owing to the adults. While this species is certainly not proximity of the Maltese Islands to the native Seriola dumerili (Risso), we Lampedusa, there is a high probability that cannot assign it with certainty to any of the Etrumeus teres will also occur in Maltese alien species of Seriola that have been waters. recorded from the Mediterranean. The [28] Seriola fasciata has not description provided by SAMMUT (2001) yet been recorded from the Maltese more or less fits that of juvenile Seriola Islands as far as we are aware, however, fasciata and the author himself says that during fishing and experimental surveys his species is ‘closely related to a similar between 1994 and 1998, ANDALORO et species S. fasciata’, however, it does not al. (1999) report collecting 42 individuals agree with this species in all characteris- from Sicilian waters and from near tics, and the rather poor drawing that Lampedusa. Owing to the position of the SAMMUT (2001) includes has elements Maltese Islands in the Straits of Sicily, that are reminiscent of Seriola rivoliana there is a high probability of S. fasciata (Valenciennes in Cuvier & Valenciennes), also occurring in waters around the Mal- for example, the arched dorsal profile rel- tese Islands. We therefore include this ative to the ventral profile, the seven divid- species as ‘?’. ed dark vertical bars on the body, the [29] As for Seriola fasciata, Seriola rather elongate first dorsal and anal rays. carpenteri has not yet been recorded from The latter species has not been recorded the Maltese Islands; however, from Maltese waters but there is a record PIZZICORI et al. (2000) report capturing of a single specimen caught 40 nautical 148 specimens of this species 42 nautical miles west of Lampedusa (CASTRIOTA miles east of Lampedusa during a stock et al., 2002). Because of the uncertain assessment study in 1997. Owing to the identity of the species recorded by close proximity of the capture area to the SAMMUT (2001) we are including it in Maltese Islands, there is a high probability the catalogue as Seriola sp. with a ‘?’. of S. carpenteri also occurring in Maltese waters. We therefore include this species as ‘?’. Additional notes on species imported for [30] SAMMUT (2001) records a Aquaculture species of Amberjack that he gives as Seri- ola samstriata (Rio) and states that it is Species of bivalves that occur natural- occasionally frequent around Malta and ly in the Maltese Islands but stock of which Gozo; he considers this a Western Atlantic had been imported from elsewhere for the species that has entered the Mediter- aquaculture industry during the mid-1970s ranean through the Straits of Gibraltar, include Ostrea edulis (Linnaeus), Mytilus and a new record for the Mediterranean. edulis (Linnaeus), Mytilus galloprovin- However, this species is neither cited in cialis (Lamarck), and Ruditapes (= ESCHMEYER (1998), nor in the Tapes) decussatus (Linnaeus) (AGIUS et FishBase database (www.fishbase.org). al., 1977, 1978; CACHIA et al., 2004; SAMMUT (2001) provides a good Carmelo Agius, personal communication

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | 2007). Spat of O. edulis was imported from Discussion Anglesey, Wales; the Mytilus spp. were imported from Italy, and R. decussatus was The present review lists a total of 48 imported from France (although it is not alien marine species that occur or have known if from the Atlantic or Mediter- been reported from the Maltese Islands. ranean coast). As a consequence of these Of these, 39 species are accepted and the deliberate introductions, non-indigenous rest are doubtful records, either because populations which may potentially be information on the presence of these genetically different from those native to species in Maltese waters is insufficient, or the Maltese Islands exist. because the species have only been tran- Dicentrarchus labrax (Linnaeus) and siently recorded from Maltese waters (for Sparus aurata Linnaeus are native to the example, Megabalanus tintinnabulum Maltese Islands. However, stock of these tintinnabulum). The most represented two species was imported from elsewhere groups are molluscs (14 species), fish (13 for aquaculture purposes (SCHEMBRI & species) and macrophytes (10 species). LANFRANCO, 1996; Carmelo Agius, According to the classification scheme for personal communication 2007). Finger- ‘status’ used here, 25 species are consid- lings of D. labrax have been imported ered to be ‘established’, of which 6 species from Italy, the Atlantic and Mediter- are ‘invasive’ (Fig. 1). ranean coasts of France, Cyprus, Greece The six species considered invasive and Tunisia; fingerlings of S. aurata have (Lophocladia lallemandii, Womersleyella been imported from northern Spain setacea, Caulerpa racemosa var. cylin- (Carmelo Agius, personal communication dracea, Percnon gibbesi, Fistularia com- 2007). Similarly, stocks of Argyrosomus mersonii and Sphoeroides pachygaster) regius (Asso) have been imported for aquaculture purposes from the Atlantic coasts of France (Carmelo Agius, personal communication 2007). Therefore, non- indigenous (Atlantic) genetic stock of all three species has been imported to the Maltese Islands. Stock of the freshwater/brackish Saba- ki Tilapia Oreochromis spilurus spilurus (Gunther), native to Africa, was imported into Malta from Mombasa (Indian Ocean) for aquaculture purposes and was experi- mentally converted from freshwater to marine water and cultured in the sea (Carmelo Agius, personal communication 2007). Although this species is no longer cultured in the Maltese Islands, we are Fig. 1: Establishment status in the Maltese Islands of the alien species included in the present review. recording its previous occurrence since Those with a doubtful occurrence or whose status there is a remote possibility that individu- is both ‘questionable’ and doubtful are excluded. als may have escaped captivity. The categories used are defined in the text.

