Updating the list of recent non-indigenous ascidians (Chordata: Tunicata) and its spreading in the Mediterranean Sea. Ten years later (2009-2019)
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1
Research Marine Centre, University of Alicante, Spain
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2
University of Alicante, Spain
Introduction:
A decade ago, a revision of the recent non-indigenous ascidians in the Mediterranean Sea was made (Izquierdo-Muñoz et al 2009). The study showed ten species considered as new aliens to the Mediterranean sea, since the revision of Pérès (1958); we consider the Pérès study as temporal mark (after 1950’s) to consider one species as recent invader or not.
Ten years later, a deeper revision of the literature shows a total of 20 recent NIS ascidians. In 2009 we consider 14 species (Izquierdo et al. 2009) belonging to 7 families. Ten years later, 6 new NIS have been added to the list (Aplidium accarense, Didemnum vexillum, Polyclinum constellatum, Ecteinascidia thurstoni, Botrylloides anceps, Micocosmus anchylodeirus) and related to 9 families. The species are classified into the categories proposed by Zenetos et al (2005), and discuss status, vectors, and habitats.
Results and discussion
We have considered recent NIS ascidians, those recorded later to the 1950 (Pérès, 1958) and whose date of first record is known. In this regard, we can establish the following categories (Zenetos et al. 2005): established, casual and questionable.
a) Casual: Some species were cited once in the Mediterranean Sea, in a specific habitat: Ecteinascidia styeloides, E. thurstoni, Perophora multiclathrata, Botrylloides anceps, Botrylloides violaceous and Microcosmus anchylodeirus.
b) Established: Those species that have been located in 2 or more sites and spread across the Mediterranean Sea. We can consider two categories: i) located in anthropic and natural environments; and ii) located in anthropized environments (ports, marinas, aquaculture zones). In the naturalized ones we find: Distaplia bermudensis, Herdmania momus, Microcosmus exasperatus, M. squamiger, Phallus nigra, Rhodosoma turcicum, and Symplegma brakenhielmi. In those located in anthropic environments: Aplidium accarense, Ascidia cannelata, Didemnum vexillum, Polyandrocarpa zorritensis, Polyclinum constellatum and Styela clava. Ghobashy & Abdel Messeih (1991) cited Aplidium accarense and Styela clava in Alexandria and Port Said, respectively, a further verification of these records would be necessary.
Figure 1: Location of non-indigenous ascidians in the Mediterranean Sea. Families are indicated by the following symbols: Δ Polyclinidae ▼Didemnidae ● Polycitoridae o Corellidae ▲Perophoridae ■ Ascidiidae x Styelidae ♦ Pyuridae
c) Questionable: Species were cited once but its description or the lack of it, require further verification and possibly not found in Mediterranean waters. In this category we include: Eusynstyela hartmeyeri cited by Harant (1939) in Port Said; Ascidia corelloides by Pérès (1959) in the Balearic Islands; and Aplidium retiforme, Didemnum moseleyi, Eudistoma angolanum and Polyclinum saturnium by Halim and Abdel Messeik (2016) in Egyptian Mediterranean waters. These last authors also find boreal species (Ascidia obliqua, Cnemidocarpa mollis, Leptpclinides faeroensis), never mentioned in the Mediterranean. Polysyncraton amethysteum has recorded in Balearic Islands by Pérès (1957), and cited in Egypt by Halim & Abdel Messeik (2016), however, we also consider this species as questionable, since they have not been observed elsewhere in the Mediterranean.
d) Cryptogenic: We have considered cryptogenic species those ones in which the first record in the Mediterranean is not clear. Some of them were introduced centuries ago and are already naturalized; or by genetic studies represent different populations that have subsequently been NIS, coming from other regions: i) Tropical Atlantic and NW Temperate, coming in the hulls of ships from America (Botrylloides niger, Clavelina oblonga, Ecteinascidia turbinata, Perophora viridis, Molgula manhattensis, M. occidentalis) ii) cosmopolitan distribution (Ciona robusta, Styela canopus, S. plicata); iii) Indo-Pacific distribution (Cystodytes philippinensis, Trididemnum cf. savignii); and iii) originally native to the Atlantic NE (Ascidiella aspersa, Botrylloides leachii, Botryllus schlosseri, Clavelina lepadiformis, Ciona intestinalis). We exclude them from this revision by failing to comply with the temporal criterion discussed at the introduction.
The main vector of transport of these organisms is maritime traffic, attached to the ships as hull fouling. These NIS ascidians occur in harbours and there is some dispersion mainly by colonization of degraded and/or artificial habitats. A few species are associated to aquaculture, being the most likely introduction vector adhered to the shells of cultivated bivalves. This would be the case of Styela clava and perhaps Botrylloides violaceous, Didemnum vexillum, and Polyandrocarpa zorritensis. In these cases, its habitat is currently restricted to coastal lagoons or deltas, where there are marine farms.
The range of distribution of some species considered here would be greater than described. This could be because of the difficult of proper identification of the species of the group; and there are very large areas (as the African coasts of the Mediterranean) that are under-sampled.
Table 1.
References
Ghobashy, A. F. A., Adbel Messeih, M. K. (1991). Ascidians in Egyptian waters. J Egypt Ger Soc Zool, 4, 313-326.
Halim Y, Abdel Messeik M (2016). Aliens in Egyptian waters. A checklist of ascidians of the Suez Canal and the adjacent Mediterranean waters. Egyp. J. Aquat. Res. 42: 449–457
Harant H (1939) Les fonds de pêche près d’Alexandrie : Ascidiacea. Notes et Mémoires, Institut Fouad I Hydrobiologie et Pêche 28: 1-12
Izquierdo-Muñoz, A., Díaz-Valdés, M., & Ramos-Esplá, A. A. (2009). Recent non-indigenous ascidians in the Mediterranean Sea. Aquatic Invasions, 4(1), 59-64.
Pérès JM (1957) Ascidies récoltées dans les parages des Baléares par le ‘Professeur Lacaze-Duthiers’ (2e. partie): Iviza et San Antonio. Vie Milieu, suppl. 6 : 223-234
Pérès JM (1958) Origine et affinites du pleuplement en ascidies de la Mediterranee. Rapports et Procès Verbaux de la CIESM 14: 493-502
Pérès JM (1959) Campagnes de la ‘Calypso’ en Mer d’Alboran et dans la baie Ibéro- Marocaine I : Ascidies. Annales de l’Institut Océanographique de Paris 37: 295-313
Zenetos, A., Çinar, M. E., Pancucci-Papadopoulou, M. A., Harmelin, J. G., Furnari, G., Andaloro, F., Bellou, N., Streftaris, N., Zibrowius, H. (2005). Annotated list of marine alien species in the Mediterranean with records of the worst invasive species. Mediterranean marine science, 6(2), 63-118.
Keywords:
ascidians,
invasive species,
exotic species,
Mediterraenan sea,
Harbours
Conference:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.
Presentation Type:
Poster Presentation
Topic:
Global Change, Invasive Species and Conservation
Citation:
Izquierdo Muñoz
A and
Ramos-Esplá
AA
(2019). Updating the list of recent non-indigenous ascidians (Chordata: Tunicata) and its spreading in the Mediterranean Sea. Ten years later (2009-2019).
Front. Mar. Sci.
Conference Abstract:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) .
doi: 10.3389/conf.fmars.2019.08.00188
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Received:
19 May 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Mx. Andres Izquierdo Muñoz, Research Marine Centre, University of Alicante, Santa Pola, Spain, andres.izquierdo@ua.es