Research Article |
Corresponding author: Anna Maria Mannino ( annamaria.mannino@unipa.it ) Corresponding author: Maurizio Pinna ( maurizio.pinna@unisalento.it ) Academic editor: Klaus Henle
© 2019 Anna Maria Mannino, Francesco Cicero, Marco Toccaceli, Maurizio Pinna, Paolo Balistreri.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Mannino AM, Cicero F, Toccaceli M, Pinna M, Balistreri P (2019) Distribution of Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman & Procaccini in the Mediterranean Sea. Nature Conservation 37: 17-29. https://doi.org/10.3897/natureconservation.37.33079
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The Non-Indigenous Species (NIS) Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman & Procaccini has been reported for the first time in the Mediterranean Sea along the coast of South Turkey. This NIS is actively expanding into the Eastern and Western Mediterranean Sea. In this paper, we present an overview of the current distribution of this alga in the Mediterranean Sea, based on relevant scientific publications, grey literature and personal observations. New records from the Sicilian coast (Italy) are also reported. Caulerpa taxifolia var. distichophylla was found over a wide range of environmental conditions (depth, light and substratum), suggesting a broad ecological plasticity of this alga which makes it a potential threat for the Mediterranean benthic communities. In this respect, artificial structures, often linked to harbours and maritime traffic, seem to provide suitable habitats for this NIS. Since maritime traffic is intense in the Mediterranean Sea, further expansion of C. taxifolia var. distichophylla in this region is to be expected. For this reason, it is very important to build up an overview on the current distribution of the species and its possible pattern of colonisation in relation to environmental conditions, as well as in view of future climate change scenarios.
Non-Indigenous species (NIS), Caulerpa taxifolia var. distichophylla, Sicily coast, artificial marine infrastructures, Mediterranean Sea
The spread of Non-Indigenous Species (NIS, i.e. organisms introduced outside of their natural, past or present range and outside of their natural dispersal potential) has been pointed out as a major threat to biodiversity (
Amongst the NIS recorded in the Mediterranean Sea, Caulerpa taxa (Caulerpa cylindracea Sonder, Caulerpa taxifolia (M. Vahl) C. Agardh and Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman and Procaccini) have raised serious concern due to their potential or ascertained impact on the native communities (
Later, C. taxifolia var. distichophylla, has been reported from other Sicilian sites (
Map showing countries in the Mediterranean Sea where Caulerpa taxifolia var. distichophylla has been recorded (see Table
Known sites of occurrence of Caulerpa taxifolia var. distichophylla in the Mediterranean Sea.
Country | Locality | Substrate | Depth (m) | Coverage level | Benthic assemblage | References |
Turkey | Gulf of Iskenderun | silted sand | 11 | m.d. | m.d. |
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Italy | Punta Braccetto | rock | 0.5–20 | m.d. | m.d. |
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Capo Passero, Isola delle Correnti, Punta Braccetto | rock | m.d. | m.d. | m.d. |
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Punta Braccetto | rock | 0.5–20 | m.d. | m.d. |
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Turkey | Kas, Antalya, Gulf of Iskenderun | m.d. | m.d. | m.d. | m.d. |
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Cyprus | Agios Philon Church Bay, Dipkarpaz | rock | 6–8 | m.d. | Cystoseria spp., Posidonia oceanica |
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Cavo Greco, Famagusta | rock | m.d. | m.d. | m.d. |
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Italy | Sant’Ambrogio, Donnalucata, Ragusa, Punta Secca, Torre di Mezzo, Punta Braccetto, Marina di Torre Salsa | dead matte, sand with pebbles, cobbles and boulders, rock | 0–5 | from < 10 to > 50% | Caulerpa cylindracea, Cymodocea nodosa, Posidonia oceanica, macroalgae |
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Malta | White Rocks, Exiles in Sliema | rock and sediment | 3–15 | patches from 0.35 × 0.35 m to 22.0 × 4.0 m | Posidonia oceanica |
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Italy | Isola delle Correnti, Foce Fiume Irminio, Punta Braccetto, Marina di Acate, Malerba, Realmonte | dead matte, sand, sabellaria | 3–9 | from 10 to 5584 filloid*m-2 | Macroalgae, Posidonia oceanica, Sabellaria, C. cylindracea |
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Termini Imerese, Portopalo di Capo Passero, Isola delle Correnti | rock, sand, shipwreck | 1–10 | from 1 to 50% and > 50% | Cymodocea nodosa | Present study (2015) | |
Cyprus | Cavo Greco, Agios Philon Church Bay, Rizokarpaso (Dipkarpaz), Sunrise Bay | biogenic sand, mud, biogenic hard substrate | < 1, 22, 34, 42, 48 | 99–100% | Caulerpa cylindracea, Caulerpa prolifera, Codium bursa, Cymodocea nodosa, Halophila stipulacea |