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:06 | are classified as such on the basis of their it has colonized the coasts of 12 nations distribution and abundance, their capacity throughout the entire sea (STREFTARIS for proliferation, and their impact on & ZENETOS, 2006; OULD-AHMED & native species and/or biotic communities. MEINESZ, 2007). Since its first record All six are included in the list of the top from the Maltese Islands in 1997, this alga 100 ‘worst invasives’ in the Mediterranean has spread to most Maltese coasts, where it by STREFTARIS & ZENETOS (2006). has formed dense stands on infralittoral In a study by CILIA (1999), W. setacea hard substrata and sparse stands on was found to occur with a percentage infralittoral soft substrata (BORG et al., cover of 13.33 ± 11.11% and 35.56 ± 1997). In the Maltese Islands, C. racemosa 17.78% on two maerl beds off the north- var. cylindracea inhabits a depth range of eastern coast of Malta. The densely between 0.1m and 40m, with a percentage branched filamentous thalli of this cover that varies between 1% and 70% for rhodophyte grow on and between living different sites around the islands and non-living rhodoliths and entangle the (MIFSUD & LANFRANCO, 2007). The surface layers, binding them together into highest percentage cover values were a crust. Whereas this stabilised surface found at sites subject to anthropogenic dis- layer of the maerl bed provides an addi- turbance, suggesting that degraded locali- tional substratum for settlement of foliose ties favour expansion and enhanced macroalgae on the maerl, a high cover of growth of this species (MIFSUD & W. setacea could affect the settlement of LANFRANCO, 2007). other species negatively, particularly those Since the first record from Malta in living interstitially amongst the rhodoliths, 2001 (BORG & ATTARD- by depriving propagules of settling sites. In MONTALTO, 2002), Percnon gibbesi has addition, extensive algal cover can be become widespread in the Maltese Islands, detrimental to the rhodoliths in that it cuts where it shows a strong affinity for boulder down the amount of photosynthetically habitats (SCIBERRAS, 2005). In such active radiation reaching the photosyn- habitats, the crab occurs in densities rang- thetic tissues of the rhodolith-forming ing between 1.5 ± 0.5 to 11.9 ± 7.1 indi- algae, as well as preventing them from viduals per m2 (SCIBERRAS & turning – a requirement for their survival. SCHEMBRI, 2007a). The occurrence of Moreover, sediment trapped in the surface berried females and of juveniles shows that crust may create an anoxic boundary-layer this species has established self-regenerat- around the thallus of the rhodolith-forming populations in the Maltese Islands. ing algae, smothering them and limiting Direct observations in the field suggest rhodolith growth. Therefore, the monopo- that P. gibbesi interacts with the native lization of the substratum by W. setacea grapsid Pachygrapsus marmoratus Fabri- can have a negative effect on the assem- cius. However, field observations and lab- blages associated with maerl beds (CILIA, oratory experiments suggest that in such 1999), which are habitats of conservation encounters, P. marmoratus is the competi- concern (BIOMAERL TEAM, 2003). tive dominant species (SCIBERRAS & Caulerpa racemosa var. cylindracea SCHEMBRI, 2007b). Nonetheless, the has occurred in the Mediterranean Sea wide distribution and high densities of P. since at least the early 1990s, and to date, gibbesi imply that this alien is utilizing

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:07 | space that is potentially available for other native species. Percnon gibbesi is predomi- nantly herbivorous (PUCCIO et al., 2006; MS, unpublished data), and its voracious appetite might have an impact on the abundance of the algal species on which it feeds and on the structure of the communities of which they form part. The puffer fish Sphoeroides pachygaster probably appeared in Maltese waters in the early 1900 s , at first a rare curiosity, it is now fished regularly, show- ing that it has spread and become common in the space of about 15 years; very little is know about its ecology in Maltese waters, Fig. 2: Mode of introduction in the Maltese however. The cornet fish Fistularia com- Islands of alien species included in the present mersonii was first recorded from the Mal- review. Those with a doubtful occurrence or tese Islands in 2005, but in the space of less whose establishment status is both ‘questionable’ than two years seems to have become very and doubtful are excluded. The categories are: common and is now occurring in shoals on Lessepsian migration (introduction via the Suez rocky reefs. The impact of both species on Canal), Aquaculture (accidental or intentional introduction for aquaculture purposes), Shipping Maltese benthic ecosystems is completely (transport in ballast tanks or as fouling organisms unknown. on ship hulls), Aquarium trade (intentional or For some aliens listed in the present accidental release of alien species from aquaria), work, the mode of introduction is and Unknown (species with an unknown or unknown or assumed, whereas in some doubtful mode of introduction in the Maltese cases introduction is thought to have been Islands). Species that may have been introduced by multiple modes (for example, Percnon gibbesi facilitated by more than one vector (for and Crepidula fornicata) have been included example, Crepidula fornicata and Percnon under each category. gibbesi). Immigration through the Suez Canal and transportation via shipping and ranean close to main shipping routes, as in connection with aquaculture (both for well as to the harbour, dockyard and tran- stocking and due to accidental transport) shipment facilities offered by the islands. account for 31.8%, 20.5% and 11.4% Introductions due to aquaculture may be respectively, of those species with a known intentional or unintentional; Crepidula for- mode of introduction (Fig. 2). Vessels pro- nicata and Gibbula cineraria are two exam- vide suitable transportation habitats in bal- ples of the latter. Westward spreading of last waters, sediment in ballast tanks, sedi- Lessepsian immigrants accounts for 32% ment attached to anchors, and hull fouling of the species (Fig. 2); such spreading may (CARLTON, 1985; COUTTS et al., 2003). be natural range extension of aliens now Nine species in the list presented here established in the Eastern Mediterranean, were probably introduced by shipping or it may be facilitated by human trans- (Fig. 2), and this is related to the island’s port. Natural range extension seems to position at the centre of the Mediter- operate particularly in the case of fish,

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:07 | both Lessepsian immigrants (for example, quence of the general warming trend of Fistularia commersonii and Siganus luridus) Mediterranean waters in recent years and those originating from the Atlantic (BIANCHI, 2007; GALIL, 2007; (Sphoeroides pachygaster). OCCHIPINTI-AMBROGI, 2007); if this Since the early 1900 s, there has been is the case, then further arrivals are to be an increasing trend in the number of expected, which makes monitoring of the marine alien species reported from the alien marine biota of the Maltese Islands Maltese Islands (Fig. 3). However, these of critical importance both as an indicator data should be interpreted with care. For of change in the Mediterranean marine example, the high peak in the 1990s is the environment, and for the ecological effects result of an intensive survey of benthic that such alien species may have on local marine algae carried out in 1994 species, communities and ecosystems. (CORMACI et al., 1997) in which most alien species of algae were reported for the Acknowledgements first time, and the publication of a revised edition of Lanfranco’s catalogue of Mal- We thank the various persons who tese fish (LANFRANCO, 1993) wherein a contributed valuable personal observa- number of alien species were recorded, tions of alien species in the Maltese also for the first time, from Maltese Islands, in particular Dr. Joseph A. Borg, waters. Mark Dimech, Sarah Gauci Carlton, The high proportion of warm-water Edwin Lanfranco and Dr. José Templado. species of Indo-Pacific and subtropical Special thanks are due to Prof. Carmelo Atlantic origin that now occur in Maltese Agius and Mr Edwin Lanfranco (Depart- waters, including many that have only ment of Biology, University of Malta) for recently been reported and which may information on species in aquaculture in therefore be new arrivals, may be a conse- Malta and on marine algae, respectively. We are grateful to Dr. Argyro Zenetos (Hellenic Centre for Marine Research, Greece) for inviting this review, for providing data for Malta from her database of Mediterranean alien species and for much other help. We are also grateful to two anonymous referees for suggesting improvements to this paper. This work was supported in part by research grants from the University of Malta, for which we are thankful.