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Rhodes Island (Greece) | Lindos Bay, Charaki Bay, Karakonero Bay, Lahania | sand, sand/mud, mud, rock, pebbles/shells | 9–18, 20, 35, 50, 100 | 99–100% | m.d. |
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Italy | San Saba- Acqualadrone-Tono | sand | 3–6 | from < 8 to 26% | Halophila stipulacea, Penicillus capitatus, Posidonia oceanica |
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Lebanon | El Madfoun and Byblos | sand and gravels | 16–48 | m.d. | m.d. |
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Libya | Tripoli | sand | m.d. | m.d. | Seagrass meadow |
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Italy | Termini Imerese | sand | 9–10 | from 1 to 50% and > 50% | Cymodocea nodosa |
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Cefalù, Punta delle Formiche-Pachino and Concerie-Pachino | sand, rock | 2–5 | from 20 to 50% and > 50% | Posidonia oceanica | Present study (2017) | |
Tunisia | Alataya Harbour, Djerba,Tabarka | sand, rock, dead matte | 0.2–2 | m.d. | Posidonia oceanica |
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Italy | Stagnone di Marsala, Terrauzza Bay, Brucoli Bay, Augusta Harbour, Vendicari Natural Reserve, Scala dei Turchi Beach, Scilla (Calabria), Cagliari (Sardegna) | dead matte, sand, rock | 0–4 | m.d. | Cymodocea nodosa, Posidonia oceanica |
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This invasive alien taxon, whose plausible pathway of introduction and spread is maritime traffic, has been pointed out as a potential threat for the indigenous communities but also for fishing activities (
In the Mediterranean, maritime traffic plays an important role in the introduction and spread of NIS (
Field surveys were carried out (summer 2015 and 2017) by the authors in six localities along the coast of Sicily (North-western Mediterranean) (see Fig.
At each site, specimens (n = 20) of the alga were collected by snorkelling, at a depth of 0–10 m. Specimens were identified in the laboratory as C. taxifolia var. distichophylla on the basis of morphological characters (stolon, fronds, pinnules, rhizoidal pillars, midrib) used by
All the relevant publications, grey literature and reports dealing with C. taxifolia var. distichophylla in the Mediterranean, from its first record in the area and updated till 2018, were also searched and analysed. A search, based on the following string: Caulerpa AND taxifolia AND “var. distichophylla” AND Mediterranean*, was performed using standard scientific databases (Scopus, Web of Science) (
During the surveys, three new records of C. taxifolia var. distichophylla have been registered: Concerie-Pachino and Punta delle Formiche-Pachino, located along the southern coast and Cefalù located along the Northern coast. The alga was growing on both natural (mainly on rock) and artificial substrates, from 1 to 10 m depth (mainly in shallow waters). In all sites, only sterile specimens were found. We report below detailed information for each surveyed site.
Concerie-Pachino: the alga (fronds about 10 cm long) was found in shallow waters (at a depth of about 3 m) both on rocky substrate, forming patches of class 2 or 3 and on sandy substrate, forming patches of class 2.
Punta delle Formiche-Pachino: the alga (fronds not exceeding 10 cm in length) was recorded on rocky substrate in very shallow waters (at a depth of about 2 m), forming patches of class 2 or 3.
Isola delle Correnti (Figs
Portopalo di Capo Passero: the alga, with fronds not exceeding 10 cm in length, settled on rocky substrate in very shallow waters (at a depth of about 1–2 m), forming patches of class 2.
Cefalù: the alga, with fronds 5–10 cm long, was found at a depth of about 4–5 m on rocky substrate and at the base of Posidonia oceanica (L.) Delile, forming patches of class 2.
Termini Imerese: the alga, with fronds 5–10 cm long, was found on sandy substrate at a depth of about 9–10 m, forming patches of class 1 along the borders of a Cymodocea nodosa (Ucria) Ascherson meadow (Fig.
The analysis of literature data also highlighted that C. taxifolia var. distichophylla is able to thrive under a wide range of environmental conditions (see Table
Though there is a certain limitation in the collection of data by snorkelling, this technique allows the gathering of useful data and information on NIS, mainly in shallow waters (
Moreover, it seems to prefer rocky and artificial substrates (patches of class 3) more than sandy bottoms. In particular, the alga really flourished on the structures of the shipwreck. Caulerpa taxifolia var. distichophylla, as well as the congeneric C. cylindracea, seem to grow well on artificial structures (e.g. shipwrecks, present study and
The recent records of C. taxifolia var. distichophylla along the Sicilian coasts, in Rhodes Island (
Sicily and circum-Sicilian Islands are inhabited by a rich biota (e.g.
Moreover, a warmer and drier Mediterranean region, as forecast for the 21st century (
For a better understanding of the invasive potential and spread dynamics of NIS, a quick sighting of any newly colonised area (