Addendum

Fig. 3: The number of alien species recorded from While the present review was in press, the Maltese Islands and surrounding waters per YOKES et al. (2007) published their decade. Species with a doubtful occurrence or whose establishment status is both ‘questionable’ records of the foraminiferan Amphistegi- and doubtful are excluded. na lobifera Larsen from the Maltese

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http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 25/09/2021 11:19:07 | Islands. Live specimens were collected Regions (ICZEGAR). Kavala, 17-21 from four stations in Malta, Gozo and May 1999. (Abstract). Comino in June 2006, suggesting that this AZZURRO, E., PIERMARINI, R., species is well established. This SCARPATO, A. & ANDALORO, F., foraminiferan is widely distributed in the 2007. Notes on the reproductive con- Indo-Pacific and Atlantic; in the Mediter- dition of early colonizing S. luridus in ranean, where it is an alien, this species has the Sicily Straits (Mediterranean Sea). been recorded from Israel, Lebanon, Rapport du Congrès de la Commis- Greece, Turkey and the Sea of Marmara sion Internationale pour l'Exploration in the Eastern Mediterranean basin, and Scientifique de la Mer Méditerranée, from Libya and Tunisia in Central 38: 423. Mediterranean (YOKES et al., 2007). How BARBARA, J., 1961. Ismijiet tal-hut tal- Amphistegina lobifera arrived in the Mal- Mediterran (nomenclature standard for tese Islands is not known. With the present Mediterranean fishes). Malta, Depart- record, the number of marine aliens ment of Fisheries. 20pp. known from the Maltese Islands is 49 BEBBINGTON, A., 1970. Aplysiid species, of which nine are dubious records. species from Malta with notes on the Of the accepted records, 65% are estab- Mediterranean Aplysiomorpha (Gas- lished; of the established species, 15% are tropoda, Opisthobranchia). Pubbli- considered invasive; 17.5% are casual, and cazioni della Stazione Zoologica di 17.5% are questionable. Napoli, 38: 25-46. BIANCHI, C.N., 2007. Biodiversity issues References for the forthcoming tropical Mediter- ranean Sea. Hydrobiologia, 580: 7-21. AGIUS, C., SCHEMBRI, P.J. & BIANCHINI, M.L. & RAGONESE, S., JACCARINI, V., 1977. A preliminary 2007. Presenze di specie ittiche report on organism fouling oyster cul- esotiche come possibili indicatori di tures in Malta (central Mediter- cambiamenti climatici: il caso dello ranean). Memorie di Biologia Marina e Stretto di Sicilia. p.513-516. In: di Oceanografa n.ser, 7: 51-59. CARLI, B., CAVARRETTA, G., AGIUS, C., JACCARINI, V.J. & RITZ, COLACINO, M. & FUZZI, S. (Eds). D.A., 1978. Growth trials of Cras- Clima e cambiamenti climatici le sostrea gigas and Ostrea edulis in attivita’ di ricerca del CNR. Roma, inshore waters of Malta (Central Italy: Consiglio Nazionale delle Mediterranean). Aquaculture, 15: Ricerche; xxviii+871pp. 195-218. BIOMAERL TEAM, 2003. Conservation ANDALORO, F., PIPITONE, C., and management of northeast Atlantic POTOSCHI, A., BADALAMENTI, and Mediterranean maerl beds. F. & D’ANNA, G., 1999. Seriola fasci- Aquatic Conservation: Marine and ata (Osteichthyes, Carangidae), an Freshwater Ecosystems, 13 suppl.1: alien species spreading in central S65-S76. Mediterranean waters. 8th Interna- BORG, J.J. & ATTARD-MONTALTO, tional Congress on the Zoogeography J., 2002. The grapsid crab Percnon and Ecology of Greece and Adjacent gibbesi (Milne Edwards, 1853) (Crus-

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